Buildingup of Shafts

[mech471]

Shafts of our fin fan coolers were damaged/worn out/undersized due to the relative movement between inner race of bearings and shafts. The reason for the relative movement was that there were grub screws to be tightend on shafts. Any way we repaired/builded up the undersized shafts by applying welding on the damaged portion. Welding was done carefully, electrode material was carefuly slected to match the shaft material. Runout/sag of shafts was checked. The builded portion of shafts were then machined to required size. Bearings and shafts were assembeled now correctly and the fin fan coolers are working satisfactorily.

Another method to buildup the undersized shafts is to mount sleeve on the undersized portion to over size and then machining of oversized sleeve to required size

I need your comments/expertise which of the above mentioned methods is oftenly used.
Is there any code/standard which describes the method to build up the undersized shafts.

Note: The applicabe code for said fin fan coolers is API 661

 

[garys]

It is common to grind the damaged area, plate, and regrind to specs.
Gary

 

[gdodd]

You need to be careful building up the surface of shafts by welding as there is always the possibility of introducing defects, holes or inclusions which might reduce the fatigue strength. Personal experience with a press shaft.

 

[bobc]

we routinely repair large journals with a roundabout welding overlay. most of our work is done on high chrome, high carbon material and we experience very little problem with defects.
the key is a very experienced operator and a well defined operating procedure. almost all of our work is done with submerged arc and has been tracked for years to define good and bad procedure.
you can use the expertise of almost all the major players in the welding consumable industry free of charge. i have found lincoln electric to be very co-operative in sharing their research.

 

[SnowCrash]

Grub screws suck in this application. The welds may be more brittle that the base material and you will get rapid deterioration of the interface. Look for some of the other methods of securing the system such as locking tapered collets or eccentric collars.
What you really asked was about standards, however. This would be totally dependant on your applications and design specifications.
As to the characteristics of welding versus sleeving, keep in mind that welding will to some degree restore strength to the shaft since material is added. Reducing the diameter to allow room for a sleeve reduces the strength of the shaft. The sleeve will not restore stiffness in bending but it will carry shear.

Crashj

 

[sbi]

We have also build up hundreds of shafts
we do both welding and flame spray build up
if you are worried you should find a jobbing machine shop that has done
these, ask around and let them do it, they will give you a warrentie.
if they do not, find some one else

 

[mech471]

Regards for all your comments
I agree with CrashJ (Snowcrash)for his preference the welding over sleeving but a negative point goes to welding that PWHT (post weld heat treatmetn) shall be required to relieve thermal stresses produced due to welding and extra care must be required for welding
In sleeving dia of shaft is reduced to very small extent to create room for sleeve and sleeve is mounted on shaft and this fit is interference fit so in my point of view sleeving should prefered over welding
I need your comments

 

[mech471]

I agree with CrashJ (Snowcrash)for his preference the welding over sleeving but a negative point goes to welding that PWHT (post weld heat treatmetn) shall be required to relieve thermal stresses produced due to welding and extra care must be required for welding
In sleeving dia of shaft is reduced to very small extent to create room for sleeve and sleeve is mounted on shaft and this fit is interference fit so in my point of view sleeving should prefered over welding
I need your more comments