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Ultrasonic foil installed under the wire on a paper machine
An Ultrasonic foil is part of the drainage table section of paper machines. A series of hydrofoil blades (called foils) create pressure/vacuum pulses that dewater the fibre/water slurry (called stock) on a moving conveyor belt (the wire). Flexible ceramic foils have been used for years,[1] but ultrasonic foils produce paper of higher quality. High-power ultrasonics create millions of pressure pulses from imploding cavitation bubbles which keep the fibres apart, giving them a more uniform distribution. This results in better fibre formation, stronger paper and smoother paper surfaces.