2007 TAPPI EUROPEAN PLACE Modern Extrusion Coating Die Technology - PowerPoint PPT Presentation

2007 TAPPI EUROPEAN PLACE Modern Extrusion Coating Die Technology Sam Iuliano Extrusion Dies Industries, LLC

Performance Needs • Precise control of coat weight uniformity • Trouble-free coating width variation • Ability to reduce edge bead size

Extrusion Die Developments • Sophisticated flow distribution channel design • Internal deckles combined with external deckles • Advanced automatic lip adjusting systems • A potential tool to enhance web stability and reduce neck-in is under investigation.

Basic Flow Channel Design • Constant cross section. • Sometimes called a Keyhole design. • Allows for adjustable internal deckle plugs.

Advanced Flow Channel Design • Varying cross section. • Requires less lip adjustment. • Normally deckled externally.

Sophisticated Flow Channel Design • Manifold/preland interface in the center of the channel has a curvature that promotes lateral flow distribution. • Allows a wider variety of coating materials to be processed.

External-Only Deckles • Advantage: A saw-tooth wedge type of compressible seal system provides convenience and leak-free operation.

External-Only Deckles • Disadvantage: External-only deckles increase edge bead size and create stagnation areas within the die flow channel.

Internal-Only Deckles • Advantages: Flow channel is streamlined at all operating widths. Internal blades can be adjusted to minimize edge bead size.

Internal-Only Deckles • Disadvantage: Require rigorous procedures to adjust and maintain.

Deckles for Width Adjustment and Edge Profile Control • Combined internal and external deckling

Relative Positions of Internal Blades Influence Edge Bead Size and Shape

Edge Instability is the Limitation

Restabilizing the Edge

Further Edge Reduction

Internal Deckle Tuning • Influences velocity of the material exiting the die lips.

Longer Lip Lands Delta P in Lip is directly proportional to land length. • Some internally deckled dies utilize a short final lip land at the exit of the die (only 3 to 5mm long). • Longer lands will reduce die swell and provide better lip tuning control.

Advanced Automatic Lip Adjusting Systems • Off-mounted to reduce thermal “cross-talk”. • Beryllium-copper alloy translator with high thermal conductivity provides rapid response. • Large stroke (+/- 0.38mm of thermal movement).

Factors Influencing Neck-In • Coating material properties (melt strength). • Air gap. • Draw ratio. • Line speed.

External Edge Guides • An attempt at reducing the amount of neck-in. • Preliminary results are promising.

External Edge Guides • With a temperature match and the correct geometry, the curtain can be influenced and web stability is enhanced.

Edge Guides Combined with Internal & External Deckles

Edge Guides – A Closer Look

Summary Convenient coating width adjustment. Reduced overcoat requirement. Rapid and accurate control of coat weight uniformity. New developments are underway for neck-in and web stability control.

Acknowledgements Special thanks go to: Mark Miller Paul Wenaas BJ Kays Brian Gillespie Kevin Krejci Their assistance in performing and planning the edge guide trials was greatly appreciated and was key to the success of this preliminary stage in the development of this interesting technology.