Flat dies | machinery feature
Tooling technology has gradually moved from being a black art into a more exact science. We round up some of the latest innovations in flat die technology
Mind the gap: new technology in flat dies
The advent of sophisticated simulation programs – as well as the superior data crunching power – has helped to transform the die design process from one of largely trial and error to one that is now more streamlined. It has helped die developers to refine their designs much more easily than would once have been possible. Nordson has applied for a patent on a new design of dual- and multi-layer versions of its Premier and Ultracoat fluid coating dies – which will make it easier to achieve parallel alignment of the lip faces. This is critical for maintaining uniform, defect-free coating and preventing impingement of the lips against the roll, says Nordson. In the standard design for Premier fixed-lip and
Ultracoat adjustable-lip slot dies, operators make changes to the die gap – and, in turn, the wet film thickness of the coating – by inserting thin metal strips (or shims) between the die bodies. Then, more shims are used at the rear of the die, to eliminate the resulting offset of the lip faces and ensure that they are once again in the same plane. Until now, using these ‘offset shims’ has been more complicated in multi-layer dies, requiring calculations to determine which shim thickness most closely achieves lip face parallelism. The new design makes such calculation unneces- sary, ensures a more precise lip face alignment, and prevents human error. Nordson has achieved this improvement by reconfig- uring the die bodies of multi-layer Premier and Ultracoat systems so that the offset blocks, where the offset shims are inserted, are now in the same plane as the lip face.
As in the past, body shims and offset shims are
available in thicknesses ranging up to 0.060in. (-1.524 mm). With the new design, the accuracy of the offset adjustment is independent of body shim thickness.
www.filmandsheet.com
“Our new design for multi-layer dies makes it easier
for web converters to achieve the substantial cost savings and productivity benefits obtained by applying multiple fluids in a single pass,” said Keith Wheeler, business unit director for fluid coating systems. “Besides being more accurate and user-friendly, the new design for multi-layer dies eliminates the cause of lip misalignment and helps to prevent the costly damage to both die and roll that can result from simple human error in calculating the lip offset.” Replacing multiple coating passes with a single
product run means an increase in output and reduction in machine use, energy consumption, and scrap. Extra cost savings result from control over the thickness of each layer, preventing over-use of expensive, high- functionality fluids. At the same time, the converter can return to single-layer production simply by closing the feed valve to the flow channel that is not in use.
April 2017 | FILM & SHEET EXTRUSION 13
Nordson EDI says that its
Autoflex VI-E lip adjusting system is
smaller and
more stream- lined than before
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