The Causes and Prevention of Injection Moulding Defects in Large Ceramic Sections
During the solidification stage, a range of defects appears in large ceramic sections in conventional injection moulding. These include shrinkage voids and cracks which may appear after storage or reheating. The origins of these defects are being explored experimentally in terms of material properties and machine conditions and quantitatively by computer modelling. Several interventions are described which have in common the objective of eliminating voids without resort to high hold pressures. These include the use of an enlarged sprue, a heated sprue and modulated hold pressure.
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