Free Jet Applicator: Advantages and Features, 1998 Coating Conference Proceedings

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Increasing speed requirements for blade coaters (up to 2000 mpm) have forced paper machinery manufacturers to develop coating equipment capable of avoiding the shortcomings in quality and improve the runnability of flooded nip applicators.

Application principles with a high speed potential, such as short dwell time applicators, free jet applicators, and nozzle applicators with blade pre-metering, have existed for many years. Adapting these applicators to today’s requirements has created the base for a leap in both sheet quality and runnability.

Trials results comparing flooded nip and free jet operations are presented. Developments in free jet applicators had to address known critical limitations such as jet flutter and coating profile uniformity. Features such as header design, nozzle geometry, and impingement angle are described and assessed in this paper. Computer flow simulations allowed the design to be optimized for stable flow profiles with different coating color rheologies.