Polymer gear surface thermal wear and its performance prediction

Mao, Ken; Li, W.; Hooke, C. J.; Walton, D.

doi:10.1016/j.triboint.2009.07.006

Cited by 63 publications

(37 citation statements)

References 13 publications

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“…Surface thermal surface: Localized softening of the tooth profile as a result of excessive heat, resulting in the melting of the material, material tears and deterioration of the profile [11,15,18]. Root fatigue: A stress concentration in the teeth roots initiates microcracking that propagates, causing the gear to fail later in the gear life.…”

Section: Gear Damage Modesmentioning

confidence: 99%

See 1 more Smart Citation

Life and damage mode modeling applied to plastic gears

Bravo

Koffi

Toubal

et al. 2015

Engineering Failure Analysis

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Section: Gear Damage Modesmentioning

confidence: 99%

“…Temperature is often described as the main cause of failure in plastic gears because of their low melting point and low conductive properties [18]. The heat generated locally remains concentrated and does not dissipate.…”

Section: Introductionmentioning

confidence: 99%

Life and damage mode modeling applied to plastic gears

Bravo

Koffi

Toubal

et al. 2015

Engineering Failure Analysis

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“…Besides increasing the module and tooth width, using gears with a contact ratio above 2, and tooth profile modifications was proposed. Mao et al (2009Mao et al ( , 2010 studied the wear of polymer gears. Different combinations with POM and PA materials were tested.…”

Section: Introductionmentioning

confidence: 99%

Different teeth profile shapes of polymer gears and comparison of their performance

Zorko

Kulovec²,

Tavčar

et al. 2017

JAMDSM

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This article presents a lifespan testing analysis of polymer gears manufactured by cutting. Compared to injection molding, machine cutting provides higher accuracy of gear geometry. Two different tooth flank geometries were tested; i.e. involute and S-gears. In theory, S-gears have several advantages over involute gears due to the convex/concave contact between the matching flanks. The theoretical tooth flank geometry of S-gears provides more rolling and less sliding between the matching flanks, compared to involute gears. The convex/concave contact leads to lower contact stress, which in combination with less sliding means lower losses due to sliding friction and consequently less heat generated. The goal of our research was to prove that tooth flank geometry affects the lifetime of polymer gears, and to find the mechanisms and quantitative differences in the performance of both analyzed geometries. The gears were tested on specially designed testing equipment, which allows exact adjustment of the central axis distance. Two different material pairs (POM/POM and POM/PA66) of the drive and driven gears were tested. Each test was done at a constant moment load and a constant rotational speed. Several tests were conducted using the same conditions due to repeatability analysis. All the tests were performed till the failure of the gear pair and without lubrication. In lifespan testing, the polymer S-gears showed better performance and longer lifespan than involute polymer gears.Keywords : Polymer gears, Lifespan testing, Temperature, S-gears, Involute IntroductionThe involute shape of the tooth flank was suggested by Leonard Euler (1775). Due to its unique properties, the involute shape of the tooth flank prevailed and most of the gears nowadays are involute. The condition that a tooth flank shape should fulfil in order to provide a constant gear ratio is defined by the law of gearing. Many curves, not just the involute one, fulfil it, which has yielded many other tooth flank shapes that are rarely used in practice. The purpose of developing new gear shapes is to improve the disadvantages of involute gears, such as: the convex/convex contact, teeth undercutting, and gears with a small number of teeth have a shorter dedendum, which leads to increased sliding and losses due to friction. Besides involute gearing, cycloidal gearing is the next best known type, mainly used in wrist watch mechanisms. Kapelevich (2013) dedicated much of his research work to gears with asymmetric tooth flanks, where the active tooth flank is still of involute shape. Mohan and Senthilvelan (2014) studied the lifespan of asymmetric composite gears. Kim (2006) and Düzcükoglu (2009) also worked on improving the performance of polymer gears. They used the involute tooth profile and attempted to extend the lifespan of gears by virtue of geometric changes in teeth width. Koide et al. (2017) investigated the impact of the sine-curve gear on the tooth surface temperature and gear power transmission efficiency. Hlebanja et al. (2008) suggeste...

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“…Great efforts have been made to investigate and understand the wear mechanisms of polymer and polymer composite gears in the past 40 years such as design standard [1][2][3][4][5], sources of heat generation [6], varying temperature effect [7][8][9][10][11][12] and effect of sliding-rolling contact [13][14][15][16][17][18][19] and so on.…”

Section: Introductionmentioning

confidence: 99%

An investigation of misalignment effects on the performance of acetal gears

Mao

2017

Tribology International

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This paper concentrates on the effects of misalignment on meshing behaviour of acetal gears as hardly any misalignment investigations on polymer gears in the existing literatures. The experimental results show that the wear of acetal gears is insensitive to radial and axial misalignments but sensitive to yaw and pitch misalignments which degrade the conjugate contact action. Yaw misalignment leads to 'scoop' wear marks near tooth pitch points. Pitch misalignment causes 'superimposed palisade' wear marks and micro cracks near tooth roots. Compared with metal gears, the effects of small pitch angle on acetal gears are insignificant which may be linked closely to polymer's low elastic modulus. Strikingly different wear striations and various debris morphologies are observed by using scanning electronic and optical microscope (SEM, OM) and misalignment effects can be noted.

show abstract

Polymer gear surface thermal wear and its performance prediction

Cited by 63 publications

References 13 publications

Life and damage mode modeling applied to plastic gears

Life and damage mode modeling applied to plastic gears

Different teeth profile shapes of polymer gears and comparison of their performance

An investigation of misalignment effects on the performance of acetal gears

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