Manufacturing services · Chapter A · Method 06

LSR injection moulding

Core TCI route

Two-part liquid silicone is metered, mixed and injected into a heated tool, curing in seconds. The route for high-volume, consistent silicone parts.

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All-electric injection moulding machine of the type fitted with LSR dosing for silicone parts. Representative process photo · Sumitomo (SHI) Demag · CC BY 4.0 · Wikimedia Commons

How it works

LSR injection 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 lsr injection moulding works — Schematic · not to scale. Drawn by TCI Group.

STEP 01

Meter & mix

A and B components are pumped 1:1 through a static mixer.

STEP 02

Inject

A cooled screw injects silicone into the hot tool.

STEP 03

Cure

Platinum cure completes in seconds at tool temperature.

STEP 04

Eject & post-cure

Parts are ejected, inspected and post-cured if required.

Reference figures

What to expect.

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

Cavity Tolerance±0.13 mm + 0.002/mmWhen machining the tool

Repeatability±0.10 mm or lessPart to part

HardnessShore A 10–80LSR grades

Volume10,000s +Automated cycles

Materials	Standard, medical, food-contact, optically clear, self-lubricating and self-adhesive LSR grades.
Finishes	Polished, EDM-textured or blasted tool finishes; colour by masterbatch; flash-free with a well-built tool.
Design guidance	Uniform walls, typically 0.5–3 mm; avoid thick slugs. Allow for silicone shrink (around 2–3 %) in the tool. Plan vents and ejection; LSR flows into very fine gaps.
Best suited to	Baby and kitchen products, seals, valves, medical and wearable parts, and high-volume food-contact items.
Watch-outs	High tooling cost; tools need very tight shut-offs to avoid flash.

Other methods in Silicone & rubber

Previous: Transfer moulding Next: Rubber & silicone extrusion

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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.