LSR medical molding is not just about the material. It is about the full system: validated processes, documented material traceability, and a controlled manufacturing environment. Here is what that actually means in practice.
Why LSR for Medical Devices
Liquid silicone rubber has a combination of properties that make it the material of choice for many medical components:
● Biocompatibility: LSR can be formulated to meet ISO 10993 biocompatibility requirements, including cytotoxicity, sensitization, and implantation testing for appropriate contact types and durations.
● Sterilization resistance: LSR maintains its properties through autoclaving (steam at 134 degrees C), gamma irradiation, and ethylene oxide (ETO) sterilization. Most thermoplastics cannot survive all three.
● No leachables: Platinum-cured LSR has very low extractable and leachable content, which is critical for drug delivery devices and long-term implantables where chemical migration to the body or drug product is unacceptable.
● Wide temperature range: LSR remains flexible from minus 60 degrees C to 200 degrees C, which covers surgical sterilization cycles and cold chain storage.
The LSR Process: What Makes It Different
LSR is a two-part liquid system. Component A (the base polymer) and Component B (the crosslinker and catalyst) are stored separately and mixed in a 1:1 ratio just before injection. This prevents premature curing.
The mixed LSR is injected into a heated mold at 160 to 200 degrees C. Curing happens rapidly, often in 15 to 60 seconds for small parts. This allows for fully automated, continuous molding in a controlled environment. Unlike many thermosets, LSR parts do not require post-cure in a separate oven, though post-curing is sometimes used to drive off residual volatile content for medical applications.
LSR also has very low viscosity, which allows it to fill intricate part geometries and thin walls (down to 0.3mm in some cases) that are difficult with solid silicone.
Critical Compliance Points for ISO 13485
ISO 13485 is the quality management system standard for medical device manufacturers. For LSR molding in a medical context, key requirements include:
● Material traceability: Every lot of LSR used in a medical part must be traceable from the resin supplier certificate of conformance through mixing, molding, and final product. If a batch issue is discovered, you must be able to identify every part made with that material.
● Validated processes: The molding process must be validated through IQ (installation qualification), OQ (operational qualification), and PQ (performance qualification). This proves that the process consistently produces conforming parts across its full operating range.
● Cleanroom environment: Medical LSR molding typically occurs in a Class 7 or Class 8 cleanroom (ISO 14644-1) to control particulate contamination. The molding cell, personnel gowning, and material handling are all controlled.
● Validated cleaning protocols: Equipment cleaning and changeover between materials or products must follow validated procedures to prevent cross-contamination.
Typical Parts Made with Medical LSR
LSR is used across a wide range of medical and healthcare device applications:
● Respiratory masks and interfaces (CPAP, anesthesia, oxygen delivery)
● Surgical instrument grips and handles
● Drug delivery device seals, plungers, and tip caps
● Ophthalmic device components
● Hearing aid ear tips and domes
● Wearable medical sensor interfaces
Next Step: NICE Rapid is ISO 13485 certified and operates cleanroom LSR molding. Request a medical LSR quote with full documentation at nicerapid.com.