Micropitting of carburized gears lubricated with biodegradable low-toxicity oils

• Type: Article in International Scientific Journal
• Date: 2009

Authors

Cardoso, NFR (Author) Other; Martins, RC (Author) FEUP; Seabra, JHO (Author) FEUP

Journal

Title: Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology

Vol. 223

Pages: 481-495

ISSN: 1350-6501

Publisher: SAGE

Indexing

ISI Web of Knowledge - 4 Citations

Scopus - 6 Citations

Scientific classification

FOS: Engineering and technology > Mechanical engineering

Other information

Authenticus ID: P-003-KMG

DOI: 10.1243/13506501jet495

Abstract (EN): Environmental issues are leading to a growing interest in bio-lubricants, which can have similar or even better performance than mineral and synthetic oils. In this work, the biodegradability and toxicity characteristics of ester-based gear oils are presented and their physical, chemical, and wear properties are compared with those of a commercial mineral oil. In an earlier work, power loss tests were performed on the FZG test rig, using carburized gears and several different lubricants. The operating temperatures of the oil and of the FZG gearbox wall were measured for different values of the input torque and speed. An energetic model of the FZG test gearbox was developed, taking into account the power loss mechanisms inside the gearbox and the heat flow mechanisms from the gearbox to the surrounding environment. Using this model it was possible to quantify the influence of lubricant formulation on the average friction coefficient between gear teeth. Gear micropitting tests were performed on the FZG test rig, using carburized gears and different oils. Post-test analysis included the mass loss measurement of the gear, the ferrometric analysis of lubricant samples collected during the tests, and the visual inspection of the gears. The tooth flanks were inspected using surface topography measurements to assess the number and depth of micropits. In comparison with the gear lubricated with mineral oil, the gears lubricated with ester-based oil showed significantly higher mass loss (3-4 times higher), smaller number of micropits, and less deep micropits. If carefully formulated, biodegradable low-toxicity ester-based gear oils, beside their environmental advantages, enhance gear performance when compared with the mineral lubricant providing (a) lower friction coefficients and lower operating temperatures of gearboxes and (b) lower number of micro-pits (with depths greater than 4 mu m). One of the ester-based gear oils passed the FVA gear micropitting criterion.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 15