What Is Vacuum Forming?

If you’re new to this technique, here’s a briefing on how it works. Let’s go back a bit first. In the early days, plastic items were made by draping a heated and softened sheet of plastic over a mould and sucking out the air. The plastic responded by wrapping itself tightly on to the shape of the mould. As it cooled down, it hardened.

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The basic technology of vacuum moulding, as this technique is also called, hasn’t changed that much. However, these days it’s often combined with cutting-edge techniques such as 3D printing. It still, though, offers manufacturers a number of advantages. Tooling up is not expensive or complicated, it’s easy to prototype a product while it’s in development and production runs are rapid.

The exciting part is that it isn’t only plastic that can be heated, softened and moulded in this way. In fact, university departments and commercial researchers are looking for new materials that can be treated like this – they’re called “thermoformable” materials. The range of finishes, properties, textures and colours that can be produced is constantly expanding.

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Minimal Waste, Maximum Recycling

Most manufacturers have looked at the amount they’re sending to landfill. Vacuum moulding is very eco-friendly in that waste offcuts can simply be recycled back into the process with zero waste. The heat used in the process can be recaptured too. So it’s a very thrifty process, in environmental terms, compared to traditional manufacturing.

3D Printers and Plastic Moulding

The process of Vacuum Forming doesn’t use very high pressure. So it’s cheap and easy to set up. The tools to produce the moulds and the moulds themselves can be made of cost-effective materials and quickly built. In fact, the 3D printer can print both moulds and tools.

Key Challenge – Frame Design

The frame needs to be able to handle plastic sheets of up to 10mm thickness without losing heat at the edges. Cooling fans, heating elements, cables and sensors must all be protected. The plastic sheets are softened by heat conducted by electrical elements – these were ceramic but today are often quartz. The important thing is to achieve a uniform heat across the plastic.

When it’s time to cool the plastic, a cooling mist of chilled vapour can be used to speed up the process.

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