Gas-assisted injection molding

From Wikipedia, the free encyclopedia

Gas-assisted injection molding
Gas-assisted injection moulding concept.jpg
Basic concept diagram of gas-assisted injection molding
Process typeInjection moulding process

Gas-assisted injection molding is a molding process where an inert gas is introduced at pressure, pushing the plastic melts into the mold extremities at the end of the polymer injection phase.

Basic concept[]

Gas-assisted injection molding to provide an internal hollow shape (Green and blue colors indicate inert gas and polymer melt respectively)

The basic concept of the gas-assisted molding process is quite similar to regular injection moulding process. In this gas-assisted molding, the plastic material is melted with the help of extruder barrel and injected into the mold cavities like the regular injection moulding process but only up to 70%~80% of the mold voulme. Plastic melts in contact with the mold walls begins to solidify and 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 and finally the molded part is ejected like the regular injection molding process.[1]

Advantages[]

This process forms a hollow, plastic injection molded part and parts are lighter, greener and cheaper than traditionally injection molded equivalents. Moulded parts also cool faster in this process because of constant pressurization by the gas. There is also usually less shrinkage as the thicker wall sections are hollowed out by the pressurised gas resulting no sink mark problems.[2]

Some of the benefits of this process are:[3]

  • Thicker parts can be moulded
  • No sink marks
  • Minimal residual stresses
  • Reduced part deformation (warpage)
  • Low clamp force
  • Lightweight products

Disadvantages[]

This molding technique is very difficult to apply for multi-cavity mold, especially if the cavity sizes are dissimilar. Clear or transparent plastic materials are an inappropriate option for this technique as cosmetic-appearance can deteriorate.[4]

See also[]

References[]

  1. ^ "Real-time diagnostics of gas/water assisted injection molding using integrated ultrasonic sensors". NRC Publications Archive, from National Research Council Canada. Retrieved November 9, 2020.
  2. ^ "What is gas assisted injection moulding?". Dienamics. Retrieved November 9, 2020.
  3. ^ "External Gas Molding Squeezes Out Sinks". Plastics Technology. Retrieved November 10, 2020.
  4. ^ "New Methods Expand Roles of Gas-Assist Molding". Plastics Technology. Retrieved November 9, 2020.
Retrieved from ""