Plastics are incredibly versatile materials. These synthetic substances are available with a wide variety of characteristics. Manufacturing processes using plastics as feedstock are also quite diverse. Their low production costs and recyclability make plastics an attractive manufacturing profile. Versatility and low cost make these materials ideal for developing prototype parts. Inventors and entrepreneurs can make small incremental product adjustments without incurring prohibitive re-tooling expenses.
The most common plastic manufacturing technique is injection molding. Typical injection molding involves melting plastic feedstock and then forcing it, under high pressure, into a metal mold. Metal molds are often fashioned with two halves of the mold cavity to facilitate easy part removal. After the liquified plastic is forced into the mold, it cools and hardens. The mold halves are then separated, and the part is removed by a machine operator.
Additive manufacturing, like 3-D printing, is another technology used to make plastic parts. 3-D printers consist of a movable, robot-controlled heated nozzle mounted to a frame. A plastic filament is fed through the nozzle. Liquified by the heat, small controlled amounts of plastic are deposited on a flat surface (printer bed). The filament quickly re-hardens as the nozzle is repositioned to deposit more plastic. Parts are built up layer by layer on the printer bed in this manner. Almost any conceivable shape can be “printed” by 3-D printers. Three of the most popular types of plastic filaments for 3-D printing are acrylonitrile butadiene styrene (ABS), polylactide (PLA) and polyethylene terephthalate (PET).
ABS Plastic Filament
This type of 3-D printing filament is popular because of its durability and impact resistance. These characteristics make it ideal for constructing prototype parts and consumer products. ABS is non-toxic at room temperatures, making it well-suited for small, hard, plastic toys like Lego bricks.
PLA Plastic Filament
PLA is a popular option for making molds. After a shape has been printed, it can be encased in a plaster-type material then the PLA shaped part can be melted out of the casting material. This leaves a cavity mold into which melted metal can be poured. PLA is also biodegradable and non-toxic, making it a useful material for medical devices that are implanted in the human body.
PET Plastic Filament
Because it is FDA approved food safe, the most common applications for PET plastic are food containers and kitchen utensils. PET plastics are also recyclable. Plastic bottles like those used to contain soda drinks are purchased worldwide at a rate of a million every minute. A large percentage of these could be recycled to make filament feedstock for 3-D printing.
Since their discovery, plastics have become an integral part of the manufacturing industry. These materials are used to create inexpensive and versatile items around the globe. As 3-D printing gains momentum there will undoubtedly be new efforts to use recyclable plastics as feedstock. Plastics have a promising future.