Vacuum Forming

Vacuum forming is the process in which a sheet of plastic is heated and then pressed against a model by a vacuum to create a mold.

How the Process Works

First, the desired model is made from a material such as wood or foam. It’s sides should be shaped at an angle so that the formed plastic can be easily removed.

A clamp frame is applied to hold down the plastic sheet. The heater then heats up the plastic to make the sheet moldable.

Once the plastic is heated to a malleable state, the mold is lifted to the sheet from below and a vacuum is applied to eliminate trapped air and suck the sheet into the mold.

The sheet is then cooled and ejected from the frame, having been formed to the shape of the model. (Sometimes, fans or nozzles are used to speed up the cooling process, by spraying a water mist onto the mold.)

After the mold is formed, excess material can be removed and recycled.

Material

The materials used for vacuum forming are thermosoftening, so that they become pliable when heated to a certain temperature and can solidify after cooling.

Common Materials Used:

Acrylonitrile Butadiene Styrene ABS
Polyester Copolymer PETG
Polystyrene PS
Polycarbonate PC
Polypropylene PP
Polyethylene PE
Polyvinyl Chloride PVC
Acrylic PMMA

What It's Useful For

The vacuum forming process is useful as an easy way to create molds for unusual shapes. It allows for the creation of cohesive forms from multiple smaller parts, and provides for inexpensive and quick fabrication.

Vacuum forming is used for a wide range of products such as packaging, medical equipment and vehicle parts. On campus, it is most likely useful for architecture and design, to produce parts for models and prototypes.

Some typical applications include:

Machinery Guards
Electrical Enclosures
Parts for medical devices
Bath & shower Trays
Parts of vehicle cabs
Packaging
Signage

Limitations

Problems that can occur during the vacuum forming process include webs forming around the mold if parts are too close together or plastic is overheated, and bubbles emerging from absorbed moisture, which weakens the plastic material.

Cost

On campus, the vacuum forming machine is free if you are an architecture student, and in general, the process is not expensive, (it only requires the cost of the plastic sheet & energy to heat up).