Troubleshooting Injection Moulding (Rapra Review Reports)

Injection moulding is one of the most commonly used processing technologies for plastics materials. Proper machine set up, part and mould design, and material selection can lead to high quality production. This review outlines common factors to check when preparing to injection mould components, so that costly mistakes can be avoided. Sometimes problems occur in producing parts of the desired quality and there are visible surface defects. Due to the complex interrelationship between the part and the mould, the moulding compound and the processing, it is often hard to recognise the source of the problem to remedy it. Defects can be classified into: sink marks, streaks, gloss differences, visible weld lines, jetting, diesel effect (burns), record grooves effect, stress whitening or cracking, incompletely filled parts, flash, visible ejector marks, deformation during demoulding, flaking of the surface, cold slugs or cold flow lines, entrapped air and blister formation, dark spots, and dull spots near the sprue. This review examines the different types of surface defects that can be identified in plastics parts and looks at ways of solving these problems. Useful flow charts to illustrate possible ways forward are included. Case studies and a large number of figures make this a very useful report. There have been many papers published on the topic of troubleshooting in injection moulding. Over 400 of the latest references from the Rapra Polymer Library database accompany the review, to facilitate further reading. A subject index and a company index are included. The review section of this report is drawn from the ARBURG Practical Guide to Injection Moulding.