Finally, the temperature profile was a key factor in the foamforming
process. The temperature in the injection zone should be
enough low to keep the foaming agent in a liquid state. On the
other hand, the temperature along the barrel should be enough
high to soften the carrier material to prevent the torque from
becoming too elevated. More importantly, the temperature of the
die was found to play a crucial role in creating the foamed strands.
If the temperature at the die was too high, the extrudate would be
blown apart by the internal pressure before solidifying enough to
maintain its structure. In contrast, if the die temperature was not
enough high the extrudate would not be molten to swell. Upon
exiting the die, the foamed strands were still soft. To accommodate
for this, the strands exiting the die were synchronized with a conveyer
belt, which allowed the strands to cool to the point of structural
integrity. With this system setup, the torque and die pressure
were found to be highly stable. All collected extrudates appeared to
be highly uniform.