Manufacturing services · Chapter A · Method 03

Vacuum casting

Core TCI route

Resin is mixed and poured into a silicone tool under vacuum, removing air so thin walls and fine detail fill cleanly. The bridge from prototype to low-volume production.

Ask about this method All Silicone & rubber methods

Degassing pot used to remove air before casting. TCI workshop

How it works

Vacuum casting, step by step.

A labelled schematic of the process (not to scale), and the four steps every job goes through.

Labelled diagram showing how vacuum casting works — Schematic · not to scale. Drawn by TCI Group.

STEP 01

Master & tool

Make an SLA or CNC master and cast a silicone tool.

STEP 02

De-air

Degas the resin and silicone in the vacuum chamber.

STEP 03

Cast

Pour under vacuum; release to atmosphere to push resin in.

STEP 04

Cure & finish

Oven cure, demould, trim and finish the parts.

Reference figures

What to expect.

Typical industry values to help you plan. We agree the figures for your part on the drawing.

Tolerance±0.5 mm typicalTighter on request

Min Wall0.75–1.5 mmSmall to medium parts

Parts10–50 per toolMaterial dependent

Draft1–2° helpfulEases demoulding

Materials	Polyurethane resins simulating ABS, PP, PC and rubber (Shore A 30–95); clear and pigmented grades; cast silicone.
Finishes	Matte to gloss from the master; colour matched in the resin; painted or soft-touch coated after casting.
Design guidance	Keep walls even to avoid sink and distortion. Bosses at least 1 mm high and wide; ≤60 % of nominal wall thick. Avoid sharp internal corners; they tear the silicone tool.
Best suited to	Pre-production samples, marketing models, low-volume end-use parts and bridge tooling.
Watch-outs	Material properties approximate, not equal, injection-moulded plastics. Tools wear with each shot.

Other methods in Silicone & rubber

Previous: Cast silicone tooling Next: Compression moulding

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Reference figures are typical published industry values for planning, not a guarantee; final tolerances, materials and finishes are agreed in writing for each project.