Influence of tribofilms on failures and friction of gears with particular focus on running-in

Ziegltrum, A.; Emrich, Stefan; Lohner, Thomas; Michaelis, Klaus; Brodyanski, A.; Merz, Rolf; Kopnarski, Michael; Hoehn, Bernd-Robert; Stahl, Karsten

doi:10.1108/ilt-09-2018-0356

Cited by 3 publications

(3 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Figure 2 shows the mechanical layout of the considered test rig in back-to-back configuration with a center distance of 91.5 mm. Only the main features of the test rig are described based on the description and wording of Lohner et al (2017), Yilmaz et al (2019) and Ziegltrum et al (2017, 2019). For more details, the reader may be referred to Hinterstoißer(2014) and Lohner (2016).…”

Section: Methodsmentioning

confidence: 99%

DLC-coated spur gears – part I: friction reduction

Schwarz

Ebner

Lohner

et al. 2021

ILT

Self Cite

View full text Add to dashboard Cite

Purpose This paper aims to address the influence of diamond-like carbon (DLC) coatings on the frictional power loss of spur gears. It shows potentials for friction and bulk temperature reduction in industrial use. From a scientific point of view, the thermal insulation effect on fluid friction is addressed, which lowers viscosity in the gear contact due to increasing contact temperature. Design/methodology/approach Thermal insulation effect is analyzed in detail by means of the heat balance and micro thermal network of thermal elastohydrodynamic lubrication contacts. Preliminary results at a twin-disk test rig are summarized to categorize friction and bulk temperature reduction by DLC coatings. Based on experiments at a gear efficiency test rig, the frictional power losses and bulk temperatures of DLC-coated gears are investigated, whereby load, speed, oil temperature and coatings are varied. Findings Experimental investigations at the gear efficiency test rig showed friction and bulk temperature reduction for all operating conditions of DLC-coated gears compared to uncoated gears. This effect was most pronounced for high load and high speed. A reduction of the mean gear coefficient of friction on average 25% and maximum 55% was found. A maximum reduction of bulk temperature of 15% was observed. Practical implications DLC-coated gears show a high potential for reducing friction and improving load-carrying capacity. However, the industrial implementation is restrained by the limited durability of coatings on gear flanks. Therefore, a further and overall consideration of key durability factors such as substrate material, pretreatment, coating parameters and gear geometry is necessary. Originality/value Thermal insulation effect of DLC coatings was shown by theoretical analyses and experimental investigations at model test rigs. Although trial tests on gears were conducted in literature, this study proves the friction reduction by DLC-coated gears for the first time systematically in terms of various operating conditions and coatings. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-07-2020-0257/

show abstract

Section: Methodsmentioning

confidence: 99%

DLC-coated spur gears – part I: friction reduction

Schwarz

Ebner

Lohner

et al. 2021

ILT

Self Cite

View full text Add to dashboard Cite

show abstract

“…While lubricant has a major impact on reducing running-in time, careful selection is needed to achieve the best results for the running-in method. The impact of running-in and tribofilms on gear failures and friction was studied by Ziegltrum et al [12], and the results revealed that during running-in, tribofilm production can be more important than surface roughness change in terms of gear failures and friction. The central film thickness for electrohydro-dynamic lubrication was investigated by Dowson et al [13] and showed for the first time full numerical film thickness and pressure distributions and a curve fitted minimum film prediction.…”

Section: Introductionmentioning

confidence: 99%

Investigation of running-in process based on surface roughness parameters, real contact area ratio and tribological properties

Horng¹,

Biswas²,

Adhitya³

et al. 2021

FME Transactions

View full text Add to dashboard Cite

The running-in process is the initial process for the new moving parts wearing against each other to establish the shape adjustment that will regulate them into a stable relationship for the rest of their working life. The objective of this research is to investigate and evaluate the running-in process by using disk-on-block line contact device. Due to its empirical nature and well-ploughed analysis, an asperity micro-contact model is considered. The experiment is performed by varying the surface roughness of the block with rigid smooth sphere surface under specific condition. The effects of surface roughness, load, speed, and lubrication on the running-in behaviour is studied. The running-in process encourage plastic deformation of asperities and created microstructural changes on contact surfaces. The theoretical and experiment result shows that the plasticity index ps, surface roughness parameter b, real contact area ratio * A0 and specific film thickness l is influenced by the running-in process.

show abstract

“…Friction and wear of rolling contacts are influenced by boundary layers, which prevent direct metallic contact. The characteristics of these boundary layers depend mainly on the finishing process and the wear in of the contact partners (Brecher et al, 2017;Ziegltrum et al, 2017;Brinksmeier, 1982;Mach, 2003;Schulz, 2009;Berlet et al, 2010). In the conventional production of gears, the tooth flanks of the gears are ground in the final manufacturing process step.…”

mentioning

confidence: 99%

Influence of hard rolling and the cooling lubricant on the material properties and the rolling strength of PM gears

Klocke

Bergs

Löpenhaus

et al. 2019

ILT

View full text Add to dashboard Cite

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.

show abstract

Influence of tribofilms on failures and friction of gears with particular focus on running-in

Cited by 3 publications

References 22 publications

DLC-coated spur gears – part I: friction reduction

DLC-coated spur gears – part I: friction reduction

Investigation of running-in process based on surface roughness parameters, real contact area ratio and tribological properties

Influence of hard rolling and the cooling lubricant on the material properties and the rolling strength of PM gears

Contact Info

Product

Resources

About