Polypropylene is one of the most widely used plastics in the world, yet it presents specific challenges in vacuum forming that make it a more specialised material choice than the more commonly used ABS, HIPS, and PETG. At Jabro Games, we work with polypropylene for applications where its specific properties — chemical resistance, food safety, and the ability to form living hinges — are required.
Properties of Polypropylene
Polypropylene offers excellent chemical resistance, is approved for food contact in its food-grade form, and has a relatively high melting point that provides useful temperature resistance in use. It is lightweight, relatively flexible at room temperature compared to ABS or HIPS, and produces a slightly waxy or milky surface finish in its natural form. It can be pigmented to a wide range of colours and is widely recyclable.
The Living Hinge: Polypropylene’s Unique Property
One of polypropylene’s most remarkable properties is its ability to form an extremely thin, flexible hinge — known as a living hinge — that can flex hundreds of thousands of times without failure. This property is exploited in vacuum formed packaging where a hinged lid is required: the tray and lid are formed as a single part with a thin polypropylene section at the hinge point that flexes to open and close the package. Lunch boxes, tool cases, and food containers commonly use this approach.
Challenges in Vacuum Forming
Polypropylene is more challenging to vacuum form than materials such as ABS or HIPS. Its processing window — the temperature range over which it can be successfully formed — is narrower, and it has a tendency to sag excessively when heated, which can cause problems with sheet handling and uniform forming. It also has a higher tendency to spring back from the mould surface than stiffer materials, which can affect dimensional accuracy. Experienced operators and well-designed tooling are particularly important when working with polypropylene.
Applications
Polypropylene vacuum forming is used for food-safe packaging and storage containers, medical device packaging requiring chemical resistance, automotive components requiring temperature resistance, and any application where a living hinge is part of the design.
Discuss polypropylene and other material options with the Jabro Games team at jabrogames.com.