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Should You Fix Your Worn Out and Damaged Splined Shaft

June 15, 2018

A splined shaft is typically used in high load and high torque applications, usually being highly mechanically stressed in its operation. It is, therefore, inevitable that the splined shaft will wear out, break and get damaged from time to time, regardless of how thorough maintenance is. Metal fatigue will do that.


As high load bearing components splined shafts naturally face significant mechanical stresses and will wear out over time. But a damaged shaft can be cause for concern.


When your splined shaft suffers damage or you notice wear and tear one option is to simply replace it with another. Alternatively, a salvaging operation can be resorted to, to save the part. Note, however, a repaired part is unlikely to preface the same strength and confidence as one that is new.


Wear and tear is relatively easier to compensate for than actual break in the splined shaft coupling. Fused powder and alloys can be coated onto the internals of the shaft to help restore tolerances. However, any heating applied in the application of the new material will soften the overall metal. If your operation has sufficient scope for alteration in the properties of the shaft, this is a viable option.


If splined shaft repair requires welding, a number of other considerations must be taken into account too. Welding will introduce significant heat into the damaged and surrounding portions of the splined shaft. Check to see what effect this heating will have on your metal. Again, as in the previous, heating will likely soften the metal or, possibly, make it more brittle. Welding also has the propensity to introduce distortions into the shaft. These can become cause for future structural failure, changing the loading experienced in the shaft, and may affect the tolerances within and outside of the splined shaft.


Whereas wear and tear is an inevitable part of the splined shaft, it is a significant indicator that the shaft is worn unevenly, worn out prematurely or damaged. These may be signs of an incorrectly installed shaft, uneven load distribution or unexpected stresses being passed through the splined shaft. Safe to say, this warrants a check-up for the machine as well.


Ultimately, whether a splined shaft ought to be repaired is very much an assessment a metallurgical expert should make. Simply ‘eyeballing’ it or trialing it in the machine is far from a definitive test of whether the repaired splined shaft is fit for purpose. Micro fractures and cracks now submerged under a layer of alloy coat cannot be found without specialist equipment.