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Multiple accurate components from a single master model in materials that closely mimic many production plastics

The Process

Vacuum Casting is a process used to produce multiple accurate components from a single master model in materials that closely mimic many production plastics. A liquid Silicone rubber is used to encapsulate the master (normally an SLA model) and then, once cured, cut open to create the mould tool. The mould is then placed under vacuum, where a 2-component Polyurethane resin is used to fill the cavity and create the casting.

The silicone tools have a limited production capacity with the number of parts we would expect a single tool to produce dependant on a number of factors:

  • The geometry of the part (long draws and undercuts/clips can accelerate wear)
  • The PU resin required (filled or clear parts can decrease the quantity)
  • The Finish required on the parts (gloss finishes can accelerate wear and high quality finishes my reduce castings achievable)

As a guide we would expect around 20x castings per tool but this can increase to 25x-30x (low finish or softer Shore A material) or decrease to 10x parts (filled resins or thick section parts). The creation of multi-cavity moulds, where possible, will greatly improve the number of castings we can achieve as well as cost effectiveness and we will advise where this is feasible.

The Benefits

  • Materials closely mimic many production plastics including:
    • Rigid (ABS, Nylon, POM etc.)
    • Elastomers (30A to 95A Shore hardness)
    • Transparent, water clear (UV stable)
    • Hi temperature resistant
    • Flame Retardant
    • Semi rigid (Polypropylene/PP)
  • Wide range of off-tool surface finishes available (from Fine Texture to Satin to High Gloss)
  • Short lead times to production parts
  • Cost-effective method of producing multiple prototypes
  • Two shot, over moulding options
  • Moulded in threaded inserts.


  • Very popular in: Automotive, Medical, Aerospace and Industrial sectors
  • Pre-production Samples for: Marketing, Design Evaluation, Fit & Function Testing, Assembly line trialling, Shock & Vibrations Testing, Thermal & Air Flow Trials
  • Low Volume Manufacture
  • Property Specific Applications: Clear, Flame Retardant, High Temperature, Textured, Pigmented, Flexible etc.
  • Metallisation Substrate (for real metal coatings: Copper, Silver, Gold, Chrome, Nickel, etc.)

Machines & Materials

There are an ever-growing range of materials available for vacuum casting but the most popular include:

ABS Clear Flame Retardant Flexible
Semi-rigid/PP High Temperature Nylon/Filled POM


Further information on popular materials can be found in the Materials section.

For information on the wider range of materials available, or if you have specific properties in mind, then please contact us on 01495 249232.

Silicone Castings

We are developing the vacuum casting process to allow us to create SLA or 3D Printed moulds which allow the casting of silicone resins. The suitability of this process is dependent on part geometry. If you are interested in this process and would like more information then please contact us on 01495 249232.

Typical Lead Time

This is very dependent on the project requirements but first-off castings can be available in as little as 5 working days.

Beautiful design & robust options

Examples of our Vacuum Casting Capabilities

We look forward to working with you.

Give us a call and talk through your project with one of our experts. We’ll help you choose the best path to your perfect product.