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ANALYSIS OF PLASTIC PART FAILURES by RAPRA
High failure cause to low failure cause- in descending order
Moulding inconsistency and failure due to moulded-in stress are the major problem observed in moulding shop. Moulding inconsistency means shot to shot variation in quality parameters.
I have observed that if the following three balances are taken care of during the design stage, then moulding consistency is generally ensured.
These THREE balances also prevent or reduce the moulded-in stress, thereby avoiding major cause of part failure in service.
It is observed that moulded-in stress is behind most of the problems. It could be due to following reasons:
It is observed that over packing increases the density of the moulding. If we measure the density at different region of the moulding, you may find the variation in density if the mould filling is
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