Why Foam Injection Molding Simulation?

Foam injection molding, like MuCell® and chemical blowing agent (CBA), is capable of mass-producing parts with complex geometries and excellent dimensional stability, and is widely used in automotive, electronic/electrical products, construction, outdoor products and many other applications. In MuCell® process, supercritical fluid (SCF), usually nitrogen (N2) or carbon dioxide (CO2), is mixed with polymer melt to create a single-phase polymer/gas solution, which is then injected into the mold cavity, and finally bubbles are formed in the product. In CBA process, the chemical foaming agents are mixed with plastic granules as colorants or additives. The chemical reaction is completed in barrel and the gas is dissolved in the melt. The gas bubbles start growing during filling stage while the release of pressure and formed in the product.

*MuCell® is a registered trademark of Trexel Inc.

Foam Injection Molding

Illustration of essential steps in microcellular injection molding

The benefits of the technology are lower injection pressures, lower temperatures, shorter cycle times, less energy and less material. Despite all the advantages, the addition of supercritical fluid brings the complexity of flow behavior, material morphology and product surface quality, which hampers the development and broad acceptance of the process.


  • Bubble number, bubble size distribution are dependent on process conditions and are crucial to the success of product development.
  • Weld line and air traps are crucial factors for optimizing gate number and locations.
  • Part geometry, part wall and rib thickness design rules are different from the conventional injection molding process.
  • Potential surface quality problems

What Can Moldex3D Do?

  • Simulate the nucleation and growth of bubbles when the melt flow is injected into cavity
  • Calculate cell size, cell number, density distribution, volumetric shrinkage, etc.
  • Predict the interaction between the melt flow and bubble development
  • Predict the effects of bubble structure on part warpage 
Comparison of Dimensional Stability between Solid part and MuCell® part
Comparison of Dimensional Stability between Solid part and MuCell® part

 Applicable Industries

  • Electronics
  • Automotive
  • Medical
  • Consumer Product

Applicable Moldex3D Package

  • Moldex3D eDesign Package
  • Moldex3D Professional Package
  • Moldex3D Advanced Package

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