Vacuum forming is accomplished by taking a flat piece of plastic, heating it until it softens, then using a vacuum to pull it onto a contoured surface where it is held until it cools and hardens. Tooling costs for this process are the lowest of any plastic molding process.

Pressure forming is vacuum forming that uses air pressure to assist the vacuum. This results in much better definition on the part surface.

Twin sheet forming is two pressure or vacuum forming operations occurring simultaneously, which are joined to produce an integrally welded hollow part.

Process Characteristics
Part Cost - moderate to high Tool Cost - low Production Rate - low Capable of producing very large parts Parts are molded without stress, so they are very stable
Examples
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