What are the stages in vacuum forming?
Vacuum Forming is a form of thermoforming. They are both the process by which plastic sheets are heated and stretched over a preformed mould and then forced up against that mode by the use of a vacuum. Many items can be created using this process and it is one of the techniques that have been around for many many years. When you sit down to think about all the items that are made from plastic in specific shapes you can very quickly think of tens if not hundreds of examples.
There are essentially six main stages to vacuum forming:
- A mould of the item required is made. These moulds can be made from a variety of different materials including wood, MDF, polystyrene and aluminium. The mould will have the imprint of the item required in it. For example the plastic insert that you find in boxes of chocolate to hold the individual treats are created using vacuum forming. At the edges of the mould there will be angled edges to help the mould come away from the formed plastic at the end of the process.
- The mould is then placed in the vacuum with a sheet of plastic suspended above it and clamped into place. It is important that this sheet of plastic is not touching the mould as this will create issues during the next stages.
- The heating mechanism is brought down above the plastic sheet and turned on. This will slowly heat the plastic to make it pliable and mouldable. There is an optimum temperature for each type of plastic to reach before it can be placed over the mould.
- Once the optimum temperature has been reached the mould is moved up towards the plastic and is pushed into the now pliable warm plastic.
- The vacuum is then switched on, which means that all the air is removed from the machine. The plastic then forms around the mould and takes on its shapes and indentations.
- After the plastic has cooled the plastic sheet is removed from the machine and any excess plastic can be
- trimmed from around the edges as may be required. Now you have the final product.
Once this process is repeated for the required number of items needed from each mould, these can be packaged and sent off to the customer to be included in their product.