Category Archives: machines

robotic vacuum cleaner

A robotic vacuum cleaner, often called a robovac, is an autonomous robotic vacuum cleaner that has intelligent programming and a limited vacuum cleaning system. Some designs use spinning brushes to reach tight corners. Others combine a number of cleaning features (mopping, UV sterilization, etc.) simultaneous to vacuuming, thus rendering the machine into more than just a robot “vacuum” cleaner.

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History[edit]

A cleaning robot seen from below

File:Roomba video.ogv

Video of a Roomba operating

Long-exposure photo showing the path taken by a Roomba over 45 minutes

The first robot cleaner to be put into production was Electrolux Trilobite by the Swedish household and professional appliances manufacturer, Electrolux. In 1996, one of Electrolux’s first versions of the Trilobite vacuum was featured on the BBC‘s science program, Tomorrow’s World.[1]

In 2001, the British technology company Dyson built and demonstrated a robot vacuum known as the DC06. However, due to its high price, it was never released to the market.[2]

In 2002, the American advanced technology company, iRobot launched the Roomba floor vacuuming robot. Initially, iRobot decided to produce 15,000 units and 10,000 more units depending on the success of the launch. The Roomba immediately became a huge consumer sensation. By the Christmas season, iRobot produced 50,000 units to meet the holiday demand. After this success, major specialty retailers as well as more than 4,000 outlets such as Target, Kohl’s and Linens ‘n Things began to carry the Roomba.[3]

Since 2002, new variations of robotic vacuum cleaners have appeared in the market. For example, the Canadian bObsweep robotic vacuum that both mops and vacuums,[4] or the Neato Robotics XV-11 robotic vacuum, which uses laser-vision rather than the traditional ultrasound based models.[5]

In 2014, Dyson announced the release of its new robotic vacuum called Dyson 360 Eye, equipped with a 360 degree camera that is mounted on the top of the robot vacuum cleaner and is supposed to provide a better navigation than other brands. The robot vacuum was scheduled for a Japan-only release in spring 2015 with international launches to follow later in the year.[6] Moreover, Dyson announced that the 360 Eye has twice the suction of any other robot vacuum. The accuracy of this claim is doubtful however, since Dyson has been sued for similar claims on multiple occasions before. [7]

from wikipedia

air filter

A particulate air filter is a device composed of fibrous materials which removes solid particulates such as dust, pollen, mould, and bacteria from the air. Filters containing an absorbent or catalyst such as charcoal (carbon) may also remove odors and gaseous pollutants such as volatile organic compounds or ozone.[1] Air filters are used in applications where air quality is important, notably in building ventilation systems and in engines.

Some buildings, as well as aircraft and other human-made environments (e.g., satellites and space shuttles) use foam, pleated paper, or spun fiberglass filter elements. Another method, air ionisers, use fibers or elements with a static electric charge, which attract dust particles. The air intakes of internal combustion engines and air compressors tend to use either paper, foam, or cotton filters. Oil bath filters have fallen out of favor. The technology of air intake filters of gas turbines has improved significantly in recent years, due to improvements in the aerodynamics and fluid dynamics of the air-compressor part of the gas turbines.

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Automotive cabin air filters[edit]

The cabin air filter is typically a pleated-paper filter that is placed in the outside-air intake for the vehicle’s passenger compartment. Some of these filters are rectangular and similar in shape to the combustion air filter. Others are uniquely shaped to fit the available space of particular vehicles’ outside-air intakes.

The first automaker to include a disposable filter to clean the ventilation system was the Nash MotorsWeather Eye“, introduced in 1940.[2]

Being a relatively recent addition to automobile equipment, this filter is often overlooked, and can greatly reduce the effectiveness of the vehicle’s air conditioning and heating performance. Clogged or dirty cabin air filters can significantly reduce airflow from the cabin vents, as well as introduce allergens into the cabin air stream. The poor performance of these filters is obscured by manufacturers by not using the MERV rating system. Some people mistakenly believe that some of these are HEPA filters.

Internal combustion engine air filters[edit]

The combustion air filter prevents abrasive particulate matter from entering the engine’s cylinders, where it would cause mechanical wear and oil contamination.

Most fuel injected vehicles use a pleated paper filter element in the form of a flat panel. This filter is usually placed inside a plastic box connected to the throttle body with ductwork. Older vehicles that use carburetors or throttle body fuel injection typically use a cylindrical air filter, usually a few inches high and between 6 inches (150 mm) and 16 inches (410 mm) in diameter. This is positioned above the carburetor or throttle body, usually in a metal or plastic container which may incorporate ducting to provide cool and/or warm inlet air, and secured with a metal or plastic lid. The overall unit (filter and housing together) is called the air cleaner.

Paper[edit]

Main article: Filter paper

Pleated paper filter elements are the nearly exclusive choice for automobile engine air cleaners, because they are efficient, easy to service, and cost-effective. The “paper” term is somewhat misleading, as the filter media are considerably different from papers used for writing or packaging, etc. There is a persistent belief amongst tuners, fomented by advertising for aftermarket non-paper replacement filters, that paper filters flow poorly and thus restrict engine performance. In fact, as long as a pleated-paper filter is sized appropriately for the airflow volumes encountered in a particular application, such filters present only trivial restriction to flow until the filter has become significantly clogged with dirt. Construction equipment engines also use this.

Foam[edit]

Oil-wetted polyurethane foam elements are used in some aftermarket replacement automobile air filters. Foam was in the past widely used in air cleaners on small engines on lawnmowers and other power equipment, but automotive-type paper filter elements have largely supplanted oil-wetted foam in these applications. Foam filters are still commonly used on air compressors for air tools up to 5Hp. Depending on the grade and thickness of foam employed, an oil-wetted foam filter element can offer minimal airflow restriction or very high dirt capacity, the latter property making foam filters a popular choice in off-road rallying and other motorsport applications where high levels of dust will be encountered. Due to the way dust is captured on foam filters, large amounts may be trapped without measurable change in airflow restriction.

Cotton[edit]

Oiled cotton gauze is employed in a growing number of aftermarket automotive air filters marketed as high-performance items. In the past, cotton gauze saw limited use in original-equipment automotive air filters. However, since the introduction of the Abarth SS versions, the Fiat subsidiary supplies cotton gauze air filters as OE filters.

Stainless steel[edit]

Stainless steel mesh is another example of medium which allow more air to pass through. Stainless steel mesh comes with different mesh counts, offering different filtration standards. In an extreme modified engine lacking in space for a cone based air filter, some will opt to install a simple stainless steel mesh over the turbo to ensure no particles enter the engine via the turbo.

Oil bath[edit]

An oil bath air cleaner consists of a sump containing a pool of oil, and an insert which is filled with fibre, mesh, foam, or another coarse filter media. When the cleaner is assembled, the media-containing body of the insert sits a short distance above the surface of the oil pool. The rim of the insert overlaps the rim of the sump. This arrangement forms a labyrinthine path through which the air must travel in a series of U-turns: up through the gap between the rims of the insert and the sump, down through the gap between the outer wall of the insert and the inner wall of the sump, and up through the filter media in the body of the insert. This U-turn takes the air at high velocity across the surface of the oil pool. Larger and heavier dust and dirt particles in the air cannot make the turn due to their inertia, so they fall into the oil and settle to the bottom of the base bowl. Lighter and smaller particles are trapped by the filtration media in the insert, which is wetted by oil droplets aspirated there into by normal airflow.

Oil bath air cleaners were very widely used in automotive and small engine applications until the widespread industry adoption of the paper filter in the early 1960s. Such cleaners are still used in off-road equipment where very high levels of dust are encountered, for oil bath air cleaners can sequester a great deal of dirt relative to their overall size without loss of filtration efficiency or airflow. However, the liquid oil makes cleaning and servicing such air cleaners messy and inconvenient, they must be relatively large to avoid excessive restriction at high airflow rates, and they tend to increase exhaust emissions of unburned hydrocarbons due to oil aspiration when used on spark-ignition engines.[citation needed]

Water bath[edit]

In the early 20th century (about 1900 to 1930), water bath air cleaners were used in some applications (cars, trucks, tractors, and portable and stationary engines). They worked on roughly the same principles as oil bath air cleaners. For example, the original Fordson tractor had a water bath air cleaner. By the 1940s, oil bath designs had displaced water bath designs because of better filtering performance.

HVAC Air Filters[edit]

Filter classes[edit]

European Normalisation standards recognise the following filter classes:

Usage Class Performance Performance test Particulate size
approaching 100% retention
Test Standard
Coarse filters(used as

Primary)

G1 65% Average value >5 µm BS EN779
G2 65–80% Average value >5 µm BS EN779
G3 80–90% Average value >5 µm BS EN779
G4 90%– Average value >5 µm BS EN779
Fine filters(used as

Secondary)

M5 40–60% Average value >5 µm BS EN779
M6 60–80% Average value >2 µm BS EN779
F7 80–90% Average value >2 µm BS EN779
F8 90–95% Average value >1 µm BS EN779
F9 95%– Average value >1 µm BS EN779
Semi HEPA E10 85% Minimum value >1 µm BS EN1822
E11 95% Minimum value >0.5 µm BS EN1822
E12 99.5% Minimum value >0.5 µm BS EN1822
HEPA H13 99.95% Minimum value >0.3 µm BS EN1822
H14 99.995% Minimum value >0.3 µm BS EN1822
ULPA U15 99.9995% Minimum value >0.3 µm BS EN1822
U16 99.99995% Minimum value >0.3 µm BS EN1822
U17 99.999995% Minimum value >0.3 µm BS EN1822

from wikipedia

Evaporative cooler

An evaporative cooler (also swamp cooler, desert cooler and wet air cooler) is a device that cools air through the evaporation of water. Evaporative cooling differs from typical air conditioning systems which use vapor-compression or absorption refrigeration cycles. Evaporative cooling works by exploiting water’s large enthalpy of vaporization. The temperature of dry air can be dropped significantly through the phase transition of liquid water to water vapor (evaporation), which can cool air using much less energy than refrigeration. In extremely dry climates, evaporative cooling of air has the added benefit of conditioning the air with more moisture for the comfort of building occupants.

The cooling potential for evaporative cooling is dependent on the wet bulb depression, the difference between dry-bulb temperature and wet-bulb temperature. In arid climates, evaporative cooling can reduce energy consumption and total equipment for conditioning as an alternative to compressor-based cooling. In climates not considered arid, indirect evaporative cooling can still take advantage of the evaporative cooling process without increasing humidity. Passive evaporative cooling strategies offer the same benefits of mechanical evaporative cooling systems without the complexity of equipment and ductwork.

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Overview[edit]

Schematic diagram of an ancient Iranian windcatcher and qanat, used for evaporative cooling of buildings

An earlier form of air cooling, the windcatcher was used in ancient Egypt and Persia thousands of years ago in the form of wind shafts on the roof, which caught the wind, passed it over subterranean water in a qanat and discharged the cooled air into the building. Nowadays Iranians have changed the windcatcher into an evaporative cooler (Coolere Âbi) and use it widely.[1]

A traditional air cooler in Mirzapur, Uttar Pradesh, India

The evaporative cooler was the subject of numerous US patents in the 20th century; many of these, starting in 1906,[2] suggested or assumed the use of excelsior (wood wool) pads as the elements to bring a large volume of water in contact with moving air to allow evaporation to occur. A typical design, as shown in a 1945 patent, includes a water reservoir (usually with level controlled by a float valve), a pump to circulate water over the excelsior pads and a centrifugal fan to draw air through the pads and into the house.[3] This design and this material remain dominant in evaporative coolers in the American Southwest, where they are also used to increase humidity.[4]In the United States, the use of the term swamp cooler may be due to the odor of algae produced by early units.[5]

Externally mounted evaporative cooling devices (car coolers) were used in some automobiles to cool interior air—often as aftermarket accessories[6]—until modern vapor-compression air conditioning became widely available.

Passive evaporative cooling techniques in buildings, such as evaporative cooling towers, have only been developed and studied in the last 30 years. In 1974, William H. Goettl invented the “Combination Refrigeration and Evaporative Cooling Air Conditioner” in Arizona after noticing that evaporative cooling technology works better in arid climates rather than humidity but that a combination unit would be more effective. In 1986, two researchers at the University of Arizona, Tucson, W. Cunningham and T. Thompson, constructed the first passive evaporative cooling tower in Tucson, AZ. This performance data from this experimental facility became the foundation of today’s evaporative cooling tower design guidelines, developed by Baruch Givoni.[7]

Physical principles[edit]

Evaporative coolers lower the temperature of air using the principle of evaporative cooling, unlike typical air conditioning systems which use vapor-compression refrigeration or absorption refrigerator. Evaporative cooling is the addition of water vapor into air, which causes a lowering of the temperature of the air. The energy needed to evaporate the water is taken from the air in the form of sensible heat, which affects the temperature of the air, and converted into latent heat, the energy present in the water vapor component of the air, whilst the air remains at a constant enthalpy value. This conversion of sensible heat to latent heat is known as an adiabatic process because it occurs at a constant enthalpy value. Evaporative cooling therefore causes a drop in the temperature of air proportional to the sensible heat drop and an increase in humidity proportional to the latent heat gain. Evaporative cooling can be visualized using a psychrometric chart by finding the initial air condition and moving along a line of constant enthalpy toward a state of higher humidity.[8]

A simple example of natural evaporative cooling is perspiration, or sweat, secreted by the body, evaporation of which cools the body. The amount of heat transfer depends on the evaporation rate, however for each kilogram of water vaporized 2,257 kJ of energy (about 890 BTU per pound of pure water, at 95 °F (35 °C)) are transferred. The evaporation rate depends on the temperature and humidity of the air, which is why sweat accumulates more on humid days, as it does not evaporate fast enough.

Vapor-compression refrigeration uses evaporative cooling, but the evaporated vapor is within a sealed system, and is then compressed ready to evaporate again, using energy to do so. A simple evaporative cooler’s water is evaporated into the environment, and not recovered. In an interior space cooling unit, the evaporated water is introduced into the space along with the now-cooled air; in an evaporative tower the evaporated water is carried off in the airflow exhaust.

Other types of phase-change cooling[edit]

A closely related process, sublimation cooling differs from evaporative cooling in that a phase transition from solid to vapor, rather than liquid to vapor occurs.

Sublimation cooling has been observed to operate on a planetary scale on the planetoid Pluto, where it has been called an anti-greenhouse effect.

Another application of a phase change to cooling is the “self-refrigerating” beverage can. A separate compartment inside the can contains a desiccant and a liquid. Just before drinking, a tab is pulled so that the desiccant comes into contact with the liquid and dissolves. As it does so it absorbs an amount of heat energy called the latent heat of fusion. Evaporative cooling works with the phase change of liquid into vapor and the latent heat of vaporization, but the self-cooling can uses a change from solid to liquid, and the latent heat of fusion to achieve the same result.

Applications[edit]

Before the advent of refrigeration, evaporative cooling was used for millennia. A porous earthenware vessel would cool water by evaporation through its walls; frescoes from about 2500 BC show slaves fanning jars of water to cool rooms.[9] A vessel could also be placed in a bowl of water, covered with a wet cloth dipping into the water, to keep milk or butter as fresh as possible.[10]

California ranch house with evaporative cooler box on roof ridgeline

Evaporative cooling is a common form of cooling buildings for thermal comfort since it is relatively cheap and requires less energy than other forms of cooling.

Psychrometric chart example of Salt Lake City

The figure showing the Salt Lake City weather data represents the typical summer climate (June to September). The colored lines illustrate the potential of direct and indirect evaporative cooling strategies to expand the comfort range in summer time. It is mainly explained by the combination of a higher air speed on one hand and elevated indoor humidity when the region permits the direct evaporative cooling strategy on the other hand. Evaporative cooling strategies that involve the humidification of the air should be implemented in dry condition where the increase in moisture content stays below recommendations for occupant’s comfort and indoor air quality. Passive cooling towers lack the control that traditional HVAC systems offer to occupants. However, the additional air movement provided into the space can improve occupant comfort.

Evaporative cooling is most effective when the relative humidity is on the low side, limiting its popularity to dry climates. Evaporative cooling raises the internal humidity level significantly, which desert inhabitants may appreciate as the moist air re-hydrates dry skin and sinuses. Therefore, assessing typical climate data is an essential procedure to determine the potential of evaporative cooling strategies for a building. The three most important climate considerations are dry-bulb temperature, wet-bulb temperature, and wet-bulb depression during the summer design day. It is important to determine if the wet-bulb depression can provide sufficient cooling during the summer design day. By subtracting the wet-bulb depression from the outside dry-bulb temperature, one can estimate the approximate air temperature leaving the evaporative cooler. It is important to consider that the ability for the exterior dry-bulb temperature to reach the wet-bulb temperature depends on the saturation efficiency. A general recommendation for applying direct evaporative cooling is to implement it in places where the wet-bulb temperature of the outdoor air does not exceed 22 °C (71.6 °F).[7] However, in the example of Salt Lake City, the upper limit for the direct evaporative cooling on psychrometric chart is 20 °C (68 °F). Despite this lower value, this climate is still suitable for this technique.

Evaporative cooling is especially well suited for climates where the air is hot and humidity is low. In the United States, the western/mountain states are good locations, with evaporative coolers prevalent in cities like Denver, Salt Lake City, Albuquerque, El Paso, Tucson, and Fresno. Evaporative air conditioning is also popular and well-suited to the southern (temperate) part of Australia. In dry, arid climates, the installation and operating cost of an evaporative cooler can be much lower than that of refrigerative air conditioning, often by 80% or so. However, evaporative cooling and vapor-compression air conditioning are sometimes used in combination to yield optimal cooling results. Some evaporative coolers may also serve as humidifiers in the heating season. Even in regions that are mostly arid, short periods of high humidity may prevent evaporative cooling from being an effective cooling strategy. An example of this event is the monsoon season in southern Arizona in July and August.

In locations with moderate humidity there are many cost-effective uses for evaporative cooling, in addition to their widespread use in dry climates. For example, industrial plants, commercial kitchens, laundries, dry cleaners, greenhouses, spot cooling (loading docks, warehouses, factories, construction sites, athletic events, workshops, garages, and kennels) and confinement farming (poultry ranches, hog, and dairy) often employ evaporative cooling. In highly humid climates, evaporative cooling may have little thermal comfort benefit beyond the increased ventilation and air movement it provides.

Other examples[edit]

Trees transpire large amounts of water through pores in their leaves called stomata, and through this process of evaporative cooling, forests interact with climate at local and global scales.[11]

Evaporative cooling is commonly used in cryogenic applications. The vapor above a reservoir of cryogenic liquid is pumped away, and the liquid continuously evaporates as long as the liquid’s vapor pressure is significant. Evaporative cooling of ordinary helium forms a 1-K pot, which can cool to at least 1.2 K. Evaporative cooling of helium-3 can provide temperatures below 300 mK. These techniques can be used to make cryocoolers, or as components of lower-temperature cryostats such as dilution refrigerators. As the temperature decreases, the vapor pressure of the liquid also falls, and cooling becomes less effective. This sets a lower limit to the temperature attainable with a given liquid.

Evaporative cooling is also the last cooling step in order to reach the ultra-low temperatures required for Bose–Einstein condensation (BEC). Here, so-called forced evaporative cooling is used to selectively remove high-energetic (“hot”) atoms from an atom cloud until the remaining cloud is cooled below the BEC transition temperature. For a cloud of 1 million alkali atoms, this temperature is about 1μK.

Although robotic spacecraft use thermal radiation almost exclusively, many manned spacecraft have short missions that permit open-cycle evaporative cooling. Examples include the Space Shuttle, the Apollo Command/Service Module (CSM), Lunar Module and Portable Life Support System. The Apollo CSM and the Space Shuttle also had radiators, and the Shuttle could evaporate ammonia as well as water. The Apollo spacecraft used sublimators, compact and largely passive devices that dump waste heat in water vapor (steam) that is vented to space.[citation needed] When liquid water is exposed to vacuum it boils vigorously, carrying away enough heat to freeze the remainder to ice that covers the sublimator and automatically regulates the feedwater flow depending on the heat load. The water expended is often available in surplus from the fuel cells used by many manned spacecraft to produce electricity.

However the ice crystals from dumped urine, water etc., which are flying through space at orbital velocities, have been found to “sand blast” space craft.

Evaporative cooler designs[edit]

Evaporative cooler illustration

Most designs take advantage of the fact that water has one of the highest known enthalpy of vaporization (latent heat of vaporization) values of any common substance. Because of this, evaporative coolers use only a fraction of the energy of vapor-compression or absorption air conditioning systems. Unfortunately, except in very dry climates, the single-stage (direct) cooler can increase relative humidity (RH) to a level that makes occupants uncomfortable. Indirect and Two-stage evaporative coolers keep the RH lower.

Direct evaporative cooling[edit]

Direct evaporative cooling

Direct evaporative cooling (open circuit) is used to lower the temperature and increase the humidity of air by using latent heat of evaporation, changing liquid water to water vapor. In this process, the energy in the air does not change. Warm dry air is changed to cool moist air. The heat of the outside air is used to evaporate water. The RH increases to 70 to 90% which reduces the cooling effect of human perspiration. The moist air has to be continually released to outside or else the air becomes saturated and evaporation stops.

A mechanical direct evaporative cooler unit uses a fan to draw air through a wetted membrane, or pad, which provides a large surface area for the evaporation of water into the air. Water is sprayed at the top of the pad so it can drip down into the membrane and continually keep the membrane saturated. Any excess water that drips out from the bottom of the membrane is collected in a pan and recirculated to the top. Single stage direct evaporative coolers are typically small in size as it only consists of the membrane, water pump, and centrifugal fan. The mineral content of the municipal water supply will cause scaling on the membrane, which will lead to clogging over the life of the membrane. Depending on this mineral content and the evaporation rate, regular cleaning and maintenance is required to ensure optimal performance. Generally, supply air from the single-stage evaporative cooler will need to be exhausted directly (one-through flow) because the high humidity of the supply air. Few design solutions have been conceived to utilize the energy in the air like directing the exhaust air through two sheets of double glazed windows, thus reducing the solar energy absorbed through the glazing.[12] Compared to energy required to achieve the equivalent cooling load with a compressor, single stage evaporative coolers consume less energy.[7]

Passive direct evaporative cooling can occur anywhere that the evaporatively cooled water can cool a space without the assist of a fan. This can be achieved through use of fountains or more architectural designs such as the evaporative downdraft cooling tower, also called a “passive cooling tower”. The passive cooling tower design allows outside air to flow in through the top of a tower that is constructed within or next to the building. The outside air comes in contact with water inside the tower either through a wetted membrane or a mister. As water evaporates in the outside air, the air becomes cooler and less buoyant and creates a downward flow in the tower. At the bottom of the tower, an outlet allows the cooler air into the interior. Similar to mechanical evaporative coolers, towers can be an attractive low-energy solution for hot and dry climate as they only require a water pump to raise water to the top of the tower.[13] Energy savings from using a passive direct evaporating cooling strategy depends on the climate and heat load. For arid climates with a great wet bulb depression, cooling towers can provide enough cooling during summer design conditions to be net zero. For example, a 371 m² (4,000 ft²) retail store in Tucson, Arizona with a sensible heat gain of 29.3 kJ/h (100,000 Btu/h) can be cooled entirely by two passive cooling towers providing 11890 m³/h (7,000 cfm) each.[14]

For the Zion National Park Visitor’s Center, which uses two passive cooling towers, the cooling energy intensity was 14.5 MJ/m² (1.28 kBtu/ft;), which was 77% less than a typical building in the western United States that uses 62.5 MJ/m² (5.5 kBtu/ft²).[15] A study of field performance results in Kuwait revealed that power requirements for an evaporative cooler are approximately 75% less than the power requirements for a conventional packaged unit air-conditioner.[16]

Indirect evaporative cooling[edit]

The process of indirect evaporative cooling

Indirect evaporative cooling (closed circuit) is a cooling process that uses direct evaporative cooling in addition to some type of heat exchanger to transfer the cool energy to the supply air. The cooled moist air from the direct evaporative cooling process never comes in direct contact with the conditioned supply air. The moist air stream is released outside or used to cool other external devices such as solar cells which are more efficient if kept cool. One indirect cooler manufacturer uses the so-called Maisotsenko cycle which employs an iterative (multi-step) heat exchanger that can reduce the temperature to below the wet-bulb temperature.[17] While no moisture is added to the incoming air the relative humidity (RH) does rise a little according to the Temperature-RH formula. Still, the relatively dry air resulting from indirect evaporative cooling allows inhabitants’ perspiration to evaporate more easily, increasing the relative effectiveness of this technique. Indirect Cooling is an effective strategy for hot-humid climates that cannot afford to increase the moisture content of the supply air due to indoor air quality and human thermal comfort concerns. The following graphs describe the process of direct and indirect evaporative cooling with the changes in temperature, moisture content and relative humidity of the air.

Passive indirect evaporative cooling strategies are rare because this strategy involves an architectural element to act as a heat exchanger (for example a roof). This element can be sprayed with water and cooled through the evaporation of the water on this element. These strategies are rare due to the high use of water, which also introduces the risk of water intrusion and compromising building structure.

Two-stage evaporative cooling, or indirect-direct[edit]

In the first stage of a two-stage cooler, warm air is pre-cooled indirectly without adding humidity (by passing inside a heat exchanger that is cooled by evaporation on the outside). In the direct stage, the pre-cooled air passes through a water-soaked pad and picks up humidity as it cools. Since the air supply is pre-cooled in the first stage, less humidity is transferred in the direct stage, to reach the desired cooling temperatures. The result, according to manufacturers, is cooler air with a RH between 50-70%, depending on the climate, compared to a traditional system that produces about 70–80% relative humidity in the conditioned air.[citation needed]

Hybrid. Direct or Indirect cooling has been combined with vapor-compression or absorption air conditioning to increase the overall efficiency and /or to reduce the temperature below the wet-bulb limit.

Materials[edit]

Traditionally, evaporative cooler pads consist of excelsior (aspen wood fiber) inside a containment net, but more modern materials, such as some plastics and melamine paper, are entering use as cooler-pad media. Modern rigid media, commonly 8″ or 12″ thick, adds more moisture, and thus cools air more than typically much thinner Aspen media.[18] Another material which is sometimes used is corrugated cardboard.[19][20]

Design considerations[edit]

Water use[edit]

In arid and semi-arid climates, the scarcity of water makes water consumption a concern in cooling system design. From the installed water meters[original research?] 420938 L (111,200 gal) of water were consumed during 2002 for the two passive cooling towers at Zion National Park Visitor Center.[citation needed] However, such concerns are addressed by experts who note that electricity generation usually requires a lot of water, and evaporative coolers use far less electricity, and thus comparable water overall, and cost less overall, compared to chillers.[21]

Shading[edit]

Allowing direct solar exposure to the media pads increases the evaporation rate. sunlight may however, degrade some media, In addition to heating up other elements of the evaporative cooling design. Therefore, shading is advisable in most applications.

Mechanical systems[edit]

Apart from fans used in mechanical evaporative cooling, pumps are the only other piece of mechanical equipment required for the evaporative cooling process in both mechanical and passive applications. Pumps can be used for either recirculating the water to the wet media pad or providing water at very high pressure to a mister system for a passive cooling tower. Pump specifications will vary depending on evaporation rates and media pad area. The Zion National Park Visitor’s center uses a 250 W (1/3 HP) pump.[22]

Exhaust[edit]

Exhaust ducts and/or open windows must be used at all times to allow air to continually escape the air conditioned area. Otherwise, pressure develops and the fan/blower in the system is unable to push much air through the media and into the air conditioned area. The evaporative system cannot function without exhausting the continuous supply of air from the air conditioned area to the outside. By optimizing the placement of the ‘cooled air’ inlet, along with the layout of the house passages, related doors and room windows, the system can be used most effectively to direct the cooled air to the required areas. A well designed layout can very effectively scavenge and expel the hot air from desired areas without the need for an above ceiling ducted venting system. Continuous airflow is essential, so the exhaust windows or vents must not restrict the volume and passage of air being introduced by the evaporative cooling machine. One must also be mindful of the outside wind direction, as for example a strong hot southerly wind will slow or restrict the exhausted air from a south facing window. It is always best to have the downwind windows open, while the upwind windows are closed.

Different types of installations[edit]

Typical installations[edit]

Typically, residential and industrial evaporative coolers use direct evaporation, and can be described as an enclosed metal or plastic box with vented sides. Air is moved by a centrifugal fan or blower, (usually driven by an electric motor with pulleys known as “sheaves” in HVAC terminology, or a direct-driven axial fan), and a water pump is used to wet the evaporative cooling pads. The cooling units can be mounted on the roof (down draft, or downflow), or exterior walls or windows (side draft, or horizontal flow) of buildings. To cool, the fan draws ambient air through vents on the unit’s sides and through the damp pads. Heat in the air evaporates water from the pads which are constantly re-dampened to continue the cooling process. Then cooled, moist air is delivered into the building via a vent in the roof or wall.

Because the cooling air originates outside the building, one or more large vents must exist to allow air to move from inside to outside. Air should only be allowed to pass once through the system, or the cooling effect will decrease. This is due to the air reaching the saturation point. Often 15 or so air changes per hour (ACHs) occur in spaces served by evaporative coolers, a relatively high rate of air exchange.

Evaporative (wet) cooling towers[edit]

Main article: Cooling tower

Large hyperboloid cooling towers made of structural steel for a power plant in Kharkov (Ukraine)

Cooling towers are structures for cooling water or other heat transfer media to near-ambient wet-bulb temperature. Wet cooling towers operate on the evaporative cooling principle, but are optimized to cool the water rather than the air. Cooling towers can often be found on large buildings or on industrial sites. They transfer heat to the environment from chillers, industrial processes, or the Rankine power cycle, for example.

Misting systems[edit]

Mist spraying system with water pump beneath

Misting systems work by forcing water via a high pressure pump and tubing through a brass and stainless steel mist nozzle that has an orifice of about 5 micrometres, thereby producing a micro-fine mist. The water droplets that create the mist are so small that they instantly flash evaporate. Flash evaporation can reduce the surrounding air temperature by as much as 35 °F (20 °C) in just seconds.[23] For patio systems, it is ideal to mount the mist line approximately 8 to 10 feet (2.4 to 3.0 m) above the ground for optimum cooling. Misting is used for applications such as flowerbeds, pets, livestock, kennels, insect control, odor control, zoos, veterinary clinics, cooling of produce, and greenhouses.

Misting fans[edit]

A misting fan is similar to a humidifier. A fan blows a fine mist of water into the air. If the air is not too humid, the water evaporates, absorbing heat from the air, allowing the misting fan to also work as an air cooler. A misting fan may be used outdoors, especially in a dry climate.It may also be used indoors with packed party goers.

Small portable battery-powered misting fans, consisting of an electric fan and a hand-operated water spray pump, are sold as novelty items. Their effectiveness in everyday use is unclear.[citation needed]

Performance[edit]

Understanding evaporative cooling performance requires an understanding of psychrometrics. Evaporative cooling performance is variable due to changes in external temperature and humidity level. A residential cooler should be able to decrease the temperature of air by 3 to 4 °C(or in Fahrenheit scale by 5 to 7 °F).

It is simple to predict cooler performance from standard weather report information. Because weather reports usually contain the dewpoint and relative humidity, but not the wet-bulb temperature, a psychrometric chart or a simple computer program must be used to compute the wet bulb temperature. Once the wet bulb temperature and the dry bulb temperature are identified, the cooling performance or leaving air temperature of the cooler may be determined.

For direct evaporative cooling, the direct saturation efficiency, {\displaystyle \epsilon }\epsilon , measures in what extent the temperature of the air leaving the direct evaporative cooler is close to the wet-bulb temperature of the entering air. The direct saturation efficiency can be determined as follow

[24]
{\displaystyle \epsilon ={\frac {T_{e,db}-T_{l,db}}{T_{e,db}-T_{e,wb}}}}\epsilon ={\frac {T_{{e,db}}-T_{{l,db}}}{T_{{e,db}}-T_{{e,wb}}}}
Where:

{\displaystyle \epsilon }\epsilon = direct evaporative cooling saturation efficiency (%)
{\displaystyle T_{e,db}}T_{{e,db}} = entering air dry-bulb temperature (°C)
{\displaystyle T_{l,db}}T_{{l,db}} = leaving air dry-bulb temperature (°C)
{\displaystyle T_{e,wb}}T_{{e,wb}} = entering air wet-bulb temperature (°C)

Evaporative media efficiency usually runs between 80% to 90%. Most efficient systems can lower the dry air temperature to 95% of the wet-bulb temperature, the least efficient systems only achieve 50%.[24] The evaporation efficiency drops very little over time.

Typical aspen pads used in residential evaporative coolers offer around 85% efficiency while CELdek[further explanation needed] type of evaporative media offer efficiencies of >90% depending on air velocity. The CELdek media is more often used in large commercial and industrial installations.

As an example, in Las Vegas, Nevada, with a typical summer design day of 42 °C (108 °F) DB/19 °C (66 °F) WB or about 8% relative humidity, with 85% efficiency, the leaving air temperature of a residential cooler would be:

{\displaystyle T_{l,db}}T_{{l,db}} = 42° – ((42° – 19°) x 85%) = 22.45 °C (72.41 °F)

However, either of two methods can be used to estimate performance:

  • Use a psychrometric chart to calculate wet bulb temperature, and then add 5–7 °F as described above.
  • Use a rule of thumb which estimates that the wet bulb temperature is approximately equal to the ambient temperature, minus one third of the difference between the ambient temperature and the dew point. As before, add 5–7 °F as described above.

Some examples clarify this relationship:

  • At 32 °C (90 °F) and 15% relative humidity, air may be cooled to nearly 16 °C (61 °F). The dew point for these conditions is 2 °C (36 °F).
  • At 32 °C (90 °F) and 50% relative humidity, air may be cooled to about 24 °C (75 °F). The dew point for these conditions is 20 °C (68 °F).
  • At 40 °C (104 °F) and 15% relative humidity, air may be cooled to nearly 21 °C (70 °F). The dew point for these conditions is 8 °C (46 °F).

(Cooling examples extracted from the June 25, 2000 University of Idaho publication, “Homewise).

Because evaporative coolers perform best in dry conditions, they are widely used and most effective in arid, desert regions such as the southwestern USA and northern Mexico.

The same equation indicates why evaporative coolers are of limited use in highly humid environments: for example, a hot August day in Tokyo may be 30 °C (86 °F), 85% relative humidity, 1,005 hPa pressure. This gives dew point 27.2 °C (81.0 °F) and wet-bulb temperature 27.88 °C (82.18 °F). According to the formula above, at 85% efficiency air may be cooled only down to 28.2 °C (82.8 °F) which makes it quite impractical.

Comparison to air conditioning[edit]

A misting fan

Comparison of evaporative cooling to refrigeration-based air conditioning:

Advantages[edit]

Less expensive to install and operate

  • Estimated cost for professional installation is about half or less that of central refrigerated air conditioning.[25]
  • Estimated cost of operation is 1/8 that of refrigerated air conditioning.[26]
  • No power spike when turned on due to lack of a compressor Power consumption is limited to the fan and water pump, which have a relatively low current draw at start-up.
  • The working fluid is water. No special refrigerants, such as ammonia or CFCs, are used that could be toxic, expensive to replace, contribute to ozone depletion and/or be subject to stringent licensing and environmental regulations.

Ease of installation and maintenance

  • Equipment can be installed by mechanically-inclined users at drastically lower cost than refrigeration equipment which requires specialized skills and professional installation.
  • The only two mechanical parts in most basic evaporative coolers are the fan motor and the water pump, both of which can be repaired or replaced at low cost and often by a mechanically inclined user, eliminating costly service calls to HVAC contractors.

Ventilation air

  • The frequent and high volumetric flow rate of air traveling through the building reduces the “age-of-air” in the building dramatically.
  • Evaporative cooling increases humidity. In dry climates, this may improve comfort and decrease static electricity problems.
  • The pad itself acts as a rather effective air filter when properly maintained; it is capable of removing a variety of contaminants in air, including urban ozone caused by pollution, regardless of very dry weather. Refrigeration-based cooling systems lose this ability whenever there is not enough humidity in the air to keep the evaporator wet while providing a frequent trickle of condensation that washes out dissolved impurities removed from the air.

Disadvantages[edit]

Performance

  • Most evaporative coolers are unable to lower the air temperature as much as refrigerated air conditioning can.
  • High dewpoint (humidity) conditions decrease the cooling capability of the evaporative cooler.
  • No dehumidification. Traditional air conditioners remove moisture from the air, except in very dry locations where recirculation can lead to a buildup of humidity. Evaporative cooling adds moisture, and in humid climates, dryness may improve thermal comfort at higher temperatures.

Comfort

  • The air supplied by the evaporative cooler is generally 80–90% relative humidity and can cause interior humidity levels as high as 65%; very humid air reduces the evaporation rate of moisture from the skin, nose, lungs, and eyes.
  • High humidity in air accelerates corrosion, particularly in the presence of dust. This can considerably reduce the life of electronic and other equipment.
  • High humidity in air may cause condensation of water. This can be a problem for some situations (e.g., electrical equipment, computers, paper, books, old wood).
  • Odors and other outdoor contaminants may be blown into the building unless sufficient filtering is in place.

Water use

  • Evaporative coolers require a constant supply of water to wet the pads.
  • Water high in mineral content (hard water) will leave mineral deposits on the pads and interior of the cooler. Depending on the type and concentration of minerals, possible safety hazards during the replacement and waste removal of the pads could be present. Bleed-off and refill (purge pump) systems can reduce but not eliminate this problem. Installation of an inline water filter (refrigerator drinking water / ice maker type) will drastically reduce the mineral deposits.

Maintenance frequency

  • Any mechanical components that can rust or corrode need regular cleaning or replacement due to the environment of high moisture and potentially heavy mineral deposits in areas with hard water.
  • Evaporative media must be replaced on a regular basis to maintain cooling performance. Wood wool pads are inexpensive but require replacement every few months. Higher-efficiency rigid media is much more expensive but will last for a number of years proportional to the water hardness; in areas with very hard water, rigid media may only last for two years before mineral scale build-up unacceptably degrades performance.
  • In areas with cold winters, evaporative coolers must be drained and winterized to protect the water line and cooler from freeze damage and then de-winterized prior to the cooling season.

Health hazards

  • An evaporative cooler is a common place for mosquito breeding. Numerous authorities consider an improperly maintained cooler to be a major threat to public health.[27]
  • Mold and bacteria may be dispersed into interior air from improperly maintained or defective systems, causing Sick Building Syndrome and adverse effects for Asthma and allergy sufferers.
  • Wood wool of dry cooler pads can catch fire even by small sparks.

Air Ioniser

An air ioniser (or negative ion generator or “Chizhevsky’s chandelier”) is a device that uses high voltage to ionise (electrically charge) air molecules. Negative ions, or anions, are particles with one or more extra electrons, conferring a net negative charge to the particle. Cations are positive ions missing one or more electrons, resulting in a net positive charge. Most commercial air purifiers are designed to generate negative ions. Another type of air ioniser is the electrostatic discharge (ESD) ioniser (balanced ion generator) used to neutralise static charge. In 2002, Cecil Alfred ‘Coppy’ Laws was credited with being the inventor of the domestic air ioniser in an obituary in The Independent newspaper.

Air ionisers have been used to eliminate the occurrence of air-borne bacterial infections and to reduce static electricity buildup in electronics.

click the link below to buy any of your home products from a needle to a sowing mechine from a spoon to refrigerator from a funnel to a wine cooler  at the best prices

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Ionic air purifiers[edit]

Air ioniser and purifier with its dust collection plates removed

Air ionisers are used in air purifiers to remove particles from air. Airborne particles are attracted to the electrode in an effect similar to static electricity. These ions are de-ionised by seeking earthed conductors, such as walls and ceilings.[dubious ] To increase the efficiency of this process, some commercial products provide such surfaces within the device. The frequency of nosocomial infections in British hospitals prompted the National Health Service (NHS) to research the effectiveness of anions for air purification, finding that repeated airborne acinetobacter infections in a ward were eliminated by the installation of a negative air ioniser—the infection rate fell to zero, an unexpected result. Positive and negative ions produced by air conditioning systems have also been found by a manufacturer to inactivate viruses including influenza.[1]

The SARS epidemic fueled the desire for personal ionisers in East Asia, including Japan (where many products have been specialised to contain negative ion generators, including toothbrushes, refrigerators, air conditioners, air cleaners, and washing machines). There are no specific standards for these devices.[2]

Ions versus ozone[edit]

Ionisers are distinct from ozone generators, although both devices operate in a similar way. Ionisers use electrostatically charged plates to produce positively or negatively charged gas ions (for instance N2 or O2) that particulate matter sticks to in an effect similar to static electricity. Even the best ionisers will also produce a small amount of ozone—triatomic oxygen, O3—which is unwanted. Ozone generators are optimised to attract an extra oxygen ion to an O2molecule, using either a corona discharge tube or UV light.[citation needed]

At concentrations that do not exceed public health standards, ozone has been found to have little potential to remove indoor air contaminants.[3] At high concentrations ozone can be toxic to air-borne bacteria, and may destroy or kill these sometimes infectious organisms. However, the required concentrations are sufficiently toxic to humans and animals that the US FDA declares that ozone has no place in medical treatment[4] and has taken action against businesses that violate this regulation by offering therapeutic ozone generators or ozone therapy.[5] Ozone is a highly toxic and extremely reactive gas.[6] A higher daily average than 0.1 ppm (100 ppb, 0.2 mg/m³) is not recommended and can damage the lungs and olfactory bulb cells directly.

Adverse health effects[edit]

A number of studies have been carried out on negative ion generators. Some studies show that the ozone generated can exceed guidelines in small, non ventilated areas.[7] One study showed that ozone can react with other constituents, namely cleaning agents to increase pollutants such as formaldehyde (importantly, this study had as its objective the testing of the use of cleaning products and air fresheners indoors and associated health risks as opposed to adverse health effects of air ionisers). [8]

Consumer Reports court case[edit]

Consumer Reports, a non-profit US-based product-testing magazine, reported in October 2003 that air ionisers do not perform to high enough standards compared to conventional HEPA filters. The exception was a combination unit that used a fan to move air while ionizing it. In response to this report, The Sharper Image, a manufacturer of air ionisers (among other products), sued Consumer’s Union (the publishers of Consumer Reports) for product defamation. Consumer Reports gave the Ionic Breeze and other popular units a “fail” because they have a low Clean Air Delivery Rate (CADR). CADR measures the amount of filtered air circulated during a short period of time, and was originally designed to rate media-based air cleaners. The Sharper Image claimed that this test was a poor way to rate the Ionic Breeze, since it does not take into account other features, such as 24-hour-a-day continuous cleaning, ease of maintenance, and silent operation.

The United States District Court for the Northern District of California dismissed the case, reasoning that The Sharper Image had failed to demonstrate that it could prove any of the statements made by Consumer Reports were false. The Court’s final ruling in May 2005 ordered The Sharper Image to pay US $525,000 for Consumer Union’s legal expenses.[9]

Electrostatic neutraliser in electronics[edit]

Air ionisers are often used in places where work is done involving static-electricity-sensitive electronic components, to eliminate the build-up of static charges on non-conductors. As those elements are very sensitive to electricity, they cannot be grounded because the discharge will destroy them as well. Usually, the work is done over a special dissipative table mat, which allows a very slow discharge, and under an air gush of ioniser.[10]

from wikipedia

Machine embroidery

Machine embroidery is an embroidery process whereby a sewing machine or embroidery machine is used to create patterns on textiles. It is used commercially in product branding, corporate advertising, and uniform adornment. Hobbyists also machine embroider for personal sewing and craft projects.

There are multiple types of machine embroidery. These include free-motion sewing machine embroidery, this uses a basic zigzag sewing machine. Much commercial embroidery is still done with link stitch embroidery[1] the patterns may be manually or automatically controlled. More modern computerized machine embroidery,[2] uses an embroidery machine or sewing/embroidery machine that is controlled with a computer that will embroider stored patterns, these may have multiple heads and threads

click the link below to buy any of your home products from a needle to a sowing mechine from a spoon to refrigerator from a funnel to a wine cooler  at the best prices

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Free-motion machine embroidery[edit]

In free-motion machine embroidery, embroidered designs are created by using a basic zigzag sewing machine. As it is used primarily for tailoring, this type of machine lacks the automated features of a specialized machine.

To create free-motion machine embroidery, the embroiderer runs the machine and skillfully moves tightly hooped fabric under the needle to create a design. The operator lowers or covers the “feed dogs” or machine teeth and moves the fabric manually. The operator develops the embroidery manually, using the machine’s settings for running stitch and fancier built-in stitches. In this way, the stitches form an image onto a piece of fabric. An embroiderer can produce a filled-in effect by sewing many parallel rows of straight stitching. A machine’s zigzag stitch can create thicker lines within a design or be used to create a border. Many quilters and fabric artists use a process called thread drawing (or thread painting) to create embellishments on their projects or to create textile art.

Free-motion machine embroidery can be time-consuming. Since a standard sewing machine has only one needle, the operator must stop and re-thread the machine manually for each subsequent color in a multi-color design. He or she must also manually trim and clean up loose or connecting threads after the design is completed.

As this is a manual process rather than a digital reproduction, any pattern created using free-motion machine embroidery is unique and cannot be exactly reproduced, unlike with computerized embroidery.

With the advent of computerized machine embroidery, the main use of manual machine embroidery is in fiber art and quilting projects. Though some manufacturers still use manual embroidery to embellish garments, many prefer computerized embroidery’s ease and reduced costs.

Computerized machine embroidery[edit]

Most modern embroidery machines are computer controlled and specifically engineered for embroidery. Industrial and commercial embroidery machines and combination sewing-embroidery machines have a hooping or framing system that holds the framed area of fabric taut under the sewing needle and moves it automatically to create a design from a pre-programmed digital embroidery pattern.

Depending on its capabilities, the machine will require varying degrees of user input to read and sew embroidery designs. Sewing-embroidery machines generally have only one needle and require the user to change thread colors during the embroidery process. Multi-needle industrial machines are generally threaded prior to running the design and do not require re-threading. These machines require the user to input the correct color change sequence before beginning to embroider. Some can trim and change colors automatically.

A multi-needle machine may consist of multiple sewing heads, each of which can sew the same design onto a separate garment concurrently. Such a machine might have 20 or more heads, each consisting of 15 or more needles. A head is usually capable of producing many special fabric effects, including satin stitch embroidery, chain stitch embroidery, sequins, appliqué, and cutwork.

History[edit]

Before computers were affordable, most embroidery was completed by punching designs on paper tape that then ran through an embroidery machine. One error could ruin an entire design, forcing the creator to start over.

In 1980, Wilcom introduced the first computer graphics embroidery design system to run on a minicomputer. Melco, an international distribution network formed by Randal Melton and Bill Childs, created the first embroidery sample head for use with large Schiffli looms. These looms spanned several feet across and produced lace patches and large embroidery patterns. The sample head allowed embroiderers to avoid manually sewing the design sample and saved production time. Subsequently, it became the first computerized embroidery machine marketed to home sewers.

The economic conditions of the Reagan years, coupled with tax incentives for home businesses, helped propel Melco to the top of the market. At the Show of the Americas in 1980, Melco unveiled the Digitrac, a digitizing system for embroidery machines. The digitized design was composed at six times the size of the embroidered final product. The Digitrac consisted of a small computer, similar in size to a BlackBerry, mounted on an X and Y axis on a large white board. It sold for $30,000. The original single-needle sample head sold for $10,000 and included a 1″ paper-tape reader and 2 fonts. The digitizer marked common points in the design to create elaborate fill and satin stitch combinations.

Melco patented the ability to sew circles with a satin stitch, as well as arched lettering generated from a keyboard. An operator digitized the design using similar techniques to punching, transferring the results to a 1″ paper tape or later to a floppy disk. This design would then be run on the embroidery machine, which stitched out the pattern. Wilcom enhanced this technology in 1982 with the introduction of the first multi-user system, which allowed more than one person to work on the embroidery process, streamlining production times.

Brother Industries entered the embroidery industry after several computerized embroidery companies contracted it to provide sewing heads. Later, the Japanese company Tajima provided sewing heads that were capable of using multiple threads. Singer failed to remain competitive during this time. Melco was acquired by Saurer in 1989.

The major embroidery machine companies eventually adapted their commercial systems and marketed them to companies such as Janome for home use.

Since the late 1990s, computerized machine embroidery has grown in popularity as costs have fallen for computers, software, and embroidery machines. Many machine manufacturers sell their own lines of embroidery patterns. In addition, many individuals and independent companies also sell embroidery designs, and there are free designs available on the internet.

The computerized machine embroidery process[edit]

Machine embroidery in progress.

Machine Embroidery is not as ‘push button’ as many people tend to believe and can be a very tedious process depending on numerous variables. The basic steps for creating embroidery with a computerized embroidery machine are as follows:

  • purchase or create (can take hours for the smallest/simplest of designs and the software is costly) a digitized embroidery design file that works with the brand of machine
  • edit the design and/or combine with other designs with costly software (optional)
  • load the final design file into the embroidery machine after making sure it is the right format and it will fit in the hoop you need
  • stabilize the fabric and place it in the machine
  • start and monitor the embroidery machine, to change thread colors, rethread machine, troubleshoot problems, etc. and have plenty of needles, bobbins, a can of air (or small air compressor), a small brush, and scissors on hand
  • Toss out botched project due to wrong stabilizer for item, machine malfunction, wrong thread, badly digitized design, etc.
  • Repeat process from the beginning till its right

Design files[edit]

Digitized embroidery design files can be either purchased or created with industry-specific embroidery digitizing software. Embroidery file formats broadly fall into two categories. The first, source formats, are specific to the software used to create the design. For these formats, the digitizer keeps the original file for the purposes of editing. The second, machine formats, are specific to a particular brand of embroidery machine. Here, the files are available for use with particular embroidery machines and are not easily edited or scaled.

Wilcom developed the .EMB file format which is the designer’s file format of choice ensuring optimum stitch quality. This format stores the true object based properties and means that they can easily resize, re-color, adjust for fabric types, etc with a simple click for each project. Once ready the .EMB is exported into any machine format required for that specific stitch-out.

Embroidery machines generally have one or more machine formats specific to their brand. However, some formats such as Tajima’s .dst, Melco’s .exp/.cnd and Barudan’s .fdr have become so prevalent that they have effectively become industry standards and are often supported by machines built by rival companies.

Machine formats generally contain primarily stitch data (offsets) and machine functions (trims, jumps, etc.) and are thus not easily scaled or edited without extensive manual work.

Many embroidery designs can be downloaded in popular machine formats from embroidery web sites. However, since not all designs are available for every machine’s specific format, some machine embroiderers use conversion programs to convert from one machine’s format file to another, with various degrees of reliability.

A person who creates a design is known as an embroidery digitizer or puncher. A digitizer uses software to create an object-based embroidery design, which can be easily reshaped and edited. These files retain important information such as object outlines, thread colors, and original artwork used to punch the designs. When the file is converted to a stitch file, it loses much of this information, rendering editing difficult or impossible.

Software vendors often advertise auto-punching or auto-digitizing capabilities. However, if high quality embroidery is essential, then industry experts highly recommend either purchasing solid designs from reputable digitizers or obtaining training on solid digitization techniques.

Editing designs[edit]

Once a design has been digitized, an embroiderer can use software to edit it or combine it with other designs. Most embroidery programs allow the user to rotate, scale, move, stretch, distort, split, crop, or duplicate the design in an endless pattern. Most software allows the user to add text quickly and easily. Often the colors of the design can be changed, made monochrome, or re-sorted. More sophisticated packages allow the user to edit, add, or remove individual stitches. Some embroidery machines have rudimentary built-in design editing features.

Loading the design[edit]

After editing the final design, the file is loaded into the embroidery machine. Different machines require different formats that are proprietary to that company. Common design file formats for the home and hobby market include .ART, .HUS, .JEF, .PES, .SEW, and .VIP. Embroidery patterns can be transferred to the computerized embroidery machines through cables, CDs, floppy disks, USB interfaces, or special cards that resemble flash or compact cards.

File Type/Extension Company/Machine Compatibility
.ART Bernina artista OESD
.ASD Melco
.CND Melco condensed
.CSD POEM, Singer EU, Viking Huskygram
.DST Tajima, Brother, Barudan, Babylock, Melco, Richpeace
.DSB Barudan
.EDD Richpeace
.EMB Wilcom, EmbroideryStudio, Richpeace, Hatch Embroidery
.EMD Elna Expressive
.EXP Bernina, Melco
.FHE Singer (Futura)
.GNC Great Notions Condensed
.HUS Viking Husqvarna
.JEF/.JEF+ Janome, New Home
.OEF OESD Condensed
.OFM Melco
.PCD, .PCS, .PCQ Pfaff
.PEC, .PEL, .PEM, .PES Baby Lock, Bernina Deco, Brother, Simplicity, Melco
.PHB, .PHC Baby Lock, Bernina Deco, Brother
.RPF Richpeace Welcome
.SEW Elna, Janome, New Home, Kenmore
.SHV Viking Husqvarna
.STI Toyota/Data Stitch
.STX Toyota/Data Stitch
.VIP VIP Customizing
.VP3 Pfaff, Husqvarna Viking
.XXX Singer, Compucon

[3][4][5]

Stabilizing the fabric[edit]

To prevent wrinkles and other problems, the fabric must be stabilized. The method of stabilizing depends on the type of machine, the fabric type, and the design density. For example, knits and large designs typically require firm stabilization. There are many methods for stabilizing fabric, but most often one or more additional pieces of material called stabilizers or interfacing are added beneath or on top of the fabric, or both. Stabilizer types include cut-away, tear-away, solvy water-soluble, heat-n-gone, filmoplast, and open mesh, sometimes in various combinations.

For embroidered wearable items, the fabric is placed in a hoop. This is then attached to the machine . An X and Y drive mechanism moves the hoop under the needle following the design coordinates created when the design was digitized for embroidery.

Learn more on choosing the right stabilizer for your embroidery job here

Embroidering the design[edit]

Finally, the embroidery machine is started and monitored. For commercial machines, this process is more automated than for the home machines. Many designs require more than one color and may involve additional processing for appliqués, foam, or other special effects. Since home machines have only one needle, every color change requires the user to cut the thread and change the color manually. In addition, most designs have one or more jumps that need to be cut. Depending on the quality and size of the design, sewing a design file can require anywhere from a few minutes to over half a day!

Embroidery machines[edit]

Not all machines are solely used for embroidery; some are also used for sewing. Some of the more advanced features becoming available include a large color touchscreen, a USB interface, auto threading, built-in design editing software, embroidery adviser software, and design file storage systems. Commercial embroidery machines can be purchased with a set number of needle colors per head(1, 2, 3, 4, 6, 12, 15,18 or more colors). Industrial embroidery machines are available with 1 to 56 heads.

Commercial and contract embroidery factories[edit]

Factories can have a few small machines or many large machines, or any combination of machines. Contract embroidery is done on goods that the customer supplies to the embroidery house and is limited to the trade, “ASI” and marketing firms use these services almost exclusively. A company offering contract embroidery sews designs onto wearable items for brokers, other embroiderers, specialty firms, and screen printers at a wholesale rates. The customer of a contract embroiderer usually supplies the items to the factory and only pays for the embroidery service.

Commercial embroiderers, and some contract embroiderers, offer their services to the public, and can supply the wearable items, and usually have a vast collection of stock designs and text available, Keeping up with current market trends, and offering names and personalization as well as designs for embroidery.

Other supplies[edit]

Almost any type of fabric can be embroidered, given the proper stabilizer. Base materials include paper, fabric, and lightweight balsa wood.

Machine embroidery commonly uses polyester, rayon, or metallic embroidery thread, though other thread types are available. 40 wt thread is the most commonly used embroidery thread weight. Bobbin thread is usually either 60 wt or 90 wt. The quality of thread used can greatly affect the number of thread breaks and other embroidery problems. Polyester thread is generally more color-safe and durable. High quality embroidery thread is produced by Exquisite, Gunold, Madeira, Amann and Robison-Anton.

Other associated costs are thread, stabilizer, purchased designs, needles, bobbins, and other miscellaneous tools and supplies.

Embroidery glossary[edit]

A more thorough list of applicable terminologies is available at http://abcoln.com/glossary.php.

Appliqué
French term meaning applying, usually by sewing, one piece of fabric to the surface of another. A cut piece of material stitched to another adds dimension and texture and reduces the stitch count.
Backer/Stabilizer
Backing and stabilizer are often used interchangeably to refer to materials, generally non-woven textiles, which are placed inside or under the item to be embroidered. The backing provides support and stability to the garment which will improve the quality of the finished embroidered product. Backings come primarily in two types: cutaway and tear-away. With cutaway, the excess backing is cut with a pair of scissors. With tear-away, the excess is torn away after the item is embroidered. Additional types of stabilizer can be dissolved by water or heat.
Bobbin
A small spool of thread inside the rotary hook housing of a sewing machine. The bobbin thread forms the stitches on the underside of the garment. Bobbin thread holds the top embroidery thread to the garment. The bobbin on an embroidery machine works in the same manner and for the same purpose as on a standard sewing machine.
Digitize
The computerized technique of turning a design image into an embroidery program. Special software is used to create plotting commands for the embroidery machine. The commands are transferred to the machine’s logic head by a designated embroidery language.
Fill Stitch
Fill stitches are a series of running stitches sewn closely together to form broad areas of embroidery with varying patterns and stitch directions.
Hoop
A clamping device used to hold the backing and fabric in place in the machine.
Running Stitch
One straight line of stitches, often used for fine details, outlining, and underlay.
Satin Stitch
Also known as zigzag stitch, a satin stitch is a line, border or edge produced by thread being alternately stitched to either side of a baseline. Satin stitches are generally limited to a maximum of 1/2″ in stitch length before some alternate technique must be used, such as split stitching or fill stitching.
Underlay
A stabilizing pattern of embroidery which, if used, precedes the main body of satin or fill stitching. It consists of one or a combination of running stitches for centering, edging, paralleling, or zigzagging the design area. A money and time saving technique is to use, instead of a large amount of embroidery thread for underlay, a fancy specialty stitch saver patch material that simulates underlay.

from wikipedia

sewing machine

A sewing machine is a machine used to stitch fabric and other materials together with thread. Sewing machines were invented during the first Industrial Revolution to decrease the amount of manual sewing work performed in clothing companies. Since the invention of the first working sewing machine, generally considered to have been the work of Englishman Thomas Saint in 1790,[1]the sewing machine has greatly improved the efficiency and productivity of the clothing industry.

Home sewing machines are designed for one person to sew individual items while using a single stitch type. In a modern sewing machine the fabric easily glides in and out of the machine without the inconvenience of needles and thimbles and other such tools used in hand sewing, automating the process of stitching and saving time.

Industrial sewing machines, by contrast to domestic machines, are larger, faster, and more varied in their size, cost, appearance, and task.

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History[edit]

Invention[edit]

Charles Fredrick Wiesenthal, a German-born engineer working in England was awarded the first British patent for a mechanical device to aid the art of sewing, in 1755. His invention consisted of a double pointed needle with an eye at one end.[2]

Newton Wilson’s copy of Saint’s sewing machine.

Thomas Saint’s chain stitch used on the first ever complete sewing machine design for leather work. An awl preceded the eye pointed needle to make a hole in preparation for the thread.

In 1790, the English inventor Thomas Saint invented the first sewing machine design, but he did not successfully advertise or market his invention.[3] His machine was meant to be used on leather and canvas material. It is likely that Saint had a working model but there is no evidence of one; he was a skilled cabinet maker and his device included many practically functional features: an overhanging arm, a feed mechanism (adequate for short lengths of leather), a vertical needle bar, and a looper.

His sewing machine used the chain stitch method, in which the machine uses a single thread to make simple stitches in the fabric. A stitching awl would pierce the material and a forked point rod would carry the thread through the hole where it would be hooked underneath and moved to the next stitching place, where the cycle would be repeated, locking the stitch.[4] Saint’s machine was designed to aid the manufacture of various leather goods, including saddles and bridles, but it was also capable of working with canvas, and was used for sewing ship sails. Although his machine was very advanced for the era, the concept would need steady improvement over the coming decades before it could become a practical proposition. In 1874, a sewing machine manufacturer, William Newton Wilson, found Saint’s drawings in the London Patent Office, made adjustments to the looper, and built a working machine, currently owned by the London Science Museum.

In 1804, a sewing machine was built by the Englishmen Thomas Stone and James Henderson, and a machine for embroidering was constructed by John Duncan in Scotland.[5] An Austrian tailor, Josef Madersperger, began developing his first sewing machine in 1807. He presented his first working machine in 1814.

The first practical and widely used sewing machine was invented by Barthélemy Thimonnier, a French tailor, in 1829. His machine sewed straight seams using chain stitch like Saint’s model, and in 1830, he signed a contract with Auguste Ferrand, a mining engineer, who made the requisite drawings and submitted a patent application. The patent for his machine was issued on 17 July 1830, and in the same year, he opened (with partners) the first machine-based clothing manufacturing company in the world to create army uniforms for the French Army. However, the factory was burned down, reportedly by workers fearful of losing their livelihood following the issuing of the patent.[6]

A model of the machine is exhibited at the London Science Museum. The machine is made of wood and uses a barbed needle which passes downward through the cloth to grab the thread and pull it up to form a loop to be locked by the next loop. The first American lockstitch sewing machine was invented by Walter Hunt in 1832.[7] His machine used an eye-pointed needle (with the eye and the point on the same end) carrying the upper thread and a falling shuttle carrying the lower thread. The curved needle moved through the fabric horizontally, leaving the loop as it withdrew. The shuttle passed through the loop, interlocking the thread. The feed let the machine down, requiring the machine to be stopped frequently and reset up. Hunt eventually lost interest in his machine and sold individual machines without bothering to patent his invention, and only patenting it at a late date of 1854. In 1842, John Greenough patented the first sewing machine in the United States. The British partners Newton and Archibold introduced the eye-pointed needle and the use of two pressing surfaces to keep the pieces of fabric in position, in 1841.[8]

The first machine to combine all the disparate elements of the previous half-century of innovation into the modern sewing machine was the device built by English inventor John Fisher in 1844, thus a little earlier than the very similar machines built by the infamous Isaac Merritt Singer in 1851, and the lesser known Elias Howe, in 1845. However, due to the botched filing of Fisher’s patent at the Patent Office, he did not receive due recognition for the modern sewing machine in the legal disputations of priority with Singer, and it was Singer who won the benefits of the patent.

Industrial competition[edit]

Elias Howe, born in Spencer, Massachusetts, created his sewing machine in 1845, using a similar method to Fisher’s except that the fabric was held vertically. An important improvement on his machine was to have the needle running away from the point, starting from the eye.[9] After a lengthy stay in England trying to attract interest in his machine, he returned to America to find various people infringing his patent, among them Isaac Merritt Singer.[10] He eventually won a case for patent infringement in 1854, and was awarded the right to claim royalties from the manufacturers using ideas covered by his patent, including Singer.

Singer had seen a rotary sewing machine being repaired in a Boston shop. As an engineer, he thought it was clumsy and decided to design a better one. The machine he devised used a falling shuttle instead of a rotary one; the needle was mounted vertically and included a presser foot to hold the cloth in place. It had a fixed arm to hold the needle and included a basic tension system. This machine combined elements of Thimonnier, Hunt and Howe’s machines. Singer was granted an American patent in 1851, and it was suggested[by whom?] he patent the foot pedal or treadle, used to power some of his machines; unfortunately, the foot pedal had been in use too long for a patent to be issued. When Howe learned of Singer’s machine he took him to court, where Howe won and Singer was forced to pay a lump sum for all machines already produced. Singer then took out a license under Howe’s patent and paid him $1.15 per machine before entering into a joint partnership with a lawyer named Edward Clark. They created the first hire-purchase arrangement to allow people to buy their machines through payments over time.

Meanwhile, Allen B. Wilson developed a shuttle that reciprocated in a short arc, which was an improvement over Singer and Howe’s. However, John Bradshaw had patented a similar device and threatened to sue, so Wilson decided to try a new method. He went into partnership with Nathaniel Wheeler to produce a machine with a rotary hook instead of a shuttle. This was far quieter and smoother than other methods, with the result that the Wheeler & Wilson Company produced more machines in the 1850s and 1860s than any other manufacturer. Wilson also invented the four-motion feed mechanism that is still seen on every sewing machine today. This had a forward, down, back and up motion, which drew the cloth through in an even and smooth motion. Charles Miller patented the first machine to stitch buttonholes.[11][12] Throughout the 1850s more and more companies were being formed, each trying to sue the others for patent infringement. This triggered a patent thicket known as the Sewing Machine War.[13]

In 1856, the Sewing Machine Combination was formed, consisting of Singer, Howe, Wheeler, Wilson, Grover and Baker. These four companies pooled their patents, with the result that all other manufacturers had to obtain a license and pay $15 per machine. This lasted until 1877, when the last patent expired. James Edward Allen Gibbs (1829–1902), a farmer from Raphine in Rockbridge County, Virginia patented the first chain stitch single-thread sewing machine on June 2, 1857. In partnership with James Willcox, Gibbs became a principal partner in Willcox & Gibbs Sewing Machine Company.

Willcox & Gibbs commercial sewing machines are still used in the 21st century.

Spread and maturation[edit]

Jones Family CS machine from around 1935

William Jones started making sewing machines in 1859 and in 1860 formed a partnership with Thomas Chadwick. As Chadwick & Jones, they manufactured sewing machines at Ashton-under-Lyne, England until 1863. Their machines used designs from Howe and Wilson produced under licence.[14] Thomas Chadwick later joined Bradbury & Co. William Jones opened a factory in Guide Bridge, Manchester in 1869.[15] In 1893 a Jones advertising sheet claimed that this factory was the “Largest Factory in England Exclusively Making First Class Sewing Machines”.[16] The firm was renamed as the Jones Sewing Machine Co. Ltd and was later acquired by Brother Industries of Japan, in 1968.[17]

Vintage sewing patterns

Clothing manufacturers were the first sewing machine customers, and used them to produce the first ready-to-wear clothing and shoes. In the 1860s consumers began purchasing them, and the machines—ranging in price from £6 to £15 in Britain depending on features—became very common in middle-class homes. Owners were much more likely to spend free time with their machines to make and mend clothing for their families than to visit friends, and women’s magazines and household guides such as Mrs Beeton’s offered dress patterns and instructions. A sewing machine could produce a man’s shirt in about one hour, compared to 14 1/2 hours by hand.[18]

In 1877 the world’s first crochet machine was invented and patented by Joseph M. Merrow, then-president of what had started in the 1840s as a machine shop to develop specialized machinery for the knitting operations. This crochet machine was the first production overlock sewing machine. The Merrow Machine Company went on to become one of the largest American Manufacturers of overlock sewing machines, and continues to be a global presence in the 21st century as the last American over-lock sewing machine manufacturer.

In 1885 Singer patented the Singer Vibrating Shuttle sewing machine, which used Allen B. Wilson’s idea for a vibrating shuttle and was a better lockstitcher than the oscillating shuttles of the time. Millions of the machines, perhaps the world’s first really practical sewing machine for domestic use, were produced until finally superseded by rotary shuttle machines in the 20th century. Sewing machines continued being made to roughly the same design, with more lavish decoration appearing until well into the 1900s.

The first electric machines were developed by Singer Sewing Co. and introduced in 1889.[19] By the end of the First World War, Singer was offering hand, treadle and electric machines for sale. At first the electric machines were standard machines with a motor strapped on the side, but as more homes gained power, they became more popular and the motor was gradually introduced into the casing.

Design[edit]

Stitches[edit]

The bobbin driver of a Husqvarna 3600 sewing machine

Sewing machines can make a great variety of plain or patterned stitches. Ignoring strictly decorative aspects, over three dozen distinct stitch formations are formally recognized by the ISO 4915:1991 standard, involving one to seven separate threads to form the stitch.[20]

Plain stitches fall into four general categories: chainstitch, lockstitch, overlock, and coverstitch.

Chainstitch[edit]

Chainstitch was used by early sewing machines and has two major drawbacks:

The basic chain stitch.

  • The stitch is not self-locking, and if the thread breaks at any point or is not tied at both ends, the whole length of stitching comes out. It is also easily ripped out.[21]
  • The direction of sewing cannot be changed much from one stitch to the next, or the stitching process fails.

A better stitch was found in the lockstitch. The chainstitch is still used today in clothing manufacture, though due to its major drawback it is generally paired with an overlock stitch along the same seam.

Lockstitch[edit]

Formation of a lock-stitch using a boat shuttle as employed in early domestic machines

Lockstitch utilising a rotating hook invented by Allen B Wilson. This is employed on many modern machines

Formation of the double locking chain stitch

Lockstitch is the familiar stitch performed by most household sewing machines and most industrial “single needle” sewing machines from two threads, one passed through a needle and one coming from a bobbin or shuttle. Each thread stays on the same side of the material being sewn, interlacing with the other thread at each needle hole by means of a bobbin driver. As a result, a lockstitch can be formed anywhere on the material being sewn; it does not need to be near an edge.

Overlock[edit]

A Zoje industrial overlocker

Overlock, also known as “serging” or “serger stitch”, can be formed with one to four threads, one or two needles, and one or two loopers. Overlock sewing machines are usually equipped with knives that trim or create the edge immediately in front of the stitch formation. Household and industrial overlock machines are commonly used for garment seams in knit or stretchy fabrics, for garment seams where the fabric is light enough that the seam does not need to be pressed open, and for protecting edges against raveling. Machines using two to four threads are most common, and frequently one machine can be configured for several varieties of overlock stitch. Overlock machines with five or more threads usually make both a chainstitch with one needle and one looper, and an overlock stitch with the remaining needles and loopers. This combination is known as a “safety stitch”. A similar machine used for stretch fabrics is called a mock safety.

Coverstitch[edit]

Coverstitch is formed by two or more needles and one or two loopers. Like lockstitch and chainstitch, coverstitch can be formed anywhere on the material being sewn. One looper manipulates a thread below the material being sewn, forming a bottom cover stitch against the needle threads. An additional looper above the material can form a top cover stitch simultaneously. The needle threads form parallel rows, while the looper threads cross back and forth all the needle rows. Coverstitch is so-called because the grid of crossing needle and looper threads covers raw seam edges, much as the overlock stitch does. It is widely used in garment construction, particularly for attaching trims and flat seaming where the raw edges can be finished in the same operation as forming the seam.

Zigzag stitch[edit]

Zigzag stitch

A zigzag stitch is a variant geometry of the lockstitch. It is a back-and-forth stitch used where a straight stitch will not suffice, such as in preventing raveling of a fabric, in stitching stretchable fabrics, and in temporarily joining two work pieces edge-to-edge.

When creating a zigzag stitch, the back-and-forth motion of the sewing machine’s needle is controlled by a cam. As the cam rotates, a fingerlike follower, connected to the needle bar, rides along the cam and tracks its indentations. As the follower moves in and out, the needle bar is moved from side to side.[22] Very old sewing machines lack this hardware and so cannot natively produce a zigzag stitch, but there are often shank-driven attachments available which enable them to do so.

Feed mechanisms[edit]

Besides the basic motion of needles, loopers and bobbins, the material being sewn must move so that each cycle of needle motion involves a different part of the material. This motion is known as feed, and sewing machines have almost as many ways of feeding material as they do of forming stitches. For general categories, there are: drop feed, needle feed, walking foot, puller, and manual. Often, multiple types of feed are used on the same machine. Besides these general categories, there are also uncommon feed mechanisms used in specific applications like edge joining fur, making seams on caps, and blindstitching.

Drop feed[edit]

Presser foot raised with feed dogs visible

The drop feed mechanism is used by almost all household machines and involves a mechanism below the sewing surface of the machine. When the needle is withdrawn from the material being sewn, a set of “feed dogs” is pushed up through slots in the machine surface, then dragged horizontally past the needle. The dogs are serrated to grip the material, and a “presser foot” is used to keep the material in contact with the dogs. At the end of their horizontal motion, the dogs are lowered again and returned to their original position while the needle makes its next pass through the material. While the needle is in the material, there is no feed action. Almost all household machines and the majority of industrial machines use drop feed. Differential feed is a variation of drop feed with two independent sets of dogs, one before and one after the needle. By changing their relative motions, these sets of dogs can be used to stretch or compress the material in the vicinity of the needle. This is extremely useful when sewing stretchy material, and overlock machines (heavily used for such materials) frequently have differential feed.

Needle feed[edit]

A needle feed, used only in industrial machines, moves the material while the needle is in the material. In fact, the needle may be the primary feeding force. Some implementations of needle feed rock the axis of needle motion back and forth, while other implementations keep the axis vertical while moving it forward and back. In both cases, there is no feed action while the needle is out of the material. Needle feed is often used in conjunction with a modified drop feed, and is very common on industrial two needle machines. Household machines do not use needle feed as a general rule.

Walking foot[edit]

Vintage Davis vertical feed (walking foot) sewing machine produced around 1890

A walking foot replaces the stationary presser foot with one that moves along with whatever other feed mechanisms the machine already has. As the walking foot moves, it shifts the workpiece along with it. It is most useful for sewing heavy materials where needle feed is mechanically inadequate, for spongy or cushioned materials where lifting the foot out of contact with the material helps in the feeding action, and for sewing many layers together where a drop feed will cause the lower layers to shift out of position with the upper layers.

Puller feed[edit]

Some factory machines and a few household machines are set up with an auxiliary puller feed, which grips the material being sewn (usually from behind the needles) and pulls it with a force and reliability usually not possible with other types of feed. Puller feeds are seldom built directly into the basic sewing machine. Their action must be synchronized with the needle and feed action built into the machine to avoid damaging the machine. Pullers are also limited to straight seams, or very nearly so. Despite their additional cost and limitations, pulling feeds are very useful when making large heavy items like tents and vehicle covers.

Manual feed[edit]

A manual feed is used primarily in freehand embroidery, quilting, and shoe repair. With manual feed, the stitch length and direction is controlled entirely by the motion of the material being sewn. Frequently some form of hoop or stabilizing material is used with fabric to keep the material under proper tension and aid in moving it around. Most household machines can be set for manual feed by disengaging the drop feed dogs. Most industrial machines can not be used for manual feed without actually removing the feed dogs.

Needles[edit]

Main article: Sewing machine needle

Sewing machines use special needles tailored to their needs and to the character of the material being sewn.

Industrial vs domestic[edit]

Industrial Sewing Machine (left), Domestic Sewing machine (right)

Industrial sewing machines are larger, faster, and more varied in their size, cost, appearance, and task. Industrial machines, unlike domestic machines, perform a single dedicated task and are capable of long hours of usage and as such have larger moving parts and comparatively much larger motors. Industrial machines are also more generic; a motor for almost any type of machine can work on any brand. Sewing feet and bobbins between brands are interchangeable. However, with domestic machines the motor, and to a lesser extent bobbins and sewing feet, are brand specific.

The motors on industrial machines, as with most of their components, lights, etc., are separate, usually mounted to the underside of the table. Domestic machines have their OEM motors mounted inside the machine. There are two different types of motor available for industrial machines: a servo motor (which uses less electricity and is silent when not in use), and the more traditional clutch motor (which is always spinning; even when not in use).[23]

Social impact[edit]

Seamstresses in 1904

Before sewing machines were invented women spent much of their time maintaining their family’s clothing. Middle-class housewives, even with the aid of a hired seamstress, would devote several days of each month to this task. It took an experienced seamstress at least 14 hours to make a dress shirt for a man; a woman’s dress took 10 hours;[24] and a pair of summer pants took nearly three hours.[25] Most individuals would have only two sets of clothing: a work outfit and a Sunday outfit.

Sewing machines reduced the time for making a dress shirt to an hour and 15 minutes; the time to make a dress to an hour;[24] and the time for a pair of summer pants to 38 minutes.[25] This reduced labor resulted in women having a diminished role in household management, and allowed more hours for their own leisure as well as the ability to seek more employment.[24]

Woman using a treadle sewing machine manufactured by Singer

Women working in a clothing factory in Montreal, Quebec in 1941

Industrial use of sewing machines further reduced the burden placed upon housewives, moving clothing production from housewives and seamstresses to large-scale factories.[24] The movement to large-scale factories also resulted in a decrease in the amount of time clothing production took, which caused the prices for clothing to drop significantly. This is because manufacturers were able to decrease the number of workers needed to produce the same amount of clothing, resulting in reduced costs. Increased supply also lowered the cost.[25]

The initial effects of sewing machines on workers were both positive and negative, however in the long run the negative effects decreased. Many of the women who had previously been busy at home could now seek employment in factories, increasing the income for their family. This allowed for families to be able to afford more sets of clothing and items than they previously could.[25] For seamstresses, home sewing machines allowed them to produce clothing for the average person during periods when demand for fitted clothes was low, effectively increasing their earnings. When industrial sewing machines initially became popular many seamstresses working in factories as well as those working at home lost their jobs as it meant that fewer workers could produce the same output.[24] In the long run these now unemployed workers along with thousands of men and children would eventually be able to gain employment in jobs created as the clothing industry grew.[25]

The sewing machine’s effects on the clothing industry resulted in major changes for other industries as well. Cotton production needed to increase in order to match the demand of the new clothing factories. As a result, cotton became planted in new areas where it hadn’t previously been farmed. Other industries involved in the process benefited as well such as metal companies who provided for parts of the machines and shippers to move the increased amounts of goods.[26] Gun makers visited clothing factories in order to perfect their own mass production techniques.[27] In addition to being important for clothing production, sewing machines also became important in the manufacturing of furniture with upholstery, curtains and towels, toys, books, and many other products.[26]

Variations[edit]

There are other variations of sewing machines aside from purely human-driven ones. These include:

  • High-speed industrial sewing machine
  • Electrical, programmable, automatic pattern stitching sewing machine

Manufacturers[edit]

Not included in list of above category link includes:

 

from wikipedia