Liquid Silicone Rubber
Liquid Silicone Rubber (LSR) is a high-performance, versatile material used across a wide variety of sectors, including medical, automotive, electronics, food-grade manufacturing, and industrial applications. At Kea-Flex, we specialise in liquid silicone rubber injection moulding, producing high-precision components such as face mask seals for life-saving respiratory equipment.
Thanks to its unique chemical composition and the advanced liquid injection moulding process, LSR offers superior performance in demanding environments where consistency, durability, and hygiene are essential.
Biocompatibility – LSR is known for its excellent compatibility with human tissue. As a safe silicone rubber, it is hypoallergenic and biocompatible, making it suitable for prolonged skin contact. Unlike some other elastomers, it resists bacterial growth and does not stain or corrode adjoining materials, which is vital in both medical and hygiene-sensitive environments.
Tasteless and odourless – LSR is both tasteless and odourless, and can be manufactured to comply with FDA standards, making it ideal for food-grade and baby care products such as bottle teats and soothers. Its non-reactive nature ensures no transfer of taste or smell, even after prolonged use.
Durable and chemical resistant – LSR’s resistance to chemicals, water, and environmental degradation makes it suitable for use in applications ranging from automotive engine compartments to industrial gaskets. It can withstand exposure to oxidation, acids, and alkalis and can be sterilised using methods like autoclaving, gamma irradiation, and ethylene oxide, further enhancing its value in the medical sector.
Temperature resistance – One of the key advantages of LSR is its temperature resistance. It remains stable and flexible across a wide range, from -60°C up to +180°C, with some grades reaching even higher. This property makes it suitable for high-consistency rubber alternatives in extreme thermal environments.
Electrical Properties – Thanks to its superior dielectric strength and resistance to corona discharge, LSR is excellent for electrical insulation. It can also be modified with conductive fillers, making it suitable for producing electronic components where both flexibility and conductivity are required.
Mechanical Properties – LSR has excellent mechanical performance, including high tear resistance, good elongation, and strong tensile strength. It retains its elasticity and flexibility over time and can be manufactured in Shore A hardness values from 5 to 80, making it comparable to materials like RTV silicone rubber, but more efficient for injection moulding.
Colour – LSR can be easily coloured using compatible pigments. This is useful for branding, colour-coded safety parts, and visual differentiation in assemblies. Pigments can be mixed directly into the liquid formulation before moulding.
Applications – Liquid Silicone Rubber is ideal for producing parts that must withstand harsh conditions or require high hygiene standards. Common LSR applications include:
Respirator masks
Diaphragms and seals
Bellows and gaskets
Sensors and connectors
Baby bottles and soothers
Hearing aid tips and personal hygiene products
Industrial products such as valves, gaskets, and pump components
Its ability to maintain flexibility and structural integrity makes LSR the go-to material for both static and dynamic sealing applications.
How the Liquid Silicone Rubber Injection Moulding Process Works
Liquid Silicone Rubber (LSR) injection moulding, also known as Liquid Injection Moulding (LIM), is a highly efficient process that uses a two-part platinum-catalysed silicone system. The components are kept separate until they are mixed and injected into a heated mould cavity, where they rapidly cure into flexible, durable parts.
This process combines a silicone base with silica fillers, resulting in a material that offers an ideal balance of strength, flexibility, and chemical resistance. Whether you’re manufacturing medical tubing, automotive connectors, or soft, vinyl-like components, LSR injection moulding delivers fast cycle times, minimal waste, and consistent, high-quality results.
Common LSR Products and Their Uses
Liquid Silicone Rubber (LSR) is one of the most adaptable materials used in manufacturing today. Thanks to its flexibility, durability, and resistance to heat, chemicals, and moisture, it’s the go-to choice for a wide range of products across many industries. From life-saving medical components to rugged automotive parts, LSR delivers consistent performance where it matters most. Here are some of the most common products made using LSR — and why they’re so effective:
Respirator Masks and Medical Seals
LSR’s biocompatibility makes it ideal for medical-grade products that come into close contact with the skin. Respirator masks, face seals, and soft-touch medical gaskets benefit from its hypoallergenic properties, while its ability to be sterilised ensures safety and hygiene in clinical settings.
Respirator Masks and Medical Seals
LSR’s biocompatibility makes it ideal for medical-grade products that come into close contact with the skin. Respirator masks, face seals, and soft-touch medical gaskets benefit from its hypoallergenic properties, while its ability to be sterilised ensures safety and hygiene in clinical settings.
Diaphragms and Fluid Seals
Used in both medical devices and industrial applications, diaphragms made from LSR are valued for their flexibility and resilience. These products must maintain their shape under pressure and over repeated cycles — a task LSR handles with ease.
Bellows and Gaskets
In automotive and machinery environments, LSR bellows and gaskets are designed to absorb motion, seal out contaminants, and withstand exposure to oils, fuels, and extreme temperatures. The material’s ability to maintain performance across a wide temperature range makes it a reliable choice.
Sensors and Connectors
Electrical insulation is one of LSR’s standout properties. It’s used in soft-touch housings for sensors, overmoulded connectors, and components that require precise sealing and electrical isolation, especially in the automotive and consumer electronics sectors.
Baby Bottles and Soothers
Because it’s tasteless, odourless, and FDA-compliant, LSR is commonly found in baby care products such as bottle teats, soothers, and pacifiers. Its softness and safety make it perfect for delicate applications involving infants and toddlers.
Hearing Aid Tips and Personal Hygiene Products
LSR is used to mould ear tips for hearing aids and wearable health devices thanks to its comfort and long-lasting fit. In personal hygiene and wellness products, it offers a smooth, non-irritating surface that’s easy to clean and sterilise.
Valves, Gaskets, and Pump Components
In industrial settings, LSR is used for durable parts such as valves and pump seals. These products often operate under high pressure and temperature, and LSR’s chemical resistance and mechanical strength ensure long service life without degradation.
Silicone Rubber Moulding FAQs
What is liquid silicone rubber used for?
With its high chemical and thermal stability, Liquid Silicone Rubber (LSR) is a perfect material for creating injection moulding parts. These LSR moulds can be used in industrial fields such as automobiles or food manufacturing, textiles, and medical, where they have been proven time after time to produce excellent results.
Is liquid rubber the same as silicone?
A major difference between silicone and rubber is the fact that the majority of rubber contains carbon-containing polymer chains while rubber has silicon rather than carbon. A major difference between silicone and carbon-based polymers in natural rubbers like Latex (which most people are familiar with) concerns their Main ingredient – Silicate molecules which provide resilience while preserving elasticity; they’re not too rigid like plastics either
How does LSR compare to epoxy resins or polyurethane?
While epoxy resins and polyurethane offer rigidity and adhesion, they lack LSR’s flexibility, biocompatibility, and thermal resistance. LSR is preferable when flexibility, hygiene, and long-term durability are priorities.
What’s the difference between LSR and High Consistency Rubber (HCR)?
High Consistency Rubber is gum-based and typically used in compression or transfer moulding. LSR, with its low viscosity, is designed for automated liquid silicone rubber injection moulding—faster, cleaner, and more efficient for high-volume production. Additionally, LSR offers greater consistency between parts and reduced waste, making it the preferred choice for precision applications in medical, automotive, and consumer products.
Can LSR be overmoulded onto other materials?
Yes, LSR is excellent for overmoulding onto thermoplastics or metals to provide seals, grip surfaces, or flexible interfaces.
6 Reasons to use Liquid Silicone Rubber (LSR)
1. Ideal for Complex Moulded Parts
Liquid Silicone Rubber is the material of choice for many applications, including certain automotive equipment and medical devices. LSR can be used in single- or two shot injection molding to create parts like gaskets; it’s also excellent at creating instruments with complex systems within them!
2. Excellent Durability and Shape Retention
Liquid Silicone Rubber is a fantastic material for making components that need to be durable. It has low creep and compression set, which means it can take on any shape without compromising performance or durability in the long run!
A great option for use in automotive components as the materials provides one of our most dynamic strengths: flexibility with an ability withstand harsh conditions while still delivering high quality results time after time.
3. Reliable Thermal Stability
Liquid Silicone Rubber is the perfect material for a wide range of applications. With excellent thermal stability, it can be used in both hot and cold environments without losing its shape or ability to flexible – which makes this type great choice when you need products that will last through tough conditions like fridge trays or baking cups!
4. Great Outdoor performance
Liquid Silicone Rubber is the perfect material for outdoor use . It has thermal stability, which means that even if you are outside all day long your LSR parts won’t melt or lose their shape – they’ll be just fine! It can also resist bacteria growth thanks to its resistance against mold and mildew as well UV rays (which cause fading). And don’t worry about water damage either; this material doesn’t absorb any moisture so nothing will stick after being exposed awhile in rainstorms/heavy dewfalls etc.
5. Safe for Sterile and Wet Environments
Liquid Silicone Rubber is not only moisture-resistant to hot and cold water and making it an excellent choice for plumbing hardware like gaskets or valves. It is also used in a variety of different products that can be sterilized using steam, within medical devices. Additionally its durability means that you can put your trust in these materials without worry about them degrading over time!
6. Superior Electrical Insulation
LSR is a material that offers excellent insulating properties due to its resistance to corona discharge. It has been shown not only to maintain insulation but also to provide high resistance to electrical stress. Additionally, it can be formulated with conductive materials, making it suitable for use in the production of electrical components.
