Slide Angle

Definition
The coefficient of friction is the resistance to movement of one sheet of linerboard when placed against another sheet of the same specimen. It simulates the friction between stacked corrugated sheets or boxes.

Influence
How slippery the linerboard surfaces are can be critical to the efficiency and safety of corrugating and product-use operations form roll handling through the handling of packed containers. Most of the problems arise with linerboards that are too slippery, but those with too high resistance to slip can also create difficulties.

Potential Problems
Low slide angle, or low coefficient of friction, can cause problems in the handling of roll stock with clamp trucks. Extremely slippery surfaces can lead to telescoping of rolls when they are picked up with the core axis vertical during the unloading of cars, transfer to roll storage, or delivery to the corrugator. Slippery board can also lead to instability of stacks of combined board, boxes during movement through the converting plant, or both. Product users also experience problems with the stability of unrestrained units of filled containers during handling and transport. In addition to potential waste due to damaged roll stock, combined board, and customer product, these conditions may represent a potential safety hazard to personnel.

High slide angle, or high coefficient of friction, can cause excess drag on the corrugator double-facer as the board moves over the hot plates. High friction also can lead to feed problems on machines that are kicker fed from the bottom of piles. Excess drag can exceed the resistance of the board edge to the force of the kicker, causing jam-ups. Surface peeling also may occur.

Source
McGrattan, W. "Key characteristics of linerboard, corrugating medium, and roll stock mechanical condition and their influence on the manufacture of corrugated products, part 1." Tappi Journal (1990): 99-108.

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