Pressure forming, a plastic production method that delivers lower tooling cost and speedy prototypes is a great alternative to injection molding. It is also ideal for replacing components made from sheet metal, fiberglass and wood. The process for pressure forming consists of compressed air being used to push the back of the plastic sheet against a mold. Parts are produced three dimensional with features and aesthetics that contend with more expensive processes.
Pressure forming produces parts with:
• Sharp radii
• Zero or negative draft angles
• Finely detailed molded shape
• Molded-in textures, tight corners
• Embossed wording or logos
• Uniform wall thickness
• Undercut details which deliver superior fit up to matching components.
With pressure forming, a pressure box is added to the non-mold side of the sheet. A seal is created from the hot plastic between the pressure box and the mold. Unlike vacuum forming, which can only handle atmospheric pressure up to 14.7 pounds per square inch (PSI), but air pressure with pressure forming can reach up to 100 PSI. With capabilities of up to 6 times that of vacuum forming, pressure forming enables creating thermoformed parts with much sharper detail. The Mold side of a pressure formed part can look identical to an injection molded part, but with a significantly lower tooling cost. Molds for pressure forming can be textured just like an injection mold so the texture can be formed directly into the finished part. Larger parts are more cost effective using pressure forming as opposed to similar thermoforming processes.
Pressure forming is only ideal for medium to large sized parts with moderate to low production volumes. Another disadvantage is that tooling cannot easily be modified to account for changes in the design of the product.
Examples of pressure formed parts include:
• Outdoor Plastic Housings
• Medical Enclosures
• Point of Purchase Displays & Retail Items
• Recreational Equipment
Better detail can be achieved through pressure forming than through other plastic production methods. Without the high mold costs or long lead-times of traditional plastic production, pressure forming can save money and time.
Pressure forming machines give accuracy of forming, fine definition, great finish and excellent material distribution. Thermoformable materials are fed in by a reel under a heater to ensure balanced heat for the material. Components are trimmed in place with the mold, then formed components are cleared from the mold with an air blast.