Gemini provides specialist Liquid Silicone Rubber (LSR) injection moulding services in the UK, supporting customers across medical, automotive, industrial and performance engineering sectors.
The Material
Liquid silicone rubber is a high-performance elastomer known for its durability, flexibility, and resistance to extreme environments. Our in-house capability allows us to deliver both rapid prototyping and medium volume production, giving customers a seamless route from development to manufacture.
By combining advanced process control with decades of silicone expertise, we produce precision-moulded Liquid Silicone Rubber components engineered for reliability and repeatability.
Liquid silicone rubber moulding suits parts that need to seal, flex, insulate or feel soft in the hand, including:
Gaskets, membranes, one-way and duckbill valves where a repeatable hardness and a reliable seal matter.
Device components and skin-contact parts in biocompatible, FDA grade silicones.
Grips, buttons and sealed assemblies where soft silicone is bonded onto a rigid moulded body.
Our Process
We operate a uniquely developed speed mixer system specifically designed for prototype silicone mouldings.
Unlike traditional silicone injection moulding machinery, which can require hours of downtime and generates significant material waste when changing silicone grades, our system allows material changeover in seconds with virtually no waste.
This flexibility enables engineers to refine component performance efficiently and accurately before committing to production tooling.
Advantages
Rapid iteration during product development
Incremental hardness sampling for valves and seals
Reduced material waste and lower development costs
Faster validation of functional performance
Production
To complement our prototyping capability, we have invested in a dedicated BOY 55 LSR injection moulding machine for consistent, cost-effective production. Customers benefit from a scalable solution that maintains quality standards from initial prototype through to full production.
This machine has been retrofitted with a 2KM mixing system, enabling automatic colour dosing at the point of injection. Colouring LSR at the injection stage enhances both efficiency and customisation, supporting diverse product requirements.
This enables us to offer
Medium volume manufacturing
Tight process control and repeatability
Improved cycle efficiency
Greater consistency across production batches
Which provides the following advantages:
Greater flexibility for material changes
Accurate colour consistency
Reduced downtime between production runs
Material Benefits
Liquid Silicone Rubber offers a wide range of performance advantages:
These properties make LSR moulding ideal for demanding environments where conventional thermoplastic elastomers may not perform reliably.
Get startedUK-Based Liquid Silicone Rubber Injection Moulding
Manufacturing LSR components in-house in the UK provides significant advantages:
Reduced lead times
Elimination of overseas shipping costs
Greater supply chain reliability
Direct collaboration with our engineering team
Strict quality control standards
FAQ
Liquid silicone rubber moulding is an injection process for LSR, a high-performance elastomer known for its flexibility, durability and resistance to extreme environments. The liquid silicone is injected into a mould and cured under heat to form a finished part. It suits components that need to flex, seal or withstand conditions that would defeat a standard thermoplastic.
LSR injection is a different material class from thermoplastic injection moulding. LSR is a thermoset, so it cures rather than simply cooling, and it needs different tooling, handling and process control. Gemini runs LSR moulding as a dedicated specialism rather than as an add-on to plastic moulding.
Silicone injection moulding suits seals, valves and gaskets, medical and skin-contact parts, soft-touch grips and over-moulded components. It's chosen where a part needs to stay flexible, form a reliable seal, or hold up to heat, chemicals or repeated use.
Liquid silicone rubber is elastic with good tensile strength and compression set resistance. It is UV, ageing, chemical and bacteria resistant, and performs reliably from -55°C to +300°C. It is also odourless and tasteless, with medical and FDA-compliant grades and biocompatible options available.
Yes. Gemini has developed a process for over-moulding silicone onto thermoplastic substrates, using controlled surface treatment to form a permanent bond between the silicone and the plastic. It suits soft-touch interfaces, sealed assemblies, grip surfaces and integrated valve and sealing systems.
Yes. A speed-mixer system built for prototype silicone mouldings changes material grades in seconds with very little waste, which allows rapid iteration and incremental hardness sampling during development. For volume, a dedicated BOY 55 LSR injection moulding machine handles consistent medium volume production, so a part moves from prototype through to production on one site.
Yes. LSR components are moulded in-house in the UK, which cuts lead times, removes overseas shipping, and gives customers direct contact with the engineering team and tighter quality control throughout.
Send us details about your part and we'll get back to you within 24 hours.
