Thermoplastics in Engineering
Plastic has a reasonably short but highly influential history in the engineering world. In the 1960s only a small fraction of annual consumption of materials was plastic, at the end of the century 150 million metric tons of plastic was produced each year. One of the most important kinds of plastic, thermoplastics have taken centre stage both in the engineering world and in everyday use of plastics. This article will look at the history, advantages and current applications of thermoplastics.
Thermoplastics were first engineered in the 1930s with the first manifestation of a thermoplastic, nylon being patented in 1931. Before the Second World War acrylic and polyester resins were discovered and in the 1950s styrene-based copolymers, polycarbonates and acetal resins were introduced. It was in the 1960s – 1980s that the majority of high performing polymers were developed. Production of new synthetic thermoplastic resins then slowed down as the demand for them in industry decreased until a short flourish in the 1990s (see p.172 Fig 1.) where new conditions meant new materials could be easily created.
AdvantagesThermoplastics are polymers that become liquid when heated and return to a solid state once cooled. They offer a whole variety of advantages which make them suitable for a range of applications. Some of these advantages are:
High strength: Thermoplastics are generally very high strength whether they’re manufactured to be flexible or rigid. They offer advantages over metals in that they can often have better fatigue properties than some metals and can tolerate larger deflections without deforming.
Don’t rust or degrade: Since thermoplastics aren’t metal they don’t rust in the same way making them ideal for applications where exposure to water is likely.
Lightweight: you can replace metal with thermoplastics in a lot of applications and the result is a much lighter end product.
Low processing costs: Often thermoplastics are a lot cheaper to manufacture. You can make components out of thermoplastic in high volumes which are precise and low cost.
Withstand high temperatures? Contrary to what you might predict if you use engineering thermoplastics then they’ll be able to stand high temperatures. The main disadvantage of thermoplastics is their susceptibility melting under high temperatures but increasingly thermoplastics can be manufactured to withstand high temperatures.
Current applications and the thermoplastic ball bearingThermoplastics are used in nearly every industry you can think of from packaging food to clothing, aviation, office equipment, medical instruments and devices, sports goods and more. Increasingly thermoplastics are being used to construct components in the engineering world.
Manufacturers have started producing thermoplastic ball bearings to complement the stainless steel bearing. These are particularly suitable for use in any environment where wash-downs are regular, like the food and beverage industry, as the bearings can’t rust like their metal counterparts.