Plastic forming is a group of manufacturing procedures that takes thermoplastics and forms them through molding processes into a wide variety of plastic products for industrial, commercial, and domestic applications. Forming offers low tooling costs, quick start-up and cost efficiency for small to medium production runs.
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Applications of Plastic Forming
These industries commonly use plastic forming:
- Food and Beverage
- Sporting Goods
- Commercial Goods
The most common products made from plastic forming processes are plastic packaging. The three different types include blister packs, clamshells, and plastic trays, all of which are used to protect, transport, and display many different commercial products for sale. Many different plastics are formed, including polyester (PET), used for packaging, high density polyethylene (HDPE), which makes bottles and bags, polyvinyl chloride (PVC), used for food wrap, vegetable oil bottles and blister packaging, polypropylene (PP) food containers and caps, high grades of polystyrene (PS), which are best for products like disposable plastic silverware, CD cases, and cartons. Other materials that may be used in plastic forming services include acrylonitrile butadiene styrene (ABS), acrylics, polycarbonate and Kydex, which is a PVC-based thermoplastic.
Process of Plastic Forming
There are different methods of plastic forming, the most popular of which is vacuum forming. Vacuum forming, also called thermoforming, is one of the oldest plastic forming techniques. The process begins when a plastic sheet of uniform thickness is fed into a heating device. Using electric, infrared, or natural gas, the material is heated until it reached the desired level of softness and pliability. Time and temperature vary considerably depending upon the specific properties and thickness of the polymer used for a given application. While still hot, the sheet is transferred to a forming station where two mating molds made of aluminum enclose the sheet in chamber. A vacuum pump removes all the air from this molding environment, forcing the sheet of plastic to adhere with the mold. After the newly formed part has dried and cured, it is ejected from the mold and trimmed if necessary.
Pressure forming and twin sheet thermoforming are slightly different techniques. Pressure forming uses the vacuum environment and additional air pressure to increase the tightness of the sheet to the mold to create more detailed products. Twin sheet thermoforming takes 2 separate sheets of plastic, forms mirror images of each, and then welds them together, which creates a hollow product with a small seam running down the middle. The process chosen depends largely on the intended use and essential properties of the finished product.