Gas-Assisted Injection Molding and Water-Assisted Injection Molding

Gas-Assisted Injection Molding (GAIM)

Molding Principle of GAIM:

Gas-Assisted Injection Molding (GAIM) refers to injecting high-pressure inert gas into the mold cavity when the plastic is appropriately filled (90%~99%). The gas propels the molten plastic to continue filling the cavity, and gas pressure is used to replace the plastic pressure holding process. It is an emerging injection molding technology.

Characteristics of GAIM:

  • Reduce residual stress and mitigate warping issues.
  • Eliminate sink marks.
  • Lower mold locking force.
  • Decrease runner length.
  • Save materials.
  • Shorten production cycle time.
  • Extend mold lifespan.
  • Reduce mechanical losses of injection molding machines.
  • Applicable to products with significant thickness variations.


GAIM can be used to produce tubular and rod-shaped products, plate-shaped products, as well as complex products with uneven thickness.

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Water-Aided Injection Molding (WAIM)

Molding Principle of WAIM:

Water-Aided Injection Molding (WAIM) is a developed auxiliary injection molding technology based on GAIM, and its principles and processes are similar to GAIM. WAIM uses water instead of N2 in GAIM as the medium for venting, penetrating the melt, and transferring pressure.

Characteristics of WAIM:

Compared to GAIM, WAIM has several advantages.

  • The thermal conductivity and heat capacity of water are much greater than N2, resulting in shorter product cooling times and shorter molding cycles.
  • Water is cheaper than N2 and can be recycled.
  • Water is incompressible, reducing the likelihood of the finger effect and resulting in more uniform wall thickness in the product.
  • Gases are prone to permeate or dissolve in the melt, causing roughening of the inner wall and even bubbles. Water, on the other hand, is less likely to permeate or dissolve in the melt, resulting in smooth inner walls of the product.
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