Effects of Solid Film Lubricant Coating Weights on the Tribological Properties of Bare and Coated Sheet Steels 900282
A systematic study was conducted to evaluate the effects of solid film lubricant (SFL) coating weights on the frictional properties of sheet steels used in stamping plants. Samples of cold rolled, hot-dipped galvanized, electrogalvanized, and galvannealed sheet steels were coated from 0.11 to 3.22 gm/m2 (10 to 300 mg/ft2) with a SFL. Static and dynamic friction coefficients and percent elongation changes, as a function of SFL coating weights, were determined with a sliding friction apparatus. Changes in surface morphology as a function of SFL coating weight, after sliding friction testing, were ascertained by profilometry and scanning electron microscopy. The obtained results were related to and shown to be consistent with friction mechanisms postulated by current friction theory. The effect of low friction on sliding velocity was examined with a sliding draw bead apparatus. Field trials demonstrated formability improvements associated with the use of solid film prelubricated sheet steels.