Laboratory simulation to select oil seal and surface treatment

Abstract

Reliability of rotary oil seals depends on many parameters related to seal design and material, shaft material, hardness and surface texture, medium; operating conditions, etc. This presentation will describe the accelerated testing methodology development as well as the results of shaft surface roughness and hardness analyses to decrease wear in rotary oil seal lips. Seals went through 200 h of accelerated testing which not only reproduced operating conditions but duplicated field service mode or seal lip and shaft wear mechanisms during accelerated testing. Dana's new oil seal accelerated tester has many unique features: (1) reproduction of several extreme operating conditions including oil temperature cycling and superposition of reciprocal motion; (2) devices to easily change shaft-to-bore misalignment and shaft eccentricity, and (3) measurement equipment for torque evaluation and photo-optical oil leak detection. The methodology consists of establishing simple engineering parameters including the number of tested cycles before the leak, oil seal lip wear path, shaft surface groove depth under oil lip, varieties of shaft surface roughness, and friction forces between seal lip and shaft surface. An important part of this methodology is detailed metallurgical and metrological examination of the field and lab test usage of the oil seal lips and shaft surfaces including SEM and EDX analysis. The shaft surface hardness and roughness characteristics, including core roughness depth, reduced peak height and valley depth, their ratios, and their influence on seal lip wear will be presented.