Successful processing of Polycarbonate (PC), especially glass-filled grades, requires careful mold and machine design. A recommended mold temperature is 80-100°C (100-130°C for glass-filled grades). Gate design is critical: needle gates are suitable for small parts, with a depth of about 70% of the part's thickest section. Other effective types are ring and rectangular gates. The general principle is that larger gates are preferred to minimize shear-induced material degradation. Venting is essential, with vent depths typically less than 0.03-0.06mm, and runners should be short and rounded to facilitate smooth flow. A draft angle of 30 minutes to 1 degree is standard.
On the machine side, the melt temperature for standard PC generally ranges from 270-320°C (lower for some modified grades). An air-shot technique can help determine the optimal temperature. Injection speed should be adjusted accordingly, often starting slow and switching to fast to fill the mold. A back pressure of around 10 bar is standard, which can be lowered if no air entrapment or color mixing issues are present. It is crucial to minimize the melt's residence time at high temperatures to prevent degradation, which causes yellowing and the release of CO2. For purging the barrel, Polystyrene (PS) is recommended; materials like LDPE, POM, ABS, or PA should be avoided. Our company specializes in a wide range of engineering plastics including PA6, PA66, PBT, POM, PPS, TPU, PEI, PEEK, ABS, PC, PP, PMMA, and PC/ABS alloys, which can be customized with reinforcements, additives, and colors to meet specific requirements.
