Heavy Equipment Axle Shaft Repair Using Thermal Arc Spray Case Studies

Project Summary:

Worn bearing journals and sealing surfaces can make heavy equipment axle shafts unsuitable for continued service, but replacement is not always necessary. This project demonstrates how US Hydraulics combined thermal arc spray technology with precision CNC machining to restore two worn axle shafts, providing a cost-effective alternative to replacement or new manufacture.



The objective was to determine whether the existing shafts could be repaired economically while restoring the critical fits and surface finishes required for reassembly.

Axle shafts received for repair.

Axle shaft before surface restoration.

The Challenge:

Inspection and measurement identified wear on multiple bearing and sealing surfaces. These areas require precision diameters and surface finishes for proper bearing fit and seal performance.


US Hydraulics evaluated repair, replacement, and manufacture of new shafts. Although manufacturing new shafts was within our capabilities, the condition of the existing components made surface restoration the more economical option.

The Solution:

The repair approach combined low-heat material buildup with finish machining to restore the worn areas without unnecessarily exposing the shafts to welding heat.


The worn surfaces were measured and prepared for thermal arc spraying. In this process, an electric arc melts feedstock wire, and compressed air propels the molten particles onto the prepared surface. Unlike conventional MIG or stick weld buildup, thermal arc spraying deposits material without melting the shaft base metal. The resulting lower heat input reduces the potential for thermal distortion, helping preserve shaft straightness and dimensional integrity during restoration.


Thermal arc spray material was applied with sufficient buildup to allow for precision finish machining. Using our CNC lathe, the restored bearing journals and sealing surfaces were machined to the required diameters and surface finishes, providing the dimensional accuracy necessary for proper bearing fit and seal performance.

Machined shaft surfaces during the repair project.

Comparison of shaft surfaces during restoration.

Thermal arc spray buildup before finish machining.

Restored shaft surfaces after finish machining.

The Outcome:

Both axle shafts were successfully restored, allowing the customer to retain the original axle shafts while avoiding the higher cost of replacement or new manufacture. The completed repairs restored the damaged surfaces and provided the shafts ready for reassembly.

After machining, the finished surfaces were inspected. The shafts were then protected and packaged for shipment.



This project illustrates where thermal arc spray and precision machining can offer a practical alternative to replacement when the underlying component remains suitable for repair.

Completed axle shafts packaged for shipment.

Project Highlights

  • Evaluated repair, replacement, and new-manufacture options
  • Assessed wear on critical bearing and sealing surfaces
  • Used thermal arc spray to restore worn areas with reduced heat input
  • Precision-machined bearing journals and sealing surfaces to required specifications
  • Inspected and prepared restored components for reassembly
  • Delivered a cost-effective alternative to replacement
  • Preserved valuable existing assets


At US Hydraulics, we evaluate each component to determine whether repair, replacement, or new manufacture provides the best solution. By combining technical expertise, precision machining, and specialized restoration processes, we help customers recover valuable equipment components, control maintenance costs, and return critical assets to productive service.