AGMA 21FTM08 PDF

In defining total contact temperature the tooth flank temperature is as significant in the calculation as the flash temperature. Work done in preparation to writing 19FTM24 revealed that the applied k_sump multiplier value for applications with spray lubrication should be greater than > 1.2 for high speed gears when calculating a tooth flank temperature. This procedure is described in AGMA 925-A03, Section 6.3.1 equation (91). In order to have a comparable risk assessment with MAAG “63”, MAAG “83” and ANSI/AGMA 6011-J14, Annex B, it was determined a value of k_sump = 1.42 is necessary otherwise AGMA 925 is not reliable for assessing scuffing risk for high speed gears. However, further investigation suggests variable values of k_sump are required to accurately calculate the tooth flank temperature relative to pitch line velocity. Referenced documents, with supporting comprehensive test data and testing results of high speed gears both indicate a higher range of tooth body temperatures increasing with pitch line velocity. This is corroborated by field experience conducted by Artec Machine Systems. This paper improves the methodology for determining the tooth flank temperature. Two methods are proposed for assessing scuffing risk when applying AGMA 925 for high speed gears. Both methods provide similar results.