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Research Papers: Elastohydrodynamic Lubrication

# Running Torque of Ball Bearings With Polymer Lubricant (Running Torque Formulas of Deep Groove Ball Bearings Under Axial Loads)

[+] Author and Article Information
Masayuki Kanatsu

Basic Mechanics Laboratory, Basic Technology Research Center, Corporate Research and Development Center, NSK Ltd., 1-5-50 Kugenuma Shinmei, Fujisawa, Kanagawa 251-8501, Japankanatsu@nsk.com

Hiroyuki Ohta

Department of Mechanical Engineering, Nagaoka University of Technology, 1603-1 Kamitomioka, Nagaoka, Niigata 940-2188, Japanohta@mech.nagaokaut.ac.jp

It is considered that the exuded mineral oil from the polymer lubricant exists between the bearing rings and the polymer lubricant (6,8,10,13).

It is known that the $RRi$ and $RRa$ take the slightly larger value than the ball diameter to about $0.575d$ ($d$ is the ball diameter) (21-22).

Test bearing A in the previous papers (14,25).

Test bearing C in the previous papers (14,25).

Measured values obtained by the disassembled bearings of the same lot.

$mbx$ is constant in temperatures of $25–70°C$(14).

J. Tribol 130(4), 041507 (Aug 07, 2008) (10 pages) doi:10.1115/1.2959119 History: Received October 23, 2007; Revised June 23, 2008; Published August 07, 2008

## Abstract

A running torque analysis was performed on axially loaded deep groove ball bearings lubricated with a polymer lubricant. The analysis included a Type I and a Type II bearing. The Type I bearing has a stamped steel riveted cage with its cavity packed with the polymer lubricant. The ball surface, except for the contact points of the ball and the raceways, was covered with the polymer lubricant. The Type II bearing had the polymer lubricant packed only on the riveted parts of the cage; the balls were not covered with the polymer lubricant. The analysis was applied to a 6206 deep groove ball bearing axially loaded in a range typical of preloads applied in actual application to this size bearing to establish bearing tare torque. The results were compared to an available database. The running torque formulas for deep groove ball bearings with polymer lubricant under axial load were proposed as the sums of the running torque caused by the shearing resistance of the mineral oil between the bearing rings and the polymer lubricant, the elastic hysteresis, the differential slip, the spinning friction of the balls, the elastohydrodynamic lubrication (EHL) viscous rolling resistance, and the friction between the balls and the polymer lubricant (or the cage). The effects of the sources of the running torque were investigated. In the case of the Type I bearing, the running torque caused by the friction between the balls and the polymer lubricant, the EHL viscous rolling resistance, and the shearing resistance of the mineral oil between the bearing rings and the polymer lubricant significantly affect the running torque. In the case of the Type II Bearing, the running torque caused by the EHL viscous rolling resistance and the shearing resistance of the mineral oil between the bearing rings and the polymer lubricant significantly affect the running torque. A reasonable correlation exists between the analysis and the database. However, the analysis needs to be further validated with bearing data from different size deep groove ball bearings run under varying loads and speeds.

###### FIGURES IN THIS ARTICLE
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Copyright © 2008 by American Society of Mechanical Engineers
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## Figures

Figure 1

Types of deep groove ball bearings with polymer lubricant: (a) Type I bearing and (b) Type II bearing

Figure 2

Enclosure forms of polymer lubricant: (a) Type I bearing and (b) Type II bearing

Figure 3

Mineral oil between the bearing rings and the polymer lubricant: (a) Type I bearing and (b) Type II bearing

Figure 4

Comparison of the calculated running torque with the measured running torque (rotational speed of 2500rpm): (a) Type I bearing and (b) Type II bearing

Figure 5

Effects of the sources of the running torque on the running torque M (rotational speed of 2500rpm; axial load of 98.0N): (a) Type I bearing and (b) Type II bearing

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