Crankpin repair

SWD-Wartsila 280 – Journal annealing and grinding

A power plant in Ecuador suffered a severe casualty involving one of their generators. Assessment of the 220 mm diameter crankpin journal showed that the big end bearing had failed and damaged the crankpin journal surface.

The Crankpin journal surface was severely scored with scratches measuring up to 0.40 mm deep (shown right). Additionally, the bearing failure had generated significant heat causing areas of severe hardness above 650 Brinell and run-out measurement of the adjacent main journal showed the shaft was bent with a run-out of 0.10mm.

Goltens initially ground 1.00mm from the crankpin to remove the heat cracks, scratches and hopefully the hardness. After this initial machining, the areas of high hardness remained. Further grinding 3.00mm total from the diameter revealed continued hardness up to 500 Brinell. Given that the maximum crankpin reduction of diameter is 5.00mm on this engine, Goltens advised the client that the only way to save the shaft was to stop the grinding process, anneal the crankpin to remove the hardness, and then complete the repair with a final grinding process.