washing machine

 

A washing machine, or washer, is a machine designed to clean laundry, such as clothing, towels and sheets. The term is mostly applied only to machines that use water as the primary cleaning solution, as opposed to dry cleaning (which uses alternative cleaning fluids, and is generally performed by specialist businesses) or even ultrasonic cleaners.

All washing machines work by using mechanical energy, thermal energy, and chemical action. Mechanical energy is imparted to the clothes load by the rotation of the agitator in top loaders, or by the tumbling action of the drum in front loaders. Thermal energy is supplied by the temperature of the wash bath.

Clothes washing history

Clothing has been hand-washed for thousands of years, by flushing water through the fabric to remove loose dirt, rubbing with soap to remove oils and stains, and applying fragrances to cover odours. For particularly dirty clothing caked with mud or dirt, it was necessary to constantly rub and flex the cloth to break apart solids and help the soap penetrate through thick, dry, or sticky layers of soil on the cloth. At first this was done by pounding or rubbing the clothing with rocks in a river, and later developed into the corrugated wash board. In Roman times a fuller would whiten clothing by stomping on it in a bucket full of fermented urine.

Washing machine technology was initially developed as a way to reduce the physical drudgery of this laborious scrubbing and rubbing process, by providing an open basin or sealed container with paddles or fingers to automatically agitate the clothing. The earliest machines were often hand-operated but were built with the belief that the machine itself was faster and easier to operate than washing the clothing by hand directly. As electricity was not commonly available until at least 1930, these early machines were often operated by a low-speed single-cylinder hit and miss gasoline engine.

Because water usually had to be heated on a fire for washing, the warm soapy water was precious and would be reused over and over, first to wash the least soiled clothing, then to wash progressively dirtier clothing. The load of soaking wet clothing would be removed, and another load of dirty clothes added to the machine. While the earliest machines were constructed entirely from wood, later machines made of metal permitted a fire to burn below the washtub, to keep the water warm throughout the day's washing.

Removal of soap and water from the clothing after washing was originally a separate process. The soaking wet clothing would be formed into a roll and twisted by hand to extract water. To help reduce this labor, the wringer/mangle was developed, which uses two rollers under spring tension to squeeze water out of the clothing. Each piece of clothing would be fed through the wringer separately. The first wringers were hand-operated, but were eventually included as a powered attachment above the washer tub. The wringer would be swung over the wash tub so that extracted wash water would fall back into the tub to be reused for the next wash load.

The modern process of water removal by spinning did not come into use until electric motors were developed. Spinning requires a constant high-speed power source, and was originally done in a separate device known as an extractor. A load of washed clothing would be transferred from the wash tub to the extractor basket, and the water spun out. These early extractors were often dangerous to use since unevenly distributed loads would cause the machine to shake violently. Many efforts have been made to counteract the shaking of unstable loads, first by mounting the spinning basket on a free-floating shock-absorbing frame to absorb minor imbalances, and a bump switch to detect severe movement and stop the machine so that the load can be manually redistributed. Many modern machines are equipped with a sealed ring of liquid around the top of the basket that works to counteract any imbalances.

What is now commonly referred to as an automatic washer was at one time referred to as a washer/extractor, which combines the features of these two separate devices into a single machine, plus also includes the ability to fill and drain water by itself. It is possible to take this a step further, to also merge the automatic washing machine and clothes dryer into a single device, but this is generally uncommon because the drying process tends to use much more energy than using two separate devices; a combined washer/dryer not only must dry the clothing, but also needs to dry out the wash chamber itself.

Washing Machine Milestones

The first English patent under the category of Washing and Wringing Machines was issued in 1691.^{[citation needed]} A drawing of an early washing machine appeared in the January 1752 issue of "The Gentlemen's Magazine," an English publication. In Germany, Jacob Christian Schäffer's washing machine design was published in 1767.[1] In 1782 Henry Sidgier was issued a British patent for a rotating drum washer.

The first United States Patent titled "Clothes Washing" was granted to Nathaniel Briggs of New Hampshire in 1797. Fire destroyed the patent office and no description of the device exists so it is not known what kind of washing device Briggs "invented."

The electric washing machine was first mass-produced in 1906. It is not known who first invented the electric washer. Alva J. Fisher has been incorrectly credited with the invention of the electric washer. The US patent office shows at least one patent issued before Mr. Fisher's US patent number 966677 (e.g. Woodrow's US patent number 921195).

Although somewhat cyclic, US electric washing machine sales increased after World War I, reaching 913,000 units in 1928, the main reason why so many people bought the washing machine was because it saved people lots of time in domestic tasks, and the result was that society's expectations for cleanliness went up. However, high unemployment in the Depression years hit sales; by 1932 the number of units shipped was down to about 600,000.

The first laundromat opened in Fort Worth, Texas in 1934. It was run by Andrew Clein. Patrons used coin-in-the-slot facilities to rent washing machines. Since then, laundromats have become common.

Washer design improved markedly during the 1930s; the mechanism was now enclosed within a cabinet; more attention was paid to electrical safety; spin dryers were introduced, to replace the dangerous power wringers of the day.

Early automatic washing machines were usually connected to the water supply via temporary slip-on connectors to the sink taps. Later, permanent connections to both the hot and cold water supplies became the norm. Most modern front-loading European machines now only have a cold water connection (i.e. cold fill) and rely completely on electric heaters to raise the water temperature.

By 1940, 60% of the 25,000,000 wired homes in the United States had an electric washing machine. Many of these machines featured a power wringer, although built-in spin dryers were not uncommon.

Bendix introduced the first automatic washing machine in 1937,^[1] having applied for a patent in the same year.^[2] In appearance and mechanical detail, this first machine is not unlike the front loading automatic washers produced today. Although it included many of the today's basic features, the machine lacked any drum suspension and therefore had to be anchored to the floor to prevent "walking".

Many of these early automatic machines had coin-in-the-slot facilities and were installed in the basement laundry rooms of apartment houses. Naturally, after the attack on Pearl Harbor, US domestic washer production had to be suspended for the duration of World War II. However, many US appliance manufacturers were given permission to undertake the research and development of washers during the war years. Many took the opportunity to develop automatic machines, realising that these represented the future for the industry.

An improved front loading automatic model, the Bendix Deluxe (which retailed at $249.50) was introduced in 1947.^[3]

General Electric introduced the first top loading automatic also in 1947. This machine had many of the features that are incorporated into modern machines.

A large number of US manufacturers introduced competing automatic machines (mainly of the top loading type) in the late 1940s/early 1950s. Several manufacturers even produced semi-automatic machines, where the user had to intervene at one or two points in the wash cycle. A common semi-automatic type (available from Hoover in the UK until at least the 70's) included 2 tubs: one with an agitator or impeller for washing and/or rinsing; another, smaller, tub for water extraction or centrifugal rinsing.

Since their introduction in the late 1930s/mid 1940s, automatic washing machines have relied on mechanical timers to sequence the washing and extraction process. Mechanical timers consist of a series of cams on a common shaft. At the appropriate time in the wash cycle, each cam actuates a switch to engage/disengage a particular part of the machinery (e.g. drain pump motor). The timer shaft is driven by a small electric motor via a reduction gearbox.

On the early mechanical timers the motor ran at a constant speed throughout the wash cycle, although it was possible for the user to truncate parts of the program, by manually advancing the control dial. However, by the 50s demand for greater flexibility in the wash cycle led to the introduction of electronic timers to supplement the basic mechanical timer. These electronic timers enable greater variation in such functions as the wash time. With this arrangement, the electric timer motor is periodically switched-off to permit the clothing to soak, and is only re-energised just prior to a micro-switch being engaged/disengaged.

Despite the high cost of automatic washers, manufacturers had difficulty in meeting the pent-up demand. Although there were material shortages during the Korean War, by 1953 automatic washing machine sales in the US exceeded those of wringer-type electric machines.

In the UK, electric washing machines did not become popular until the 1950s. The early electric washers were single tub, wringer-type machines, automatic washing machines being extremely expensive. During the 1960s, twin tub machines briefly became very popular, helped by the low price of the Rolls Razor washers. Automatic washing machines did not really become common in the UK until well into the 1970s.

In early automatic washing machines, any changes in impeller/drum speed were achieved by mechanical means or by a rheostat on the motor power supply. However, since the 1970s electronic control of motor speed has become a common feature on the more expensive models.

Early front loading machines, especially those manufactured in Mediterranean countries (e.g. Italy), had relatively low spin speeds (e.g. 800rpm or less). Nowadays, a spin speed of 1200rpm is common and a peak spin speed as high as 1600rpm is available on some machines. Now models in Europe have speeds of 1800rpm and one washing machine has a spin speed of 2000rpm. However, because they were not susceptible to gravitational forces, some early top loading machines had spin speeds in excess of 1000rpm, although some were as low as 360rpm.

In the late 1990s, the British inventor James Dyson launched a type of washing machine with two cylinders rotating in opposite directions; which, it is claimed, reduces the wash time and produces cleaner results; however, this machine is not currently in production.

In the 1990s, upmarket machines incorporated microcontrollers for the timing process. These proved reliable, so many cheaper machines now incorporate microcontrollers, rather than mechanical timers. Washing machines are a classic application for fuzzy logic.

In 2001, Whirlpool Corporation introuced the first High Efficiency washing machine to be Top-Loading. The machine was known as the Calypso. A washplate in the bottom of the tub nutated to bounce, shake, and toss the laundry around. As this happened, water containing detergent was sprayed on to the laundry. The machine proved to be one of the best machines in terms of cleaning but quickly gained a bad reputation due to frequent breakdowns and destruction of laundry and the washer was eventually recalled with a class-action lawsuit and pulled off the market.

Modern machines

Modern washing machines are available in two main configurations: top loading and front loading. The top loading design, most popular in the United States, Canada, Australia and some parts of Europe, places the clothes in a vertically-mounted perforated basket that is contained within a water-retaining tub, with a propeller-like agitator in the center of the bottom of the basket. Clothes are loaded through the top of the machine, which is covered with a hinged door. During the wash cycle, the outer tub is filled with water sufficient to suspend the clothing freely in the basket, and the movement of the agitator pulls the clothing downward in the center towards the agitator paddles. The clothing then moves outward and up the sides of the basket to repeat the process. Top-loaders are not well-suited to cleaning large objects such as pillows or sleeping bags due to the tendency for them to just float on the surface of the water without circulating, and the aggressive agitator action can damage delicate fabrics.

In most top loading washers, if the motor spins in one direction, the gearbox drives the agitator; if the motor spins the other way, the gearbox locks the agitator and spins the basket and agitator together. Similarly if the pump motor rotates one way it recirculates the sudsy water; in the other direction it pumps water from the machine during the spin cycle. Because they usually incorporate a gearbox, clutch, crank, etc, top loading washers are mechanically more complex than front loading machines but are generally lower maintenance since there is no need for a complex door seal (described below).

The front loading design, most popular in Europe and the Middle East, mounts the inner basket and outer tub horizontally, and loading is through a glass door at the front of the machine. Agitation is supplied by the back-and-forth rotation of the cylinder and by gravity. The clothes are lifted up by paddles on the inside wall of the drum and then dropped. This motion flexes the weave of the fabric and forces water and detergent solution through the clothes load. Because the wash action does not require the clothing be freely suspended in water, only enough water is needed to moisten the fabric. Because less water is required, front-loaders typically use less soap, and the aggressive dropping and folding action of the tumbling can easily produce large amounts of foam.

Front-loaders control water usage through the surface tension of water, and the capillary wicking action this creates in the fabric weave. A front-loader washer always fills to the same low water level, but a large pile of dry clothing standing in water will soak up the moisture, causing the water level to drop. The washer then refills to maintain the original water level. Because it takes time for this water absorption to occur with a motionless pile of fabric, nearly all front-loaders begin the washing process by slowly tumbling the clothing under the stream of water entering and filling the drum, to rapidly saturate the dry cloth with water.

Front loading washers are mechanically relatively simple compared to top-loaders, with the main motor normally being connected to the drum via a grooved pulley belt and large pulley wheel, without the need for a gearbox, clutch or crank. But front-load washers suffer from their own technical problems, due to the drum lying sideways. For example, a top loading washer keeps water inside the tub merely through the force of gravity pulling down on the water, while a front-loader must tightly seal the door shut with a gasket to prevent dripping water onto the floor during the wash cycle. This access door is locked shut during the entire wash cycle, since opening the door with the machine in use could result in water gushing out onto the floor. For front-loaders without viewing windows on the door, it is possible to accidentally pinch fabric between the door and the drum, resulting in tearing and damage to the pinched clothing during tumbling and spinning.

Nearly all front-loader washers for the consumer market must also use a folded flexible bellows assembly around the door opening, to keep clothing contained inside the basket during the tumbling wash cycle. If this bellows assembly were not used, small articles of clothing such as socks could slip out of the wash basket near the door, and fall down the narrow slot between the outer tub and basket, plugging the drain and possibly jamming rotation of the inner basket. Retrieving lost items from between the outer tub and inner basket can require complete disassembly of the front of the washer and pulling out the entire inner wash basket. Commercial and industrial front-loaders used by businesses (described below) usually do not use the bellows, and instead require all small objects to be placed in a mesh bag to prevent loss near the basket opening.

This bellows assembly around the door is the source of problems for the consumer front-loader. The bellows has a large number of flexible folds to permit the tub to move separately from the door during the high speed extraction cycle. These folds can collect lint, dirt, and moisture, resulting in mold and mildew growth and a foul odor. Some front-loading washer operating instructions say the bellows should be wiped down monthly with a strong bleach solution, while others offer a special freshening cycle where the machine is run empty with a strong dosing of bleach.

A top-loading washer suffers from none of these continued maintenance problems and needs no regular freshening. During the spin cycle, a top-loading tub is free to move about inside the cabinet of the machine, using only a lip around the top of the inner basket and outer tub to keep the spinning water and clothing from spraying out over the edge.

There are many variations of these two general themes. Top loading machines in Asia use impellers instead of agitators. Impellers are similar to agitators except that they do not have the center post extending up in the middle of the wash tub basket. There is also a top loading variant of the horizontal axis design that is loaded from the top, through a small door in the circumference of the drum. These machines usually have a shorter cylinder and are therefore smaller, but offer the efficiency of a front-loader while eliminating the problems of the flexible bellows. This kind of washing machine is sold and popular in Europe, especially in small households, because it offers the same drum system as front loaders, just with a smaller footprint.

Front-loaded machines are ideal for fitted/finished kitchens, since they can be installed under a countertop/worktop. A front loading washing machine, in a fully-fitted kitchen, is often disguised as an ordinary base cabinet/unit. They are also ideal for small homes and apartments with limited space, because the dryer can be installed directly above the washer.

Many front loading machines have electrical heating elements to heat the wash bath to near boiling, if desired. Chemical action is supplied by the detergent and other laundry chemicals. Front loaders use special detergents that are designed to release different chemical ingredients at different temperatures. This is so that different type of stains and soils will be cleaned from the clothes as the wash water is heated up by the electrical heater. Front loaders also need to use low sudsing detergents because the tumbling action of the drum folds air into the clothes load that can cause over-sudsing. Due to the concentration of water and detergent, though, the sudsing issue of front-loaders can also be controlled by simply using less detergent without lessening cleaning action.

Tests comparing front loading and top loading machines have shown that, in general, front-loaders wash clothes more thoroughly, cause less wear, and use less water and energy than top-loaders. As a result of using less water, they require less detergent to be used, or conversely, they can use the same amount of detergent with less water, which increases detergent concentration and increases the amount of chemical action. They also allow a dryer to be more easily mounted directly above the washer.

Top-loaders have had the advantage that they complete a washing cycle much faster and allow clothes to be removed at intermediate stages of the cycle (for instance, if some clothes within a wash are not to be spun). Many current front-loaders, though, can be stopped and added-to or removed-from because the water level in the horizontal tub is still below the door level.. They also tend to be easier to load and unload, since reaching into the tub does not require stooping. Again, this issue can be mitigated due to the offering of risers (usually with storage drawers underneath) to raise the door opening closer to the user's level. The top loader's spin cycle between washing and rinsing allows an extremely simple fabric softener dispenser, which operates passively through centrifugal force and gravity. The same objective must be accomplished by a solenoid-operated valve on a front loader. Another advantage to the top loading design is the reliance on gravity to contain the water, rather than potentially trouble-prone or short-lived front door seals.

Traditionally, top loading machines have tended to be more complex mechanically than front loading washers, because the former generally require a gearbox, clutch, crank, etc to perform the wash cycle. However, the recent introduction of direct drive motors has greatly simplified some of the top loading washers on the market. Also, because of the introduction of electronics, modern machines are far less complex than the early automatic washers. Consequently, the price of automatic machines, in real terms, has fallen considerably.

Top Loading versus Front Loading

The choice of a top-loading Washer or a front-loading is strongly based on user preference. A top-loader leans more towards efficiency with dramatically faster wash times and a better cleaning method, although that's being debated by Europeans who have lived in the US and have had a chance to compare the overall cleanliness of clothes after using top-loaders. Front-loaders, on the other hand, lean toward less consumption with dramatically lower amounts of water and less detergent required.

Consumer

Feature	Top Loading Washer	Front Loading Washer
Price (Cheapest)	√[4]	-
US Market Share	95%	5%
European Market Share	10%	90%

In the United States, top-loading machines are the most commonly used. On the other hand, in Europe the front-loading style is more preferred probably due to greater efficiency and also because a front loader doesn't use a spindle that will cause additional wear and tear on the clothes' fabric. The top-loading style may be mainly preferred in the U.S. because of the United States fast-pace culture that prefers faster wash time. ^{[citation needed]} Some might also say that the rule of "if it ain't broke, don't fix it" prevalent in many everyday household items in the U.S. applies to top-loaders as well. Another example for that would be light switches in the U.S. that almost always follow the classic flip-switch design. In Europe, there's a plethora of switches with different functionality available and in use.

Usage

Feature	Top Loading Washer	Front Loading Washer
Water	-	√
Detergent	-	√**
Energy	Varies by manufacture	Varies by manufacture

Though front-loaders feature a wash style that requires less water than a top-loader, a front-loader's wash time is much longer than a top-loader's.

• **Front-loading washers require less detergent but require a special, more expensive, HE detergent. However it must be noted that in Europe all the detergents are HE, and there's no price difference, standard detergent disapeared with the introduction of the automatic washers.

Washing Process

Feature	Top Loading Washer	Front Loading Washer
Cycle Time (fastest)	√	-
Cycle Options	√	√
Cleaning Effectiveness	√	√

European Standards

Capacity and cost are the main considerations when purchasing a washing machine. If intended for use by a single person, a capacity of under 5 kg should be sufficient (thus saving energy and running costs).

Washing machines display an EU Energy Label with grades for washing performance, energy efficiency and spin efficiency. Grades run from A to G (best to worst), and provide a simple method for judging running costs and performance. An A++ machine will denote top performance in the three categories.

Commercial Washing machine

A commercial washing machine is typically intended for more frequent and long-term usage than a standard consumer washing machine. Because function is more important than style, most commercial washers have a very sharp-edged square appearance, often with completely stainless steel exteriors to minimize rust and corrosion in a constantly moist environment. They are built with large easy-to-open service covers, and the washer mechanisms are internally laid out in a manner that does not require access to the underside of the unit for service. Often commercial washers are installed in long rows with a wide access passageway behind all the machines to allow maintenance without moving the heavy machine.

Many commercial washers are built for use by the general public, and are installed in publicly accessible laundromats or laundrettes, operated by money accepting devices or card readers. The features of a commercial laundromat washer are typically more limited than a consumer washer, offering just two or three basic wash types plus an option to choose wash cycle temperatures.

Commercial washers for business (still often referred to as a washer/extractor) can include extra features that are never seen in the consumer market. Many commercial washers often an option for automatic chemical injection of five or more different chemical types, so that the operator does not have to deal with constantly measuring out soap products and fabric softeners for each load. Instead a precise metering system draws the detergents and wash additives directly from large liquid-chemical storage barrels and injects them as needed into the various wash and rinse cycles.

Some computer-controlled commercial washers offer the operator complete control over the various wash and rinse cycles, allowing the operator to program custom washing cycles to specifically meet their industry needs.

One special type of continuous-processing washer is known as the tunnel washer which does not have separate, distinct wash or rinse cycles, but combines them all in sequence inside a single long large-diameter rotating tube.

Industrial Washing machine

An industrial clothes washer extends from the commercial washer to include extremely large capacities, severe-abuse textiles cleaning and processing, and automated robotic assembly-line systems.

These can be used to batch process up to 300 pounds of textiles at once, and can be used for extremely machine-abusive washing tasks such as stone washing or fabric bleaching and dyeing.

An industrial washer can be mounted on heavy shock absorbers and attached to a concrete floor so that it can extract water from even the most severely out-of-balance and heavy wash loads.

It may even be mounted on hydraulic cylinders, permitting the entire washer to be lifted and tilted so that fabrics can be automatically dumped from the wash drum onto a conveyor belt once the cycle is complete.

See also

• Bleach
• Centrifugation
• Clothes dryer
• Combo washer dryer
• Detergent
• Energetic efficiency
• Fabric softener
• Home appliance and major appliance
• Hotpoint
• Ironing
• Laundry detergent
• Laundry symbols
• Tunnel washer

References

External links

• Preservation and exhibition of vintage washing machines
• History of Washing Machines
• Washing Machine Diagnostic and Repair Guide
• How Washing Machines Work Article by HowStuffWorks.com
• Washing Machine repair and troubleshooting
• Washing Machine Museum
• Washing Machine repairs
• How to choose a washing machine?
• HE Washing Machine Buying Guidezh-yue:洗衣機

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