Two-shot injection moulding (2K) is attractive on paper: two materials, one part, no assembly. Industrial reality is more nuanced, and for many projects the right answer is elsewhere.
Two-shot and overmoulding: two processes, one result
Two-shot moulding injects two materials in the same cycle, on a press with two injection units and a rotary mould. Overmoulding reaches the same part in two steps: mould the rigid body first, then place it in a second mould where the second material covers it. The end result is comparable; the project economics are not.
What 2K really costs
Two-shot requires a specific press and a significantly more complex mould. That premium pays off at high volume. At small and medium series, the 2K mould never pays for itself, and two-step overmoulding almost always wins the calculation. That is our workshop position: for series running on our 50 to 250 tonne presses, overmoulding is the pragmatic route. When a project genuinely justifies high-volume 2K, we say so and route it with our partners.
⚠️ Material compatibility decides everything
Soft on rigid only holds if both materials bond chemically. A standard TPE bonds well to polypropylene but not to polyamide, which needs a specifically formulated TPE grade. Without that check, the soft zone peels off in first use.
Send us your 3D file: our partner LGR analyses feasibility free of charge, and we tell you frankly which route fits your volume.