| A twin-center-sleeve die for coex tubing, which distributes melt via coat-hanger fl ow channels over a central mandrel, has been used for years to make multilayer PVC pipe. What's new is combining the die with a breaker plate to achieve more uniform layer distribution and to use the improved arrangement to coextrude polyolefi ns. Battenfeld Extrusionstechnik in Germany (represented here by American Maplan, McPherson, Kan.) built the fi rst such die with a breaker plate last year for fi ve-layer barrier pipe.
Battenfeld worked with NIKA GmbH, a German developer of software for fl uid fl ow and heat-transfer simulation. NIKA merged last year with Flomerics Group in the U.K., which has offi ces in Marlborough, Mass. Using NIKA's software, the breaker plate for the outside (thickest) layer was designed with holes at different angles to give them different fl ow lengths in order to achieve more homogeneous fl ow and less disruption of minor layers. Simulation software reportedly has made the dies much easier and less expensive to design and build. Maplan: (620) 241-6843/www.maplan.com . Flomerics: (508) 357-2012 . www.flomerics.com |
