Two-Shot Overmoulding Expertise
Overmoulding combines two or more materials in a single part, creating multi-functional products impossible to achieve with single-material moulding. This project involved overmoulding a soft TPE grip onto a rigid ABS body, producing an ergonomic handle with chemical bonding between materials—no adhesives, no assembly.
Our 2K injection moulding presses (150-300 ton) feature rotary platens and dual injection units for true two-shot moulding. This produces parts in a single cycle, maximising throughput while ensuring perfect material alignment.
Material Combinations
ABS + TPE (thermoplastic elastomer) is our most common overmoulding combination, offering Shore A 40-90 soft-touch surfaces on rigid substrates. We also process ABS + PC, ABS + PMMA (transparent window), ABS + PA (structural reinforcement), and ABS + silicone (medical grade).
Material compatibility is critical for bond strength. We validate every combination through peel testing (>5 N/mm) and environmental ageing (500 hours at 85°C/85% RH) before production commitment.
Manufacturing Process
The rotary mould first forms the ABS substrate, then rotates 180° for the TPE overmoulding shot. Both shots occur simultaneously, halving cycle time compared to transfer moulding. Typical cycle: 30-40 seconds for complete two-material parts.
For complex geometries requiring more than two materials or colours, we offer sequential overmoulding using a pick-and-place robot to transfer substrates between moulds on adjacent presses.
Design Engineering
Successful overmoulding starts in the design phase. We advise on: material selection for chemical compatibility, interlock geometry for mechanical bond (in addition to chemical bond), shut-off design to prevent flash, and gate placement to avoid wash-out of the substrate.
Quality Control
Bond strength testing (peel, shear, pull) on every batch. Cross-section microscopy validates interface quality. ISO 9001:2015 certified. Full material traceability from resin to finished part.
Frequently Asked Questions
What Shore hardness range is available for soft-touch overmoulding?
We process TPE from Shore A 20 (very soft, gel-like) to Shore A 90 (firm rubber-like). The most common range for grip applications is Shore A 50-70.
Can overmoulding replace snap-fit assembly of two parts?
In most cases, yes. Overmoulding eliminates the snap-fit interface, reducing part count, assembly time, and failure modes. The chemical bond is permanent and withstands ageing better than mechanical joints.
Technical Specifications
Materials: ABS + TPE / PC / PMMA / PA / silicone | Shore range: A20-A90 | Bond strength: >5 N/mm peel | Press: 150-300 ton 2K | Cycle: 30-40s | Part weight: up to 800g