COATING
SOLUTIONS

Coating Solutions and Common Slot Die Defects

At Precision Die Systems, we understand that achieving flawless coatings is critical for your production success. Slot die coating is one of the most precise methods available, but even the best systems can encounter common defects like streaks, uneven coatings, or edge build-up. These challenges can slow your processes, waste materials, and impact the quality of your final product. Our expertise in diagnosing and resolving process coating issues ensures your operations remain efficient and your products exceed industry standards.

Chatter

Causes:
-Fluctuations in flow rate
-Mechanical vibrations
-Coating bead Oscillations
Solution: Minimize or eliminate vibration and/or oscillation

Ribbing

Cause: Instability in the coating bead

Solution: Reduce the coating gap

Air Entrainment

Cause: Air is drawn in at the dynamic wetting line
Solutions: -Utilize vacuum systems
-Apply an electrostatic field
-Ensure surface energy compatibility with surface tension (using corona, plasma, flame, or primer treatments)

A dynamic wetting line issue that leads to bubble formation under the coating, becoming more challenging to manage as line speed increases is "Air Entrapment".

Air Entrapment

Cause: Air in the fluid before it reaches the pump
Solutions: -Allow time for air to dissipate
-Implement cone flow
-Use a dampening chamber
-Apply sonic techniques

Dewetting

Cause: Surface tension gradient
Solutions:
-Use a vacuum system
-Apply an electrostatic field
-Ensure surface energy compatibility with surface tension

Streaks

Causes: -Presence of particles
-Bubbles
-Non-uniform wetting at the slot exit

Solutions: -Clean the surface
-Simulate and adjust the process

Particles

Causes:
-Contamination
-Gel formation

Solutions:
-Clean the affected area
-Minimize recirculation zones

Chevrons

Causes: -Acoustic waves in the vacuum chamber
-Close proximity to the substrate
Solutions: -Measure frequency and clean/replace as necessary
-Adjust vacuum level
-Move closer to the substrate

Hashmarks

Cause: A gravity-driven defect in curtain coating

Solution: Adjust flow rate and line speed to control fluid impact

Uneven Coating Thickness

Cause: Misaligned slot dies, fluctuating fluid viscosity, or web tension instability.

Solution: Realigning slot dies, fine-tuning fluid properties, and enhancing web tension control for consistency.

Edge Build Up/Coating Overlap

Cause: Improper die setup or fluid overflow.

Solution: Precision adjustments to slot die lips and integrating edge guides to control fluid flow.

Slot Die

Why Choose Precision Die Systems?

We bring decades of experience in slot die technology to help you overcome any coating challenges. From troubleshooting defects to designing tailored solutions, we’re committed to improving your production quality and efficiency.

Let’s Solve It Together

If you’re facing coating defects, don’t let them derail your progress. Contact Precision Die Systems today to learn how we can help resolve your slot die coating issues and keep your production moving forward.

Not sure how to resolve a process issue? Test our expertise, we are happy to help!

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COATING SOLUTIONS