rectify+rectile tree

[Marcus990]

Good evening to all,
are rotten and work in a company that deals with the design and manufacture of industrial compressors for medium and large enterprises.
we are facing a particular problem at this time that consists in the rectification + rectification of a tree in 39crnimo3 (of the compressor) that will be thrown into an elastic joint, which will be thrown into another tree (of the electric motor), if it is not clear the scheme is as follows:
the 2 trees (motor and compressor) are coaxial and have a radial esiguous scaffolding, however after the remediation phase (tempra + tempering) it occurs that the compressor shaft (the one designed by us) goes out of tolerance, which I ovviato doing a first phase with overmetal then reclaim and finally the final processing.
the professional who deals with doing these thermal treatments told us that the tempering for such a small tree (23 mm diameter) comes to the heart and then after hardnesses greater than 60 hrc becomes difficult to work.
Moreover with the solution echoed before, i.e. a tempra located only to the area that interests us it happened that the tree was disallined and also with the overmetal of 4/6 tenths it was impossible to recover it and bring it to the tolerances from drawing.
therefore the solution that comes to mind is to make an hardening on all the piece only superficially so that the overmetal to be lifted is not very much, however the one who heats us the trees said that by dive does not make it to harden them only superficially.
advice?

 

[PIETRO2002]

But if you do an induction hardening, the piece can be put between the tips, the heating resistance is followed immediately by the cooling jets.
logically depends on the system that is available.
Even induction hardening, it will have to be expected of the overmetal to be removed for grinding and normally, before grinding a straightening is carried out on press.

 

[meccanicamg]

are very small trees and certainly difficult to treat thermally fast without distorting them.
question: Shouldn't you try the pre-bonified bar on those diameters? it works and remains such.
the surface tempering that does not distort (or little) is the laser.
Alternatively, you can try to make an empty gas nitriding or carbonitrution.

 

[meccanicamg]

But if you do an induction hardening, the piece can be put between the tips, the heating resistance is followed immediately by the cooling jets.
logically depends on the system that is available.
Even induction hardening, it will have to be expected of the overmetal to be removed for grinding and normally, before grinding a straightening is carried out on press.

I think the treatmentist has the equipment for big trees and on these toys he runs off the process.

 

[TETRASTORE]

if it is important production batches it is advisable to use a 20mncr5 steel leaving the grinding overmetal and making a cementing and tempering treatment, considering also straightening following the indications given by those who perform heat treatment.
This solution is the cheapest (for substantial batches) and is normally adopted by manufacturers of gearboxes for the construction of the input shafts with diameters from 9 mm up.
for small quantities I agree with the solution @ pietro2002.

 

[stevie]

I don't understand the problem...
work hardened pieces at 60 hrc? we do it regularly using cbn inserts or ceramics
for the pieces that deform after treatment proceed with straightening.

 

[meccanicamg]

I don't understand the problem...
work hardened pieces at 60 hrc? we do it regularly using cbn inserts or ceramics
for the pieces that deform after treatment proceed with straightening.

I just think it's a small business problem that's not used to hardened material processing. They tend in many to complain that they can't take the tempered... and even there are those who know how to do it. the boron insert exists for a long time yet there are still those that besides widia have not gone.