Crankshaft journals failure is common case that the majority of shipping companies worldwide are coming across with. Bad operation, lack of lubrication, poor quality bearings or mishandling during maintenance, is some of the reasons that may lead to journal damage, main or crankpin.
Once occurred, and depending on extent of damage, a crankshaft can be salvaged or be considered as scrap. Often a crankpin or main journal has suffered scratches on the running surface and light polishing may only needed. If those scratches or marks are deep enough or the cylindricity of journal has been affected, then machining is inevitable. In situ machining/grinding is a solution which saves time as it is carried out onboard, without removing crankshaft from place. Quite often the presence of overhardness or hot spots makes the repair more difficult as machining needs to be extensive in order to remove such abnormalities. If hard spots do not removed or hardness does not fall to acceptable levels, the crankshaft cannot be used further. The more the diameter drops due to machining, the more undersize bearings are becoming an issue of availability/delivery time. If diameter is reduced beyond a certain limit that maker considers safe, the engine must be derated and this is something that no shipping company wishes.
Laser Cladding has come to front these scenarios in the best way, as it literally builds up the worn journals, to original dimensions and surface specifications. Together with National Technical University of Athens, Bureau Veritas and European Institutes we have developed an approved process for the buildup of worn crankshafts journals by Laser Cladding. The technology offers outstanding benefits amongst which are the following:
- Low heat input and therefore minimum distortion
- Swallow yet strong metallurgical bond
- Variety of powders for achieving desired surface properties
- Up to 10mm thick, radial layers can be applied
- Fast lead times
The benefit of that process is that restores the operational life and value of crankshafts because a strong metallurgical bond is achieved between the journal material and the filler material, without distorting the crankshaft. It is that kind of bond that guarantees 100% reliable and safe repair. Crankshafts that are considered as scrap, due to extensive machining that needs to be carried out, or undersize bearings have long delivery time can now be salvaged successfully, fast and cost effectively.