A Guide to Compression Molding

Compression molding uses a heated mold in combination with precise amounts of material and applied pressure to create solid components from a wide range of available and custom formulated materials. In this blog, we offer a concise overview of the compression molding process, its benefits, and its uses for various industries. 

What is Compression Molding? 

Compression molding is a highly specialized manufacturing process that uses heated reusable molds and melted thermoset materials to create highly accurate and exceptionally strong components. The process applies intense pressure to force the molten material firmly into all mold cavities, which makes it ideal for producing components with complex geometries or fine details. Compression-molded materials also exhibit an exceptionally high level of strength due to the permanent cross-linking of molecules in the material during the molding process. 

The Compression Molding Process 

Compression Molding Equipment

The compression molding process can be broken down as follows: 

  • Design and fabricate a mold around the exact specifications of the desired component. 
  • Heat the mold and and place the specified material into the preheated mold, and close the mold. 
  • Apply extremely high pressure to the material in the mold to remove air and fill all available space, so that even the most detailed components are completed to a high degree of accuracy. 
  • Allow the material to cure and solidify, then remove from the mold cavity. 

Compression Molding Uses and Applications 

Thermoset materials used in the compression molding process exhibit a favorable strength-to-weight ratio, which facilitates the production of parts that are precise, strong, and low weight. This makes compression molded components ideal for a variety of applications, touching every market segment including: 

  • Automotive parts 
  • Aerospace components 
  • Material handling tools 
  • Industrial equipment 
  • Medical components 
  • Construction and architectural components 

Advantages and Disadvantages of Compression Molding 

Compression molding offers some unique advantages over other molding processes: 

  • Enhanced component material strength. The combination of heat and pressure result in exceptionally strong components. 
  • Superior detail and accuracy. The application of pressure ensures that every detailed cavity of the mold is filled, resulting in components with a high degree of detail and precision. 
  • Cost-effectiveness. Compression molding creates exceptionally durable, accurate components at a lower overall cost than other production methods. Because the mold is reusable, the process can be used for production runs at relatively low costs. 
  • Metal replacement. Due to their high strength and lightweight nature, compression molded thermosets are often used to replace metal components in various aerospace, industrial, and automotive assemblies and medical components are molded with this method as well. 

Although compression molding offers a wide range of benefits, it is not necessarily the best option for all parts. The cycle times are often longer than comparable molding processes, and the cost offset by additional cavities in a mold to make more parts per process cycle which will increase the cost of tooling. 

Common Rubber Materials in Compression Molding

Compression Molded Part

Compression molding can be used to create components from a wide range of polymers, including: 

  • Fiber-reinforced materials 
  • Neoprene 
  • SBR 
  • Silicone 
  • Fluorosilicone 
  • FKM 
  • Natural Rubber 
  • Nitrile 
  • Butyl 

What is the Difference Between Injection Molding and Compression Molding? 

Although injection molding and compression molding are similar, they exhibit some distinct differences: 

  • Injection molding is ideal for small parts, while compression molding can be used for much larger components. 
  • Injection molding is faster, as it does not require the same amount of finishing work. 
  • Compression molding equipment has excellent production capacity and gains economies of scale through multi cavity tooling, which makes it better for high-volume production runs. 
  • Compression molding equipment is easier to repair and maintain than injection molding. 

Compression Molding Services at Elastomer Technologies 

With more than 40 years of experience, Elastomer Technologies is a leading expert in compression molding and fabrication services. We pride ourselves on providing quality manufactured products using equipment and processes that meet and exceed even the most stringent industry standards. 

Contact us today for more information about our compression molding services!

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