Service de surmoulage
Bond soft rubber directly onto hard plastic parts. We deliver comfortable grips and waterproof seals that never peel off, crack, or leak.
- 50+ Validated Rigid-Soft Pairings
- Zero Delamination & Flash-Free Edges
- Shore A 30 to D 80 Custom Grips
Compatible Overmolding Applications
In product design, you often need to improve grip, add waterproofing, or enhance appearance by wrapping a soft material (like TPE, TPU, or silicone) around a rigid plastic base. This is exactly what overmolding achieves. You see this everyday in tool handles, toothbrush grips, and rugged phone cases.
Unlike manual assembly or gluing, overmolding is a multi-step injection process that permanently bonds the second material directly onto the hard plastic substrate. For your projects, this means instantly adding ergonomic or protective features with no assembly gaps and zero peeling.
Ergonomic Grips & Tactile Surfaces
Adds soft, non-slip TPE or TPU to hard plastic parts. Commonly used for power tool handles, wearables, and control knobs.
Integrated Seals & Gaskets
Bonds rubber directly to housings to replace separate O-rings. Creates reliable IP67/IP68 waterproof and dustproof seals.
Impact Protection & Insulation
Uses thick rubber layers to absorb shock or provide electrical insulation. Ideal for rugged device corners and cable strain reliefs.(
Two-Tone Aesthetics & Structure
Combines different colors or materials in one part to reduce assembly. Used for brand logos, cosmetic finishes, and soft hinges.
Case Study: Resolving Shrinkage in Thick-Walled Parts
Thick plastic components, such as cosmetic caps, often develop sink marks due to uneven cooling. In this video, our Engineering Director explains how splitting a thick section into a two-step overmolding process eliminates surface distortion while maintaining the required structural thickness.
Overmolding Equipment & Specifications At First Mold
Two-step overmolding runs on standard injection molding machines, meaning the true quality of the part is determined by the mold tooling. To machine exact shut-off surfaces and prevent liquid rubber from flashing, we build our molds using industry-leading equipment, including Haas 5-axis CNCs, GF+ high-precision CNCs, and Makino EDMs. The specifications below outline our production capabilities and key design parameters.
| Caractéristiques techniques | Capacité | Caractéristiques techniques | Capacité |
|---|---|---|---|
| Elastomer Hardness | Shore A 30 – Shore D 80 | Optimal Overmold Thickness | 1.5 – 2.5 mm (for ideal tactile feel); feasible down to 1.0 mm |
| Min. Substrate Thickness | ≥ 1.5 mm (general guide to withstand injection pressure) | Recommended Draft Angle | 1.0° – 2.0° standard; add 0.5° – 1.0° for textured surfaces |
| Méthodes de collage | Chemical Adhesion & Mechanical Interlocking | Adhesion Testing Standard | ASTM D903 (Peel) / ASTM D3359 (Cross-Hatch) |
| Parts Standard Tolerance | ±0,1 mm (±0,004 pouces) | Shut-off Precision (No Flash) | ±0,05 mm (±0,002 pouce) |
| Custom Color Matching | Pantone, RAL, Masterbatch Compounding | Conformité des matériaux | RoHS, REACH, FDA Class VI, Biocompatible |
Combinaisons de matériaux pour la technologie du surmoulage
Handling 2+ new overmolding production commissions every month, First Mold’s engineering team has mastered the practical application of diverse resins and elastomers. We know exactly how to achieve a permanent, glue-free bond and prevent delamination.
| Soft Overmold | Excellent Bond | Good Bond | Poor Bond | Exemples d'application |
|---|---|---|---|---|
| TPE | PP | ABS, PC, PS | POM, Nylon | Automotive anti-rattle overmolds; strain-relief boots; diagnostic equipment grips |
| TPU | ABS, PC, PC/ABS | Nylon (PA) | PP, PE | Valve spool encapsulation; robotic cable joints; rugged sensor housings |
| VPT | PP | Nylon (special grade) | ABS, PC | Under-hood duct seals; EV charging weatherseals; outdoor equipment gaskets |
| TPR | PS, HIPS | PP | PC, Nylon | Precision instrument isolation pads; soft/soft suction cups; anti-vibration mounts |
| TPE biosourcé | PLA, PBAT | PP | – | Diagnostic device housings; personal-care grips; compostable closures |
Why Partner with First Mold for Overmolding?
Ask yourself about your current supplier: Are their molds built in-house or outsourced? What is their aging degradation data for peel strength? When production defects arise, do they solve the root cause, or just point fingers?
Overmolding is an unforgiving process. Here is how First Mold ensures absolute accountability, verifiable quality, and the lowest total cost of ownership.
Unified Tooling & Molding Team
Whether an overmolded bond holds and whether the shut-off stays clean are about 80% decided during mold design. Because our tooling makers and molding engineers work together under one roof, no one points fingers. You never have to act as the go-between for different vendors—if a problem comes up, we find the root cause and fix it ourselves.
Data-Backed Precision & Bonding
We measure adhesion and precision—and prove the numbers. Our parts consistently achieve 180° peel strengths of 1.5–3.0 N/mm (and 4.5 N/mm or higher with plasma activation). We hold flash at critical shut-offs to ≤0.05 mm, with parting line clearances under 0.01 mm, so we can guarantee zero delamination in 72-hour salt spray tests.
Deep DFM Intervention
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Predictive Warpage Compensation
Surmoulage vs. Moulage par insertion Vs. Moulage bicolore
Le surmoulage consiste à injecter un matériau sur un substrat existant (plastique dur ou métal, par exemple). Ce processus est réalisé en plusieurs étapes pour former une couche protectrice ou fonctionnelle. Dans le cas du moulage par insertion, les inserts, tels que les composants métalliques ou électroniques, sont d'abord placés dans le moule d'injection. Le plastique est ensuite injecté pour fixer et intégrer les inserts. Dans le cas du moulage en deux temps, un moule rotatif est utilisé pour injecter deux matériaux différents au cours du même cycle.
| Dimension | Surmoulage | Moulage par insertion | Moulage bicolore |
|---|---|---|---|
| Étapes du processus | Injection en deux étapes : noyau dur → surmoulage souple | Placement avant insertion → Encapsulation en une seule fois | Injection en deux temps (moule rotatif/coulissant) |
| Combinaison de matériaux | Liaison souple-dure (par exemple, PP+TPE) | Plastique + métal/insert (par exemple, PA66+cuivre) | Plastiques bicolores (par exemple, ABS+PC) |
| Exigences en matière d'équipement | Machine standard + moule compatible | Machine standard + placement d'inserts robotisé/manuel | Machine bicolore dédiée + moule rotatif (±0,02mm) |
| Interaction des matériaux | Liaison chimique (compatibilité thermodynamique) | Verrouillage mécanique (pas de liaison chimique) | Couche physique (synchronisation du point de fusion) |
| Différence structurelle | Encapsulation en couches (intégration fonctionnelle) | Noyau d'insertion (renforcement composite) | Superposition sans couture (fusion esthétique) |
| Coût des moisissures | $$ | $ | $$$ |
| Cycle de production | 30-60 sec (nécessite un refroidissement entre les couches) | 45-90 sec (mise en place manuelle de l'insert) | 20-40 sec (double prise de vue automatisée) |
| Produits typiques | Poignées d'outils, instruments médicaux | Connecteurs automobiles, électrodes médicales | Feux arrière bicolores, touches de clavier translucides |
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