Barrier Screws Cut Injection Molding Cycle Time

Battenfeld’s Rapidmelt barrier screws for its TM and HM injection machines reportedly plasticate 30 to 70% faster than general-purpose screws while delivering improved melt quality. They are available in diameters up to 50 mm, can be used with a range of thermoplastics, and are well-suited to machines running multicavity or multidaylight molds, as well as optimized mold-cooling systems, where high shot weight is combined with low cooling time and metering time is the limiting factor in further reducing cycle time.

The screws have a supplementary flight in the compression section downstream of the feed section. This flight is not as high as the main flight, so melt can flow over it. It thus divides melted material from solid material, preventing solids from entering the space in front of the screw, a common occurrence with three-section screws.

Towards the front of the screw, the melt channel becomes deeper, and the solids channel shallower, ensuring low melt friction and improving heat transfer to the solids. Downstream of the barrier section, the single-channel metering section can be fitted with mixing or shear elements. Battenfeld of America Inc., James P. Murphy Ind. Highway, West Warwick Industrial Park, West Warwick, RI 02893 www.sms-k.com