Gas Assisted Injection Moulding (GAM) is a relatively new technology in plastics injection moulding that offers opportunities to reduce moulding costs, improve quality and allows designers to be even more imaginative in the creation of injection moulded components.

Gas assisted moulding involves the introduction of nitrogen under pressure to the mould cavity at a set time during the moulding cycle.  The aim is to either hollow out thick section mouldings or eliminate sinkage and/or warpage in thin section injection mouldings.  Gas injection can also result in stronger parts due to the ‘box section’ effect.


  • Reduced material content
  • Reduced production cycle times
  • Reduced assembly costs through single moulding replacing two halves, for example in the manufacture of handles
  • Use of smaller moulding machine due to a lower locking force being required


  • Reduced flow marks
  • Eliminates sink marks
  • Reduced distortion.  This also has a cost implication as there is a reduced need to jig mouldings and there may be reduced cycle times.


  • Variable thickness sections can be included
  • Hollow sections can be moulded without the need for mechanical cores
  • Rigidity can be achieved through hollow box sections
  • Several components may be combined on a single part
  • Inclusion of strengthening ribs, bosses and other features can be included without impairing surface appearance


There is now a wide variety of injection moulded applications for gas assisted injection moulding.  Not just thick section mouldings that require hollowing out, but many thin section applications also.

Apart from different types of handles for all industries, GAM is also used in the automotive industry for engine parts, internal and external trim and instrument panels among other things.  Less obvious uses are front bezels and rear covers for TV cabinets, base frames for washing machines, shower heads, plumbing fittings and even strengthening ribs for plastic pallets.

The list is growing all the time with new gas injection applications being added on a regular basis.  Material choice is not a constraint as gas injection moulding can be used with the majority of polymers.