Overmoulding and Insert Moulding
Get custom plastic parts molded with two materials or metal inserts. Upload a part to get an online quote.
Certifications
ISO 9001:2015 | Critical to Quality Inspections
Our overmoulding and insert moulding processes produce custom prototypes and on-demand production parts in as fast as 15 days. We use aluminium moulds that offer cost-efficient tooling, producing parts from a range of thermoplastic and liquid silicone rubber materials.
Overmoulding and insert moulding are frequently used for:
- low-volume production parts
- bridge tooling
- pilot runs
- functional prototyping and testing
Additional Notes
- Height may be limited if using a silicone as the overmould material, and deeper parts are limited to a smaller outline.
- Minimum part volume is 40.98 cu. mm.
- With substrate moulds, we can maintain a machining tolerance of ±0.08mm with an included resin tolerance that can be greater but no less than 0.002mm/mm.
- With thermoplastic overmoulds, tolerances remain the same as substrate moulds, however, if the overmould is LSR, then tolerances shift to 0.025mm.
Overmoulding Material Bonding
Chemical bonding between overmoulded materials is possible, but material compatibility should be considered in order to achieve desired bond strength. Incorporation of an adequate mechanical bond is strongly recommended if bonding is critical to your application. An undercut is a good example of a mechanical bond.
| Substrate Material | ||||||
|---|---|---|---|---|---|---|
| Overmould Material | ABS POLYLAC PA-717C | ABS/PC BAYBLEND T65 XF | PC MAKROLON 2458 | PBT CELANEX 2002-2 | PP MOPLEN RP348R | NYLON 66 ZYTEL 70G30HSLR |
| TPU Pearlthane 11T85 | C | C | C | C | M | M |
| TPV Sarlink 3170 | M | M | M | M | C | M |
| TPE Thermolast K TC6 MLZ | C | C | C | M | M | M |
| LSR Elastosil 3003/30 AB/B | - | - | M | M | - | M |
| TPC Hytrel 4068FG | C | C | C | C | M | M |
M = mechanical bond (recommended)
C = chemical bond
Insert Moulding for threading
Instead of a mould that produces a final part using two separate shots like overmoulding, insert moulding generally consists of a preformed part—often metal—that is loaded into a mould, where it is then overmoulded with plastic to create a part with improved functional or mechanical properties.
One way insert moulding is used is with threaded inserts, which reinforce the mechanical properties of plastic parts’ ability to be fastened together, especially over repeated assembly. Bushings and sleeves are another great way to increase part durability for mating components that need more abrasion resistance due to moving parts.
About Overmoulding and Insert Moulding
What is overmoulding?
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.
What is insert moulding?
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.
How do overmoulding and insert moulding work?
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.
Why choose overmoulding or insert moulding?
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.
Resources
