Process
MuCell is a foam injection molding process in which nitrogen or carbon dioxide is dosed into the melt as a supercritical fluid during plasticizing and forms a microcellular (10–100 µm) structure in the cavity. Part weight drops by up to 20%, sink marks and warpage are reduced, and the required clamping force and cycle time are lower. Because there is no chemical blowing agent residue, the part can be recycled.
The system consists of three components: gas supply (a nitrogen generator or cylinder) with a booster, the unit that doses the gas into the melt at supercritical pressure, and a specially designed screw and barrel. The gas dissolves in the melt; when it enters the cavity the pressure drops and nucleation begins; the cells take the place of holding pressure.
It is applied to almost all thermoplastics except LCP; results are best with filled materials. Surface appearance may differ from standard injection molding; on visible surfaces it requires adjustment of mold temperature and gas ratio.
For thick-walled parts prone to sink marks and parts sensitive to weight and warpage: automotive interior parts, connector housings, parts with thick bases and ribs. It is not suitable for thin-walled transparent parts.