Dynamic Surface Resistance
The ratio of the friction force to the normal force during steady-state sliding determines how easily sheets glide past each other on automated machinery. A low kinetic coefficient of friction prevents dragging and misfeeds during the feeding, printing, and folding stages. This property is particularly critical for high-speed folding cartons and automated multi-pack packers.
Sliding Interface Process
Moving sheets rub against each other or against metal guide plates, encountering resistance from surface asperities. A kinetic coefficient of friction that is too high causes sheets to stick together, leading to double-feeds or conveyor jams. Conversely, an excessively low value can make the stacks unstable, causing them to slide and fall during palletization.
Papermakers control this surface property by applying specific sizing agents, starches, or synthetic slip additives during the coating and calendering steps.
Measurement Protocol Standard
Laboratory testing utilizes a horizontal plane and a sled of known mass to measure the force required to maintain motion. Standards like ISO 8295 and TAPPI T 816 define the test parameters, including the sled speed and surface preparation, to ensure repeatable results. Changes in relative humidity can alter the surface moisture of the board, directly impacting the sliding resistance.
Maintaining consistent surface chemistry and moisture levels prevents unexpected behavior on the packaging line, ensuring stable throughput.
