Mini-Encyclopedia of Papermaking Wet-End
Part Three: Equipment & Unit Operations
The slice is a slit-like opening in a headbox from which a jet of dilute fiber furnish emerges and then lands on the forming fabric. Papermakers can control the width of the slice opening to adjust such parameters as the jet speed, the basis weight profile, and the amount of dilution water added at the fan pump. They also can adjust the relative positions of the opening and a protruding lower lip of the slice. Such adjustments will affect the angle at which stock strikes the forming fabric, making it possible to practice pressure forming, velocity forming, or intermediate forming conditions. Chemical-related deposits on either slice lip can have a major adverse effect on product uniformity, creating wake effects and associated machine-directional streaks in the product.
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