One of the favorite plastics technologies of processing experts globally is a physical foaming process called MuCell originally developed at the Massachusetts Institute of Technology.
Many academic technology spinoffs fail to gain commercial traction, not because they are
bad ideas, but because there is significant manufacturing (and installed investment) to overcome.
MuCell, being commercialized by a company called Trexel (Wilmington, Mass.), has 800 active applications and has been recording annual sales growth of 24 percent since 2010. Trexel was formed in 1995.
The global drive to reduce weight of cars, trucks, and aircraft has been the most important driver. The process also cuts costs and improves design flexibility. The process allows engineers to design wall thickness optimized for functionality and not for the injection molding process. MuCell works with virtually all resins and does not require special formulations.
In the MuCell process, the pack-and-hold phase in the injection cycle is replaced with cell growth, resulting in reduced built-in stresses and less warpage. Sink marks are also eliminated. Smaller molding machines can be used to produce the same part. Parts can be produced faster. It’s easily the most important innovation in injection molding in the last 25 years.
Sales took off three years ago after company officials changed their revenue model from one that was license-based to one based on sales of equipment, basically a plastication system tied to a dosing unit.
In an interview at K2013 in Düsseldorf, Germany, CEO Stephan G. Braig discussed important developments:
- Trexel worked with ABC Group in Toronto to develop MuCell blow molding. The first fruit of the work is a reinforced polyethylene air duct with 1.5 to 2 mm wall thickness. There is a 32 percent net weight saving. Other target applications include ducts, washer/brake fluid containers and intake manifolds.
- A new dosing and delivery system for super critical fluids was introduced. The system converts carbon dioxide or nitrogen into a super critical fluid. It produces SCF on demand only, eliminating the need for hardware mounted on the injection unit.
- Trexel and 3M have developed a marketing collaboration teaming MuCell with 3M’s tiny glass bubbles. Density reductions of 20% are possible with no sacrifice in mechanical properties.