---
title: "Overmolding Services | Two-Shot & Soft-Touch | OpenSpindle"
description: "Get overmolding quotes from qualified manufacturing partners. TPE/TPU grips molded over rigid ABS, nylon, or PC substrates, plus two-shot (2K) molding, for grip, seal, and soft-touch parts."
canonical: https://openspindle.com/capabilities/overmolding
---

# Get quotes for custom overmolded parts

Overmolding molds a soft or second material over a rigid substrate for grip, a seal, vibration damping, or a soft-touch feel. It is done as a two-shot (2K) process in a single tool and cycle, or by loading a pre-molded insert into a second tool and overmolding around it. Upload your part and we'll source competitive quotes from qualified manufacturing partners.

## How to design for Overmolding

Overmolded parts succeed or fail on the bond between the two materials. These rules keep the overmold attached and free of the defects unique to a second shot.

| Design rule | Typical spec | Why |
| --- | --- | --- |
| Material bond compatibility | chemical or mechanical | Some substrate/overmold pairs (e.g. PC + TPU) bond chemically at the molecular level; others do not bond at all and need a mechanical interlock instead. |
| Min overmold wall thickness | 0.040 in | Thinner sections short-shot or lose their grip on the substrate. |
| Mechanical interlock features | undercuts, holes, ribs | Required whenever the two materials do not bond chemically, to lock the overmold on mechanically instead. |
| Draft angle | 1 to 2 deg per side | Applies to both the substrate and the overmold shot so each releases cleanly from its half of the tool. |
| Bond line / parting design | set by the tool | Where the overmold meets the substrate is a visible line and a potential leak or peel point; place it off cosmetic and sealing surfaces where you can. |

Exact bond behavior depends on the specific resin pair. Send both materials and a shop confirms chemical bond vs. mechanical interlock before cutting steel.

## Overmolding vs alternatives

Overmolding adds a second material to one part. Here is when a different approach fits better.

| Process | Best for | Typical volume | Choose it over Overmolding when |
| --- | --- | --- | --- |
| [Insert Molding](https://openspindle.com/capabilities/insert-molding.md) | Rigid or metal inserts | Prototype to production | Your insert is a rigid or metal component such as a threaded boss or terminal, not a second polymer layer. Overmolding is specifically two plastics. |
| Assembly / adhesive bonding | Low volume, separate parts | Prototype to low volume | You are bonding two separately molded parts together with adhesive. It is cheaper at low volume and needs no two-shot tooling, but the seal and bond are weaker than a molded-in overmold. |
| [Injection Molding](https://openspindle.com/capabilities/injection-molding.md) | Single-material parts | Prototype to production | Your part only needs one material. Overmolding is the step up when you need grip, a seal, or soft-touch feel that a single resin cannot give you. |

## Industries Served

- Consumer products
- Medical devices
- Power tools
- Electronics
- Automotive

Overmolding shows up wherever a rigid part needs a soft grip, a sealed interface, or a cushioned edge, from hand tools and toothbrushes to medical device housings and automotive knobs.

## Frequently Asked Questions

### What is overmolding?

Overmolding is molding one material over another, typically a soft elastomer like TPE or TPU over a rigid substrate like ABS, nylon, or polycarbonate. It is used for grip, a soft-touch feel, sealing, or vibration damping, and is done either as a two-shot (2K) process in one tool and cycle, or by loading a pre-molded insert into a second tool.

### Overmolding vs insert molding: what is the difference?

Overmolding covers a rigid substrate with a second polymer layer, such as a soft grip over a hard handle. Insert molding places a rigid or metal component, like a threaded boss, pin, or terminal, into the tool and molds plastic around it. The difference is what goes in: a second plastic (overmolding) or a non-plastic insert (insert molding).

### Which materials bond well in overmolding?

TPE and TPU bond chemically to many rigid substrates including PC, ABS, nylon, and PC/ABS blends when the resin families are compatible, which is the simplest and strongest overmold. Silicone generally does not bond chemically to most rigid plastics and needs a mechanical interlock instead. Tell the shop both materials and they confirm the bond before tooling.

### Do I need a chemical bond or a mechanical interlock?

A chemical bond, where the overmold resin fuses to the substrate at the molecular level, gives the strongest and cleanest result and is preferred when the material pair supports it. When the two materials will not bond chemically, the part needs mechanical interlock features, such as undercuts, through-holes, or ribs, that lock the overmold in place physically instead.

### How much does overmolding cost compared with a single shot?

Overmolding costs more than a single-material shot because it needs either a two-shot press and a more complex tool, or two separate molding steps with an insert-transfer operation. Tooling is typically higher than an equivalent single-shot mold, and the two-shot cycle adds time. Upload your part to see actual tooling and piece pricing from qualified manufacturing partners.

### Can overmolding create a watertight seal?

Yes, a soft overmold such as TPE or TPU commonly forms a gasket-like seal around a rigid housing, button, or cable entry point. Whether it holds a specific ingress rating depends on the design, the bond, and the compression at the sealing interface, so call out the sealing requirement so the shop can design and test for it.

### Can overmolding be added to an existing part design?

Sometimes, but the substrate usually needs design changes to overmold well, such as added draft, interlock features if the materials do not bond chemically, and a bond line moved off cosmetic surfaces. Send your existing part and a shop can advise what changes the overmold needs.

## Other Capabilities

- [Injection Molding](https://openspindle.com/capabilities/injection-molding.md)
- [Insert Molding](https://openspindle.com/capabilities/insert-molding.md)
- [Prototype Molding](https://openspindle.com/capabilities/prototype-molding.md)
- [CNC Machining](https://openspindle.com/capabilities/cnc-machining.md)

## Get overmolding quotes

Upload your part and we'll source two-shot and insert overmolding pricing from qualified manufacturing partners.