Crankshaft machining

Client: Confidential
Industry: Power Generation
Location: Africa
Duration: Completed within days
Service: In-Situ Crankshaft Repair  

Overview 

Royce Onsite Machining was contracted to carry out an urgent in-situ crankshaft repair after a significant engine failure on a power generation unit. Crankpin No. 6 exhibited visible surface damage, heat cracks, and excessive hardness readings of 600 Brinell — well beyond OEM operating limits. 

To prevent a full crankshaft replacement and extended downtime, the client required a complete in-situ recovery. Our technicians were mobilised within days to assess, machine, heat-treat, and fully restore the crankpin — without removing the crankshaft from the engine block.  

Work Performed 

Crack Removal 

• Initial proof machining exposed persistent cracking. 
• MPI (Magnetic Particle Inspection) confirmed the presence of heat-related surface cracks. 
• Further machining and testing ensured complete crack elimination. 

Heat Treatment (Annealing) 

• The crankpin surface showed excessive hardness (600 Brinell). 
• A 14-hour in-situ annealing process successfully reduced hardness to within OEM standards. 

Crankshaft Straightening 

• Run-out checks on adjacent journals revealed a shaft bend. 
• After OEM consultation, we applied our specialist peening method, using multiple peening sessions to restore correct shaft alignment. 

Redesign of Radii & Final Machining 

• The OEM specified a new radii profile to accommodate the reduced pin diameter. 
• We produced custom orbital tooling to match the revised specification. 
• Final machining brought Crankpin No. 6 to –3.00 mm undersize, followed by high-precision polishing. 

Finishing 

• Due to the exceptional finish achieved, the client requested polishing of all remaining crankpins to ensure consistent bearing surface quality across the engine.  

Technical Highlights 

• Crankpin Final Size: –3.00 mm undersize 
• Original Hardness: 600 Brinell 
• Post-Annealing Hardness: Within OEM limits 
• Flatness Restored: 98% 
• Surface Finish Achieved: 0.2 Ra 
• Run-Out Correction: Completed using in-situ peening method  

Outcome 

The full repair was completed in-situ within days, avoiding disassembly, shipping, or replacement delays. The engine was successfully reassembled, load tested, and returned to full operational condition. 

This project demonstrates Royce Onsite Machining’s ability to deliver OEM-standard repairs under challenging field conditions, significantly reducing downtime, cost, and risk.