vacuumforming

Vacuum forming is a simplified thermoforming process in which a sheet of plastic is heated and drawn over a mold by applying a vacuum. It is used for producing shallow to moderately deep parts with smooth exterior surfaces and is common for low- to mid-volume production.

In typical operation, the plastic sheet is clamped over a frame or a mold. Heaters raise the sheet to its forming temperature. The mold is positioned, and a vacuum pulls the sheet against the mold, capturing its contours. After cooling, the formed part is released and trimmed from the excess material.

Common sheet materials include ABS, polystyrene, PETG, polycarbonate, and acrylic, usually in thicknesses from about 0.5 to 3 millimeters. Molds are often made as female cavities from aluminum, wood, or epoxy, though male or plug-type molds are also used. Draft angles and draft lines are important to permit removal.

Vacuum-formed parts are widely used for packaging trays, consumer enclosures, signs, automotive interior trim, display components, and hobby or prototype models. The process offers relatively low tooling costs and fast lead times, making it attractive for short runs and rapid prototyping.

Limitations include limited depth of draw, thinning or thickening of walls, surface detail that may be less pronounced than in other processes, and the need for venting and draft. Post-processing such as trimming, deburring, or secondary finishing is often required.

Variants such as pressure forming use air pressure to assist drawing, and twin-sheet forming uses two sheets to create hollow parts. Vacuum forming remains popular for parts that require simple geometry and visible outer surfaces.