Taper shaft machining
Client: Melita Marine Group
Industry: Marine & Shipbuilding
Location: Malta
Duration: Completed within a days
Service: https://royceonsitemachining.com/services/shaft-journal-repair-machining/
Project Overview
Royce Onsite Machining was contracted by Melita Marine Group to carry out a precision in-situ repair on a historic vessel following a propeller failure. The incident resulted in significant damage to the propeller shaft taper journal — a critical interface requiring accurate restoration to avoid full shaft replacement and extended downtime.
Given the vessel’s heritage status and the tight dry-dock schedule, an on-site machining solution was required to restore the shaft while preserving its original geometry and integrity.
Scope of Work
To restore the shaft, our team deployed custom-built orbital machining equipment, designed and manufactured in-house for this specific application. Using specialised tooling, the damaged taper journal was machined in situ, with only the minimum material removed to maintain structural integrity and service life.
Key elements of the operation included:
- Establishing accurate machining datums on a worn shaft surface
- Machining and polishing across an existing keyway
- Maintaining tight tolerances while minimising material removal
- Preserving the original centreline of the taper shaft
Technical Highlights
- Shaft diameter: 180 mm
- Taper angle: 2.37°
- Machining tolerance: within 0.02 mm
- Flatness achieved: 99%
- Surface finish: 0.3 Ra
Outcome
With the vessel in dry dock and a strict deadline in place, the in-situ repair was completed within a single day.
- The propeller was replaced while the original shaft was retained and returned to service
- The client avoided the cost and delay associated with manufacturing a new shaft
- All dimensional, alignment, and performance requirements were met, allowing the vessel to return to service on schedule.
