Research Papers: Applications

Wear and Mechanical Contact Behavior of Polymer Gears

[+] Author and Article Information
Khalid Abdulkhaliq M. Alharbi

Mechanical Engineering Department,
Umm Al-Qura University,
Makkah, Saudi Arabia;
School of Engineering,
University of Warwick,
Coventry CV4 7AL, UK
e-mail: kamharbi@uqu.edu.sa

Contributed by the Tribology Division of ASME for publication in the JOURNAL OF TRIBOLOGY. Manuscript received July 13, 2017; final manuscript received July 26, 2018; published online August 24, 2018. Assoc. Editor: Xiaolan Ai.

J. Tribol 141(1), 011101 (Aug 24, 2018) (10 pages) Paper No: TRIB-17-1274; doi: 10.1115/1.4041020 History: Received July 13, 2017; Revised July 26, 2018

Extensive investigations have been carried out in the present paper to understand polymer gear performance, i.e., wear and contact behaviors. The experimental results and possible wear mechanisms for polymer gears run against themselves have been presented, especially the wear rate of the polymer gears under different running speeds and loads. The tested samples were made of three different materials (acetal, nylon, and polycarbonate (PC)) and the effects of two different manufacturing techniques were also investigated (i.e., machine-cut and injection-molded polymer gears). The polymer gear performances (wear and life) were recorded using a uniquely designed and built test rig for this purpose. The testing results have been compared with the existing literature for polymer fatigue and wear theory. Further extensive investigations have been carried out to understand the wear phenomena on tooth flank surface profile of these gears and the data obtained have been discussed.

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Fig. 1

Polymer gears test rig

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Fig. 2

Schematic diagram for polymer gear test rig

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Fig. 3

Tooth wear measurement method and location

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Fig. 4

Wear of (a) machine-cut acetal, (b) injection-molded polycarbonate, (c) injection-molded nylon 46, and (d) machine-cut nylon 66 gear pairs at 1000 rpm and step loading

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Fig. 5

Wear rate of the four tested polymer gears

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Fig. 6

STA curve for nylon (PA46) (injection molded)

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Fig. 7

STA curve for nylon (PA66) (machine-cut)

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Fig. 8

Gear outside radius (ra) and reference radius (r)

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Fig. 9

Wear of machine-cut acetal gear pair

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Fig. 10

Scanning electron microscope for driver acetal gear tooth at (a) addendum side, (b) pitch point, and (c) dedendum side (7 N·m, 1000 rpm)

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Fig. 11

Scanning electron microscope of acetal driven gear tooth addendum side (7 N·m, 1000 rpm)

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Fig. 12

Wear of injection-molded nylon gear pair

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Fig. 13

Scanning electron microscope for driver nylon gear (a) general view, (b) addendum, and (c) debris (at 6 N·m, 1000 rpm and 8 h)

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Fig. 14

Scanning electron microscope for nylon gear (a) driver side, (b) driver pitch point, (c) driven side, (d) driven pitch point, (e) driven addendum, and (f) driven dedendum (6 N·m, 1000 rpm, and 8 h)

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Fig. 15

Wear results of injection-molded nylon gears, at different torques and the speed of (a) 500 rpm, (b) 1000 rpm, and (c) 2000 rpm

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Fig. 16

Wear rate of injection-molded nylon gears against (a) running speed and (b) torque



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