Thermoforming

Pressure Forming

What is Pressure Forming for Plastics?

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.

Advantages of Pressure Formed Parts

The best characteristics of pressure formed parts include tight tolerances, crisp detail, formed-in texture, formed-in threaded inserts and custom color parts without the need for paint. Pressure formed parts have aesthetics that rival injection molded parts at a fraction of the tooling cost.

An additional benefit of the pressure forming process is the use of undercuts which can allow for parts to be attached to mating parts as well as to the chassis or frame in ways that can reduce cost and increase repeatability as compared to traditional vacuum forming techniques.

Great Results for Less

Pressure formed parts provide cosmetically similar parts that are on par with injection molded parts.  Pressure formed tooling is typically 60%-80% less expensive than injection mold tooling depending on the part geometry and size of the parts. Pressure forming can also compete favorably against other large part processes such as reaction injection molding (RIM) and structural foam. Total program cost including both tooling and unit cost are typically favorable for pressure forming. Additionally, pressure forming does not require paint and is, therefore, more environmentally friendly while simultaneously providing better cosmetics when compared to reaction injection molding (RIM) and structural foam.