How Does a Vacuum Former Work?

Definition and uses

Vacuum formers are used to form plastic products that range from salad bowls to kayaks and canoes. They vary in size from a tabletop model to those that take up the space of a large three-car garage. They heat plastic sheets and lower them onto molds, which are negative images of the final products' designs and shapes. The plastic sheets vary in thickness, depending on the product's end use. A plastic sheet for a bowl may be 1/16 inch thick, while that for a canoe or kayak may be at least twice as thick.

Heating and suspension

The sheets of plastic are tied to an overhead grid, to which the outside edges are attached to hold the sheet in place. Large heating coils soften the plastic to the proper molding temperature, which varies depending on the type of plastic being used. The goal is to heat the plastic just enough so make it flexible without beginning to melt. When the plastic enters the vacuum former machine, it sits above the mold, read to be quickly set upon the mold when it reaches the proper temperature.

Achieving the final shape

As the plastic is set on the mold, a powerful vacuum is induced through small holes that are drilled in the mold. The vacuum pulls the flexible, warm plastic onto the mold so the final shape can be achieved. Once the shape is formed and the plastic sheet fits tightly against the mold, compressed air is blown onto the top of the molded plastic. This quickly cools the warm plastic so it can be set into the final shape. Once the plastic shape is set, compressed air comes through the vacuum holds, releasing it from the mold. The product is then stacked onto other pieces, while the vacuum former is reloaded and the process repeats. The molded product then goes to a cutting area, where the excess plastic is trimmed away and the plastic shape is finished and prepared for market. The excess plastic is always ground and extruded into other plastic sheets for making more vacuum-formed products.

Resources

• Vacuum-formed products