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Question by Zed: How to limit or reduce residual stress in injection moulding process?
Just try to limit the birefringence of polycarbonate that occured during the moulding process.

The main cause is the residual stress in the course of moulding, So how do I reduce this? Any idea?

Best answer:

Answer by a.gash
Thixomolded parts are said to exhibit mechanical properties equivalent to or better than die casting , with half the porosity , and tighter part tolerances leading to reduced shrinkage , reduced residual stress and less component distortion. No foundry is required , there is no molten metal handling with its associated losses from flux , sludge or dross , and the process eliminates the use of sulphur hexafluoride , a suspected greenhouse gas which is used in magnesium foundries .
http://www.polymer-age.co.uk/archive2.htm

These residual stresses are mainly frozen in thermal stresses due to inhomogeneous cooling , when surface layers stiffen sooner than the core region as in free quenching. Additional factors in injection molding are the effects of melt pressure history and mechanical restraints of the mold .
http://www.mmpc.mcgill.ca/page4.html

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