Injection molding systems and methods useful for making microcellular
foamed materials are provided as well as microcellular articles. Pressure
drop rate and shear rate are important features in some embodiments, and
the invention provides systems for controlling these parameters in an
injection molding system. Another aspect involves an injection molding
system including a nucleator that is upstream of a pressurized mold.
Another aspect involves an extrusion system with the reciprocating screw
for forming a single phase solution of non-nucleated blowing agent and
polymeric material. Another aspect involves very thin walled microcellular
material and very thin walled polymeric material. Another aspect provides
a method for producing high weight reductions in very thin-walled parts
with surfaces that have no noticeable differences from non-foamed parts.
