A: The specialties of low-volume products
The number of new and upgraded products made by web coating continues to expand. One of the characteristics of these new products is their specialty applications and thus low volumes. In addition, each product will have very different product requirements, such as coatweight, drying capacity, quality, coating uniformity Td & Md uniformity, substrate thickness and type, and solvent needed.
As a result, the coater must be versatile and capable of meeting new-product demands. Typically, new products will start the manufacturing cycle on an existing coater, which is just not up to the task. Often, new products are not a commercial success because the required product properties could not be economically achieved due to fundamental limitations of an existing coater that could not be overcome.
Therefore, to avoid commercial (and financial) failure with a new product because of coater limitations, it is crucial that current capabilities are known and readily available for all development personnel. Original coater-design specifications should be analyzed to identify all process parameters, and the current coater itself checked to see if it is still capable of meeting these parameters. Capabilities deteriorate with age and use. For example, if the range of drive-speed uniformity is +/-5.0%, it will be near impossible to obtain a +/-1.0% Md coatweight uniformity. Also, dryer airflow may have decreased for several reasons, and there will be a resulting loss in dryer capacity.
If limitations are detected early in product development, they can be corrected. The best way to identify limitations: Develop manufacturing basic data early in the process and compare with current capability. If limitations are detected, then changes can be made in product composition or the coater can be upgraded to meet the new product’s requirements.
Coater information dissemination
The technical information on coater-design parameters and current capability should be a readily available database so that technical personnel can easily access and use the information.
E.D. Cohen, “Web Coating Defects: Role of the Coater Module,” Converting Quarterly, 2012 Q4, page 22.
R. Wagner, Jr., and E.B. Water, Solvent-Based Coating Technology, Multilayer Flexible Packaging, Elsevier, 2nd ed., 2016.
J. Greener, G. Pearson, and M. Cakmak, Coating & Solidification, in Roll-to-Roll Manufacturing: Process Elements and Recent Advances, John Wiley & Sons, 2018.