Parting/cutting a hardened shaft

[Kevinb71]

I had asked this question before as part of another question and didn't really get much answer to this part of the question. How would I go about parting/cutting a 2" dia cylinder rod from a hydraulic cylinder. I need the pieces to be accurate in length so an abrasive chop saw would not work. My parting tool (HSS) just gets dull and the cylinder doesn't even get a line on it say nothing of being cut. I do not have a toolpost grinder, but I did mount a Dremel on the toolpost and tried that. One abrasive disk down and I'm maybe .050 into the shaft. It's about .375 thick where I need to cut it and I need four pieces. A better way must be found. I tried a carbide parting tool as well with the same results. The shaft just laughs at it. Any Ideas? What am I missing/overlooking? The surface finish of the shaft is almost chrome looking but i don't think it's plated. Thanks for helping a newbie!

 

[Matt McLeod]

Hi Kevin, I'm a bit of a noob at machining but I know a little bit about hydraulic cylinders.

The rod will almost certainly be chrome plated for corrosion protection and a smooth surface for the rod seal to run on. So you have to get through the plating some how, and it is hard. See http://en.wikipedia.org/wiki/Chrome_plating for info. They suggest industrial chrome is 66-70 on the Rockwell "C" scale, which is very hard, a lot like rolling element bearings. And the rod itself may have been heat treated before being plated. Whether or not that is the case for the specific cylinder rod you have doesn't really matter, but you have to find a tool harder than the rod in order to cut it.

Someone smarter than me might be able to suggest the right tooling, but for the exercise, why don't you see if you can part off a piece with an abrasive saw? I know you didn't want to do that, but the abrasive contents of the blade are probably the hardest thing we'd have in our home shops.

Good luck.

 

[Tom Griffin]

The carbide parting tool should have cut. Are you sure it was on center? If it's even slightly below center it won't cut because there isn't much relief on the front of the tool. Hydraulic rods are case hardened to about .050", they are chrome plated and the chrome is very hard, around Re70. That may cause problems with the carbide so you might want to try starting with a cut-off wheel and then switching to the carbide parting tool to get through the case.

Tom

 

[brasssmanget]

Wow - I found this very interesting because I went through the same thing a couple of weeks ago. I had some 3" diam pieces of what looked like polished SS bars my son brought home from some job site. I tried with HSS cutters and carbide bits. Carbide got me in maybe .020 and dulled out. My 14" chop saw cut a groove about .375 deep, but it took almost 15 minutes!

I gave up, figuring it would take 4 hours to get through it at that rate - not to mention more than one cutting disc (chuckle). It's now being used as extra weight under my bench mill in the cabinet! :biggrin:

 

[dickr]

I believe we have two fellas trying to part off . KevinB and Brassmagnet. One pc is 3"dia and the other he didn't say.
Any 300 series stainless isn't really "hard" it's tough. What either one of you have has got to be a tempered (hardened) steel. 4130,4140,etc. The plating on anthing like that is only gonna be .015 or so (probably less) The steel under that wouldn't be casehardened. That would be extraordinary. When an alloy steel is tempered it's gonna be very tough and you'd never touch it with HSS. A quality carbide material might cut it and should be centered or about.005 or so below center and slow RPM depending on your Dia. A chopsaw might do it but would take a while. Reinforced blade is slower in hard steel and if it's that hard you probably wont be able to get a satisfactory face.
There are some steels that are called stainless like 17-4, 17-7, and they can be tempered but not like alloy steel and that's what I would bet you have.
There's gotta be a lotta other fellas that would have experience with these circumstances and we'll hope the help.
Sometimes you just need to experiment with an idea and you'll learn a whole bunch.
good luck
dickr

 

[pdentrem]

I have used the abrasive saw blade technique, with the rod chucked up and in backgears, cut groove to get thought the chrome and case after that used parting tool to finish the cut. To clean the face I then mounted grinder/Dremel on tool post and traversed across the face until cleaned up or to length.
It is the only way I had success so far, other than throw the rod into the annealer with its attendant problems. If hardened right through, the annealing is the only option or select a different piece.
Pierre

 

[Abom79]

It sounds like you guys are trying to part induction hardened chrome rod. A lot of manufacturers use the induction hardened at the factory when building cylinders. The standard chrome plated rods are not hardened though and can be machined with ease using carbide tools. But trying to part through the chrome plating can be tricky. Usually you can just punch right through it if you feed in hard enough on the cross slide. But one trick you can do to remove the chrome is mount a carbide v-shaped tool like a threading tool in you tool post and turn the chrome off. He sharp point of the tool is much easier to plunge then the full width of the parting tool. If you working with the induction hardened rods, you going to have to use a chop saw to cut through it.

 

[ScrapMetal]

If you don't need both pieces to be an exact length, how about just using a chop saw, cutting the desired piece "over-size" and then try facing the rod to length?

-Ron

 

[8ntsane]

I have tried to cut into these chromed shafts before, and found the parting blade was just not cutting it. Seemed to just skid on the chrome plating. I also tried a carbide cutter shaped like a threading tool, and seemed to chip that up very quickly.
So, out come the toolpost grinder, and with a cut off wheel mounted, I probably cut in a 1/16 deep groove. I think the chrome was the first problem, then the firstbit of the OD seemed hard. After getting that done parting was still harder than normal, but doable.

 

[Kevinb71]

Well after getting some better cutoff blades for the Dremel I finally got through. I think this must be of the induction hardened type mentioned as I don't see/find any chrome plating. It took about 45 minutes to get through completely. I thought about trying the parting tool again after getting through the surface, but it's much wider than the dremel blade. Only three more to go now! Thanks for all the replies.