RA Power Solutions undertakes Grinding of Crankshaft of High Capacity Engines used in Shipping companies, Power plants and in various other sectors. The company has experience of more than forty years in undertaking successful repairs of Crankshaft and major components. As we are aware Crankshaft is a heart of engine and is most expensive part with limited availability of particular make and model.
RAP expertise lies in repair of crankshaft s which meets with a serious accident like Seizure of bearing. It is generally observed that due to rubbing of bearing steel surface with the CR Pin diameter, excessive heat is generated. Thus there is a increase in Hardness. Every manufacturer specifies the maximum limit of Hardness.
In case of Mirrlees Blackstone K and KV, major series of engine, the normal hardness at the time of manufacturing of crankshaft is between 21.5 to 26 on HRC Scale (241 to 268 on HB scale). It is obvious that after seizure of bearing, the hardness increases even to the level of 45 to 50 HRC.
The Mirrlees Blackstone allows the higher hardness under deviation maximum up to 32 HRC against the standard of maximum 26 HRC. In normal situation as per the manufacturer, the crankshaft stands rejected as it has far higher Hardness then the stipulated in the manual.
RA Power took the following action to save the Crankshaft.
I.) The Hardness was taken on various spots, not having gap of more than 15 mm.
II.) Hardness was recorded and maximum hardness of 50 HRC was observed.
III.) Since bearing line marks, taper and ovality on the crank-pin was observed, the grinding was undertaken and CR Pin dia was reduced by 3.5 mm approx.
IV.) The Hardness was reduced and the maximum Hardness of 42 HRC was observed on few spots. Although the 42 HRC Hardness was on higher side, then the maximum limit of 32 HRC specified by the manufacturer. The Crankshaft was accepted under deviation due to following reasons
a) The higher Hardness was observed in a scattered pattern.
b) The higher hardness was away from the Lubricating Oil Hole and radius fillet of the CR Pin which are considered to be critical Zone
The Crankshaft was accepted and his performance is observed as satisfactory from last more than three and half years.
The saving of Crankshaft from rejection was possible only due to the Experience RA Power solutions has of successful repair of more than ten thousand crankshaft.
RA Power Solutions undertakes Crankshaft Repair, Crankshaft Grinding and offer Onsite Crankshaft Machines to the repair companies.
Note: The writer of this article is Mr Raj Shahani, Managing Director of RA Power solutions Pvt Ltd.
Website: http://www.rapowersolutions.com/ and he is instrumental in saving number of Crankshafts from rejection.