In major industrial coating lines, the roller coating process is favored for its high production efficiency and material savings. However, despite careful product design, actual production runs often encounter a persistent defect: wavy, orange-peel-like striations on the sheet metal or wood surface, commonly known as “roller marks.” If left unaddressed, these defects compromise the aesthetic quality and value of the final product. How can we eliminate them? Here is our technical analysis and solution guide
Based on operational experience and the morphology of the defects, we can pinpoint three primary causes:
Low Application Temperature: If the ambient workshop temperature or the substrate temperature is too low, the paint’s fluidity decreases. This prevents the coating from liquefying and leveling out evenly across the surface.
Excessive Paint Viscosity: If the paint is too thick or has not been sufficiently diluted, its leveling property is compromised. High-viscosity paint holds the texture of the roller instead of flowing into a smooth film.
Incorrect Roller Gap (Film Thickness): If the gap between the Applicator Roller and the Doctor Roller (Squeeze Roller) is too wide, the applied paint volume becomes excessive. A wet film that is too thick is prone to forming ripples and uneven textures due to surface tension.
According to the analysis above, we can implement the following countermeasures to solve the roller mark problem:
Enhance Temperature Control:
Increase the ambient temperature of the workshop if possible.
Crucially, utilize IR (Infrared) Heating or a leveling tunnel immediately after coating. Heating the paint film reduces its viscosity temporarily, allowing it to flow and level out the marks naturally.
Optimize Paint Viscosity:
Strictly follow the manufacturer’s instructions for mixing ratios.
Use a viscosity cup to verify the consistency. Ensure the paint is diluted to the optimal range for roller application to promote smooth differentiation.
Precise Gap Calibration:
Adjust the gap between the Applicator Roller and the Doctor Roller using the manual handwheel or the HMI (Human-Machine Interface) control.
Reduce the gap to restrict the paint flow. A thinner, more controlled unit paint amount significantly reduces the risk of ribbing and texture buildup.
Roller marks are a common challenge, but they are solvable. By systematically troubleshooting temperature, viscosity, and mechanical settings, operators can eliminate these defects. Mastering these variables not only improves the painting effect but also guarantees the premium value of your products.
Share ：