Can Thermal Spray Fix This???

A few weeks ago, we encountered a unique issue with a shaft that showed thermal spraying wasn’t the right solution. For those of you who might think our team only applies thermal coatings, this might come as a surprise! But we do a range of services, including welding, machining, and grinding, which you can explore more on our website.

This particular shaft arrived with severe wear on both ends, and the damage was beyond what thermal spray could handle effectively. In the photos, you can see where a bearing had worn down a groove, roughly 2 inches wide and 1.5 inches deep. This extensive wear compromised the shaft’s structural integrity, leaving it unable to adequately support itself or the mounted components.

While thermal coatings are excellent for dimensional restoration, they don’t add structural strength or prolong fatigue life. Sure, we could have filled in the damaged areas with coating, re-mounted the bearings, and set everything up again. But how long would that fix really last? With continued flexing, the coating could crack, peel away, or even cause the bearings to fail. In the worst-case scenario, a total shaft failure could damage the surrounding components and cause additional damage than just the shaft itself.

Given the tight timeline, the customer preferred a repair rather than a replacement. Fortunately, the shaft’s mild carbon steel base material made it highly weldable. So, our team moved forward with filling the worn areas by welding. John, our lead welder, enjoyed this project since he usually works on finesse jobs with Stellite and Colmonoy. This time, he was able to focus on laying down a large volume of material for the repair.

By welding, we also added structural strength to the shaft, minimizing the risk of a catastrophic failure down the line. This type of repair, however, depends on a few crucial factors:

• Selecting the right base material
• Choosing compatible weld materials
• Adhering to a specific welding procedure

Once the welding was complete, we finished the shaft by machining it back to its proper dimensions and ensuring a clean, smooth surface. The repaired shaft has since been reinstalled, and it’s been operating smoothly - standing up to the demands of it's workload and proving once again the versatility of our repair methods.