Increasing diameter on SS-316L shaft 3

[cokeguy]

We need to increase the diameter of one of our 70" long 3-15/16" diameter shafts to 4" diameter even (on one of its ends only, about 10" long) in order to fit a fan whose hub was mistakenly machined to 4" inside diameter instead of 3-15/16". Any special considerations on the type of electrode that we should use for this application? Any 316L electrode will do, or do we need to use something special or with certain characteristics to be able to machine it down to specs once we apply it to the shaft? I just want to make sure that whomever we send this shaft over for repair uses the right electrode type.

Thanks a lot for your comments.

 

[metengr]

cokeguy;
Use an automatic welding machine (if possible) GMAW or GTAW process, use nice tight circumferential beads, ER316L wire, no preheat, and maintain the interpass temperature at or below 350 deg F. No PWHT is required. After machining, perform a PT of the weld overlaid surface.

 

[macmil]

I would suggest that you find someone that does HVOF metallizing. It is applied cold, so you do not get either dimensional distortion or metallurgical changes in the underlying steel. Where are you located ?

 

[metengr]

Yes, HVOF coatings have their place and function for shafts. In situations where the coating is used to simply build-up a dimension in a non-critical location, like an oil seal or press fit region of the shaft for a coupling may be acceptable. In situations where you have a keyway and no press fit, I would not recommend it.

 

[MikeHalloran]

Don't modify a good part to fit a bad one.

Sleeve the fan.



Mike Halloran
Pembroke Pines, FL, USA

 

[cokeguy]

Thanks everyone, but Í was mistaken, the shaft in that specific fan is plain carbon steel, not 316L, so I´ll simply have it sleeved or welded and machined back to spec. Thanks a lot, sorry for the inconvenience.