Compression Molding - SMC Process

Compression Molding – SMC

A premade mixture of chopped reinforcements, resins, and fillers is placed into a mold and cured under heat and pressure.

Capabilities / Processes / Compression Molding – SMC
Compression Molding SMC / DLFT Volume Graph

Raw Material

Sheet molding compound (SMC) is compounded at an operation away from the press. A highly automated process of combining chopped fiber and thermoset resin matrices produces a semi-pliable sheet that is later used to mold a part.


Due to the stresses created by high tonnage pressing, typically only P20 steel is used to create two-piece molds. Aluminum and other softer metals are utilized for prototype runs but have a significantly shorter useful life.


Compression molded parts can produce Class A finishes for decorative surfaces. They can be primed in the mold and can be delivered ready for a topcoat process.

  • High Volume Programs
    Short (2-4 minute) cycle times and the use of machined tool steel molds support annual program volumes to >500,000 units.
  • Best Tolerances in Process Suite
    High dimensional stability of SMC formulations and the use of precision matched-die tooling produce highly-stable and predictable part dimensions that, in turn, can produce tight-tolerance assemblies.
  • Class A Surfaces
    The use of precision matched-die tools that can be polished to mirror finish give the capability to achieve automotive-grade Class A surfaces that can support topcoat finishes.
  • Wide Range of Material Properties
    A wide range of material properties can be obtained with sheet molding compounds by varying the fiber content, filler materials, and performance additives. Materials can be optimized for weight, strength, environmental resistance, economy and many other attributes.

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