Injection moulding panels with some thin-wall zones - using superficial ribs to spread material across the thin-wall zones

摘要

Injection moulded plastic panels with broad thin-walled sections are made by providing parallel feeder ribs across the section at regular intervals. Material for the feeder ribs comes via relatively thick wall borders between the ends of the panel and the injection gates. The feeder ribs may have circular or semi-circular sections, i.e. depending on whether ribs are acceptable features on the second face: the radius of the rib profiles is about 0.5-1 mm. Pref. the ribs are straight: progressive filling of the webs between the ribs is assisted by capillary action. For making mouldings of varying thickness (0.5-1 mm + 2.5 mm) for e.g. enclosures for automobile heating or air conditioning systems, esp. from materials with restricted fluidity such as polypropylene contg. 40% talc filler.