Structural foam plastics can replace wood, metal, concrete, fiber glass, rotational molding and blow molding in a variety of structural foam applications with significantly reduction in cost and increases in productivity. Parts may weight up to several hundred pounds.
Structural foam plastic is a low pressure or standard injection molding process where the plastic melt is foamed with nitrogen gas, a chemical blowing agent, or a combo of the two. The combo of the lower viscosity of the mixture and the typically thicker cross section of he molded part results in less injection and clamping pressure. This produces a molded part with lower stress than a typical high pressure injection molding part. 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.
As the foamed plastic flows through the mold, the surface cells burst, a solid skin is formed against the walls of the mold while the core of the part remains foamed. This results in a part that typically weights 20% less than a high pressure part, is 3 to 4 times more rigid than a solid part, and as mentioned, produces a part with less stress.
KEY BENEFITS OF THE STRUCTURAL FOAM PROCESS
- Low mold cavity pressure
- Reduced part weight
- High stiffness to weight ratio
- Capable of molding large, complex parts
- Low cavity pressure allows lower cost tooling
- Low part stress and warp age
- Multiple molds can be run at the same time
- Capable of molding parts .500 inches thick or greater
- Functions as excellent substrate for high quality painted finish applications
- High dimensional stability
- Virtually any thermoplastic can be foamed
