LSR Injection Moulding – Advanced Silicone Technology for Precision Components

Liquid Silicone Rubber (LSR) injection moulding is a high-performance manufacturing technology used for producing flexible, durable silicone parts in large volumes. It is a versatile and efficient process that offers exceptional accuracy and consistency, making it an ideal choice for mass production.

What Is LSR Injection Moulding?

LSR injection moulding is a multi-step manufacturing process designed to shape Liquid Silicone Rubber into precise and durable components. It begins with the preparation of a mixture, typically consisting of two components – a base material and additives (e.g. pigments or fillers). These are blended into a homogeneous compound through a controlled mixing process. There are various grades of LSR available, depending on the product's specific requirements.

The injection process begins once the mould is closed using a clamping unit. The liquid silicone is injected into a cooled cylinder and then forced into a heated mould cavity. The mould is then heated to initiate the curing process (also known as vulcanisation). The tooling system includes both cold and hot runner channels – the cold runner prevents premature curing, while the hot runner ensures uniform flow into the mould. Once filled, the mould is cooled, and the final part is ejected.

Simplified Process Overview

• Preparation of the silicone mixture (base material and platinum catalyst)

• Intensive mixing at low temperatures

• Injection into a heated mould cavity

• Heat curing inside the mould to form flexible silicone parts

• Cured LSR forms solid, elastic components

LSR Injection Moulding Machines

Injection moulding machines for LSR are widely used in the production of medical devices, baby products, kitchenware, and automotive accessories. Choosing a high-quality injection moulding machine is critical to ensuring product quality and process efficiency. These machines typically consist of:

• Injectors: Increase the pressure of the LSR mixture, enabling precise injection and pressure control

• Nozzles: Deliver LSR into the mould with accurate dosing to prevent overfilling or leaks (equipped with automatic shut-off valves)

• Metering systems: Supply the correct volume of silicone compound during the production cycle

• Feed barrels (plungers): Support mixing and homogenisation; connected to pigment tanks and the main pumping unit

• Mixers: Responsible for blending LSR components evenly before injection

• Clamping units: Secure the mould during injection and release it afterward

Multi-Component and Multi-Colour LSR Injection

LSR injection moulding allows for simultaneous use of multiple components or colours in one cavity. This is achieved by injecting different grades or colours of silicone into the same mould using cooled nozzles that prevent premature curing. This system ensures perfect balance across cavities, regardless of the mould layout.

Injection systems can be adapted for use with standard thermoplastic or rubber moulding machines, regardless of clamping configuration or machine design.

Liquid Silicone Rubber (LSR) – Material Overview

LSR is a platinum-cured silicone rubber known for its excellent flowability and consistent curing properties. It is commonly used in precision moulding applications due to its stability, biocompatibility, and resilience.

Key Properties of Liquid Silicone Rubber

• Odourless and tasteless

• High tear and tensile strength

• Excellent flexibility

• Resistant to extreme temperatures – suitable for outdoor use

• Waterproof and resistant to oxidation and certain chemicals

• Sterilisable using various methods

• Maintains mechanical properties across a wide temperature range

• Biocompatible – safe for contact with human tissue and body fluids

• Excellent insulating properties

• Easy to pigment or colour

• Adheres well to other materials in overmoulding applications

LSR injection moulding is also environmentally friendly, as it generates minimal production waste.

Applications of LSR Injection Moulding

The process is cost-effective and highly efficient, producing parts that are flexible, impact-resistant, thermally stable, and chemically inert. LSR parts retain their shape and integrity, making them ideal for use in:

• Food processing equipment

• Automotive components

• Medical and healthcare devices

• Consumer electronics

• Baby care products

Common LSR Moulded Products:

• Seals and gaskets

• Kitchen utensils and accessories

• Sealing membranes

• Electrical connectors

• Baby bottles and toys

• Surgical instruments

• Catheters and respiratory masks

• Electronic covers

• Keypads and buttons

• Shock-absorbing pads

Advantages of LSR Injection Moulding

LSR moulding is the perfect solution for producing complex-shaped silicone parts. Its main benefits include:

• High dimensional accuracy

• Long-term durability (resistant to UV, ozone, etc.)

• Excellent repeatability and precision

• Reduced material waste

• Ideal for high-volume manufacturing

• Consistent product quality

• Fully automated process

• Minimal flash and reduced post-processing

Get in Touch with Our LSR Experts

Interested in LSR injection moulding solutions? Contact our team today to learn more about how this technology can benefit your production process. Call us on +48 22 292 40 24 or +48 505 16 03 03, send an email to Power@PowerRubber.com, or use our contact form – we’re here to help!