What is Vacuum Casting?

Vacuum casting is a manufacturing process that involves creating a silicone mold based on a master model, then injecting liquid resin into the mold under vacuum to produce solid parts.

This method is commonly used in the following cases:

High-mix low-volume (HMLV) production
Functional prototyping
Design mock-ups and verification
Pre-production runs for testing before mass production

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Vacuum Casting Process

1. Master Model Production

A precise master model identical in shape to the final product is created using SLA 3D printing or CNC machining.

Since the mold and the final parts inherit the surface finish of the master model, post-processing like sanding and painting is essential.

2. Silicone Mold Creation

After fixing the master model, liquid silicone is poured into a mold box to form the mold.

Once the silicone is degassed and cured, the mold is removed and the master extracted, leaving a cavity for casting.

3. Vacuum Resin Casting

The silicone mold is assembled, and resin or polyurethane material is injected using vacuum equipment.

The part is then cured, removed from the mold, and finished through processes such as gate trimming and polishing.

Advantages and Disadvantages of Vacuum Casting

Advantages

Uniform internal structure due to resin curing
Wide range of material options including ABS-, PC-, TPU-like resins
Much lower cost and lead time than metal tooling
Enables integrated multi-material products via two-shot molding
Easy to post-process

Disadvantages

Mechanical and physical properties may differ from original materials
Mold creation takes time and incurs cost
Generally limited to small-to-medium sized parts
Undercuts and parting lines must be considered in the design

※ Silicone molds can typically be reused 10–20 times, making them highly cost-effective for low-volume production.

Common Materials Used in Vacuum Casting

Material Type	Description
ABS-like PU	Excellent impact resistance and mechanical strength
PC-like PU	Ideal for clear or high-strength applications
TPU-like PU	Offers flexibility and high elasticity
PMMA-like PU	Transparent resin as an acrylic alternative
Colored/Opaque PU	Supports a wide range of colors

※ Be sure to consider properties such as heat resistance, hardness, and strength according to your product’s application.

Industry Applications of Vacuum Casting

Industry	Use Cases
Automotive	Dashboards, switch panels, interior components
Medical	Customized medical devices, component testing
Electronics	Small cases, buttons, circuit protection covers
Robotics & Drones	Lightweight structures, functional exteriors

Design & Quality Management Tips

Design Optimization

Avoid undercuts, thin walls, and sharp corners as they can hinder mold separation. Design with demolding in mind.

Quality Control

Dimensional accuracy is verified using precision tools such as calipers and 3D scanners.
Monitor mold wear over repeated use and plan for timely replacement.

At Creallo, we offer a wide selection of materials and finishing options optimized for vacuum casting, along with design consulting tailored to your product’s purpose and application.
If you're planning a project using vacuum casting, we recommend referring to this guide as a starting point for efficient product development.