Washing Machine



Background

Mechanical washing machines appeared in the early 1800s, although they were all hand-powered. Early models cleaned clothes by rubbing them, while later models cleaned clothes by moving them through water. Steam-powered commercial washers appeared in the 1850s, but home washing machines remained entirely hand-powered until the early 1900s, when several companies started making electric machines. The Automatic Electric Washer Company and Hurley Machine Corporation both began selling electric washers in 1907, while Maytag offered an electric wringer washer in 1911. In 1947, Bendix offered the first fully automatic washing machine, and by 1953 spin-dry machines overtook the wringer types in popularity.

The last wringer washer manufactured in the United States was made in June of 1990 at Speed Queen's plant in Ripon, Wisconsin. The major U.S. manufacturers today are General Electric, Maytag (Montgomery Ward), Speed Queen (Amana and Montgomery Ward), Whirlpool (Kenmore), and White Consolidated (Frigidaire and Westinghouse).

Many models with many varying features are now available; however, with a few exceptions, only the controls are different. The only difference between the washer in your home and the top-load washers in the laundromat is the ruggedness of construction.

The washing machine operates by a motor, which is connected to the agitator through a unit called a transmission. The motor and transmission are near the bottom of the machine, while the agitator extends up through the middle of the machine. The transmission is similar to the transmission in your automobile in that it changes the speed and direction of the agitator. In one direction (agitate), the transmission changes the rotation of the agitator and spin tub—the inside tub with small holes in it—into a back-and-forth motion. When the motor is reversed by the controls (spin), the transmission locks up and the agitator, transmission, and spin tub all rotate as a unit. Without the transmission changing the speed or direction, the unit uses centrifugal force to remove as much water from the clothes as possible. The motor is also connected to a pump. When the motor is moving in the spin direction, the pump removes the water from the tub and discards it through the drain pipe.

Models designed for use in other countries offer different features. One component required on all models sold in England (and possibly soon in the rest of Europe) is called the lid lock. Normally when the lid is raised the washer must stop for safety reasons. However, in England, when the washer is operating the lid must be locked closed.

Raw Materials

Many parts of a washing machine are manufactured from sheet steel, usually coated with zinc to improve rust resistance. The steel manufacturer supplies the metal in a coil, which allows the material to be cut to size with minimum waste or automatically fed into the forming process. On some models made by Speed Queen, the spin tub is made of stainless steel. All other models use a steel (called enameling iron) designed for a porcelain coating. For the wash tub, which

Most sheet metal parts, including the body, are formed by a machine that presses a piece of sheet metal between two halves of a mold (die). Because metal in parts shaped by only one die tends to wrinkle, crack, or tear, multiple dies are generally used to form each component. The tub sub-assembly is manufactured automatically. After being rolled into a drum shape, the side is welded. The weld is then smoothed out and the drum is placed on an expander, which stretches the tub into its final shape. A bottom is then welded onto the drum, and this weld is also smoothed.
Most sheet metal parts, including the body, are formed by a machine that presses a piece of sheet metal between two halves of a mold (die). Because metal in parts shaped by only one die tends to wrinkle, crack, or tear, multiple dies are generally used to form each component.
The tub sub-assembly is manufactured automatically. After being rolled into a drum shape, the side is welded. The weld is then smoothed out and the drum is placed on an expander, which stretches the tub into its final shape. A bottom is then welded onto the drum, and this weld is also smoothed.
isn't visible unless you open the machine cabinet, enameling iron with a porcelain coating is generally used. Whirlpool is the exception, using plastic instead of enameling iron for the outer wash tub.

Many other parts are plastic as well. Manufacturers receive raw plastic from which they fabricate parts in pieces about the size of a small ant, using them for machine components that do not bear weight and/or require extremely good rust resistance. Such parts include the pump, the tub guards (which prevent your clothes from being thrown out of the spin tub into the wash tub or the cabinet area), and the agitator.

The transmission is generally made from cast aluminum, which arrives from the manufacturer in ingots—20 pound slabs of aluminum. Scrap parts are usually remelted and reused. Hoses, controls (timers, switches, etc.), and motors are purchased in prefabricated form from other manufacturers.

The Manufacturing
Process

The manufacturing process is split into fabrication (making parts), sub-assembly (putting parts together to make components), and assembly (putting the components together to form the final product). The fabrication process comprises several different procedures, each specific to a particular type of raw material—sheet metal, plastic, or aluminum. Once the constituent parts have been made, they are assembled; major sub-assemblies, or components, include the transmission, the pump, the spin and wash tubs, the balance ring, and the painted parts. Finally, the sub-assemblies are put together inside the shell of the washer, which is then complete.

Fabrication

Sub-assemblies

Assembly

Quality Control

All parts purchased from outside manufacturers are spot checked before use, and most sub-assemblies are checked as well. For instance, all transmissions are automatically tested for operation, noise, and vibration. All pumps are leak-tested using air, automatically if their assembly was automated and manually if it was manual. All painted parts are visually inspected for defects. Daily samples are put in detergent, bleach, and steam baths for corrosion testing. Once it has been completely assembled, the machine is filled with water and tested for noise, vibration, and visual defects, as well as properly functional controls and mechanisms. After packaging, some units are put through severe tests to simulate the transportation conditions to test the cartoning process.

Byproducts/Waste

Leftover scraps of sheet metal are sold to metal recycling centers, and leftover aluminum is remelted for use. The leftover plastic is ground into small chunks and reused on non-visible parts because the color cannot be kept consistent. The unused paint (in powder form) is reclaimed and reused automatically. The chemicals from processes such as paint are reacted into forms of harmless waste and disposed of safely.

The Future

As motors become less expensive and more durable, it will become economical to offer washing machines driven directly by motors instead of by belts, making the washers more versatile and less noisy. Another likely trend will be the gradual displacement of top-load washers by front-load washers, which, because they require less water, satisfy government restrictions on water use. In Japan, a washer is being tested that cleans with bubbles rather than with an agitator. Using a computer, this machine "senses" how soiled each load of clothing is and then generates the bubble activity necessary to remove that amount of dirt. This is called "fuzzy logic" because it imitates human logic more closely than normal computers. If successful, these machines will become available elsewhere. Further in the future people may use washers that clean using ultrasonics—sound waves that, vibrating at frequencies of more than

Although at present most home washing machines in the United States are top-loading, these will likely be gradually displaced by front-load washers. Because they require less water, front-load washers satisfy government restrictions on water use. Also, in Japan a washer is being tested that cleans with bubbles rather than with an agitator. Using a computer, this machine "senses" how soiled each load of clothing is and then generates the bubble acfivity necessary to remove that amount of dirt.
Although at present most home washing machines in the United States are top-loading, these will likely be gradually displaced by front-load washers. Because they require less water, front-load washers satisfy government restrictions on water use. Also, in Japan a washer is being tested that cleans with bubbles rather than with an agitator. Using a computer, this machine "senses" how soiled each load of clothing is and then generates the bubble acfivity necessary to remove that amount of dirt.
20,000 cycles per second, cannot be distinguished by the human ear.

Where To Learn More

Books

Woolridge, Woody. Repair Master for Frigidaire Automatic Washers: Unimatic & Pulsamatic Design. Longhurst, Rey, 1990.

—. Repair Master for Maytag Automatic Washers: All Models. Longhurst, Rey, 1990.

Periodicals

"To Be Fuzzy, or Not To Be Fuzzy." Appliance Manufacturer. February, 1993, pp. 31-32.

"Whirlpool Goes Off on a World Tour." Business Week. June 3, 1991, pp. 98-100.

'The Future Looks 'Fuzzy."' Newsweek, May 28,1990, pp. 46-47.

Stafanides, E. J. "Frictional Damping Smooths Automatic Washer Spin Cycles," Design News. February 15, 1988.

Barry M. Marton



Also read article about Washing Machine from Wikipedia

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