Anyone have expieriance with M-4

[Chad 73]

I am interested in hearing your ideas about M-4. I have a new job cutting some, managment thinks i will be doing it hard Rc 60-64. I have had ho problem with up up Rc 56 materials but havn't had much jobs requiring anything harder. Unless i am mistaking, M-4 is difficult to even grind once hardened. I thought it was a stable material though which i might be able to cut the part finished soft and grind outsides to the cut interior dimensions. What are your thoughts or expiriences with this material please?

[Guest]

chad i use to turn on it all the time.64 rc. it sucked. ceramic inserts would just pop at anytime.i have ground it also and its like the wheel just bounces off of it.it is in a class 4 on the grinadabilty charts which isnt good.these were big round pieces about 25 in in dia with about a 16 in id.luckily my tight tolerances were only on the id. keep inserts fresh .it is a high speed tool steel.

[chris m]

In a former life we made stamping dies from M4 and it was some tough sh!t; dimensional stability was pretty good if I recall, but as Del said it laughed at the grinding wheels

[fro_matt]

We EDM tight stuff if possible, it is a be-otch, but we've never had much stabilty problems

[Fred @ Slate Industries]

Doesn't move at all.

I Finish it with .005 on it and refinish it after H.T. (Punches and dies)

 

20+ years ago I wanted to make sure everything cleaned up so I left .015+ just to be safe.

In know time the grinder hands began pulling my stuff out of the Going to H.T. box to measure it and make me leave .005/.007 !

[mcpgmr]

Just made 60 nitro clutch levers out of CPM M4. Not sure what rockwell but it came from the blanchard grinder after sawcut from 6" bar stock. They do go out for HT and come back 58-60 rockwell. Carbide e.m's ,drills and taps running speeds and feeds for A2 Tool steel. Cuts fine. Very stable before and after HT. We make some levers out of pre-hardened CPM but they are a PITA to cut. Good luck!

[Chad 73]

Thanks guys, i thought i would hear comments like that. I think i will try to finish as much as i can soft and leave .004-.005 on anything that needs to be held tighter than .001. That only leaves a few items that need +.0002 -0.0. Thanks again.