Reducing Silicone Waste with Cold Runner LSR Molding Technology

Liquid silicone injection moulding machines employ cold runner technology. After precisely blending the low-temperature liquid A and B components of silicone in the correct ratio, the mixture is pressurised by a screw and injected into the high-temperature mould cavity. Under the mould's heating action, a rapid chemical cross-linking reaction occurs, causing the material to cure and form. This achieves high-precision, high-efficiency automated production.

The core principle lies in the chemical reaction sequence of 'mixing-injection-heated vulcanisation', differing fundamentally from traditional injection moulding machines that heat solid raw materials.

1. Raw Material Delivery and Mixing: Liquid silicone rubber typically comprises two components: A (containing a catalyst) and B (containing a cross-linking agent), stored separately in material barrels. An automatic feeder or metering system conveys the A and B compounds in a fixed ratio to a static mixer where they are thoroughly blended.
2. Injection Moulding: The mixed liquid silicone is propelled by a screw through a non-return valve and switch nozzle into the cold runner system. The cold runner system maintains the silicone at a low temperature to prevent premature curing within the runner. The silicone is rapidly and uniformly injected into the preheated mould cavity.
3. High-Temperature Vulcanisation Moulding: Within the mould, heated to high temperatures via a heating system, the A and B components of the liquid silicone undergo catalysis and initiate a rapid chemical cross-linking reaction, known as thermal curing. This process rapidly solidifies the liquid silicone into elastic, stable silicone products.
4. Pressure Holding and Cooling: During curing, constant pressure is maintained to ensure dimensional accuracy of the product. After moulding, the mould cools and opens to remove the cured product.
5. Automation and Repeat Production: The entire process operates as a cyclical automated sequence, minimising manual intervention and enhancing production efficiency.

• Raw Material State: Liquid silicone injection moulding machines utilise liquid raw materials, whereas conventional injection moulding machines employ solid raw materials.
• Forming Method: Liquid silicone cures through a chemical cross-linking reaction, constituting a thermosetting moulding process; conventional injection moulding machines rely on cooling for solidification.
• Temperature Control: Liquid silicone injection requires cold runner technology to maintain low temperatures while mould heating facilitates vulcanisation. Conventional injection moulding machines heat raw materials within the barrel and mould to melt and cool them into shape.