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Showing posts from October, 2011

Motor Failures: Common causes and solutions

Bearing failures Bearings are small compared to other major motor components, making them particularly vulnerable to damage and wear. It’s no surprise, then, that studies blame more than half of all motor failures on bearing malfunction, most of which result from too little or too much lubrication. The key to avoiding these conditions is to establish a lubrication program using bearing and motor manufacturer guidelines to determine the frequency and amount of lubrication for the motor application, duty (continuous or intermittent), environmental conditions, and bearing size. Another significant cause of bearing failure is misalignment, the effect of which increases by the cube of the change. For example, an alignment value that is twice the new installation tolerance will reduce bearing life by a factor of 8 (2^3). The solution is simple: align the motor and driven equipment to new or better installation tolerances. Bearing currents are typically caused by dissymmetry

Identify the causes of premature equipment failure

Creative Disassembly is an important element of gathering the data needed to identify the causes of premature equipment failure Using Precision Maintenance saves money in repairs, reduces the need for maintenance, and gets maximum production on-time because there are fewer stoppages and slowdowns, so plant availability and productivity is maximised. Precision maintenance prevents equipment problems starting, it solves the equipment problems you have, and that means more production for less cost. The concept of Precision Maintenance is not new; organisations have practiced it since the 1980's; achieving outstanding production performance and maintenance cost reductions. A major factor in its successful implementation is to read the root cause failure message in the parts being replaced. It would be rare for a machine to fail and not give some material or historical evidence of why it has failed. Unfortunately much of this, particularly the material evidence, is not loo

Journal Bearings and Their Lubrication

J ournal or plain bearings consist of a shaft or journal which rotates freely in a supporting metal sleeve or shell. There are no rolling elements in these bearings. Their design and construction may be relatively simple, but the theory and operation of these bearings can be complex. This article concentrates on oil- and grease-lubricated full fluid film journal bearings; but first a brief discussion of pins and bushings, dry and semilubricated journal bearings, and tilting-pad bearings. Low-speed pins and bushings are a form of journal bearing in which the shaft or shell generally does not make a full rotation. The partial rotation at low speed, before typically reversing direction, does not allow for the formation of a full fluid film and thus metal-to-metal contact does occur within the bearing. Pins and bushings continually operate in the boundary lubrication regime. These types of bearings are typically lubricated with an extreme pressure (EP) grease to aid in suppo