Failure Analysis of Damaged parts of a Roller press at Jay Pee Bela Cement Plant, M.P.

Failure analysis consisting of on-site inspection, sample identification, macrofractography, microfract-ographic examination (by SEM), microstructural charact-erization (both by OM & SEM fitted with EDS microanalysis and bulk chemical analysis by optical emission spect-rometer) and microhardness evaluation (by Vicker's microhardness tester) has been carried out on various fragments (16 No.s) belonging to a damaged roller press that were supplied from Jay Pee Bela Cement Plant, M.P. Based in the findings, it is concluded that the failure
of the inner race took place primarily by fatigue frac-ture. The main cause of this was inadequate lubrication because of which local overheating took place on the bearings. Heavy noise and vibration were observed due to the above changes. Under the conditions of temperature rise (significantly), the mechanical properties partic-ularly hardness and fatigue strength (though originally alright) of the bearing were drastically reduced and cracks formed on the contact surfaces of the inner race. Subsequently, material smeared off from the inner race surface in the form of flakes and got welded on the other contacting surfaces. Both the fatigue and smearing proc-esses took place over a period of time till the final fracture took place. However, failure of pins, rollers
and cage pertaining to inner bearing was secondary and the mode of failure was not fatigue but gross overload. In addition, the above developments did not take place all of a sudden but occurred over a period of time.