Experiments were conducted on bronze sintered bearings to determine the effect of bearing wall thickness and bearing length on the coefficient of friction. Parameters such as the radial clearance, the surface roughness of the shaft and the lubricating oil were kept constant in all the test bearings during the experiments. It was found that the coefficient of friction increases with the wall thickness and decreases with an increase in bearing length. It is felt that the above result will be useful for the users of sintered bearings in making a judicious selection of the wall thickness and the length of the bearing such that the selection results in a larger bearing metal volume to store more lubricating oil giving a longer life and a reduced coefficient of friction. © 1985.

P. Iyam Perumal

METALS TESTING - FRICTION

POROUS MATERIALS - LUBRICATION

Bearings

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Experimental study on the effects of bearing wall thickness and bearing length on the frictional characteristics of sintered bearings

Wear

There are many papers on the experimental investigations of porous bearings under static loads but there is no paper on the experimental investigations under dynamic loads. In the present paper, the results of experimental investigation of porous bearings under vertical sinusoidally fluctuating loads are presented. The friction force was measured under various conditions of fluctuating load/steady load ratio, journal frequency and load frequency. The investigations were carried out in the hydrodynamic lubrication regime in a specially designed and fabricated test rig. It was found that at any given rpm, as the fluctuating specific load/steady specific load ratio, Pf/Ps, increases, the mean coefficient of friction μm increases. It was also found that the mean coefficient of friction is not affected by the load frequency even when the load frequency is half of the journal frequency. © 1998 Elsevier Science Ltd. All rights reserved.

Tribology International

Experimental investigations of porous bearings under vertical sinusoidally fluctuating loads

Sintered bearings which are porous in structure contain oil in the pores. However, with time the oil content of the bearing decreases as a result of leakage, evaporation etc. In order to determine the frictional characteristics of such oil-starved bearings, sintered bearings in which the oil contents were progressively decreased were prepared and tested. From the experiments it is shown that there is no substantial increase in the coefficient of friction as up to about 50% of the oil content is lost. When the amount of oil in the bearing is reduced further there is an increase in the coefficient of friction. Temperature measurements on the bearings also confirmed the above behaviour. To determine whether a bearing that has lost more than 50% of its oil content can be recharged by adding few drops to the surface of the bearing, oil was added to a bearing which was working at 42% of the initial oil content. As a result of this the oil content increased to 62% and the coefficient of friction decreased to the corresponding value. Thus it was found that it is possible to recharge an oil-starved sintered bearing by adding a few drops of oil to the bearing surface, wherever it is accessible, and thereby increasing the life of the bearing. © 1984.

Journal	Wear
ISSN	00431648
Open Access	No