Overmolding and Insert Molding

Low-pressure elastomer and thermoplastic overmolding for complex, multi-material assemblies

Overmolding for Precision Components

Overmolding is a multi-step injection molding process where a secondary thermoplastic material is molded over a pre-existing substrate or insert.

This approach combines mechanical strength and functionality into a single micro-scale component.

Overmolding Types

Overmolding

Two molds are typically used in overmolding. One is for the primary part layer - the substrate part and the second is for the second part to overlay the substrate. Overmolding allows plastics of different colors or physical properties to fuse together.

For example, a clear acrylic lens can be overmolded into a PCB plastic housing. So overmoulding is very similar to 2-shot process but requires more manpower and two molds but cheaper with less production.

2K molding

Multi shot overmoulding is used when several resin components have to be meld together. In this way workpiece can be moulded multi colored and with required distinct physical properties, e. g. part can consist of polymer injected hard cover and elastomer injected soft cover sections. Component resins are strongly bonded chemically and thus final product is durable and wear resistant.

Main distinction between Overmolding and 2 shot molding is that 2K is performed with more expensive and complex machining and thus is usually more expensive and breaks even at larger production volumes.

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Insert Molding

Insert molding is the process when usually electronics' components e. g. cables or circuit boards are encapsulated. Low pressure moulding (LPM) is used in such cases. Wires or PCBs are covered by layers of polymers to protect them from mechanical fatigue or environmental effects respectively.

As the name of LPM itself suggests low pressure allows low-viscosity materials, e. g. hot melt polyamide materials, to easily flow in room-temperature molds with inserts in it. When solidified, insert together with overmolded material are ejected from the cavity manually or automatically and the process is finished.

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Tooling optimized for overmolding and insert molding

Overmolding requires precise insert positioning, controlled material interfaces, and repeatable alignment between molding steps.

Our in-house tooling is designed specifically for stable multi-material micro molding.

Dedicated tooling for accurate insert fixation
Mold concepts optimized for material interface control
Stable tooling for repeatable overmolding at micro scale

Overmolding Applications

Overmolding and insert molding combine multiple materials into one functional part, enabling integration of rigid and flexible materials, electrical interfaces, and sealing features.

Used across electronics, medical, and industrial applications where protection, sealing, and functional integration are required from prototyping to series production.