What is silicone rubber compression molding?

Compression Molding is the oldest original production method for molding silicone rubber. It is ideal for low to medium production

volumes and is a particularly useful molding process for molding gaskets, seals, O-rings, and large, bulky parts. It is a widely used, efficient and economical production method for many products, particularly low production volumes of medium to large parts and higher cost materials.

Silicone Rubber compression molding is a molding process that produces a usable rubber product. Silicone Rubber products are made from uncured rubber or elastomer. An elastomer is any material with sufficient resilience or memory for returning to its original shape in response to pressure or distortions. Silicone Rubber and elastomer can be derived from natural sources, although they are mostly synthetic, produced through highly controlled chemical processes. Rubber is an excellent material for situations that require a material to expand and return to its original shape.

Silicone Rubber compression molding creates molded silicone rubber parts by pressing a block of solid silicone rubber into a silicone rubber molding metal cavity. The silicone rubber is then exposed to heat, activating a chemical reaction. While there are variations in specific methods, all silicone rubber manufacturers use heat and pressure method to form molded silicone rubber products.

Silicone Rubber Compression Molding Steps:

1.) Uncured Silicone rubber is preformed to control weight, shape and specification

2.) Solid Silicone Rubber preform is placed into the mold cavity

3.) Solid Silicone Rubber molded is closed compressing the rubber to fill the mold’s cavities

4.) Mold remains closed under pressure and temperature to reach optimal cure

5.) Compressed Silicone rubber products are removed from the mold and the process is ready to begin again

Advantages Of Silicone Rubber Compression Molding:

  • Minimal lead time- Short set up a time
  • Easy to prototype- Minimal wastage
  • Widest range of part sizes- Perfect for the manufacturing of parts with a very large cross-section
  • Dimensional stability- Capacity to process stiff, high durometer materials, Excellent for low quantities of parts requiring a long cure time
  • Low tooling and equipment costs- Tooling is simpler and more cost-effective than injection molding, Although this technique has a longer cycle time, it is a low-pressure mold, which means it’s inexpensive to produce a variety of cavities without high tooling costs.
  • Disadvantages Of Silicone Rubber Compression Molding:
  • Produces only intermediate tolerances- Parts can be less consistent
  • Parts may require deflashing – When flash (the resin that escapes between two parts) occurs, it must be manually trimmed, thus slowing down productivity. Additionally, you’re unable to regrind this excess material, which creates more waste.
  • Higher Human Capital Investments: As previously mentioned, flash is removed manually on compression molds, which generates higher labor costs.
  • Longer cure times: The time needed to start and repeat the sequence of operations is between 1-6 minutes for compression molds; a much slower cycle time than injection molding.
  • Does not all work well for complicated part configurations-This technique is best reserved for uncomplicated parts
  • Coloured Silicone can be easily contaminated
  • Transfer or injection molds may be required
  • Coloured Silicone can be easily contaminated

Conclusion

In Z.S.R Group, we have the Silicone rubber compression molding capability. Any Molded Silicone products or Compression-molded Silicone projects need technical support, Please contact us, We will support your Silicone products from idea to life.

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