Vaccum Forming is a simplified version of thermoforming, where a sheet of
plastic is heated to a forming temperature, stretched onto a single-surface
mold, and forced against the mold by a vacuum. This process
can be used to form plastic into permanent objects such as turnpike signs and
protective covers. Normally draft angles are present in the design of the mold to ease removal of the formed plastic part
from the mold. Relatively deep parts can be formed if the formable sheet is
mechanically or pneumatically stretched prior to bringing it into contact with
the mold surface and applying the vaccum
Suitable materials for use in vacuum
forming are conventionally thermoplastics. The most common and easiest to use
thermoplastic is high impact polystyrene sheeting (HIPS). This is molded around a wood, structural foam or cast or
machined aluminium mold, and can form to almost any shape. This high impact
material is hygienic and capable of retaining heat and its shape when warm
water is applied and is commonly used to package taste and odor sensitive
products.