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Nearly all forms of plastic are made from natural gas, oil, and some types of vegetation. Plastics have been demonized as a symbol of all that is wrong with society, but nearly everyone still uses them. Even the most vocal opponents express their disapproval using a plastic computer keyboard. The manufacturing method that makes these finished products possible is called thermoforming.The environmental impact of hydrocarbon use is difficult to ignore. Surprisingly, production of plastics uses less than 3% of all the oil and gas burned each year in the United States by vehicles. That is still a huge number, but illustrates how halting all production of plastic would do very little to end reliance on oil as a primary fuel, and would force consumer prices upward.The process begins by turning raw hydrocarbons into sheets of acrylic, polyvinyl chloride, polypropylene or other chemically similar polymers.

They arrive on site in varying thicknesses, and are warmed until they become malleable, but not runny. Employing one of the three most common methods of production, the warm material is then molded, cooled, and the excess cut away. The result is a durable component.During production, radiant electric devices five inches from the sheet produce heat. The amount of time plastic takes to become malleable is determined by the variety of polymer, and there are three methods that are most commonly used during molding. Vacuum forming uses principles similar to an everyday vacuum cleaner, sucking the warm plastic into a mold with carefully measured force.Vacuum processes are limited to a relatively low maximum force, but pressure forming can achieve consistently stronger levels, and is more versatile. Before heating, the sheets are pre-stretched to eliminate thin spots over uneven surfaces.

Once inserted into a mold under pressure, the air trapped inside is released, and any remaining excess can be trimmed away.Some thermoplastic processes require molds with both positive and negative sides. The warm plastic is positioned between the two, and after appropriate pressure has been applied, the material assumes the size, shape, and detailing of the interior space. While this affords greater control, costs are higher. Regardless of the process chosen, only thermoplastics can be reheated safely.Thicker sheets are used to manufacture electronics housings, medical equipment for daily care needs, external car components, and even in some bathroom accessories and fixtures. Thinner sizes are used to package cosmetics, many processed and fresh foods, and small, loose items like screws. While not biodegradable, methods of recycling and disposal are constantly improving.Genevive B. Mata has taught plastics molding techniques for over 15 years. He specializes in injection molding and thermoforming.