SLIDE 1
Performance Needs
- Precise control of coat weight uniformity
- Trouble-free coating width variation
- Ability to reduce edge bead size
2007 TAPPI EUROPEAN PLACE Modern Extrusion Coating Die Technology - - PowerPoint PPT Presentation
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
SLIDE 2
SLIDE 3
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.
SLIDE 4
Basic Flow Channel Design
- Constant cross section.
- Sometimes called a Keyhole design.
- Allows for adjustable internal deckle plugs.
SLIDE 5
Advanced Flow Channel Design
- Varying cross section.
- Requires less lip adjustment.
- Normally deckled externally.
SLIDE 6
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.
SLIDE 7
External-Only Deckles
- Advantage: A saw-tooth wedge type of
compressible seal system provides convenience and leak-free operation.
SLIDE 8
External-Only Deckles
- Disadvantage: External-only deckles increase
edge bead size and create stagnation areas within the die flow channel.
SLIDE 9
Internal-Only Deckles
- Advantages:
Flow channel is streamlined at all
- perating widths.
Internal blades can be adjusted to minimize edge bead size.
SLIDE 10
Internal-Only Deckles
- Disadvantage:
Require rigorous procedures to adjust and maintain.
SLIDE 11
Deckles for Width Adjustment and Edge Profile Control
- Combined internal and external deckling
SLIDE 12
Relative Positions of Internal Blades Influence Edge Bead Size and Shape
SLIDE 13
Edge Instability is the Limitation
SLIDE 14
Restabilizing the Edge
SLIDE 15
Further Edge Reduction
SLIDE 16
Internal Deckle Tuning
- Influences velocity of the material exiting the die lips.
SLIDE 17
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.
SLIDE 18
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).
SLIDE 19
Factors Influencing Neck-In
- Coating
material properties (melt strength).
- Air gap.
- Draw ratio.
- Line speed.
SLIDE 20
External Edge Guides
- An attempt at
reducing the amount of neck-in.
- Preliminary
results are promising.
SLIDE 21
External Edge Guides
- With a
temperature match and the correct geometry, the curtain can be influenced and web stability is enhanced.
SLIDE 22
Edge Guides Combined with Internal & External Deckles
SLIDE 23
Edge Guides – A Closer Look
SLIDE 24
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.
SLIDE 25