Why Do Metal Bearings Fail?

August 12, 2016

There’s no sinister question mark above metal bearings. It’s not as if the metal is unreliable and destined to failure. Quite the opposite, in fact, since robust alloys are designed to handle heavy loads. It’s just that this is a dynamic operating area, a place where multiple forces and environmental stresses hammer away at these crucial moving parts. In response to this overly stressed mechanical environment, the bearings are built to exacting metallurgical standards, so why do they still fail?

Metal Bearings Experience Environmental Stress 

Dirty conditions release coarse particles into the air, which is something that’s just part of the operational workplace when the bearings are installed in a mine or powdery locale. If that’s not enough, then imagine the 24-hour work ethic in place in one of these industrial domains. Reciprocating motors shake loose screened ore night and day, and powdery production lines follow suit by attacking the bearings on two fronts. Sealed housings keep these gritty pollutants away from the rolling elements, thankfully, plus a properly organized maintenance program keeps the lubricating agent flowing. It’s this thin film that protects the metal, so lubricant levels must be periodically checked.

Exploring Failure Signs 

If the bearings start to flake, then metal fatigue is a likely culprit. The contact surfaces may be running dry, so the microcrystalline structure of the bearing has become corrupted. Vibratory events and auditory noise increase when flaking is experienced, so take requisite action by replacing the malfunctioning unit. Other indications of a likely failure include heavy indentations on the race rings. These markings usually suggest poor loading. The axial-to-radial force distributing power is overloading the bearing, or the bearing could possibly be experiencing an eccentric weight, in which case brinelling is also a likely symptom. Replacement is the only tenable course, but a reoccurrence is likely unless the machinery is corrected.

Clarifying Metal Bearing Failure

Overheating – This suggests overloading and poor frictional heat dispersion

Pitting and Irregular Indentations – There’s a likely source of contamination present

Cracks and Fractures – Caused by poor installation practice and normal fatigue

False Brinelling – Unlike true brinelling, these indentations run perpendicular to race motion. Vibratory events are likely inciting motion between the rolling elements

Contaminants and poorly configured machinery top the failure chart here, but we can avoid such issues by keeping the bearings sealed, lubricated, and generally by running a diligent maintenance program.

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