Coating is the physical process of laying a liquid or solid onto the surface of a paper, fibre or fabric. The objective is to achieve uniformity of coverage (uniformity of weight distribution) while controlling the variance of thickness of the coating. Coating is most typically seen in pre-preg systems for the application of a resin to a paper or film.
KNIFE OVER ROLL COATING
· Commonly used for high viscosity coatings with high coat weights.
· Offers a low cost solution.
· Suitable for a wide range of products and substrates.
· Can coat on uneven surfaces such as textiles and woven fibres.
· Precision machined, tool steel coating knife carried above precision machined roller. The roller is commonly heated.
· Coat weight varied by adjusting the gap between the coating knife and backing roller.
· Coating applied to substrate and metered off by coating knife.
· Adjustable side dope cheeks are used to control the coating width and eliminate over running of coating at both sides of the web.