The Science Behind Liquid Silicone Rubber Injection Molding

For years, high-consistency rubber (HCR) has dominated manufacturing processes. The material has great temperature resistance; it’s a common choice for parts that see conditions ranging from -50℃ to +300℃. These elastomers also have great aging resistance, making them a staple in industries like aerospace, automotive, healthcare, and more. But while HCR has been a go-to solution for manufacturers, liquid silicone rubber (LSR) has replaced it in many areas.

Because LSRs have a lower viscosity, they are more readily processable via injection molding. HCRs don’t have this ability and must be processed through more labor-intensive methods like transfer and compression molding. Below, we’re exploring the science behind liquid silicone rubber injection molding and whether it’s right for your business.

How Liquid Silicone Rubber Injection Molding Works

Tool Preparation

The first step to liquid silicone rubber injection molding is tool preparation. You’ll need a mold into which the rubber can be injected, which creates the final part. They’re typically made from hardened tool steel. Using CNC machining, the fine details are etched into the material, creating the space for the rubber to be injected. Engineers will take into account the rubber’s shrinkage rate and the need for proper gating, venting, and heating channels. The completed mold will then be trialed, and any adjustments can be made before moving into full-scale production.

Mixing

The injection molding process begins with mixing materials together. Depending on the application, this could include combining raw rubber with curing agents, fillers, and additives. This pre-mixing process improves quality, reduces defects, ensures proper curing, and optimizes material flow into the mold.

Injection

Once the materials are mixed, the solution will move into the barrel of the injection molding machine. An internal ram will move forward to inject the liquid silicone rubber through the nozzle into the heated mold cavity.

Curing

The part is allowed to cure for a specific amount of time. Then, the mold opens, and the part can be removed.

Secondary Operations

Once the part is complete, it will likely move into secondary operations. During this stage, the part will undergo any processes needed to make it suitable for its intended use. That might include coating application or other processes like testing, assembly/sub-assembly, and more. From there, it’s ready to be shipped to its final destination.

Trust Moldtech for High-Quality Rubber Injection Molding

If you’re looking for an end-to-end rubber injection molding partner, turn to Moldtech. We offer both high-consistency rubber and liquid silicone rubber injection molding solutions to meet your exact needs. For decades, some of the biggest companies have trusted us to create products like:

In fact, Boeing, Bosch, Johnson & Johnson, and the U.S. military all rely on us for rubber components. We support them from our vertically integrated facility located in Lancaster, NY. Our team helps design, manufacture, and assemble parts in-house, which gives our customers maximum control over the process. Want to learn more about what we can do for you? Contact our team for an initial consultation.