Manufacturing services · Chapter A · Method 04

Compression moulding

Core TCI route

A measured charge of rubber or silicone is placed in a heated steel tool and pressed closed until it cures. Robust, economical tooling for seals, mats and solid rubber parts.

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Vertical rubber compression-moulding press with tool plates. Representative process photo · Konglhask · CC BY-SA 4.0 · Wikimedia Commons

Servo-hydraulic compression-moulding press. Representative process photo · Sam D. Wilbur · CC BY-SA 4.0 · Wikimedia Commons

How it works

Compression moulding, step by step.

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

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

STEP 01

Prepare charge

Weigh and cut pre-forms of uncured rubber or HCR silicone.

STEP 02

Load

Place the charge in the open, heated cavity.

STEP 03

Press & cure

Close the press under heat and pressure until cured.

STEP 04

Demould & deflash

Open, remove the part, deflash and post-cure if needed.

Reference figures

What to expect.

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

Tolerance±0.25 mmStandard; tighter by design

HardnessShore A 30–90Rubber and silicone

Volume100s– 100,000sTool life is long

ToolingSteel or aluminiumLower cost than injection

Materials	HCR silicone, EPDM, nitrile (NBR), neoprene (CR), natural rubber, fluorocarbon (FKM); also thermoset composites.
Finishes	Tool-steel finishes from polished to bead-blasted or textured; flash line trimmed by hand or cryogenically.
Design guidance	Allow for a flash land and an overflow groove. Keep sections even; thick sections lengthen cure times. Specify which flash witness lines are cosmetic.
Best suited to	Gaskets, seals, keypads, mats, bowls, larger silicone parts and medium production runs.
Watch-outs	Manual loading adds cost per part; flash removal is a separate operation.

Other methods in Silicone & rubber

Previous: Vacuum casting Next: Transfer moulding

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Send a sketch, photo, sample or CAD file with your quantity and target date. We will recommend the most sensible route and explain the trade-offs before quoting.

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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.