EXTRUSION: Feedblock Tuning Inserts Keep Lines Running

Get finer tuning of coex film/sheet layer thickness without downtime.

Nordson Extrusion Dies Industries, Chippewa Falls, Wis., has developed tuning inserts for its Ultraflow I feedblock that allow flat film and sheet processors to keep their lines running while permanent fixed inserts are being machined. They are also said to allow for greater precision in the ultimate thickness profiles of each layer across the width of the die.

In feedblocks such as the Ultraflow I, specially machined flow inserts are used to provide a target cross-direction thickness profile for each layer. Different inserts must be designed and machined for any job change involving significantly different layer ratios or polymer flow properties. But the tuning inserts now let processors keep their lines running at the target profile until a matching permanent insert can be built.

These inserts can be fine-tuned “on the fly,” making it possible for cast film and sheet processors to go through several iterations, making small additional changes in very little time and refining the geometry with great precision before machining a permanent insert, the company says. This process eliminates the need to do several re-cuts of the permanent insert before arriving at the target layer profile.

Typically about 4-in.-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. The flow-adjusting component of the new tuning insert consists of 10 segments, each of which can be adjusted to reduce or increase layer thickness by turning a corresponding screw.

Once the target profile has been established, a measurement tool supplied by Nordson EDI replicates the screw positions so that it can be used for producing a precisely matching permanent insert.