Evaluation of coefficient of friction in similar conditions to ejection of molding parts

摘要

The injection molding is the technique most used for processing polymers. Nowadays, due toeconomic demands the ejection of the parts occur as soon as possible to lead to a short cycle times. The ejectionstage is the most critical phase during the injection molding processing. During this stage, especially indeep core molding, it is possible the development high friction forces making difficult the ejection of themoldings without marks or other defects. The aim of this work is to assess the coefficient of friction betweenthe part and the mould walls in conditions similar that occurs during the ejection in the injection molding process.The assessment of the coefficient of friction was carried out with the help of one apparatus that possibilitythis type of measurement. This equipment provides that measure under controlled conditions as test temperature,replication temperature, material of the mould, and superficial roughness. The obtained results withseveral polymeric materials (semicrystalline and amorphous) show that the tribological conditions have greatinfluence on the coefficient of friction in static conditions.