A rigid handle with a soft grip, a housing with an integrated seal, a metal insert embedded in plastic: all of that is overmoulding. Less famous than two-shot injection, yet it wins the calculation in most projects. Here is how it works, when to choose it, and how we run it in our Ath workshop.
Overmoulding, concretely
A first part is moulded, then placed in a second mould where a second material covers or completes it. Two simple moulds, two injection cycles, one final part. Two main families: plastic-on-plastic (typically a TPE on a rigid body, for grip or sealing) and insert moulding, where a metal component is placed in the mould before injection.
Overmoulding or two-shot: the calculation
Two-shot moulding reaches the same result in one cycle but requires a dedicated press and a far more expensive rotary mould, which only pays off at high volume. For small and medium series, two-step overmoulding almost always wins. Full breakdown in our two-shot vs overmoulding article.
Material bonding decides everything
A soft zone that peels off in first use is an overmoulding nobody checked for chemical compatibility. Standard TPE bonds well to polypropylene but not to polyamide, which needs a specific grade or mechanical anchoring designed into the geometry. That decision belongs to the DfM analysis our partner LGR Design Studio performs free of charge on your 3D file.
Metal insert overmoulding
Embedding a threaded insert avoids an assembly operation and produces a thread that actually carries load. The critical point is insert positioning in the mould, manual or robotised depending on the series. See our insert overmoulding project.
What we do at Moulding Injection
Our three presses of 50, 100 and 250 tonnes in Ath cover small and medium series overmoulding: TPE soft-touch, integrated seals, metal inserts. A documented example: overmoulding of an ABS part. High volumes run at our ISO 9001 certified Polish partner. And if your part comes from France or elsewhere in Europe: our prices generally sit 20 to 30% below equivalent French moulders, details here.
Frequently asked questions
Does overmoulding cost twice as much as simple injection?
There are two moulds and two cycles, so a higher part cost than single injection, but far less than expected: both moulds are simple. The quote is based on your 3D file.
Which materials overmould well together?
Classic pairs: TPE on PP, TPE on ABS, TPU on PC. Polyamides need adapted grades; mechanical anchoring takes over when chemistry does not cooperate.
Send us your 3D file: our partner LGR analyses overmoulding feasibility free of charge, material compatibility and anchoring included. Detailed quote within 48h.