What Is Silicone Injection Molding?
Silicone injection molding—more precisely, Liquid Silicone Rubber (LSR) injection molding—is a highly efficient manufacturing process used to produce durable, flexible, and chemically resistant silicone parts. Unlike thermoplastic injection molding, which relies on cooling to set the material, silicone injection molding uses heat to trigger a chemical reaction called vulcanization (or curing). This reaction is irreversible: once cured, the silicone cannot be melted again.
How It Works
The process starts with a two‑component liquid silicone system—usually Part A (base) and Part B (catalyst/crosslinker). The entire cycle is highly automated:
Metering & mixing – Precision pumps draw the two components in a strict 1:1 ratio (pigments can be added here). They are thoroughly blended in a static mixer to form a uniform compound.
Cold injection – The mixed material stays in a cooled barrel (around 15–25°C) to prevent premature curing, then it is injected into the mold cavity.
Heat curing – This is the critical step. The mold is heated to 170–220°C. The high temperature instantly triggers cross‑linking, turning the liquid silicone into a solid, elastic part in just seconds to minutes.
Demolding – After a short cooling period, the finished part is ejected.
Many modern systems use a cold runner design, which keeps the material in the runner fluid and cures only the cavity content—virtually eliminating waste and enabling fully automated, flash‑free production.
Key Advantages
High efficiency – Fully automated, no flash, minimal material waste.
Precision & complexity – LSR’s low viscosity allows it to fill intricate molds, producing complex geometries with tight tolerances.
Superior material properties – Finished parts exhibit excellent resistance to extreme temperatures (–50°C to +250°C), chemicals, UV, and aging. They also offer high elasticity, biocompatibility, and good electrical insulation.
Common Applications
Thanks to its unique performance, silicone injection molding serves diverse industries:
Medical – Catheters, seals, implants, respiratory masks, and other biocompatible devices.
Automotive – O‑rings, gaskets, seals, vibration dampers, and tubing.
Consumer electronics – Waterproof gaskets for smartphones, keypads, computer keyboards, wearables.
Baby & food – Pacifiers, bottle nipples, food‑grade seals and kitchenware.
In a nutshell – Silicone injection molding combines speed, precision, and material excellence, making it the go‑to choice for high‑volume production of silicone components that demand reliability and performance.
