Friction Standard
Standardized test methods established by the Technical Association of the Pulp and Paper Industry provide a consistent framework for measuring the physical properties of substrates. TAPPI T549 describes the procedure for determining the static and kinetic coefficients of friction of uncoated and coated writing and printing paper. It uses a horizontal plane method where a weighted sled is pulled across a stationary specimen to establish the resistance between the two surfaces.
Testing Procedure
Force measurements recorded during the start and continuation of movement distinguish between the energy needed to initiate the slide and the energy needed to maintain it. Following tappi t549 ensures that data from different laboratories can be directly compared when qualifying a mill run for a specific client. This is essential for paper mills and converters who must meet the friction specifications of high speed printing presses to avoid jams.
The method specifies the size of the sled, the speed of the pull and the environmental conditions including the exact temperature and humidity of the testing room. Precision in the sled weight and the flatness of the horizontal plane prevents errors that could lead to false readings of the surface properties.
Industry Application
Accurate friction data prevents problems such as double feeding in office copiers or poor stacking in folder gluers. While tappi t549 is primarily for paper, the principles are often adapted for other flat substrates like board and films. It remains a standard of quality control in the paper industry.
