Vacuum forming
Vacuum forming 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.
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 â€" but not always - restricted to forming plastic parts that are rather shallow in depth. Thin sheet is formed into rigid cavities for unit doses of pharmaceuticals and for loose objects that are carded or presented as point-of-purchase items. Thick sheet is formed into permanent objects such as turnpike signs and protective covers.
Relatively deep parts can be formed if the formable 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 easyest being High Impact
Polystyrene Sheeting (HIPS).
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Blow molding#J.L. Throne,
Understanding Thermoforming, Hanser Gardner Publications, Inc., Cincinnati OH, 1999.
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Vacuum Forming Basics*
Vacuum Forming Guide w/ Pictures*
Vacuum Forming Process Description*
Vacuum Forming Machine
