Structural Web Molding Process

Structural Web Molding

A low-pressure injection molding process that combines inert gas (nitrogen) and a thermoplastic resin during the molding cycle. The nitrogen gas is injected into the mold through nozzles or special gas ports in the mold. After injection into the mold the pressurized nitrogen bubble hollows out the part via a network of predetermined gas channels. Creates a part with solid walls and hollow interior cavities. Surface finish is improved over structural foam molded parts.

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

Raw Material

Inert gas and thermoplastic resin.


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


Part with solid walls and hollow interior cavities.

  • 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 Web 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.​
  • Freedom in Design
    The process allows for varying wall thicknesses and complex geometries, and can include hollow interior sections, while still providing structural performance and improved appearance.
  • Improved Surface Finish
    Parts have a smoother and more cosmetic appearance than other thermoplastic processes, and sink marks are eliminated.
  • Flexible Colors and Textures
    Various colorants and textures can be molded in the part, eliminating the need for costly and environmentally sensitive painting processes.

Inquire with us about this process