Physics:Ultrasonic foil (papermaking)

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, 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.