Vertical Injection Moulding Machine Silicone Injection Molding Machine

The key to realize the precise injection molding of LSR liquid silica gel

LSR is different from traditional thermoplastic materials in shrinkage, demoulding, mold material, cold runner system and temperature control, which makes LSR more difficult to process than ordinary thermoplastic rubber.

The water-proof silicone rubber ring of smart phone is mostly formed on the original metal or plastic accessories. At the same time, its volume is smaller than that of the general use of silicone ring, and its matching degree with the shell and accessories is higher, so it needs to adopt more precise (micro) injection molding technology.

Machine Model Parameter

The key points for LSR to realize precision injection molding are as follows:

(1) Full mixing of liquid silica gel

➀ accurate mixing proportion: LSR is a and B two-component raw materials. Before injection molding, it must be fully mixed according to the accurate 1:1. If it is a colored liquid silica gel product, the color paste proportion must also be accurately controlled.

➁ mixer: the static mixer is the key part in the injection molding. Only after the static mixer is fully and evenly mixed, can the liquid silica gel injected into the mold be fully vulcanized.

(2) Sealing and temperature control of injection molding machine parts

➀ due to the low viscosity of LSR, the screw must be sealed in order to consider the backflow and leakage of materials;

➀ since the mold is heated during LSR forming, in order to prevent LSR from curing, the water-cooled nozzle can be used to ensure the temperature is low enough.

(3) Finished product control in injection molding process

➀ parting line: the position and accuracy of parting line shall be considered in advance, which is helpful to avoid air entrainment and welding and burr;

➁ shrinkage: Although LSR does not shrink in injection molding, it usually shrinks by 2% - 3% after demoulding and cooling due to its high thermal expansion coefficient;

➂ location of glue injection port: actual product shrinkage shall be considered;

➃ vacuumizing: when designing the parting line, ensure that the mold is closed, and the vacuum pump vacuumizes all cavities through the clamps under the mold switch;

➄Demoulding: generally, demoulding technology of fractionating column tray, push pin and air push is adopted, or manual demoulding is adopted.

➅ mold temperature: LSR is vulcanized in the heating process, and the temperature distribution in the mold must be controlled evenly. The temperature difference shall be controlled at + / - 10 ℃