Reconditioning is commonly preferred to the replacement of a worn piston rod as a much more cost- effective solution. However, cost-effectiveness is also related to piston rod resistance to wear after recondition. A worn piston rod causes high oil consumption and contamination of the lubricating oil system.
There are two critical factors that determine resistance to wear after recondition and these are surface hardness and roughness. Recondition procedures commonly followed are submerged arc welding and hard- chrome plating. Except for the submerged arc welding method, KIMI applies the laser cladding technique as a premium repair option that obtains high surface hardness when required, ensures high load capacity and a long lifespan of the reconditioned piston rod.
Submerged arc welding or laser cladding, whichever the welding technique applied, prior and after repair stages are the following:
- Inspection: Initially, piston rod is subjected to inspection- dimensional measurement, chemical analysis, hardness test and NDT. Initial inspection findings and certificates are offered to the customer in the form of a full report. NDT services and certificates are issued by certified personnel (Level II EN473)
- Pre-machining and after welding machining: Machining is carried out on high end CNC turning machine that ensure very good cylindricity and straightness of the entire working surface.
- Grinding and super finish: After machining, grinding and super-finish are carried out obtaining surface roughness (Ra) 0.4-0.8μm. Final machining and grinding are performed in accordance with OEM specifications and dimensions are brought back to original.
- Final inspection: Piston rod is subjected to the final inspection- dimensional measurements & NDT all in accordance with the ISO 9001 certified quality system.