What Is LSR Injection Molding?

Liquid Silicone Rubber (LSR) injection molding is a high-precision manufacturing process where liquid silicone is injected into a heated mold and cured to create durable, flexible, and heat-resistant silicone components. Unlike thermoplastic injection molding, LSR uses a thermoset material that permanently solidifies under heat, making it ideal for complex geometries and high-performance applications. Our liquid silicone rubber (LSR) molding process produces custom prototypes and end-use production parts in 15 days or less.

LSR Injection Molding Process

Material Preparation: LSR consists of two components—Part A and Part B—that are mixed in a precise 1:1 ratio. This mixture can include colorants and other additives to achieve desired properties. 

Injection: The mixed LSR is injected into a heated mold cavity under controlled pressure. Due to its low viscosity, LSR fills complex mold designs effectively, ensuring high-precision parts.

Curing: The material undergoes a curing process within the mold, typically facilitated by a platinum catalyst, which cross-links the silicone molecules, resulting in a solidified, durable part.

Cooling and Ejection: After curing, the mold is cooled, and the finished part is ejected. The inherent flexibility of LSR often eliminates the need for ejector pins, simplifying mold design.

Advantages of LSR Injection Molding

High Precision and Complex Designs: LSR injection molding can produce parts with tight tolerances and intricate geometries, making it suitable for applications in medical devices, automotive components, and consumer electronics.

Rapid Production Cycles: The fast curing times associated with LSR injection molding enable quick turnaround for prototypes and production parts, reducing time-to-market. 

Durability and Performance: LSR parts exhibit excellent mechanical properties, including high tensile strength, tear resistance, and flexibility, ensuring long-lasting performance in demanding environments.

Biocompatibility: LSR is inherently biocompatible, making it ideal for medical applications such as surgical instruments, implants, and seals.

Applications of LSR Injection Molding

Medical Devices: LSR is used to manufacture components like seals, gaskets, and diaphragms that require biocompatibility and durability.

Automotive Industry: Components such as seals, gaskets, and vibration dampers benefit from LSR's high-temperature resistance and flexibility.

Consumer Products: Items like kitchen utensils, baby products, and wearable devices utilize LSR for its safety and performance characteristics.

Electronics: LSR is employed in producing waterproof seals and gaskets for electronic devices, ensuring protection against environmental factors.

Design Considerations for LSR Injection Molding

When designing parts for LSR injection molding, consider the following guidelines to optimize manufacturability and performance:

Wall Thickness: Maintain consistent wall thickness to ensure uniform flow and curing.

Draft Angles: Incorporate appropriate draft angles to facilitate easy ejection from the mold.

Avoid Undercuts: Design parts without undercuts or incorporate lifters to prevent molding complications.

Radii and Fillets: Use generous radii and fillets to reduce stress concentrations and improve part strength.

Gate Design: Optimize gate locations and sizes to ensure efficient filling and minimize defects.

• Standard Silicone (30, 40, 50, 60, and 70 durometers)

• Medical-Grade Silicone

• Optical-Grade Silicone

• Fluorosilicone (fuel and oil resistant)

Tolerances: thingyfy can maintain a machining tolerance of +/- 0.003 in. (0.08mm) with a linear tolerance of +/- 0.025 in./in. (0.025mm/mm).

Whether you’re prototyping or scaling production, LSR injection molding delivers unmatched performance. Contact us to discuss your project and explore certified material solutions.