The silicone compression molding process is complex, and there are a couple of different ways to go about it. There are many important considerations to take into account in regards to which method of molding silicone rubber a manufacturer will use. There are various methods of molding silicone components, each with their own advantages and disadvantages. The two most common methods include compression molding and liquid silicone injection molding (LIM).

Silicone Compression Molding

This process involves labor-intensive silicone rubber, specifically a pre-catalyzed product made by adding powder to silicone. This makes it easier for the silicone to cure once heat is applied.

• Adding pigment to the silicone is performed by mixing via a two-mill roll. This is where the labor-intensive part comes into play. There’s a big risk of contamination to the silicone during this stage.
• Once the material has been pre-catalyzed and pigment has been added, technicians will then weigh it and shape it to match the needed size and configuration of the part in question.
• They then put it into the mold cavity for formation, compressing the rubber between the top and bottom plates.
• The plates are then heated to melt and cure the silicone.

Compression molding happens to be the most basic and simplest form of silicone rubber molding, but as we said earlier, it’s a very open-air labor intensive process. In terms of cost, fillers can be added to the silicone to reduce the cost of manufacturing the material.

Liquid Silicone Injection Molding (LIM)

Liquid injection molding is a process of manufacturing that molds liquid silicone rubber (LSR) into any part or product. It involves a mechanical mixing method, blending a two-component compound together into a mold.

Here at SiTECH, we prefer to use liquid silicone injection molding machines to produce the highest quality silicone rubber products the industry offers today.

Also known as LIM for short, this is a closed-loop system, meaning that the raw silicone and any additional pigments are sealed. Both the material and pigment are injected into a water-cooled barrel to keep the material from catalyzing. The material then gets injected into a hot mold.

Liquid Silicone Rubber cures at a fast rate, making it the best choice for high volume batches. Plus, unlike the open airing of compression molding, the use of a closed-loop system keeps contamination to a minimum. When you reduce the amount of handling, you greatly decrease the chance of contaminating the silicone components.

Contact Si-Tech

Ready to learn more about our molding methods? Call Si-Tech today at 757-887-8488. We utilize a unique injection molding process with Dow and GE Silicones, proud to be a competitive provider of custom keypads and other silicone rubber products. Si-Tech’s state-of-the-art process ensures that custom key shapes, housings and other features can be affordably produced.