Extrusion feedblocks bring speed and precision.
Nordson Extrusion Dies Industries has developed feedblock-tuning inserts that it says bring speed and precision to profiling of layers in flat-die film and sheet coextrusion.
Tuning inserts for the Ultraflow I feedblock that can be adjusted during coextrusion enable manufacturers of film and sheet to reduce downtime and material waste while permanent flow inserts are prepared, as well as achieving greater precision in the ultimate thickness profiles of each layer across the width of the die, says the company.
The feed block shapes molten polymers from two or more extruders into layers in a sandwich structure that is subsequently distributed to full end-product width inside a flat die. In feedblocks such as the Ultraf low I, a specially machined flow insert yields a target cross-direction thickness profile for each layer and any job change involving significantly different layer ratios or polymer flow properties makes it necessary to design and machine different inserts. The tuning inserts for Ultraflow I feedblocks enable processors to maintain production while being adjusted until the target profile is achieved and a matching permanent insert can be built.
"The new tuning inserts help processors to maximise run time and minimise waste during the week or more that is required to design and machine permanent inserts," said Sam G. luliano, Chief Technologist at Nordson EDI. "Because the tuning inserts can be fine-tuned 'on the fly,' it is possible to do several iterations, making small additional changes in very little time and refining the geometry with great precision before machining a permanent insert. This process eliminates the need to do several 're-cuts' of the permanent insert before arriving at the target layer profile."
Typically about 10 cm wide and machined from hardened stainless steel, a flow insert is specially designed to generate a corrective layer profile for a polymer with specific flow properties.
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