Custom Overmolding Services
Combine a rigid plastic or metal substrate with a soft or functional molded layer to add grip, sealing, cushioning and impact protection while reducing separate assembly steps.
*Final capability depends on the material pair, substrate geometry, bond design, mold construction and inspection method.
How Overmolding Works
A rigid substrate is positioned in a second mold, then a compatible polymer or elastomer is molded around selected areas. Bonding may be chemical, mechanical or a combination of both.
Two-Shot Molding
Two compatible materials are molded in one automated cycle using a rotating or transferring mold.
Insert Overmolding
A molded plastic or machined metal substrate is transferred and encapsulated in a second molding operation.
Substrate Preparation
Mold or machine the rigid base, then clean and preheat it when required.
Positioning
Locate the substrate securely to protect critical faces and control flash.
Second Material Shot
Inject the soft or functional material under controlled temperature and pressure.
Ejection and Inspection
Check dimensions, adhesion, overflow, color and visible defects.
Common Overmolding Material Combinations
Successful overmolding depends on verified adhesion, molding-temperature compatibility, shrinkage behavior and a geometry that mechanically retains the second material.
PP + TPE
Tool handles, household products and flexible grip zones.
ABS + Silicone
Soft-touch covers and products requiring heat or food-contact grades.
PC + Soft PVC
Electronic housings requiring cushioning and slip resistance.
Metal + TPU
Automotive and industrial components requiring grip and impact protection.
PA66 + Silicone
Sensor seals and reinforced components exposed to heat and vibration.
PC + LSR
Durable rigid parts with soft sealing or medical-grade features.
Overmolding Part Examples
Overmolding Capabilities
These values summarize the original page. Every project still requires material-pair, tooling and DFM confirmation.
| General dimensional tolerance | About ±0.05 mm |
| Precision feature reference | About ±0.02 mm after review |
| Same-part weight deviation | ≤1% reference |
| Typical cycle time | 30–90 seconds per mold |
| Maximum part size | 500 × 400 × 200 mm |
| Maximum metal insert weight | 3 kg |
| Substrate preheating | 80–120°C metal; 40–60°C plastic |
| Melt-temperature difference | Controlled within about 10°C where applicable |
Metal + Polymer
Machined or formed inserts can be encapsulated with a functional polymer layer.
Rigid + Flexible
Combine a structural base with soft-touch, damping or sealing material.
Low to Volume Runs
Tooling strategy is selected around geometry, validation and production demand.
Secondary Operations
Machining, printing, assembly and dimensional inspection can be integrated.
Overmolding Design Guidelines
Material compatibility and substrate retention should be validated before finalizing the mold.
Material Compatibility
Verify chemical adhesion, process temperatures and shrinkage before tooling.
Mechanical Retention
Use holes, undercuts, grooves or wraparound geometry when suitable.
Uniform Overmold Layer
Avoid abrupt thickness changes that create sink, voids or uneven cooling.
Draft and Shutoffs
Add draft and clearly define shutoff faces to control ejection and overflow.
Substrate Location
Use stable locating features so the insert cannot move during injection.
Venting and Flow
Position gates and vents to limit trapped air, weld lines and incomplete filling.
Overmolding Applications
Overmolding is useful when one component needs a rigid structure plus a soft, sealing, protective or ergonomic surface.
Automotive
PC + TPE controls, PA66 + silicone sensor seals and protected connectors.
Medical Devices
Stainless-steel + LSR grips and plastic + elastomer connector interfaces.
Consumer Electronics
Metal + TPU wearables and PC + silicone sealing features.
Home Appliances
Reinforced handles, soft grips and waterproof interface components.
Industrial Equipment
Vibration-damping handles, protected sensors and robot end effectors.
Consumer Products
Toothbrushes, tools, kitchen products and ergonomic handheld devices.
Why Use Overmolding?
A well-designed overmold can combine structure, comfort, sealing and protection in one repeatable component.
Poor Adhesion
Check material compatibility, drying, surface condition and mold temperature.
Overflow / Flash
Review shutoff geometry, mold closing accuracy and clamping conditions.
Bubbles or Voids
Improve resin drying, venting, filling and cooling balance.
Whitening at Joint
Reduce excessive injection stress and improve venting or transition geometry.
Frequently Asked Questions
Concise guidance on adhesion, preheating, material pairing, layer thickness and quote files.
How can poor overmold adhesion be improved?
Start with a compatible material pair, proper resin drying, clean substrate surfaces, suitable temperature and mechanical retention features.
Does a metal substrate require preheating?
Often yes. Thick aluminum or magnesium inserts may need controlled preheating to reduce rapid cooling and internal stress.
How thick should the overmold layer be?
Thickness must balance flow, grip and appearance. A common starting range is reviewed against substrate thickness, resin and geometry.
What is the difference between two-shot and insert overmolding?
Two-shot molding forms both materials in one automated tool cycle; insert overmolding transfers a prepared substrate into a second mold.
Can all plastics and elastomers bond together?
No. Chemical compatibility varies, so adhesion testing and mechanical locking features may be required.
What files are needed for a quote?
Send 3D and 2D files plus substrate material, overmold material, hardness, color, quantity and functional requirements.
Start Your Overmolding Project
Upload the design and identify the substrate, overmold material, hardness, color, quantity and required function.
Upload Your Design Files