LSR molding is a thermoset process in which the material supply system is chilled and the mold is heated, Liquid Silicon Rubber components are manufactured using an injection molding technique similar to regular plastic injection molding. Liquid silicone rubber has thermal, chemical, and electrical resistance, as well as biocompatibility.

LIQUID SILICONE RUBBER MOLDING: WHAT IS IT AND HOW DOES IT WORK?

LSR molding differs from thermoplastic injection molding because of its flexibility. An LSR molding tool is created using CNC machining, much like a standard aluminum tool, to create a high-temperature tool that can withstand the LSR mounding process. Following milling, the tool is hand polished to the customer’s specifications, with six different surface finishes to choose from.

To produce the most consistent LSR components, the finished tool is placed in an innovative LSR-specific injection molding press with precision geared shot size control. Because injector pins might impair component quality, LSR pieces are manually removed from the mold newtopsilicone. Standard silicones and specific LSR grades are available to meet a wide range of component applications and industries, including medical, automotive, and lighting.

HOW DOES THE LIQUID SILICONE INJECTION MOLDING PROCESS WORK?

In the LIM process, silicones and acrylics are often used materials. The approach needs the use of a spring-loaded pin nozzle to keep the machine components from being clogged with materials. The injection pressure can be higher than the extruder barrel pressure because of the spring-loaded system, which keeps the channel clean.

The LIM technique combines the use of a pump with proportional mixing and dispensing of LSR. The catalyst is maintained in the plunger on the other side. Each will be fed in a 1:1 ratio into a static mixer, which will start the mixing process.

After that, the liquid mixture is placed into a sealed mold and heated to temperatures between 180 and 200 degrees Celsius (355 to 390 degrees Fahrenheit). It starts off as a liquid that is heated within the mold to start curing. Once the almost finished piece has solidified, the molding machine ejects it.

TRANSFER OF MOLDING

Transfer molding, like compression molding, requires the processing of secondary raw materials into pre-forms. These pre-forms are inserted in a “pot” between the top plate and a plunger in a different way.

Because of their large cavity count, transfer molded rubber items frequently require fewer and simpler pre-forms. A single pre-form can be used to fill hundreds of voids. Some of the advantages of transfer molding over compression molding are as follows:

TOOLING THAT IS BOTH COST-EFFECTIVE AND EFFICIENT

The surplus material that leaks out of the cavity dividing line does not keep the mold open; instead, it keeps the plunger open from the pot.

A COST-EFFECTIVE APPROACH IS PROVIDED FOR MEDIUM TO HIGH PRECISION COMPONENTS

Pre-forms for color-molded rubber components can be hand-cut from raw material, eliminating contamination from compression molding’s mechanical prep or injection molding’s injection screw and barrel.

MOLDING MACHINES FOR LIQUID INJECTION

The essential components of the typical two-part liquid injection moulding process are as follows:

Supply drums: The plungers are connected to the pumping system and are also known as liquid silicone supply containers. In two-container pigment setups, a third container is frequently incorporated.

Injectors: This device transports the LSR forming material into the pumping mechanism via pressurized force. The injection rate and pressure may both be modified by the machine operator. This variable fluctuates according on the project’s needs.

Metering units: The metering device pumps the two liquid elements into a predefined ratio, ensuring that they are delivered at the same time and in the same proportion.

Mixers: The components are blended in a static mixer after the liquid forming materials have gone through the metering device. Under pressure, the combined material is squeezed into the mold.

Nozzles: The liquid compound is directed into the mold through a nozzle with an automatic shut-off valve. This valve prevents the mixture from seeping into the mold or overfilling it.