Vacuum Roll Coating Design Considerations
One simple barrier to Vacuum Roll Coating is that it is more complicated than alternatives. A shell material must be selected and the diameter and pattern of holes in the shell specified. A variety of components are needed to form the vacuum zone within the shell, which may need to be adjustable. A shell coating or covering, chosen from many options, may be required to spread the vacuum, protect the web, or improve the coefficient of friction.
Besides the roll itself, a vacuum system is required. This might comprise an exhaust connection from the roll, a vacuum gauge, an airflow control valve, the necessary tubing, and a blower.
Fortunately, Faustel takes on the burden of doing the needed calculations and applying their experience to arrive at the correct vacuum roll specification. In order to do so, the converter will need to provide the following parameters.
- Maximum and minimum web width
- Wrap angle
- Substrate types and thicknesses
- Line speed
- Tension and tension differential ranges
- Orientation of the center of the vacuum zone
- Operating environment, including web temperature, air temperature, explosion-proof requirements, elevation, and electrical power available
In addition, any special considerations with regard to the substrate, how the roll is to be driven, where it is to be mounted, or locations of adjustments or connections should be discussed.
With that information in hand, Faustel can respond with a quotation including specifications for the vacuum roll or belt.
Vacuum rolls have traditionally served as the only way to accomplish certain functions within web processing lines. But as experience with vacuum rolls and belts has grown, so has the number of ways in which they are applied. Given the unique characteristics of these vacuum devices, the likelihood is that even more applications will be found as converters and machinery builders collaborate on product development and improvement.