OVERMOLDING – CONNECTION OF THE BEST CHARACTERISTICS
COMBINE MATERIAL PROPERTIES CLEVER IN THE INJECTION
The encapsulation of thermoplastic or metal inserts in elastomer injection molding is one of our technical core competences. By overmolding we combine the best elastic material properties from the networked rubber world with high-quality thermoplastics from the world of plastics or metal. A prefabricated insert comes by encapsulation to improved functional or mechanical properties.
For the formation of rubber-metal moldings, the metal insert is inserted into the vulcanization tools and overmoulded with elastomers such as EPDM or natural rubber (NR). NR has the best possible elastic properties. NR metal moldings are therefore particularly suitable for vibration damping applications (without direct sunlight). In the outdoor area one would rather choose EPDM. The metal inserts are used i.d.R. designed in such a way that the elastomer compound mechanically anchors itself to the metal (for example, holes are provided in the metal insert). If this is not possible, the metal insert can be pretreated with a primer so that the rubber then adheres directly to the insert.
THE PROCESS OF INJECTION:
- We first inject the inserts internally on our horizontal machines and check them qualitatively before further processing.
- In elastomer injection molding, the inserts are inserted by hand or by a robot into the rubber or vulcanization tools. Here, the choice of materials and the quality of the thermoplastics is very important, as they must remain dimensionally stable during the injection process and the heating time.
- At the end of the cycle, rubber-overmolded parts can be demolded and new inserts inserted.
Depositor being overmoulded
When encapsulating inserts, custom work is required, with tight tolerances. Multi-cavity tools, in particular, require a high degree of precision in tool production and in the assembly and overmolding process itself.
Demolding after the overmoulding
After overmoulding with an elastomer or TPE, the composite moldings are removed from the mold. For small quantities, prototypes or very difficult geometries, the moldings are removed manually. Here, we draw on the many years of experience of our employees. The process is also known in the rubber and plastics industry under the name “insert molding”. Our experts will gladly advise you on the best possible combination of materials for an optimally designed production process.