Overmoulding and Insert Moulding

Part inserts are used to provide features and properties unachievable through the moulding process. 50% of the part inserts that our customers request are threaded, and it is this customer requirement we are addressing with PLSI.

Sometimes if you are supplying your own inserts this can cause delays to design and production. Protolabs Supplied Inserts will be stocked on site and will reduce lead times and make the process a lot easier leading to a better experience and faster process time.

When Protolabs provide the threaded inserts, you don’t need to worry about having to order inserts and the delays it causes. You don’t need to be concerned over scrappage rates or rejected stock. Removing unexpected costs and awkward situations relating to inserts.

When configuring your part please ensure you request an "insert moulding" quote. There will be a section labelled "insert". Here, enter the insert code (eg. PLSI 116M4) into the “insert type“ box, then you can proceed as normal.

With overmoulding, the production of the substrate parts is a standard injection moulding process involving an aluminium mould with no heating or cooling lines running through it. Cycle times are a bit longer, which allows our moulders to monitor fill pressure, cosmetic concerns, and the basic quality of the parts. When the total run of substrate parts are moulded, overmould tooling is then assembled to the press. The substrate parts are placed by hand into mould where each part is overmoulded with either a thermoplastic or liquid silicone rubber material.

Insert moulding is a similar process but instead uses a preformed part—often metal—that is loaded into a mould where it is then overmoulded with a thermoplastic resin to create a final component. When the run is complete, parts are boxed and shipped shortly thereafter.

From left to right, the components of an overmoulding press include: ram (1), screw (2), hopper (3), barrel (4), heaters (5), materials (6), nozzle (7), overmould tooling (8), and overmoulded part (9).

With overmoulding, the production of the substrate parts is a standard injection moulding process involving an aluminium mould with no heating or cooling lines running through it. Cycle times are a bit longer, which allows our moulders to monitor fill pressure, cosmetic concerns, and the basic quality of the parts.

When the total run of substrate parts are moulded, overmould tooling is then assembled to the press. The substrate parts are placed by hand into mould where each part is overmoulded with either a thermoplastic or liquid silicone rubber material.

Insert moulding is a similar process but instead uses a preformed part—often metal—that is loaded into a mould where it is then overmoulded with plastic to create a final component. When the run is complete, parts are boxed and shipped shortly thereafter.

While overmoulding requires more complex design, processing, and materials choice than single-shot injection moulding, it offers significant benefits:

• It allows materials to be combined to provide characteristics that no single resin can deliver.
• It can eliminate assembly steps, saving both time and money.
• It can meld materials in a way that assembly processes cannot match.
• Inserts add strength and durability to parts.

We offer a number of additional secondary services to support your project.