Manufacturing Capabilities
Overmolding & Insert Molding Services
Combine rigid plastic or metal components with soft-touch silicone or TPE in one integrated part — ergonomic grips, sealed assemblies, waterproof enclosures, medical devices.
What Is Overmolding?
Overmolding (also called insert molding or two-shot molding) bonds a soft elastomer — silicone, TPE, or TPU — directly onto a rigid substrate (plastic, metal, PCB). The result is a single integrated assembly with both structural strength and the performance properties of soft materials.
Compared to assembling two separate parts with adhesive or mechanical fasteners, overmolding produces a permanent, seamless bond with no assembly gaps — critical for waterproofing (IP67/68), hygienic surfaces, and ergonomic grip applications.
Our Overmolding Process
Plastic/metal inserts cleaned, pre-heated or plasma-treated as needed to maximize silicone adhesion.
Overmolding mold designed with precise parting lines and gating to avoid damaging the insert during injection.
Inserts loaded manually or via automation. Silicone/TPE injected or compression-molded over the insert. Curing occurs in the mold.
Pull tests and peel tests confirm adhesion between materials. We test before production run, not after.
Flash removal, dimensional check, visual inspection. Waterproof assemblies tested to IP67/68 spec on request.
Material Combinations We Support
| Substrate (Rigid) | Overmold (Soft) | Common Applications |
|---|---|---|
| ABS / PC / Nylon | Silicone (LSR or HTV) | Ergonomic grips, seals, waterproofing |
| Stainless Steel / Aluminum | Silicone | Sealed sensors, cookware handles, medical instruments |
| PCB / Electronics | LSR (precision) | IP67/68 wearable devices, waterproof electronics |
| Any Plastic | TPE / TPU | Soft-touch tools, consumer electronics, power tool grips |
Technical Specifications
| Parameter | Capability |
|---|---|
| Max Substrate Size | 200 × 200 × 100 mm |
| Overmold Thickness | 0.5 – 5 mm |
| Bond Verification | Pull test + peel test before production |
| Insert Tolerance | ±0.10 mm (insert must fit mold precisely) |
| Certifications | FDA (silicone) · RoHS · REACH · ISO 9001 |
Typical Applications
Smartphone cases, waterproof button seals, ergonomic grips, gaming controllers.
Sealed enclosures, soft-touch surgical instruments, wearable health monitors.
Smartwatch straps, fitness tracker bands, VR headset interfaces, hearing aid components.
Silicone-overmolded cookware handles, utensil grips, anti-slip bases.
Sealed connectors, dashboard switches, vibration-damping mounts.
Power tool grips, CNC machine handles, ergonomic knobs and levers.
Design Considerations for Overmolding
- Material Compatibility: Not all plastics bond well to silicone. We run adhesion tests before production. Plasma treatment or primer may be required.
- Insert Tolerance: The insert must fit precisely in the mold. Loose inserts cause flash. Specify insert tolerances at ±0.1 mm or better.
- Overmold Wall Thickness: Uniform 0.8–3 mm prevents sink marks and ensures complete fill.
- Parting Line: Position away from functional or aesthetic surfaces. Communicate to engineers early.
- Undercuts on Insert: Overmolding can capture undercuts. Discuss insert geometry at project start — not after tooling.
Have an Assembly That Needs Overmolding?
Upload both the substrate drawing and the overmold spec. Our engineers will review feasibility and provide a quote within 24 hours.