INSERT MOULDING (OVERMOULDING):
Insert molding is a process in which plastic is injected into a mold that contains an pre-placed insert. The result of insert molding is a single molded plastic piece with an insert surrounded by the plastic. Inserts can be made of metals or different types of plastic. Insert molding is used in many industries.
OR
Insert moulding is a process by which an object or insert is placed into the mould and the plastic is formed around the insert.
As a result, the object becomes a part of the final moulded product or a detail of the insert is left on the plastic part.
The materials used as inserts include a variety of metallic inserts, cloth, retaining rings, and film.
A metallic core can be inserted into the mould to become a part of the moulded part or to leave its profile in the moulded part.
These cores can be used to create threads in the moulded part and an operator or automation fixture in the post-mould process can back them out.
Metallic inserts can also be used to increase the strength of the moulded part or to create a metallic threaded hole or through hole.
STEPS
1. A custom-built mould is loaded with inserts. Inserts may be loaded robotically or manually.
2. Molten plastic is injected into the mould.
3. Upon cooling, the mould opens and the components are removed.
4. Components are separated from the sprues and inspected.
5. Post-moulding assembly can include a variety of secondary operations, such as:
- Die cutting of stampings into discrete circuits
- Bonding
- Microsoldering
- Circuit testing
Advantages
Reduced assembly and labour costs
As insert moulding joins numerous components with thermoplastic, assembly and labour costs are greatly minimized. For example, a single stamping can be over moulded and then perforated to create multiple circuit paths.
Reduced size and weight
By eliminating fasteners and connectors and by combining the physical strength of resin and metal inserts, insert moulding yields smaller and lighter components.
Increased reliability
Insert moulded component prevents part loosening, misalignment, improper terminations, and other problems. The thermoplastic resin also provides improved resistance to shock and vibration.
Increased design flexibility
Creating a 3D circuit board, overmoulding permits circuitry to move freely through the part, from inside to outside, up walls, down in holes-and the plastic ties it all together.
Applications
Typical parts manufactured using this process include fittings, connectors, switches, mechanical assemblies and electrical assemblies.
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