Vaccum Forming

Vaccum Forming is a process used in many secondary schools to shape sheets of plastic to a mould made from cheap woods or man-made boards, such as Medium Density Fibreboard. This is often taught in schools, as the plastics used to make vaccum formed parts are cheap and readily available. These plastics include HIPS, PVC, Polyethylene and Polystyrene.

Pupils can easily make a mould using a CNC Router or in schools with a bigger budget, a Laser Cutter. Pupils could make blister type packaging for a keyring (which ties in with my Pewter made part) just to learn how it is done at a younger age, and then when they are progressing towards GCSE, uses for Vaccum Forming in industry can be taught with specific examples.

To new Year 7 pupils who have never seen big machinery before, all the machines in the workshops can look intimidating, but if they learn to use them from the start, their confidence will start to grow and could perhaps gain more interest in the subject. The Vaccum Former is a machine which could be one of these machines taught to get them used to processes used in industry. I think the key to a successful project based on Vaccum Forming with a young class would be to overlook it, and make sure that all the designs made on 2D Design are possible to make on this type of machine. It also should be exciting to them, for example, making something which looks appealing to them, for example, in a heart shape or similar, so they can design different shapes they are interested in on CAD.

For my Vaccum Formed part, i used very thin transparent PVC. this was due to a complex shape and design, so the suction provided by the Vaccum Former wouldn't have been enough to pull the thick material into the gaps in my design. Also, the thick material couldn't reach into the gaps and would overfill them if it did manage to. The part was transparent as it is for blister packaging for my Pewter part, a Cat-shaped keyring, aimed at children. Therefore, if it were packaging, you would need to be able to see it from the outside.

The benefits of Vaccum Forming in industry, is that it is a very quick method, which costs little to run. Products can be manufactured in bulk, where big groups can be made in the space of 30 seconds, just for the plastic to heat, then the suction only lasts 5-10 seconds. The many varieties of plastics which can be used on this machine can be bought very cheap, and can come in many thicknesses, so all designs have a suitable plastic available to be able to use. Also, as it is a plastic based method of manufacture, the parts you can make on this machine come in all sorts of colours and finishes, so therefore it is a suitable method of manufacture for childrens toys.

To make my mould, i made a cat shape in 2D Design, and cut this out in 2mm MDF on the CNC Router. This piece was glued to a square backing piece of MDF which was also only 2mm thick. This was my mould. To vaccum form this, i turned the 2 most central heaters on to medium to high heat (not full as it was only thin plastic). After this had heated up, the mould was placed in the base of the former, and my sheet of plastic was clipped into place above the mould in the vaccum. The heated plates are then dragged over to heat the plastic not far above it. As the plastic needs to be of a soft and bendy consistency to let the process work, i checked the plastic every 10 seconds to check if it was melted enough to pull onto the mould, by pulling the heat away and very lightly poking the plastic to check solidity. When it was ready, the heat is removed, and the mould is pushed up into the plastic and the vaccum is turned on, bringing any air away from around the edges of the mould, so the plastic is drawn in further to the shape of the mould. When the vaccum is turned off after the plastic is drawn in, the plastic sheet can be removed and the product cut out. Then the product is finished.