Plastic pressure forming starts with an extruded sheet of plastic that is secured in a clamp frame and then brought into an oven where the sheet is heated until it reaches a malleable temperature. The clamped sheet is then removed from the oven and sandwiched between a pressure box and the forming tool. A plug assist may be utilized to pre-stretch the plastic sheet for parts with a deep draw. This is done to reduce the amount of material thinning that can occur. The plug assist also ensures the part will have a more uniform wall thickness in the finished part and can contribute to cost savings, by reducing the amount of thinning in the material. Providien will start with a thinner starting gauge of material, which reduces both raw material cost, and processing cost.
Once the sheet is secure, a strong vacuum then pulls the sheet into or over the tool with a pressure of up 85 PSI applied to the backside of the sheet. The part is forced to match the contours of the tool, then allowed to cool. It is then left unrestrained in the tool, producing a part that is free of molded in stress. The newly pressure formed part is then processed through a 5-axis CNC trimming station where it is expertly trimmed to its final dimensions. Further fabrication steps may also be done at this point, resulting in the final product.