CUSTOM MULTI-MATERIAL MOLDING
Custom Overmolding Services
Combine rigid substrates with soft-touch or functional materials to create durable, integrated parts with improved grip, protection and product performance.
- Plastic & Elastomer Combinations
- Insert and Two-Step Overmolding
- Prototype to Production Support
WHAT IS OVERMOLDING?
Two Materials. One Integrated Part.
Overmolding is a multi-step injection molding process that bonds a second material over or around a previously molded substrate. The result is a single integrated component without separate assembly or adhesive.
A rigid plastic substrate provides structural strength, while materials such as TPE or TPU add grip, sealing, impact protection or a soft-touch surface. Material compatibility, part geometry and mold design are carefully evaluated to achieve reliable bonding.
Integrated Construction
Multiple materials are permanently combined in one component.
Improved Protection
Soft materials provide sealing, cushioning and impact resistance.
Better User Experience
Textured elastomers improve grip, comfort and product handling.
Structural plastic base
TPE or TPU outer layer
Mechanical interlocks and material compatibility help create a secure bond between the two materials.
HOW OVERMOLDING WORKS
From Material Selection to Finished Overmolded Parts
Successful overmolding depends on more than adding a soft material to a rigid component. Material compatibility, substrate geometry, mold design and process control must work together.
Part & Material Evaluation
We review the part geometry, application environment and performance requirements before recommending compatible substrate and overmold materials.
- Bonding compatibility
- Wall thickness and draft
- Mechanical interlocks
Rigid Substrate Molding
The structural substrate is injection molded with the required dimensions, surface condition and locating features for the following overmolding operation.
- Stable base geometry
- Controlled shrinkage
- Accurate locating features
Overmold Material Injection
The substrate is accurately positioned in the overmolding tool, where TPE, TPU or another selected material is molded over the required surfaces.
- Accurate substrate positioning
- Controlled material flow
- Consistent soft-touch coverage
Bonding & Part Inspection
Completed parts are inspected for material coverage, adhesion, dimensions and appearance to confirm consistent performance before production release.
- Bond strength inspection
- Dimensional verification
- Surface and edge review
OVERMOLDING MATERIALS
Compatible Materials for Reliable Bonding
Material selection affects adhesion, durability, flexibility and long-term part performance. We evaluate each substrate and overmold combination according to the product’s operating requirements.
Common Rigid Substrates
The substrate provides the primary shape, dimensional stability and structural strength of the finished component.
- ABS
- PC
- PC/ABS
- PA
- PBT
- PP
Soft Overmold Materials
The second material adds grip, flexibility, sealing, cushioning or impact protection to selected part surfaces.
- TPE
- TPU
- TPR
- Silicone
Not every elastomer bonds naturally to every rigid plastic. Chemical compatibility, processing temperature and mechanical interlocks must all be considered during design.
Ask About Your Material CombinationChemical adhesion and mechanical retention
Performance in processing and end-use conditions
Selected according to grip and cushioning needs
Controlled to maintain dimensions and edge quality
DESIGN FOR OVERMOLDING
Design Details That Support Reliable Overmolding
A strong overmolded part starts with the substrate geometry. Draft, wall thickness, material flow and retention features must be considered before tooling begins.
Share your 3D model and application requirements for material and manufacturability review.
Maintain Consistent Wall Thickness
Balanced wall sections support consistent filling, cooling and shrinkage in both the substrate and overmold material.
Reduce thick transitions and isolated material massesInclude Sufficient Draft
Draft angles help the substrate and finished part release cleanly from the mold without damaging soft overmold surfaces.
Draft requirements depend on material and textureAdd Mechanical Interlocks
Holes, grooves and undercut retention features can strengthen the connection when chemical adhesion alone is insufficient.
Particularly important for challenging material combinationsControl Overmold Edge Conditions
Defined shutoff surfaces help control flash and create clean, consistent transitions between rigid and soft materials.
Avoid feathered edges that are difficult to mold consistentlyPlan Gates and Material Flow
Gate position should allow the elastomer to fill evenly without shifting the substrate or trapping air around details.
Flow analysis may be recommended for complex geometrySecure the Substrate in the Mold
Positive locating features help hold the first-shot component accurately during the second injection molding stage.
Stable positioning supports consistent overmold coverageOVERMOLDING APPLICATIONS
Where Overmolding Adds Product Value
Overmolding is used when a product requires improved grip, protection, sealing, comfort or visual differentiation without adding separate assembly steps.
Industrial Equipment
GRIP & DURABILITYSoft-touch grips, control handles and protective housings designed for frequent handling and demanding environments.
- Equipment handles
- Control grips
- Protective covers
Medical Devices
COMFORT & SEALINGErgonomic device housings, sealed control areas and non-slip surfaces for handheld medical equipment.
- Handheld housings
- Sealing features
- Soft-touch controls
Consumer Products
APPEARANCE & COMFORTMulti-material enclosures and ergonomic surfaces that improve handling while creating a distinctive product appearance.
- Electronic enclosures
- Personal care products
- Household devices
Automotive Components
PROTECTION & CONTROLFunctional seals, dampening surfaces and grip areas for interior controls and under-hood plastic components.
- Interior controls
- Connector seals
- Vibration protection
Soft-Touch Grip
Impact Protection
Sealing Performance
Reduced Assembly
Inspection plans can be adapted to your drawing, product function and production requirements.
QUALITY CONTROL
Quality Built Into Every Overmolded Part
Overmolded components require control of both the rigid substrate and the second molded material. We verify critical dimensions, bonding, material coverage and appearance throughout the process.
Bonding & Adhesion
Verify that the overmold remains securely attached to the substrate under expected handling conditions.
Dimensional Inspection
Measure critical dimensions, overmold thickness and interface locations against the approved drawing.
Material Coverage
Check that the second-shot material fills the intended areas consistently without short shots or exposed gaps.
Surface & Edge Quality
Inspect parting lines, color consistency, texture, flash and transitions between the two materials.
- First Article Inspection
- Dimensional Reports
- Visual Acceptance Standards
- Production Traceability
WHY HORDRT
One Manufacturing Partner for Tooling and Overmolding
From design review and mold manufacturing to material validation, injection molding and inspection, HordRT supports the complete overmolding process under one coordinated workflow.
COMPLETE PROJECT SUPPORT
Move from Design to Production with Fewer Handoffs
Our engineering, tooling, molding and quality teams work together to identify material, geometry and process risks before they affect production.
In-House Mold Manufacturing
Overmolding tools and substrate molds are manufactured and validated within our tooling operation, improving communication between mold design and molding teams.
Material Selection Support
We review substrate and elastomer compatibility, hardness, processing temperatures and application requirements before confirming the material combination.
Design for Manufacturability Review
Engineers review wall thickness, draft, shutoff surfaces, mechanical interlocks and substrate positioning before tooling begins.
Prototype to Production Support
Flexible tooling and production options support design validation, bridge quantities and repeat production without requiring a fixed minimum order quantity.
Controlled Quality Validation
Inspection can include dimensional reports, adhesion checks, material coverage review and documented visual acceptance standards.
Certified Quality Systems
Manufacturing is supported by ISO 9001, IATF 16949, ISO 13485 and ISO 14001 certified management systems.
OVERMOLDING CASE STUDIES
Overmolding Solutions for Real Product Requirements
Each overmolding project requires a different balance of material compatibility, product function, appearance and manufacturing control. Here are several representative applications.
INDUSTRIAL EQUIPMENT
Impact-Resistant Industrial Handheld Controller
A rigid engineering-plastic housing required a durable soft-touch exterior that could improve handling while protecting the product during repeated industrial use.
Improved grip and impact protection
Rigid substrate with textured TPE overmold
Consistent bonding around complex housing edges
MEDICAL DEVICE
Soft-Touch Medical Device Enclosure
A rigid medical housing combined with a soft perimeter to improve handling and protect frequently contacted edges.
AUTOMOTIVE
Sealed Automotive Connector Housing
An integrated elastomer sealing feature reduced separate components while protecting the connector interface.
Rules of Overmolding Design and Production
Applications of Overmolding
START YOUR OVERMOLDING PROJECT
Have a Multi-Material Part Ready for Review?
Send us your 3D models, drawings, material requirements and expected production volumes. Our engineering team will review the design and recommend a suitable overmolding solution.
- Design and Material Review
- Tooling and Molding Support
- No Minimum Order Quantity
Get the Perfect Parts with HordRT Overmolding Services
Work with a professional overmolding manufacturer like HordRT.
FREQUENTLY ASKED QUESTIONS
Overmolding FAQs
Find answers to common questions about overmolding materials, tooling, bonding, production quantities and part design.
STILL HAVE QUESTIONS?
Talk to Our Engineering Team
Send us your drawings, material requirements and expected production volume. We will review your project and recommend a suitable overmolding solution.
Ask an Engineer01 What is overmolding?
Overmolding is a manufacturing process in which one material is molded over an existing substrate or previously molded component. It is commonly used to add soft-touch grips, sealing features, impact protection, insulation or functional surfaces to rigid plastic or metal parts.
02 What materials can be used for overmolding?
Common overmolding materials include TPE, TPU, TPV and silicone, combined with rigid substrates such as ABS, PC, PC/ABS, nylon and polypropylene. Material selection depends on bonding compatibility, hardness, chemical resistance, operating temperature and end-use requirements.
03 How do you ensure adhesion between the two materials?
Reliable adhesion begins with selecting chemically compatible materials. Mechanical locking features such as holes, undercuts, grooves and wraparound geometry can also improve retention. Mold temperature, surface condition and processing parameters must be carefully controlled during production.
04 What is the difference between overmolding and insert molding?
Overmolding typically combines two polymer materials to create one finished component. Insert molding places a preformed component—often a metal insert, threaded fitting or electrical contact—inside the mold before plastic is molded around it.
05 Can you support low-volume overmolding production?
Yes. HordRT supports prototype, bridge and production overmolding projects with no fixed minimum order quantity. The tooling and production approach can be selected according to part geometry, material requirements and expected volume.
06 What design features are important for overmolded parts?
Important considerations include uniform overmold thickness, suitable draft angles, smooth material transitions, secure shutoff surfaces and adequate mechanical retention. The design should also account for material shrinkage and prevent thin edges that may fill inconsistently.
07 What information is needed for an overmolding quote?
Please provide your 3D CAD files, 2D drawings, preferred substrate and overmold materials, color and hardness requirements, estimated quantities and any functional or testing requirements. Our engineering team will review the information before preparing a quotation.