Low Pressure Structural Foam Molding
Low pressure structural foam molding. Superior all the way to the core!
What is Structural Molding?
Plastic parts made using the Structural Foam Molding technology have a cellular or structural core, surrounded by dense outer skins which combine to give the parts a high strength to weight ratio and up to twice the rigidity of solid parts of the same weight and material.
The Structural Foam process is similar to conventional injection molding with the exception that a foaming agent, typically nitrogen gas, is mixed with the melted polymer and injected into a mold at low pressures. During injection the mold is not completely filled or packed out with resin as it would be with high pressure molding. Immediately following injection the gas/polymer mixture is allowed to expand to pack out the mold and to create a density reduced, rigid, plastic part.
Structural Foam products can be used to replace wood, concrete, metals, fiberglass, and solid plastics in a variety of applications.
Structural Foam – Benefits
There are many benefits in producing products using Structural Foam technology:
- Part weight can be reduced between 10% and 30%, resulting in lower material costs without affecting structural integrity.
- A large shot size capability of up to 150 lbs (68 kg) per shot. Larger products can be designed to combine many smaller parts, with different functions, into one part to reduce cost and increase efficiency.
- Low pressure molding uses less energy per pound of plastic and less raw material in the finished product.
- The low pressure process is better suited to using recycled materials. Many Structural Foam plastic products are made from 100% post consumer resin meaning more plastic is diverted from landfill. All Structural Foam plastic products are 100% recyclable.
- Low pressure Structural Foam machines have multi-nozzle capability, meaning that multiple molds can be run on the same press at the same time, reducing cost and reducing lead times.
- Chemical blowing agents can be eliminated with the use of Nitrogen gas which is simply extracted directly from the atmosphere and used to foam the plastic.
- Due to the large platen sizes, family molds are able to run together to make complete assemblies in a single shot. Color variation between components is eliminated and all parts fit together smoothly.
- The low pressure injection and uniformly expanding nitrogen gas result in parts with less internal stress; they remain straighter and more dimensionally stable when subjected to changes in temperature, rough handling, and long term weather exposure. Structural Foam parts often hold flatness tolerances better than ones made using high pressure injection molding machines.
- Due to the structural nature of the core, parts have better strength to weight performance than many other options, producing better performance per pound of plastic.
- Structural Foam products can be made from a wide variety of resins, everything from commodity polyethylene and polypropylene resins right up to highly engineered resins and additives.
- The Structural Foam process offers a high quality, repeatable, and fast way to make large plastic components efficiently and cost effectively.