Hairy Knurls

Good day,

I am operating a Profiroll machine that we use to put a 5x6 knurl on a shaft diameter. the pre-knurl diameter of the shaft is 5.33mm and knurl diameter is 5.65mm once machined. I am not sure if any other information would be needed to answe the upcoming question as I am new to the CNC world.

The problem we are having is some of these knurls are coming out all hairy. Even though the go gage fits on and the nogo does not, this is still an issue as our customer would reject them. We have made sure the 2 dies are lined up correctly, made minor adjustments to the dies and the angles, tore apart the machine and set it back up etc. with no luck.

Now, we run 4 different parts on this machine. 3 of them have a larger diameter spline than this one (7.39mm pre-spline) with the only difference being the length of the knurl. The other 3 parts do not have this issue.

What are we missing?

generally I would say it means they are double tracking, or for straight knurls the diameter is wrong. I remember having to be aggressive on tool entry with some straight knurls I was doing years back to get them to track right.

gustafson said:

generally I would say it means they are double tracking, or for straight knurls the diameter is wrong. I remember having to be aggressive on tool entry with some straight knurls I was doing years back to get them to track right.

Click to expand...

we have checked to make sure that the dies are tracking correctly and after making some adjustments we were still getting the hairy knurls, just less frequently. I was thinking that the diameters would play a part in it so I wanted to go through and measure them before the knurl and document it to see if the ones that come out bad have any sort of pattern with the pre-knurl diameter that we measured.

If I were you, I'd call the company that made the knurl wheels that are being used.
Know what part number knurls you're using (and the diameters you've stated) also material and hardness of work piece.
Be prepared to send them clear (in focus) pictures or the problem.
They should be able to get right to the solution.

Lots of info here: http://www.reed-machinery.com/pdf/knurls-and-knurling-tech-data-master.pdf