Custom Overmolding Services

Transform your product design with our precision overmolding services. We combine multiple materials into seamless, high-performance components that enhance functionality, durability, and user experience.

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◆ISO 9001:2015 Certified Processes

◆ISO 13485: 2016 Medical Device

◆AS9100 Quality Management

◆No Minimum Order Quantities

◆In-Process Inspection with CMM

Plastic Injection Overmolding

What is Overmolding?

Overmolding is an advanced injection molding process that combines two or more materials into a single, integrated component. The process begins with the creation of a substrate (the base component) through standard injection molding. A second material is then molded over or around this substrate, creating a chemical or mechanical bond between the two materials.

This technique allows for the seamless integration of materials with different properties – such as rigid plastics with flexible elastomers – resulting in parts with enhanced functionality, improved ergonomics, and superior aesthetics. The overmolding process eliminates assembly steps, reduces production costs, and creates more durable products.

Overmolding vs. Insert Molding

Our insert molding tooling capabilities deliver precision-engineered molds tailored to seamlessly integrate metal inserts with plastic components, meeting the most demanding requirements for your product applications.

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Overmolding

Process: Injection of second material over first molded part
Materials: Typically plastic over plastic or TPE over plastic
Bonding: Chemical and/or mechanical bonding
Common Applications: Soft-touch grips, seals, multi-color components
Production Complexity: Higher (often requires two-shot molding)

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Insert Molding

Process: Pre-made insert placed in mold before injection
Materials: Often plastic over metal, but can be other combinations
Bonding: Primarily mechanical bonding
Common Applications: Threaded inserts, electrical components, reinforced parts
Production Complexity: Lower (can be done in single shot)

Overmolding Materials

The compatibility between substrate and bonding materials determines bond strength, durability, and performance characteristics of the final part.

ABS – Excellent impact resistance and dimensional stability
Polycarbonate (PC) – High strength, heat resistance, and optical clarity
Nylon (PA) – Superior strength and chemical resistance
PBT – Excellent electrical insulation and heat resistance
Polypropylene (PP) – Lightweight with good chemical resistance
Metal Inserts – Brass, aluminum, steel for structural components

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Material Compatibility Chart

The following chart indicates the bonding compatibility between common substrate and overmold materials.
C = Chemical bonding possible, M = Mechanical bonding recommended.

Overmold Material	ABS	PC	Nylon (PA)	PBT	PP
TPU (Thermoplastic Polyurethane)	C	C	C	C	M
TPE (Thermoplastic Elastomer)	C	C	M	M	C
TPV (Thermoplastic Vulcanizate)	M	M	M	M	C
LSR (Liquid Silicone Rubber)	M	M	M	M	M
Rigid Plastics (PC, ABS, etc.)	M	M	M	M	M

Overmolding Capabilities

Our state-of-the-art injection molding facility is equipped with advanced machinery to handle a wide range of overmolding projects.
From prototype development to high-volume production, we deliver precision parts that meet your exact specifications.

Technical Parameter	Capability
Maximum Part Size	18″ x 24″ x 8″ (457mm x 610mm x 203mm)
Minimum Part Size	0.5″ x 0.5″ x 0.1″ (12.7mm x 12.7mm x 2.5mm)
Shot Capacity	Up to 60 oz (1,770 g)
Wall Thickness	0.020″ to 0.500″ (0.5mm to 12.7mm)
Dimensional Tolerances	± 0.003″ (±0.076mm) plus material shrinkage
Surface Finish	SPI A1-D3 finishes available
Minimum Draft Angle	0.5° for textured surfaces, 0.25° for smooth surfaces
Production Volume	Prototypes to 100,000+ parts
Lead Time	As fast as 15 days for production parts
Quality Control	In-process inspection, first article inspection, CMM verification

Overmolding Design Tips

Wall Thickness – Maintain consistent wall thickness between 0.040″ to 0.120″ (1.0mm to 3.0mm) for optimal material flow and minimal warping.
Bond Enhancement – Incorporate mechanical interlocks like undercuts, dovetails, or surface texturing to improve adhesion between materials.
Material Selection – Choose compatible substrate and overmold materials that achieve the desired bond strength and performance characteristics.
Draft Angles – Design with adequate draft angles (minimum 0.5° for textured surfaces) to facilitate part ejection from the mold.
Gate Location – Consider gate placement to minimize visible gate marks and optimize material flow throughout the part.
Radii and Corners – Use generous radii (minimum 0.020″ or 0.5mm) to reduce stress concentration and improve material flow.
Overmold Thickness – Keep overmold thickness between 0.020″ to 0.100″ (0.5mm to 2.5mm) for optimal bonding and material performance.

Overmolding Finishes

Surface Textures

High-gloss polish (SPI A-1, A-2, A-3)
Semi-gloss finish (SPI B-1, B-2, B-3)
Matte finish (SPI C-1, C-2, C-3)
Textured grip patterns (SPI D-1, D-2, D-3)

Color Options

Custom color matching (Pantone, RAL)
Transparent and translucent options
Multi-color combinations
Special effects (metallic, pearlescent)

Specialized Finishes

Soft-touch coatings
Antimicrobial treatments
Chemical-resistant finishes
UV-resistant coatings

Competitive Benefits of Overmolding Application

Insert molding combines metal inserts with plastic in one efficient step, offering numerous benefits compared to traditional assembly methods.

Part Consolidation

Reduce assembly costs and improve reliability by combining multiple components into a single overmolded part. Eliminate fasteners, adhesives, and secondary operations while enhancing structural integrity.

Enhanced Ergonomics

Improve user comfort and control with soft-touch overmolded grips and interfaces. Custom textures and durometers can be tailored to specific applications, reducing user fatigue and improving safety.

Environmental Protection

Create waterproof, dustproof, and chemical-resistant seals through strategic overmolding. Protect sensitive components from harsh environments without additional gaskets or sealants.

Vibration Dampening

Reduce noise and vibration with strategically placed elastomeric overmolds. Improve equipment performance and longevity while enhancing user comfort and reducing fatigue.

Aesthetic Enhancement

Differentiate your products with multi-color, multi-texture overmolded components. Incorporate branding elements directly into the part while improving visual and tactile appeal.

Cost Reduction

Lower total production costs through elimination of assembly steps, reduced part count, and minimized inventory management. Streamline your supply chain while improving product quality and consistency.

Overmolding Process

Our overmolding process combines precision engineering with advanced manufacturing techniques to create seamless, multi-material components.
Depending on your project requirements, we utilize either two-shot molding or insert molding processes.

Two-Shot Overmolding Process

Substrate Injection – The first material (substrate) is injected into the mold cavity
Mold Rotation – The mold rotates to position the substrate for the second shot
Overmold Injection – The second material is injected over the substrate
Cooling – The complete part cools within the mold
Ejection – The finished multi-material part is ejected from the mold
Quality Inspection – Each part undergoes rigorous quality control

Insert Overmolding Process

Substrate Production – Substrates are molded in a separate operation
Substrate Placement – Pre-molded substrates are manually placed in the second mold
Overmold Injection – The overmold material is injected around the substrate
Cooling – The complete part cools within the mold
Ejection – The finished multi-material part is ejected from the mold
Quality Inspection – Each part undergoes rigorous quality control

Industries We Serve

Automotive

Durable, aesthetically pleasing components for interior and exterior applications, including handles, knobs, and trim pieces.

Medical Devices

FDA-compliant materials and clean room manufacturing for surgical instruments, diagnostic equipment, and patient care devices.

Industrial

Ergonomic, durable tools and equipment with enhanced grip, vibration dampening, and environmental protection.

Overmolded Parts

Start Your Overmolding Project Today

Ready to enhance your product with custom overmolding?
Contact us today to discuss your project requirements and receive a competitive quote.

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Related Resources

How Does Overmolding Work | Everything You Need to Know

Discover how overmolding works to create multi-material injection molded parts with enhanced functionality and design flexibility.

Overmolding vs Insert Molding: Key Differences, Materials & How to Choose

Overmolding adds soft functional layers over a plastic substrate. Insert molding embeds metal or components in plastic. Comparison table, material guide, DFM tips, and decision framework inside.

Overmolding Injection Molding: Technical Process, Material Compatibility & Design Standards

Overmolding injection molding guide: two-shot process parameters, TPE/TPU material compatibility matrix, bonding strength data, DFM guidelines, and industry standards for medical/automotive applications.