Core-Back
With core-back or composite injection moulding, different materials are injected one by one.
Technique
The Technique
Once the first material has been injected into the cavity, the cavities will be swapped. Flexible sealing elements will now open the filled cavity towards the empty cavity to fill the remaining component with the second material through a second sprue. Both materials may be the same, or different thermoplastic materials, or thermoplastic elastomers respectively may be used.
For the core-back process to be used, it is a prerequisite to have a moulding geometry that allows the cavity for the second component to be made available through linear core pull movement such that both materials will adhere to each other.
Benefits
Benefits
- No double the number of cavities are required as would otherwise be for turning or shifting, which will allow the use of smaller and more effective moulds and smaller machine clamping units
- Low acquisition costs as no dial or robot is required
Applications
Application examples
- For use with polypropylene automotive components with a sealing lip where a combination of polypropylene and tetra polyethylene (PP/TPE) is used in most instances, on the one hand.
- Flip-top closures where identical polypropylene materials of different colours are used in most cases on the other hand.