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Enstark Injection Molding

Custom Overmolding Services

Two shot (2K) and multi shot overmolding in TPE, TPU, or silicone rubber over rigid plastic substrates. Superior ergonomics, vibration damping, and watertight IP68 sealing.

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Substrate Chemical Bonding
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ISO 9001:2015 Certified
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2K and Insert Overmolding
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Huawei Technologies
Samsung Electronics
Tata Motors
Delta Electronics
Lens Technology
Eveready Industries
Beijing Institute of Technology
Ansell LTD
NRTC
Chantelle
PT Wings Surya
PT Sun Paper Source
PT Supreme Paper Solution
Huawei Technologies
Samsung Electronics
Tata Motors
Delta Electronics
Lens Technology
Eveready Industries
Beijing Institute of Technology
Ansell LTD
NRTC
Chantelle
PT Wings Surya
PT Sun Paper Source
PT Supreme Paper Solution

Substrate and Overmold Material Compatibility

Bond strength depends on chemical compatibility between your substrate and overmold material, not just the elastomer you'd like to use. We select material pairings that bond reliably.

Explore Materials
Rigid Substrate Materials

Rigid Substrate Materials

ABS, polycarbonate (PC), nylon (PA), PBT, aluminum, and stainless steel.
Rigid plastic substrates generally bond best; metal substrates rely on mechanical interlock features rather than chemical adhesion.

Overmolding Finishes and Post Processing

Finishing options for both the rigid substrate and the soft overmold surface, applied to meet grip, cosmetic, and functional sealing requirements.

Grip Texturing

Grip Texturing

TexturesFine grain or mold tech texturing
BenefitsImproves hand feel & grip without secondary coatings
Two Shot Cosmetic Finish

Two Shot Cosmetic Finish

PrecisionSubstrate & overmold finished flush or defined reveal line
QualityAvoids visible flash or boundary misalignment
Secondary Pad Printing

Secondary Pad Printing

BrandingLogos & markings pad printed onto rigid substrate
SequenceApplied before or after overmolding sequence

Overmolding for
Various Industries

From soft grip power tool handles to sealed medical device housings, Enstark overmolds parts to the bond strength and material spec required.

Overmolding Quality Control

Bond quality gets verified before a tool goes into production, not discovered after parts have shipped.

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Substrate & Material Compatibility ReviewBefore machining, we confirm your substrate and overmold material combination is chemically compatible, and design mechanical interlock features for any pairing that isn't.
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In Process Bond MonitoringMold temperature, injection timing, and gate location are monitored during the run, since all three directly affect bond strength at the material interface.
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Final Pull Test InspectionEvery batch is sample tested with a bond pull test alongside standard dimensional inspection, confirming adhesion strength before parts ship.
Injection Molding Quality Control 1
Injection Molding Quality Control 2
Injection Molding Quality Control 3
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Custom Overmolding Built for a Bond That Lasts

Enstark's two shot and insert overmolding both run through the same DFM review before steel is cut, checking substrate to overmold compatibility, wall thickness at the bond line, and mechanical interlock geometry where a chemical bond isn't possible.

We pull test bonded samples before releasing to production, so delamination gets caught in the tooling stage, not in your customer's hands.

How Enstark's Overmolding Process Works

From material compatibility evaluation to bond pull-testing, T1 sample review, and full production release.

Upload CAD File

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Start by uploading your part geometry and specifying substrate and overmold materials.

Upload CAD File

Get a Quote

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We review substrate to overmold compatibility and mold flow, then return online pricing and DFM feedback in as fast as one day.

Get a Quote

Review Bond Sample

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We produce a sample part and pull test the bond interface, confirming adhesion strength before committing to full production.

Review Bond Sample

Production Begins

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After approving the bond sample, we begin full scale production, holding the same bond quality and dimensional accuracy validated at sample stage.

Production Begins

Delivery

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We ship your overmolded parts from our China facility to your location, tracked door to door.

Delivery

Ready to Start

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Your overmolding project with Enstark. Experience engineering like never before.

Ready to Start

Injection Molding Manufacturing Network

ENSTARK injection molding network combines 50 advanced machines capable of 90 to 830 tons with experienced project managers to handle projects of any size or complexity. We produce plastic molded prototypes and production parts with global shipping from China’s injection molding supplier.
50+Machines Set
120+Countries & Regions Served
20k+Customers Worldwide
Global Injection Molding Manufacturing Network Map

Overmolding Capabilities

Our overmolding service covers substrate molding, overmold bonding, and final inspection under one roof, with tight tolerances and bond verified quality.
Image (Digital caliper measuring a precision machined part)
Scroll horizontally to view specs
StandardsDescription
Process TypesTwo shot (2K) molding, insert overmolding
Substrate MaterialsABS, PC, nylon, PBT, aluminum, stainless steel
Overmold MaterialsTPE, TPU, silicone rubber
Overmold Shore Hardness20A to 90A
Minimum Overmold Thickness0.5mm
Bond VerificationPull test to confirm cohesive bond strength
Dimensional Tolerance±0.05mm
Maximum Continuous Use TempUp to 150°C (TPE/TPU), higher with silicone
Lead Time15 to 20 working days for tooling

Applications of Overmolding

ENSTARK’s injection molding infrastructure supports high-precision component production across automotive, medical devices, consumer electronics, and industrial equipment.

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Applications of Overmolding
Advantages of Overmolding
• Improved ErgonomicsA soft touch grip layer over a rigid substrate improves comfort and hand feel without a separate assembly step.
• Better SealingOvermolded gaskets and seals achieve tighter, more consistent sealing than a separately molded and assembled part.
• Reduced Assembly CostBonding two materials in the mold eliminates a downstream bonding or fastening operation.
• Design Freedom for Multi Material PartsCombine rigid structure and soft function in one part, in one material transition.
Disadvantages of Overmolding
• Higher Tooling ComplexityTwo shot tooling costs more upfront than a single material mold.
• Material Compatibility ConstraintsNot every substrate and overmold pairing bonds reliably without added interlock features.
• Bond Failure Risk If UnverifiedA poorly matched or poorly processed pairing can delaminate in the field if not pull tested during development.
• Longer Development TimeBond validation adds a testing step beyond standard injection molding sample review.

Frequently Asked Questions

Injection Molding Blueprint & CAD Review
What is the difference between two shot molding and insert overmolding?

In two shot molding, the substrate and overmold are produced in the same machine cycle while the substrate is still warm, giving the strongest possible bond. In insert overmolding, a separately molded substrate is placed into a second mold cavity, which costs less in tooling but can produce a weaker bond if the substrate has cooled or been contaminated before overmolding.

Which materials bond well together in overmolding?
How do you verify the overmold bond is strong enough?
What is the maximum operating temperature for an overmolded part?
Can you overmold onto a metal substrate?
What is the typical lead time for overmolding tooling?
Do you offer material certificates or bond test reports?