splines are not straight

[thejackal3]

Dear Members
we are facing some problem with spline hobbing of rear axle shafts, we are cutting thin splines and some splines are coming thin and also some splines are zig zag not straight. run out on cnc is O and on horizontal spline hobbing is also 0.
we clamp on side of axle in chuck and other side is centered.

we have done all the things to rectify but still in some axles these things occur.required ur inputs on this.

thanks n regards

 

[CoryPad]

Sounds like residual stress in the shaft prior to hobbing. You should perform stress relief heat treatment prior to hobbing.

 

[ornerynorsk]

Could also be that the workpiece is moving in the chuck. Eliminate all possible causes in your setup and work holding first, including toolholders, cutters, spindle adapters, machine quill/ram lock, etc.

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.