Compression Molding Process / SMC

Compression Molding Process / SMC

Closed Mold SMC Compression Process IllustrationCompression molding is the most common choice for high-volume composite parts and often associated with SMC and BMC materials.

This process produces high strength, complex parts in a wide variety of sizes. Matched metal dies are mounted in a hydraulic molding press. The material charge is manually or robotically placed in the mold, heated mold halves are closed, and up to 2,000psi of pressure is applied. Cycle time ranges from one to five minutes depending on part size and thickness.  Features such as ribs, bosses and inserts can be molded in.

Compression molded parts are characterized by net size and shape, two excellent finished surfaces and outstanding part-to-part repeatability. Trimming and finishing costs are minimal.

  • In-mold coatings are available to improve surface paintability, eliminating the need for primer.
  • Color compounds can be customized.
  • Male and female tools are commonly made from tool-grade steel. Where pressure is <400psi, other tooling materials can be used.
  • Tools are generally capable of running temps of 300˚F and pressures about 1000psi, depending on contour.
  • Tools generally run 60,000 parts before restorative shear work is needed*.

SMC Material Formulation

In addition to fabrication, MFG develops and manufacturers SMC material, offering more than 100 proprietary material formulations. Our off-the-shelf SMC can eliminate or reduce development time, translating to cost savings. In other cases, a custom formula may provide the greater cost-savings though weight reduction, shorter cycle time or design efficiency. Either way – our dedicated SMC laboratory is ready to support you. (see video for more info)

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* Volume recommendations are averages and provided only as a general guideline. Actual volume efficiencies are a more complex matter requiring detailed statistics about the part to be manufactured.

MFG's SMC Compression Molding Capabilities

Innovations in Sheet Mold Compound (SMC)

Resource Type Description
Mass Reduction With Value-Engineered Composites PDF Light-weighting (mass reduction) using advanced composite materials.
Technical Design Guide for FRP Composite Products and Parts PDF Fiberglass (FRP) composite materials and processes are explained in detail. This design guide outlines various selection criteria with helpful technical data and comparisons to alternative materials.
TechNote: Designing Ribs Into Your SMC Part PDF Designed-in ribs can add enhanced stiffness to your SMC part. Here's a quick "how-to" for incorporating ribs for optimum manufacturability.
Case Study: FRP Detectable Warning Tiles for Handicap Safety PDF Case study explaining how a start-up enterprise transitioned from rubber to FRP material to become an industry leader.
UL Certified FRP Materials from MFG PDF List of proprietary MFG materials that are UL-approved.
iNVENTA 615UL SMC Material Datasheet PDF iNVENTA 615UL is a UL 94-5V approved non-halogenated reinforced thermoset SMC material. Ideal for applications where non-flammability is crucial.
INVENTA 515UL SMC Material Datasheet PDF INVENTA 515UL is a UL approved reinforced thermoset SMC material. Ideal for HVAC components and other applications where non-flammability is crucial.
iCom 617 SMC Material Datasheet PDF iCom 617 is a non-halogenated fiberglass thermoset sheet molding compound with a UL 723 rating.

Snapshot Guide: Shapes, Uses and Considerations

All application with volumes 10,000+. Capable of detailed shapes, extremely good surface finishes (including Class A automotive surfaces), high part uniformity.