Vacuum forming

Vacuum forming

Vacuum forming, commonly known as vacuforming, is a simplified version of thermoforming, whereby a sheet of plastic is heated to a forming temperature, stretched onto or into a single-surface mold, and held against the mold by applying vacuum between the mold surface and the sheet.

The vacuum forming process can be used to make product packaging, speaker casings and even car dashboards.

Normally, draft angles must be present in the design on the mold (a
recommended minimum of 3°), otherwise release of the formed plastic and
the mold is very difficult.

Vacuum forming is usually – but not always – restricted to forming
plastic parts that are rather shallow in depth. A thin sheet is formed
into rigid cavities for unit doses of pharmaceuticals and for loose
s that are carded or presented as point-of-purchase items. Thick
sheet is formed into permanent s such as turnpike signs and
protective covers.

Relatively deep parts can be formed if the form-able sheet is
mechanically or pneumatically stretched prior to bringing it in contact
with the mold surface and before vacuum is applied.^[1]

Suitable materials for use in vacuum forming are conventionally thermoplastics, the most common and easiest being High Impact Polystyrene Sheeting (HIPS). This is molded around a wood, structural foam or
cast/machined aluminum mold and can form to almost any shape. Vacuum
forming is also appropriate for transparent materials such as acrylic
which are widely used in applications for aerospace such as PCW
(passenger cabin windows) canopies for military fixed wing aircraft and
"bubbles" for rotary wing aircraft.

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Injection molding
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