Structural Foam Molding Process

Structural Foam Molding

A low-pressure injection molding process that combines inert gas (nitrogen) and a thermoplastic resin during the extrusion cycle. The nitrogen gas and resin are combined in the extruder. After injection into the mold, the pressurized nitrogen bubbles trigger cell nucleation from the rapid pressure drop in the mold, creating a part with a solid skin and a cellular interior.

Capabilities / Processes / Structural Foam Molding
Structural Foam/Web Molding Volume Graph

Raw Material

Inert gas combined with thermoplastic resin.


Cavity injection mold, typically constructed of machined aluminum billet or castings.


Final part has a solid skin with a cellular interior.

  • Reduced Part Weight/Material
    Density is reduced from 10-30%, while maintaining strength, resulting in less material used and providing excellent strength to weight ratio.
  • Large Shot Size = Large Parts
    Provides the ability to combine smaller parts into one large part to reduce complexity. Create large parts that other processes cannot, or parts you would never think to make from plastic!
  • Large Platens = Multiple Molds/Family Tools
    Allows for multiple molds to be run together, saving cost and lead times. Multi-part assemblies can be molded in one “family” tool, providing better fit and color match as they are molded in one shot.
  • Process Flexibility – Use of Recycled Materials
    Parts can be made from up to 100% post-industrial/post-consumer materials, diverting waste from landfill. All Structural Foam products are 100% recyclable. Low Pressure molding uses less energy and material per pound than other processes, reducing the overall footprint.
  • Dimensional Stability/Repeatability
    The process puts less internal stress in the part due to the lower pressure. This results in parts with better flatness and dimensional stability both after molding, and in the field under various environmental conditions.​
  • Flexible Colors and Textures
    Various colorants and textures can be molded in the part, eliminating the need for costly and environmentally sensitive painting processes.