Foam molding

  

Foam injection molding is a low-pressure process for the production of foamed parts using physical or chemical blowing agents.

Major advantages:

  • high rigidity despite low weight
  • reduction of cycle times
  • less clamp forces needed
  • low internal stress, low warping
  • no sink marks
  • suitable for long flow paths
 

Utilization of physical blowing agents (MuCellTM process):

  • injection of nitrogen or carbon dioxide into the barrel
  • special screw design provides homogenous melt
  • especially fine foam structure

Utilization of chemical blowing agents (TSG process):

  • thermoplastic structural foam injection molding
  • chemical blowing agent (powder, liquid or masterbatch) is added to the resin before entering the barrel

 

To improve the mostly rather poor surface finish of foamed parts, two processes can be utilized:

Gas counter pressure process:

  • blowing agent is prevented from preliminary foaming during the filling process through build-up of sufficient gas pressure in the cavity prior to injection
  • injection of melt with the blowing agent into the cavity against gas counter pressure to avoid foaming during injection
  • cavity is completely filled with melt and the foaming takes place as result of the volume shrinkage during cooling

Utilizing Sandwich molding, parts with a solid surface and a foamed core are produced.
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