Vacuum forming is the oldest method of thermoforming, and refers to the use of a vacuum to remove the air between heated plastic material and a template. The subsequent vacuum causes the plastic material to fully conform to a template, capturing details, shape, and other features.
First, a plastic material, typically in the form of a sheet or a roll, is loaded onto the vacuum machine’s material carrier, where it is heated from above.
Once sufficiently softened, the vacuum-forming tool is pulled closer to the template, creating a seal. After this, a vacuum pump creates a vacuum, drawing the sheet over the template in the vacuum-forming tool.
The resultant plastic cools and sets, then is removed by hand or with the use of air. If necessary, it can then be trimmed or otherwise modified to meet certain specifications.
The vacuum forming process consists of the following main stages.
During the vacuum forming process, tools called templates are used to create molds or parts and tools. These templates can be male (also referred to as “positive”) or female (“negative”).
A male template is convex. When a heated plastic sheet is placed on it, the male template will help form the inner dimensions of the object. A female template meanwhile is concave, guaranteeing dimensional accuracy on the exterior of the part created, because the plastic sheet is formed inside the template.
In vacuum forming, male templates are more common, as the materials used are typically thinner, and the level of detail expected on applications such as packaging is not as high.
Vacuum forming offers manufacturers and end users a wide range of benefits. Among them: