Thermoforming Glossary – Allied Plastics

Understanding Terms Used in the Thermoforming Industry

Some of the Thermoform industry terminology is quite specific. This Thermoforming Glossary provides you with common industry terms and what they mean within the Thermoformed Plastic industry.

Vacuum Forming

In the Vacuum Forming process, a sheet of heated Thermoplastic is positioned over a male or female mold. The mold is then moved into the Plastic sheet, creating a seal, and vacuum suction is applied to draw out air between the sheet and the mold. After a water cooling system in the mold cools the Vacuum Formed Plastic, air is blown back through the mold to separate the Plastic part from the mold.

Twin Sheet Forming

Using a combination of Pressure Forming and Vacuum Forming, the Twin Sheet Forming process is used as an alternative to structural foam and blow molding to create Plastic parts of superior strength. Two sheets of Thermoplastic are formed on separate molds, then brought together and form welded at multiple contact points, sealing the Twin Sheet Formed Plastic parts together. This allows hollow areas to remain throughout the completed Plastic part. These hollow areas can then be filled with rigid foam or inserts can be placed between the two sheets to provide additional strength.

Pressure Forming

The Pressure Forming process uses compressed air to “push” on the backside of Pressure Formed Plastic material to create a greater level of detail on the outer surface. This offers the ability to add texture, form sharper corners for better logo or letter definition and create a tighter fit from part to part. Pressure Formed Plastic often offers a superior, more economical alternative to injection molding.

Vacuum Thermoforming

Vacuum Thermoforming is any process of forming a Thermoplastic sheet that is heated and forced to contact a mold surface and cooled to retain its shape.

Heavy Gauge

Commonly, Heavy Gauge refers to a Thermoplastic sheet with a thickness of 120 mils (0.120 inches or 3 mm) or greater.

Medium Gauge

Commonly, Medium Gauge refers to a Thermoplastic sheet thickness between 60 mils (0.060 inches or 1.55 mm) and 120 mils (0.120 inches or 3 mm).