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홈 / 오버몰딩 서비스

오버몰딩 서비스

Bond soft rubber directly onto hard plastic parts. We deliver comfortable grips and waterproof seals that never peel off, crack, or leak.

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ISO 9001:2015 | ISO 13485:2016 | NDA Available

Compatible Overmolding Applications

In product design, you often need to improve grip, add waterproofing, or enhance appearance by wrapping a soft material (like TPE, TPU, or silicone) around a rigid plastic base. This is exactly what overmolding achieves. You see this everyday in tool handles, toothbrush grips, and rugged phone cases.

Unlike manual assembly or gluing, overmolding is a multi-step injection process that permanently bonds the second material directly onto the hard plastic substrate. For your projects, this means instantly adding ergonomic or protective features with no assembly gaps and zero peeling.

Ergonomic Grips & Tactile Surfaces

Adds soft, non-slip TPE or TPU to hard plastic parts. Commonly used for power tool handles, wearables, and control knobs.

Integrated Seals & Gaskets

Bonds rubber directly to housings to replace separate O-rings. Creates reliable IP67/IP68 waterproof and dustproof seals.

Impact Protection & Insulation

Uses thick rubber layers to absorb shock or provide electrical insulation. Ideal for rugged device corners and cable strain reliefs.(

Two-Tone Aesthetics & Structure

Combines different colors or materials in one part to reduce assembly. Used for brand logos, cosmetic finishes, and soft hinges.

Case Study: Resolving Shrinkage in Thick-Walled Parts

Thick plastic components, such as cosmetic caps, often develop sink marks due to uneven cooling. In this video, our Engineering Director explains how splitting a thick section into a two-step overmolding process eliminates surface distortion while maintaining the required structural thickness.

Evaluate Your Part Design

Overmolding Equipment & Specifications At First Mold

Two-step overmolding runs on standard injection molding machines, meaning the true quality of the part is determined by the mold tooling. To machine exact shut-off surfaces and prevent liquid rubber from flashing, we build our molds using industry-leading equipment, including Haas 5-axis CNCs, GF+ high-precision CNCs, and Makino EDMs. The specifications below outline our production capabilities and key design parameters.

사양	기능	사양	기능
Elastomer Hardness	Shore A 30 – Shore D 80	Optimal Overmold Thickness	1.5 – 2.5 mm (for ideal tactile feel); feasible down to 1.0 mm
Min. Substrate Thickness	≥ 1.5 mm (general guide to withstand injection pressure)	Recommended Draft Angle	1.0° – 2.0° standard; add 0.5° – 1.0° for textured surfaces
본딩 방법	Chemical Adhesion & Mechanical Interlocking	Adhesion Testing Standard	ASTM D903 (Peel) / ASTM D3359 (Cross-Hatch)
Parts Standard Tolerance	±0.1mm (±0.004″)	Shut-off Precision (No Flash)	±0.05mm (±0.002″)
Custom Color Matching	Pantone, RAL, Masterbatch Compounding	재료 적합성	RoHS, REACH, FDA Class VI, Biocompatible

오버몰딩 기술을 위한 재료 조합

Handling 2+ new overmolding production commissions every month, First Mold’s engineering team has mastered the practical application of diverse resins and elastomers. We know exactly how to achieve a permanent, glue-free bond and prevent delamination.

Soft Overmold	Excellent Bond	Good Bond	Poor Bond	적용 사례
TPE	PP	ABS, PC, PS	POM, Nylon	Automotive anti-rattle overmolds; strain-relief boots; diagnostic equipment grips
TPU	ABS, PC, PC/ABS	나일론(PA)	PP, PE	Valve spool encapsulation; robotic cable joints; rugged sensor housings
TPV	PP	Nylon (special grade)	ABS, PC	Under-hood duct seals; EV charging weatherseals; outdoor equipment gaskets
TPR	PS, HIPS	PP	PC, Nylon	Precision instrument isolation pads; soft/soft suction cups; anti-vibration mounts
바이오 기반 TPE	PLA, PBAT	PP	–	Diagnostic device housings; personal-care grips; compostable closures

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오버몰딩 프로젝트 시작

Why Partner with First Mold for Overmolding?

Ask yourself about your current supplier: Are their molds built in-house or outsourced? What is their aging degradation data for peel strength? When production defects arise, do they solve the root cause, or just point fingers?

Overmolding is an unforgiving process. Here is how First Mold ensures absolute accountability, verifiable quality, and the lowest total cost of ownership.

Unified Tooling & Molding Team

Whether an overmolded bond holds and whether the shut-off stays clean are about 80% decided during mold design. Because our tooling makers and molding engineers work together under one roof, no one points fingers. You never have to act as the go-between for different vendors—if a problem comes up, we find the root cause and fix it ourselves.

Data-Backed Precision & Bonding

We measure adhesion and precision—and prove the numbers. Our parts consistently achieve 180° peel strengths of 1.5–3.0 N/mm (and 4.5 N/mm or higher with plasma activation). We hold flash at critical shut-offs to ≤0.05 mm, with parting line clearances under 0.01 mm, so we can guarantee zero delamination in 72-hour salt spray tests.

Deep DFM Intervention

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Predictive Warpage Compensation

오버몰딩 대. 인서트 몰딩 대. 2색 몰딩

오버몰딩은 기존 기판(예: 단단한 플라스틱 또는 금속)에 한 가지 재료를 주입하는 것입니다. 이 공정은 보호 또는 기능성 층을 형성하기 위해 별도의 단계로 완료됩니다. 인서트 몰딩에서는 금속 또는 전자 부품과 같은 인서트를 먼저 사출 금형에 배치합니다. 그런 다음 플라스틱을 사출하여 인서트를 고정하고 통합합니다. 투샷 성형에서는 회전 금형을 사용하여 동일한 사이클에 두 가지 다른 재료를 사출합니다.

차원	오버몰딩	인서트 몰딩	2색 몰딩
프로세스 단계	2단계 사출: 하드 코어 → 소프트 오버몰드	사전 인서트 배치 → 싱글 샷 캡슐화	듀얼 샷 사출(회전/슬라이딩 금형)
재료 조합	소프트-하드 본딩(예: PP+TPE)	플라스틱 + 금속/인서트(예: PA66+구리)	이중 색상 플라스틱(예: ABS+PC)
장비 요구 사항	표준 기계 + 호환 금형	표준 기계 + 로봇/수동 삽입물 배치	전용 2색 기계 + 회전 금형(±0.02mm)
머티리얼 상호 작용	화학 결합(열역학적 호환성)	기계적 잠금(화학적 결합 없음)	물리적 레이어링(융점 동기화)
구조적 차이	계층형 캡슐화(기능 통합)	인서트 코어(복합 보강재)	원활한 레이어링(미적 융합)
금형 비용	$$	$	$$$
생산 주기	30-60초(레이어 간 냉각 필요)	45~90초(수동 삽입 배치)	20~40초(자동 듀얼 샷)
일반 제품	도구 손잡이, 의료 기기	자동차 커넥터, 의료용 전극	듀얼 컬러 테일라이트, 반투명 키보드 키

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