Influence of hard rolling and the cooling lubricant on the material properties and the rolling strength of PM gears
Industrial Lubrication and Tribology
ISSN: 0036-8792
Article publication date: 26 November 2018
Issue publication date: 3 April 2019
Abstract
Purpose
The lower density of powder metallurgical (PM) gears compared to solid steel gears leads to not only a lower weight but also a lower load-carrying capacity. Therefore, PM gears are cold rolled before hardening to increase the density in the highly stressed surface zone and, thus, the flank load-carrying capacity. A further approach to increase the flank load-carrying capacity is the reduction of friction and wear in the tooth contact. The purpose of this paper is to analyze the hard rolling process as a new manufacturing step in the PM process chain to influence the boundary layer.
Design/methodology/approach
The investigation includes the new process of hard rolling, the variation of the cooling lubricant in the hard rolling process and the evaluation of its influence on the material properties and the flank load-carrying capacity. Therefore, the additives of the cooling lubricant are varied regarding the sulfur and phosphorous content. The load-carrying capacity is evaluated on disk-on-disk test rig and the material properties are evaluated by metallographic tests and boundary layer.
Findings
The results of the specimen characteristics in the micro and nano range show a significant influence of hard rolling on the residual stresses and the chemical surface composition. Because of hard rolling, residual compressive stresses as well as roughness are reduced and the flank load-carrying capacity is increased by high phosphorous content of the cooling lubricant.
Originality/value
This paper investigates a new manufacturing step to increase resource efficiency by increasing the flank load-carrying capacity of spur gears.
Keywords
Acknowledgements
The authors gratefully acknowledge financial support by the German Research Foundation (DFG) [KL500/93-2] for the achievement of the project results.
Citation
Klocke, F., Bergs, T., Löpenhaus, C., Scholzen, P. and Frech, T. (2019), "Influence of hard rolling and the cooling lubricant on the material properties and the rolling strength of PM gears", Industrial Lubrication and Tribology, Vol. 71 No. 3, pp. 406-410. https://doi.org/10.1108/ILT-06-2018-0247
Publisher
:Emerald Publishing Limited
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