Vacuum forming, called blistering, is a plastic processing technology. The main principle is to heat and soften the flat hard plastic sheet, absorb it on the surface of the mold by vacuum, and cool it before forming. It is mainly divided into two categories: thick film and thin film. It is widely used in automobile accessories, lighting, advertising, decoration, large machinery shell, display, space, large household appliances, bathroom and other industries.

The sheet used for blistering is called hard sheet or film, and the sheet with thickness greater than 2mm is called plate, Blister packaging Commonly used: PET (polyethylene terephthalate) hard sheet, PVC (polyvinyl chloride) hard sheet, PS (polystyrene) hard sheet, ABS (engineering plastics). PS hard sheet has low density, poor toughness, and is easy to burn. When burning, it will produce styrene gas (a harmful gas), so it is generally used to produce various industrial blister trays. PVC hard sheet has moderate toughness and is not easy to burn. When burning, it will produce chlorine, which will have a certain impact on the environment. PVC is easy to heat seal, and can be sealed with a sealing machine and a high-frequency machine. It is the main raw material for producing transparent blister products.

PET hard sheet has good toughness, high transparency, and is easy to burn. It does not produce harmful gases when burning. It is an environmentally friendly material, but has high price. It is suitable for making blister products. The blister shells in Europe and America generally require PET hard sheet, but it is not easy to heat seal, which brings great difficulties to packaging. To solve this problem, people compound a layer of PVC film on the surface of PET, called PETG hard sheet, But the price is higher. The materials used for thick plates mainly include ABS, acrylic (plexiglass), PS, PC, PVC, etc.