Thermoforming is a method for forming thermoplastics.
The raw material
The starting material for the manufacture of component holders is sheets of plastic, which are stacked in a special jig, lifted by suction cups and automatically fed individually into the thermoforming machine.
The tool is located in a lower section of the machine. The plastic sheet is clamped between the tool heating device.
Heating the sheets makes the material pliable. It is pulled over the tool by generating a vacuum. Finally the finished tray has yet to be cut to size.
Thermoforming tools are mostly made of aluminium. They do not have to stand up to the requirements of an injection moulding tool for long periods, and can therefore be made in a shorter time.
1. Heating Process
A plate or sheet of thermoplastic material is fitted into a clamping frame and heated up to the plastic state using a suitable heat source.
- Start of forming
Once the plate is mouldable due to heating, the radiators are retracted.
- Forming: Create overpressure
The base plate and the tool are lifted. A pump creates overpressure.
- Forming: Create a vacuum
The heated plate is pre-stretched using air pressure and the moulding tool is advanced to the pre-stretched plate. The air between the tool and plate is vacuumed out.
The atmospheric external pressure passes the soft plate to the walls of the mould in such manner, that the contours are exactly reproduced.