There are many different kinds of plastic, each with their own defining characteristics, limitations and benefits; these include acrylic, nylon, polyester, polycarbonate, polypropylene, polyvinyl chloride, polystyrene and polyethylene. Each of these is a pure plastic resin base that is melted and mixed with additives that change or enhance the plastic's properties, such as strength, temperature, chemical, moisture and abrasion resistance, durability, flexibility, hardness, ductility, lifespan, texture, surface finish and color.
All these materials are considered thermoplastics and are easily formable when heated until pliable or molten. In order to form components, plastic may be molded, cut, welded, bent/formed, stamped, milled, annealed or lathed. Most of these processes are automated and done in high volumes, which decreases the cost. The food and beverage, automotive, appliance, electronics, pharmaceutical, construction, plumbing, oil, packaging, aerospace, sports equipment and cosmetics industries, among many others, use plastic components everyday. In an industrial setting, many plastic parts like gaskets, fasteners and washers are important components of manufacturing machinery.
There are three main ways to form plastic into a component: molding, forming and assembling. Molding involves a metal mold in the shape of the desired product and heated molten or malleable plastic that forms to its shape. Some plastic molding processes involve a vacuum that ensures an air-tight fit around the mold. These products are usually larger in size and flat or hollow in form.
Plastic molding is the preferred way of fabricating complex plastic products. Flat, simple parts are formed by a couple of different processes. These include stamping, where a heavy metal ram forces a mold to cut out pieces from a flat sheet of plastic. Other plastic forming methods that produce flat components include laser cutting and die cutting, which use a high beam of concentrated light to melt away the plastic or a sharp metal needle or saw.
Many flat plastic parts require assembly in order to form a finished product. The most common way to assemble plastic is by plastic welding, a process that involves heating the edges of two plastic pieces until they have melted or softened, and pushing them together. They form a watertight seal and permanently join together to form a single part.