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Journal ArticleDOI

The influence of contact stress distribution and specific film thickness on the wear of spur gears during pitting tests

01 Jun 2012-Journal of The Brazilian Society of Mechanical Sciences and Engineering (The Brazilian Society of Mechanical Sciences and Engineering)-Vol. 34, Iss: 2, pp 135-144
TL;DR: In this article, the authors investigated the role of surface finish and surface finish on gear wear and found that the wear on the gear flanks depended on the lubricant film thickness and it was higher for the milled gears.
Abstract: One of the main gear damage mechanisms is the formation of pitting and spalling on the tooth flank. Several factors have significant influence on the damage formation, such as: contact stress level; tooth profile type; relative contact speed; surface finish and lubrication conditions. This work comprehends the global observation of all such parameters and was carried out to explain the phenomena related to this wear mechanism. The wear test equipment uses the power recirculation principle and is commonly known as FZG test rig. The gears were made from AISI 8620 steel and had two types of surface finishing (by shaving or by milling). The wear experiments were performed with two torque stages: 135 N.m (running-in) and 302 N.m (steady-state), and two test temperatures: 60oC (running-in) and 90oC (steady-state). The wear level was determined by using image analysis. In order to calculate the specific film thickness and friction coefficient, the roughness of tooth flank was measured at each test stop. After the experiments were completed, it was possible to confirm that, for both manufacturing processes, the boundary lubrication regime was adopted at the tooth flank and the specific film thickness presents a different behavior when compared to addendum, pitch diameter and deddendum regions. The wear on the gear flanks depended on the lubricant film thickness and it was higher for the milled gears.

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Citations
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Journal ArticleDOI
TL;DR: In this article, the authors used the Gear Dynamic Stress Test Rig (GDSTR) to measure the surface contact stresses at the contacting points of a meshed gear pair using the strain gauge and carbon slip rings.

33 citations

Journal ArticleDOI
TL;DR: In this paper, the authors compare gear surface characteristics generated by grinding, honing and superfinishing of case-hardened steel, including the evolution during efficiency testing with two different prior running-in loads (0.9 and 1.7 GPa).

29 citations

Journal ArticleDOI
15 Apr 2015-Wear
TL;DR: In this article, the authors investigated gear micropitting initiation and propagation when subjected to varying torque loads under a constant rotational speed and found that the specific lubricant film thickness varies considerably because of changes of surface roughness after gears are subjected to various running cycles under varying torque levels.

27 citations

Book
01 Mar 2016
TL;DR: Tribology as discussed by the authors is related to friction, wear and lubrication of machine elements and not only deals with the design of fluid containment systems like seals and gasket, but also with the liveness of surfaces in relative motion.
Abstract: Tribology is related to friction, wear and lubrication of machine elements. Tribology not only deals with the design of fluid containment systems like seals and gasket but also with the lubrication of surfaces in relative motion. This book comprehensively discusses the theories and applications of hydrodynamic thrust bearing, gas (air) lubricated bearing and elasto-hydrodynamic lubrication. It elucidates the concepts related to friction, including coefficient of friction, friction instability and stick-slip motion. It clarifies the misconception that harder and cleaner surfaces produce better results in wear. Recent developments, including online condition monitoring (an integration of moisture sensor, wear debris and oil quality sensors) and multigrid technique, are discussed in detail. The book also offers design problems and their real-life applications for cams, followers, gears and bearings. MATLAB programs, frequently asked questions and multiple choice questions are interspersed throughout for easy understanding of the topics.

22 citations

Journal ArticleDOI
TL;DR: In this paper, the evolution of surface characteristics of ground gears were followed closely from the initial 200 cycles to failure by three stages; running-in, steady progression, and degradation.

18 citations

References
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Book
01 Jan 1992
TL;DR: In this paper, surface topography and surfaces in contact are discussed, as well as surface engineering in tribology, materials for bearings and sliding wear by hard particles, friction and friction.
Abstract: Preface * Introduction * Surface topography and surfaces in contact * Friction * Lubricants and lubrication * Sliding wear * Wear by hard particles * Wear and design * Surface engineering in tribology * Materials for bearings * Author index * Subject index.

2,647 citations


"The influence of contact stress dis..." refers background in this paper

  • ...Under these conditions, some contact between th asperities will occur, and the wear will be greater than in conditions where a full fluid lubricant film is present (Hutchings, 1992)....

    [...]

Journal ArticleDOI
TL;DR: In this paper, the authors classified rolling contact failures according to their failure mode as wear, plastic flow, fatigue, and bulk failures, with the last class arising outside the immediate contact area.
Abstract: Rolling contact failures are classified according to their failure mode as (a) wear, (b) plastic flow, (c) fatigue, and (d) bulk failures, with the last class arising outside the immediate contact area. The wear failures are subdivided into mild wear by loose particle removal and smearing involving metal transfer. Plastic failures may arise due to overload or to temperature imbalance. Fatigue is of the spalling or the surface distress type. An analysis of the stress conditions in a rolling contact is sketched; the stepwise refinements of the contact model are considered, starting from Hertz theory, and progressively including surface traction, plasticity, elastohydrodynamic lubricant films, surface microtopography, and the inhomogeneities of real metals, Each failure mode is associated with the relevant severity parameters of the contact stress condition, and a description of its mode of formation is given. Guidelines are provided for the identification of that failure mode which, among competing modes, i...

253 citations


"The influence of contact stress dis..." refers background or methods in this paper

  • ...Among the friction models that describe the friction coefficient for gears in contact, emphasis should be given to (i) the DIN 3990 (1987) equation; (ii) the equation described in ISO 6336 (1996); (iii) the model proposed by Michaelis (Winter and Michaelis, 1983); (iv) the Kelly expression, and (v) an equation for FZG gears proposed by Castro (2004)....

    [...]

  • ...= −ηµ (3) In his proposal, Michaelis makes reference to the following parameters: the specific normal load (WL) in N/mm; the pinion pitch diameter (d1); the rolling speed (VR); the equivalent arithmetic average roughness of contact surfaces (RaEq); the correction factor that considers what kind of additives exist in the lubricant (XL) and the correction parameter for gears that has coated surface (XC)....

    [...]

  • ...In EHD conditions, the film variation as a function of local surface roughness is perhaps best characterized by a parameter proposed by Tallian (1967)....

    [...]

  • ...In EHD conditions, the film variation as a function of local surface roughness is perhaps best characterized by a parameter proposed by Tallian (1967). In Eq....

    [...]

  • ...Local friction coefficient – µMIC To calculate the friction coefficient on the contact path at each point of the flank of gear teeth, it was used the model proposed by Michaelis (Castro and Seabra, 2007), which is shown in Eq....

    [...]

Journal ArticleDOI
TL;DR: In this article, the influence of oil temperature on gear failure modes, as well as their introduction into load carrying capacity calculation methods are shown. But the often-applied practice of increasing the severity of a gear oil test method by increasing the oil temperature has to be revised.

126 citations

Journal ArticleDOI
Huseyin Imrek1
TL;DR: In this paper, the teeth width of Nylon 6 gears was modified and investigated, and the performance of both modified and unmodified gears were studied experimentally under three different loadings.

72 citations

Journal ArticleDOI
01 Mar 2007
TL;DR: In this article, the friction coefficient between two contacting discs with the friction between gear teeth was compared using a mixed film lubrication model developed for the evaluation of contact pressure and shear stress fields.
Abstract: This work compares the friction between two contacting discs with the friction between gear teeth, using a mixed film lubrication model developed for the evaluation of contact pressure and shear stress fields [5]. Such model is used to analyse twin-disc contacts with smooth surfaces and gear teeth contacts with rough surfaces, both lubricated with an additive-free ISO VG 150 mineral oil.Experimental lubricant traction curves [4], measured in a twin-disc machine under full film elastohydrodynamic (EHD) lubrication (Λ > 2), were used to evaluate the lubricant rheological parameters, taking into account the surface roughness of the contacting discs. Experimental power loss measurements, made during gear efficiency tests performed in a Forschungsstelle fur Zahnrader und Getriebebau (FZG) test rig [4], were used to evaluate the average friction coefficient between gear teeth along the meshing line, considering the surface roughness of the tooth flanks.The experimental friction coefficients between gear...

50 citations


"The influence of contact stress dis..." refers methods in this paper

  • ...= −ηµ (3) In his proposal, Michaelis makes reference to the following parameters: the specific normal load (WL) in N/mm; the pinion pitch diameter (d1); the rolling speed (VR); the equivalent arithmetic average roughness of contact surfaces (RaEq); the correction factor that considers what kind of additives exist in the lubricant (XL) and the correction parameter for gears that has coated surface (XC)....

    [...]

  • ...Among the friction models that describe the friction coefficient for gears in contact, emphasis should be given to (i) the DIN 3990 (1987) equation; (ii) the equation described in ISO 6336 (1996); (iii) the model proposed by Michaelis (Winter and Michaelis, 1983); (iv) the Kelly expression, and (v) an equation for FZG gears proposed by Castro (2004)....

    [...]

  • ...Local friction coefficient – µMIC To calculate the friction coefficient on the contact path at each point of the flank of gear teeth, it was used the model proposed by Michaelis (Castro and Seabra, 2007), which is shown in Eq....

    [...]