What is Pressure Forming?
Pressure forming is a process used to form plastics into predetermined shapes. With pressure forming, a hot plastic sheet is forced against a mold. Usually, this mold is a female mold, which means it is concave. Compressed air is then added to the back of the heated sheet in order to form the plastic with the mold. The air pressures used in pressure forming increase the amount of detail that can be picked up by the plastic from the mold. Therefore, pressure forming is more effective than vacuum forming for projects requiring more attention to detail. This is possible because pressure forming is capable of creating up to five times as much pressure as vacuum forming. Products made with pressure forming also do not run the risk of excessive thinning, cold flow, or other problems associated with vacuum forming. The high amount of air pressure used with pressure forming also makes it possible to achieve sharp edges and undercuts when necessary. It also has a low tooling cost and short lead
Pressure forming produces the most detail of the Thermoforming processes. The process is used to form plastics into predetermined shapes. With press forming, a hot plastic sheet is forced against a mold. Usually this mold is concave. Compressed air is then added to the back of the heated sheet in order to form the plastic with the mold.
Pressure forming uses the vacuum forming process -evacuating air from the sealed space between the heated sheet and the mold, allowing atmospheric pressure (14.7 psi) to force the sheet to conform to the mold.- with the added step of applying 20-80 psi of compressed air to heated sheet, forcing it to conform to the mold surface. This added step requires a supply of compressed air and additional sealing device on top of the sheet. Additional clamping force is used to prevent breaking the seal when applying high air pressure. The additional pressure results in superior surface finish and more accurate mold reproduction.
