Plastics are now used for components for which, until recently, only steel would have been used. These include hoods, radiator grills, door trims and energy-absorbing areas, such as fenders.
Many manufacturers have plans for the production of cars in which the body shell consists almost entirely of plastics. Even in high-strength load-bearing applications, steel panels are beginning to be discarded in favor of laminates of steel and plastics. High-strength glass-reinforced plastic (GRP) compounds are also being used for engine components in cars. The plastic carburetor and inlet manifold (which must withstand high stress at high temperatures) have already been produced. single unit – by injection molding, for example.
Plastics now replace wood in furniture, glass in windows, metals in mechanical engineering and even wool and leather in clothes and shoes. And computers are unashamedly plastic. The case, keyboard and data storage disks are plastic or plastic coated, and metals have even been largely displaced from the circuits by semiconductors and microchips embedded in plastic. Without this remarkable new range of materials, computers simply could not exist.
Metals are not the only materials being replaced. Already, polyvinyl chloride (PVC) is used extensively in place of glass. It is no more expensive, is considerably lighter and much more shatter-resistant. Polycarbonate is probably the ultimate glazing material. In addition to its high clarity and light weight, polycarbonate is virtually unbreakable, resisting blows from hammers, stones, and even some bullets. Perhaps the secret of the enormous success of plastics in the late twentieth century is that they offer not only economy in energy and cost, but also combinations of properties that were previously unobtainable.
Beside being able to withstand stress and heat, plastics can now be made electrically conductive, by the addition of carbon, or magnetic, by the addition of barium ferrite. If necessary, a plastic can be made nonconductive and weigh less than one-third of its metallic equivalent. The reduction in cost for producing plastic magnets can be 40-50 per cent of traditional methods.
Another important advantage of plastics is greater diversity in design, because of the ease with which many components can be molded as anything.