---
title: "Urethane Casting Services | Low-Volume Cast Parts | OpenSpindle"
description: "Get urethane casting (vacuum casting) quotes from independent shops. Cast roughly 10 to 200 production-like parts in real resins and elastomers from a low-cost silicone tool copied off a master, no hard tooling required."
canonical: https://openspindle.com/capabilities/urethane-casting
---

# Urethane casting from independent shops

The bridge between a 3D-printed prototype and a full injection-molded production run. A silicone tool is cast off a machined or 3D-printed master, then used to vacuum-cast urethane resins that look and feel like production plastic, roughly 10 to 200 parts per tool at a fraction of hard-tooling cost. Upload your part and hear back from independent shops with tooling and per-part pricing.

## Urethane casting companies on OpenSpindle

Independent low-volume manufacturers running silicone-tool vacuum casting, from a single bridge tool to a batch of parallel molds for a bigger run. See their cast resins, finishes, and turnaround and get a competitive quote for tooling and parts.

[Browse all urethane casting shops](https://openspindle.com/manufacturers?capability=Urethane%20casting)

## Cast resins our shops run

Two-part polyurethane systems are formulated to mimic the look, feel, and mechanical behavior of common production plastics and rubbers. Filled and flame-retardant grades are available, and shops can also cast clear and translucent parts. If your target material is not here, ask when you request a quote.

- ABS-like urethane -- Rigid, impact-resistant housings
- PP-like urethane -- Living hinges, snap-fits, flexible parts
- PC-like urethane -- Impact-resistant, semi-clear housings
- Clear / acrylic-like urethane -- Water-clear covers, lenses, light pipes
- Rubber / elastomer -- Shore 30A to 90A seals, grips, overmolds
- Glass-filled urethane -- Stiffer, more heat-resistant grade

## How to design for Urethane Casting

Cast urethane parts come off a flexible silicone tool, so the design rules lean similar to injection molding but with looser tolerances and a shorter tool life.

| Design rule | Typical spec | Why |
| --- | --- | --- |
| Nominal wall thickness | 0.060 to 0.150 in | Uniform walls cast and cure evenly. |
| Minimum wall thickness | 0.040 in | Thinner walls risk incomplete fill or fragility once demolded. |
| Draft angle | 1 to 2 degrees per side | Flexible silicone forgives less draft than steel, but draft still eases clean release. |
| General tolerance | +/- 0.010 in or +/- 0.003 in/in, whichever is greater | Resin shrinkage and the flexible tool make it looser than machined or steel-molded tolerances. |
| Silicone tool life | ~20 to 25 parts per mold | The tool degrades and tears at parting lines and undercuts; a new tool is recast off the same master. |
| Maximum part size | Bounded by the vacuum casting chamber | Large parts may need to be cast in sections and bonded, or split across multiple tools. |

Exact numbers depend on the resin system and the shop's casting chamber. Send your part and a shop confirms wall, draft, and tolerance for the cast resin you pick.

## Silicone tooling and process options

Urethane casting trades hard tooling for a soft silicone mold, which is what makes it fast and cheap for a low-volume run. These are the tooling choices shops weigh.

### Tooling and cavity layout

- **Master pattern** -- The mold is copied off a master made by SLA/DLP resin 3D printing or CNC machining, typically finished and painted to the target cosmetic quality before the silicone is poured around it.
- **Silicone (RTV) tool** -- Liquid room-temperature-vulcanizing silicone is poured around the master and cured, then cut open along a parting line to pull the master and leave a two-half cavity for casting.
- **Single-cavity mold** -- One cavity per tool, the default for prototype and low-volume runs where turnaround matters more than throughput.
- **Multi-cavity / parallel molds** -- Several silicone tools cast in parallel off the same reusable master to run a bigger order or a tighter deadline, since each tool is cheap relative to the master.

### Casting process and materials

- **Vacuum casting** -- The resin is mixed and poured or injected under vacuum to pull out air bubbles, then cured in the mold, producing dense parts free of voids.
- **Two-part polyurethane resins** -- Cast resins are formulated to mimic ABS, PP, PC, clear acrylic, and rubber-like elastomers, and can be dyed to match a target color.
- **Overmolding / multi-shot casting** -- A rigid cast part can be recast in a second, softer resin for a grip or seal, similar in concept to overmolding in injection molding.

### Tool life and lead time

- **Silicone tool life** -- A single silicone mold typically yields on the order of 20 to 25 parts before it degrades, after which a new tool is recast off the same master.
- **Turnaround** -- A master plus first silicone tool and initial cast parts usually lands in about 1 to 3 weeks, faster than cutting a production steel mold.

## Urethane casting vs other processes

Urethane casting fills the gap between a printed prototype and a production mold. When your volume, timeline, or material points elsewhere, here is the better-fit process.

| Process | Best for | Typical volume | Choose it over Urethane Casting when |
| --- | --- | --- | --- |
| [Injection Molding](https://openspindle.com/capabilities/injection-molding.md) | High-volume production | 1,000+ | You are past a few hundred parts and want the lowest per-part cost and true production resin. A steel or aluminum tool amortizes once volume climbs into the thousands. |
| [3D Printing](https://openspindle.com/capabilities/3d-printing.md) | One-offs, fastest turnaround | 1 to 50 | You need parts today and can accept as-printed finish and strength. Urethane casting takes longer to set up a tool but delivers more production-like resins and surface quality. |
| [CNC Machining](https://openspindle.com/capabilities/cnc-machining.md) | Metal or tightest tolerances | 1 to 500 | The part needs to be metal, or needs a tolerance tighter than a flexible silicone tool can hold. Casting suits plastic-like geometry where machining would be slow or costly. |

## Industries Served

- Consumer products
- Medical devices
- Robotics
- Automotive
- Electronics enclosures
- Industrial / OEM

Urethane casting shops on OpenSpindle support everything from consumer product bridge runs and trade-show samples to low-volume medical and robotics housings.

## Frequently Asked Questions

### What is urethane casting?

Urethane casting, also called vacuum casting, makes production-like plastic parts from a silicone mold instead of a machined steel tool. A master pattern (usually 3D printed or CNC machined) is used to cast a silicone tool, then two-part polyurethane resin is poured or injected under vacuum into that tool and cured. It is the standard way to get tens to a couple hundred parts that look and feel molded without paying for hard tooling.

### How many parts can one silicone mold make?

A single silicone tool typically holds up for roughly 20 to 25 casts before it degrades or tears, especially around undercuts and parting lines. Because the master pattern is reusable, a shop can cast additional silicone tools from it if you need more parts than one mold can produce.

### Urethane casting vs injection molding, when should I use each?

Use urethane casting for roughly 10 to 200 parts, when you want a production-like look and feel without paying for a steel or aluminum mold. Move to injection molding once volume climbs into the thousands, since the per-part cost drops sharply once a hard tool is amortized and you gain access to true production thermoplastics. Many programs run a casting bridge while a production mold is being cut.

### How much does urethane casting cost?

Cost has two parts: the master pattern and silicone tool, then a per-part cast price. Because the tool is cheap relative to steel and reusable for around 20 to 25 parts, urethane casting is usually far less expensive up front than injection molding for a short run, though the per-part price is typically higher than production molding at volume. Upload your part to see tooling and per-part pricing from independent shops.

### What finishes and colors are available?

Cast resins can be dyed to a target color, and shops offer painting, texture matching, pad printing, and clear or translucent casts for lenses and light pipes. Because the mold is copied off a finished master, the master's surface finish (polished, textured, or matte) transfers directly to every cast part.

### How fast is urethane casting?

A master pattern, first silicone tool, and initial cast parts typically come together in about 1 to 3 weeks, faster than cutting a production mold. Additional parts off the same tool ship quickly after that, and casting several tools in parallel from one master can compress a larger order further.

### Can urethane casting replicate rubber and elastomer parts?

Yes. Two-part polyurethane systems come in a range of durometers, typically described on the Shore A or Shore D scale, so a shop can cast anything from a soft rubber-like seal or grip to a rigid, plastic-like structural part from resins tuned to match.

## Other Capabilities

- [Injection Molding](https://openspindle.com/capabilities/injection-molding.md)
- [3D Printing](https://openspindle.com/capabilities/3d-printing.md)
- [CNC Machining](https://openspindle.com/capabilities/cnc-machining.md)
- [Sheet Metal Fabrication](https://openspindle.com/capabilities/sheet-metal-fabrication.md)

## Design Notes That Move Your Price

Not a definition of urethane casting. The design and sourcing choices that move your tooling cost, per-part price, and lead time.

- **Size the run to a tool, not a guess:** One silicone tool lasts roughly 20 to 25 casts before it needs replacing. If you need more parts than that, plan for the shop to cast a second tool off the same master rather than pushing a worn mold past its life and risking part quality.
- **Pick the resin for the job, not just the look:** Cast urethanes are formulated to mimic ABS, PP, PC, clear acrylic, or rubber, each with different stiffness, impact resistance, and heat tolerance. Tell the shop what the part needs to do (drop test, flex, chemical exposure) and let them match a resin, not just a color.
- **Finish the master, not the cast part:** The silicone tool is a direct copy of the master, so any sink, print lines, or surface texture on the master transfers to every part cast from it. Sand, polish, or paint the master to the finish you want before it goes into the silicone.
- **Use it as a bridge, not a permanent solution:** Urethane casting is most valuable for the gap between a printed prototype and a production mold: trade-show samples, user testing, a bridge run while a steel tool is cut. If your volume settles in the thousands, price out injection molding against your ongoing casting cost.

## Get urethane casting quotes

Upload your part once and compare silicone tooling and per-part pricing for low-volume cast urethane runs from independent shops.