Why Structural Foam?

Structural Foam Molding Technology

Structural foam molding is a low pressure injection molding process where an inert gas is introduced into melted polymer for the purpose of reducing density and weight of the finished product while increasing the strength. The lower pressure and forces involved allow more economical molding equipment and tooling to be utilized resulting the mass production of very large or parts or multiple parts being produced on a single machine in a single cycle at a lower cost than conventional injection molding.

The structural foam molding process utilizes a molten resin that has been injected with nitrogen gas or a chemical blowing agent. This mixture is injected into the mold, where the gas expands and fills the mold with foam. As the foam flows through the mold, the surface cells collapse. Solid skins are formed against the walls of the mold, while the core of the part remains structurally foamed. Because the outer skin is solid and the center of the wall is foam, the part weight is reduced up to 20%.

Structural foam yields parts that are larger and sturdier than injection molding. The process pressures are much lower than in injection molding, thereby producing parts that are structurally sound, nearly stress-free and have minimal warpage. Parts made are thicker and sturdier than with other processes (doubling the parts' thickness yields parts up to eight times stiffer).

KEY BENEFITS OF THE STRUCTURAL FOAM INJECTION MOLDING PROCESS

Design Advantages
  • Part weight reduced 10% to 30%
  • Increased strength and stiffness due to honeycomb structure
  • Capable of molding large, complex parts without sink marks
  • Capable of molding parts .500 inches thick or greater
  • Parts may weigh up to several hundred pounds
Product Advantages
  • HIGHEST STRENGTH-TO-WEIGHT RATIO compared to alternative manufacturing methods and materials.
  • Can replace concrete, sheet metal, metal castings, wood, fiberglass, rotational molding and blow molding in a variety of applications
  • Superior impact resistance
  • More rigid than a solid part
  • Low part stress and warpage
  • Consistent surface finish
  • Cleanability
  • Chemical and corrosion resistance does not rust
  • Parts that are impervious to the elements
  • Sound deadening characteristics
  • Electrical /thermal insulating properties
  • Parts can be sawn, screwed, nailed or stapled like wood
Production Advantages
  • Faster cycles due to better heat transfer of aluminum
  • High dimensional stability over the entire production run
  • Multiple molds can be run at the same time
  • Functions as excellent substrate for high quality painted finish applications
  • Two different materials and/or colors can be molded simultaneously
Cost Advantages
  • Low multi-nozzle injection pressure allows lower cost aluminum molds
  • Can use recycled post consumer plastics
  • Parts are recyclable and returnable for supply chain cost effectiveness
  • Significant reduction in cost and increases in productivity
  • Lower raw material cost due to use of commodity resins
  • Lifetime tooling
Cross section of structural foam
Cross section of structural foam
© 2011 Polycel Structural Foam, Inc.