Gas Assisted Plastic Injection Moulding

Gas Assisted Plastic Injection Moulding

For over 25 years, Weiss Precision has used gas assist molding for plastic injection molding in a variety of applications, offering OEMs numerous advantages. When it comes to reducing time and cost without compromising quality or design options, gas assist injection molded plastics make a great choice.




Gas Assist Molding Process

Pressurized nitrogen gas is injected into a mold, pushing the plastic into the mold extremities, while hollowing out thicker portions of the part. Gas assist molding is a process of plastic injection molding at low pressure, in which plastic is pushed into mold extremities by pressurized nitrogen gas.

During the gas assist molding process, plastic material is melted and injected into mold cavities via conventional injection molding. Plastic material in contact with the mold walls begins to solidify first. As this happens, nitrogen gas is injected into the mold through strategically designed and placed gas channels, providing pressure that pushes the plastic material into the mold extremities. Once the plastic cures, the nitrogen is vented and the gas assist injection molded plastic parts are removed from the mold.



Gas assist plastic injection molding produces parts without compromising appearance or functional performance. Other benefits include:

  • Less plastic material needed (material savings)
  • Reduced part weight (in some cases up to 40%)
  • Decreased cycle time
  • Increased part strength and rigidity
  • Reduced warpage and distortion
  • Improved part appearance (eliminates sink marks and surface blemishes)
  • Reinforces ribbed parts
  • Increased design options for complex parts, reducing multiple part assemblies, and metal to plastic conversions
  • Enables use of smaller plastic injection molding presses


Some applications benefiting from gas assist plastic injection molding include:

  • Appliance handles
  • Medical equipment housings
  • Interior and exterior automotive handles
  • Large covers and panels for office equipment
  • Lawn mower handles
  • Steering wheels
  • Basketball backboard frames
  • Long tubular shapes, such as shovel handles
  • Large parts with ribs and bosses