Physical foaming of injection molded reinforced thermoplastics parts with Ku-Fizz

Collaboration between: UW-Madison and Volkswagen Group Research  

Due to federal fuel-efficiency rules, automakers must meet a fleet average of 54.5 miles per gallon by 2025. As more efficient engines and electric powertrains will not carry the whole load, the automotive industry is pressured into finding additional solutions. One of those solutions has been light weighting car components by using microcellular injection molding (MIM). Upgrading traditional injection molding machines to offer MIM capabilities requires a high economic investment.

Due to this high initial investment as well as the complexity to control the production, Volkswagen has developed a new foaming technology – “Ku-Fizz”. The process introduces gas with pellets at moderate low pressures into the feed zone of an injection molding machine by employing a special two-chambered hopper unit. The technology eliminates the need to raise gas to a supercritical condition and employs a standard screw geometry. The process is promising for industrial scale productions; however, better understanding of the process is required before it can be safely, reliably and repeatably used for automotive components.

To advance this new MIM technology from concept to a mature process, this project involves:

  1. Obtaining fundamental knowledge on gas diffusion and solubility in the process to prove proposed concept (mathematical).
  2. Finding the gas pressure operating window for an acceptable microcellular microstructure.
  3. Understanding the process-structure relationship.
  4. Predicting the microstructure and mechanical properties of foamed parts.
  5. Conducting a successful case study on a Volkswagen instrument panel.