OptiCoat Jet coating provides very uniform and skipfree coating quality. It gives the best possible surface smoothness compared to any other coating method. OptiCoat Jet coating station applies a surplus coating layer to paperboard surface with jet nozzles. The excess coating is scraped away by metering blade and returned on a return plate to the color collection pan. The desired coatweight is achieved by adjusting the angle or pressure of the blade.The impingement pressure is maximized with closed nozzle geometry.
OptiCoat Jet produces high quality coating on paper and board in both cross and machine direction. High quality backing roll is one of the reasons for reduced MD coatweight variation. Skipfree coating is a result of a very effective de-aeration in color circulation. The application method and cross direction control capabilities are important for uniform application and excellent CD profiles.
All Valmet coating stations are fully pretested in workshop. The instrumentation and controls are integrated in the machine and all the controls located by the station frame. The interface and automation systems are user-friendly. After web breaks, coating can be re-started fast. Tailthreading is fast and reliable. A wide operating window enables good surface quality almost immediately after the coating is started.
Because of a wide operating window, coating quality is easily maintained high when speeding up the machine. The wide window and operator friendly automation facilitate finding the correct parameters for each paper or board grade. Clean coating process and easy wash-up speed up the maintaining operations.
Jet application is contactless resulting less breaks. Runnability is also improved because of a smaller doctor blade load compared to other application methods. Jet application also has excellent efficiency even at very high speeds.
Sappi Alfeld in Germany is among the first to use Valmet’s latest coating station member in the new OptiCoat family. With the improved OptiCoat Jet blade coating head, Alfeld has been able to further improve coating profiles. “Our customers are really happy with our products,” says Mill Director Stefan Karrer.