Liquid Silicone Rubber (LSR) injection molding is a high-precision process used to create durable, flexible, and heat-resistant parts. Unlike thermoplastic injection, LSR is a thermosetting process, meaning the material is kept cool until it enters a heated mold to undergo vulcanization.
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Key Components of an LSR System
To achieve consistent production, a standard setup typically requires the following integrated units:
Dosing and Mixing Unit: A high-pressure pump system (usually 1:1 ratio) that draws "Part A" and "Part B" from drums, mixes them with pigment, and feeds the chilled material into the injection unit.
Injection Unit: Features a water-cooled barrel and nozzle to prevent the silicone from curing prematurely. It uses a specialized screw designed for the low viscosity of liquid silicone.
Clamping Unit: High-tonnage hydraulic or electric presses (ranging from 30 tons to 200+ tons) that ensure the mold remains sealed against high injection pressures.
Heating System: Integrated into the mold platens to maintain temperatures typically between 160°C and 200°C for rapid curing.
Technical Advantages of LSRFeatureBenefitFlashless MoldingHigh-precision tooling reduces the need for secondary trimming.Short Cycle TimesRapid vulcanization allows for high-volume automated production.Complex GeometriesThe low viscosity of LSR allows it to fill intricate 3D molds and micro-features easily.Thermal StabilityParts remain functional in extreme temperatures ($-60$°C to $+250$°C).
Common Applications
Industrial & Automotive: Gaskets, seals, O-rings, and high-voltage cable connectors.
Consumer Goods: 3D labels, kitchenware, and wearable device straps.
Medical: Class VI biocompatible components like valves, masks, and tubing.
Electronics: Waterproof seals for smartphones and over-molded keypad components.
Cold Runner Systems: To minimize material waste, consider using a cold runner system. This keeps the silicone in the distribution channels chilled, allowing you to reuse the material in the next cycle rather than discarding "sprue" waste.
The factory behind these machines is Dongguan Jinyu Automation Equipment Co., Ltd. (often referred to as Jinyu Machinery). They are a specialized manufacturer based in the "World's Factory"—Dongguan, China.
Manufacturing Milestones
2000: Founded with a focus on PVC (plastic dropping) equipment.
2004: Expanded into heavy hydraulic machines (30T to 100T).
2017: Developed fully integrated automatic silicone and PVC production lines.
2023–2024: Launched their latest LSR (Liquid Silicone Rubber) vertical injection molding series and upgraded automatic batching/mixing systems to reduce material waste.
The factory offers a "one-stop" solution. This includes not just the hardware, but also mold making, raw material sourcing (silicone/PVC paste), and technical training. They are known for providing lifetime technical support and sending technicians abroad for on-site installation and maintenance.
