Vacuum Casting

The ultimate solution for high-fidelity plastic prototypes. Vacuum casting delivers parts with a surface finish and detail that rivals injection molding, perfect for marketing models and pre-production testing.

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A high-gloss appliance part, representing the superior finish quality of vacuum casting

The Process: Silicone Molds and Polyurethane Resins

Vacuum casting is a three-step process that uses a high-quality master pattern and a silicone mold to produce parts.

1. Create a Master Pattern

First, a perfect "master" pattern of the final part is created using a high-resolution process like SLA 3D printing or CNC machining. This pattern is meticulously sanded and finished to achieve a flawless surface.

2. Make a Silicone Mold

The master pattern is suspended in a casting box, and liquid silicone rubber is poured around it. Once the silicone cures, it is cut open, and the master pattern is removed, leaving a high-detail, flexible mold cavity.

3. Cast Urethane Parts

The two halves of the silicone mold are reassembled. A two-component polyurethane casting resin is mixed and poured into the mold inside a vacuum chamber. The vacuum removes all air bubbles, ensuring a perfect, void-free part.

Why Choose Vacuum Casting?

Exceptional Surface Finish: Because the casting resin perfectly replicates the flawless surface of the master pattern, vacuum cast parts have a beautiful finish that is comparable to injection molding.
Wide Range of Material Properties: Urethane casting resins are available in a huge range of formulations that can simulate engineering plastics, from rigid and clear to soft and rubber-like.
Cost-Effective for Low Volumes: A single silicone mold can typically produce 15-25 high-quality copies. This makes it an ideal process for producing small batches of parts for marketing, user testing, or pre-production builds.

A high-fidelity prototype of a coffee machine housing, an ideal application for vacuum casting

Vacuum Casting FAQ

How does vacuum casting compare to 3D printing?

3D printing is faster for a single part, but vacuum casting is often better for producing a small batch (e.g., 10-25) of parts. Vacuum casting offers a far superior surface finish and allows for a wider range of material properties (like true rubber-like elastomers) that can be difficult to achieve with 3D printing.

Can you overmold with vacuum casting?

Yes. Vacuum casting is an excellent method for creating overmolded prototypes. We can place a rigid machined part or a previously cast part into the silicone mold and then cast a soft, flexible urethane resin around it to create a soft-touch grip or a sealed component.

What is the typical tolerance of a vacuum cast part?

The typical tolerance for vacuum casting is ±0.3 mm for the first 100mm, plus an additional ±0.1 mm for each subsequent 100mm. It is a highly accurate process due to the quality of the master pattern and the stability of the silicone mold.