Influence of running-in on surface characteristics of efficiency tested ground gears. (November 2017)

• Record Type: Journal Article
• Authors: Mallipeddi, D.; Norell, M.; Sosa, M.; Nyborg, L.
• Is Part Of: Tribology international. Volume 115(2017)
• Page Start: 45
• Page End: 58
• Publication Date: 2017-11
• Subjects: Gears -- Running-in -- Efficiency test -- Residual stresses -- Micropitting -- Tribofilm; Tribology -- Periodicals; 621.89
• DOI: 10.1016/j.triboint.2017.05.018
• Languages: English
• ISSNs: 0301-679X

Abstract

Abstract: The effect of running-in load (0.9 or 1.7 GPa) on surface characteristics of ground spur gears, and on their development during subsequent efficiency testing (FZG rig), is examined. The effect was confined to less than 10 μm depth. Micropitting was associated with surface asperities and their plastic deformation; higher running-in load gave more micropitting, also after identical efficiency tests. Running-in increased unequal compressive residual stresses in both profile and axial directions, while after efficiency testing they approached equal levels. Deformation induced martensite is considered to form during running-in only at high load, still the amount after efficiency testing increased with running-in load. Higher surface content of phosphorous from extreme pressure additive (EP) occurred only after efficiency test following running-in at high load. Highlights: High running-in load increases the efficiency but also micropitting & cracking. Plastically deformed asperities initiate micropits during running-in. Deformation induced martensite formed already during running-in – load dependent. Only the test with higher efficiency and more micropits had a significant tribofilm. Changes in residual stress and microstructure were confined to <10 μm.