Vacuum forming has been used for nearly a century to make many of the products we see and use daily. From grocery store items to car parts, vacuum formed components are all around us. But how are they made – and how is 3D printing making them better?
What is Vacuum Forming & Thermoforming?
Vacuum forming is a type of thermoforming: heat used to form a design. Thermoforming processes include vacuum forming, pressure forming, and twin sheet forming. Each of these processes uses a mold or molds to shape heated sheets of plastic into the desired form.
Pressure forming methods require that the plastic sheet be pressed between two molds and then heated to assume the shape. In twin sheet forming, two plastic sheets are heated and fused together to form double-walled or hollow parts.
Vacuum forming is the simplest of the thermoforming methods, using only one mold at a time. As the name might indicate, vacuum forming relies on a vacuum, as suction applied to the heated plastic sheet will draw it around the mold to create the appropriate contouring.
How Does Vacuum Forming Work?
The vacuum forming process comprises a few relatively straightforward steps:
Clamp a plastic sheet in a frame
Heat the plastic sheet to the point the plastic is workable – soft enough to take on a new shape, but not heated to the point of melting or losing its integrity.
Apply vacuum to pull the plastic around the mold, shaping the heated sheet to the desired contours.
Allow the plastic to cool before removing from the mold. This may be expedited for large pieces, using fans or cool mists.
Trim excess plastic and smooth edges to final part quality.