3/8" cutter for Rockwell 60 material maybe diamond?

[bob1112]

We offer a product in which we need to profile a small part using a 3/8 cutter. The part is face hardened to approx Rockwell 50-60 or so. We can only do about 10-15 parts before our cutter is toast. We are currently using AlTiN coatings on 4fl carbides. The coating wears after about 6 parts.

So what are my options to increase parts per cutter? We genereally machine Aluminum so this is new to us. Is there a diamond coating or something that would hold up better? It there any other type of grinding wheel or somthing that we should look at that can be used in a VMC?

[Mcgyver]

others here have more expertise with this than i, but guys I know machining casehardened parts use ceramic inserts

[DareBee]

I am going to say too big DOC and too slow sfm.
Do not use coolant.
I dont do enough hard to to troubleshoot the best though.
My uncle cuts CPM and ASP at 60+ Rc for days on end without changing cutters. He DOES use a Makino for this.

[bob1112]

So smaller cutter and more RPM? Now that would be backwards of the data I have for hardened materials but I am always open. What kind of SF are you thinking?

Brandon

[stupidog]

Sounds like a job just made for CBN. They like high RPM and you should be able to get pretty decent life out it.

[bob1112]

CBN? drawing a black there. We did try with normal carbide at about 200 SF and ripped the teeth off the cutter. Right now we run coated cutters at 870SF and like 4-6ipm. VERY slow!!

Brandon

[cdlenterprises]

Maybe I missed it but what is the material? If it is Iron based you can rule out diamond. We used to do a lot of turning in 440c that was around that Rockwell range and we used CBN inserts. It is the hardest material short of a diamond. You'll probably have better luck finding something that is ceramic coated vs CBN at that diameter. I would look at OSG and see what they have to offer for cutters. I seem to remember seeing something about their tooling for hard materials...

[dfstrasser]

As cdlenterprises stated, OSG has the EXOCARB-WXS endmill that can fly in material upto 65Rc. The fixturing has to be good and they recommend heat shrink or hydraulic holders. Runout nust be vert low for the tool to work properly and give good life. The radial depth is pretty low, but the speeds and feeds are very fast. Check them out at OSGtool.com and then call their 800 number for technical help. Hope this helps.

[bob1112]

When you say "fly", what are you thinking? I talked to OSG and the girl was not much help but did recommend the Exocarb but with feeds of 1.4ipm. That is less than half of my current speed. I was expecting some good numbers on this. I would like to feed at 10ipm or more if possible. I am running 4ipm now.

Wondering if anyone has used this variable helix cutter that is out there? They look strange but say they can handle the hard stuff well.


B

[dfstrasser]

1.4ipm? I would recommend calling back and talking to an Applications Engineer or Product Specialist for milling. You should be able to explain your operation and they can make some suggestions on what tool to run. They have several that are capable of cutting 50-60HRc alot faster than 1.4ipm.

From the 2007 OSG catalog, the EXCOCARB-WXS that I spoke of earlier, shows 2400RPM and 39.4in/min for a 10mm tool in 55-60 HRc. The max radial depth of cut is 0.03XD, which works out to .014". They state that a rigid and precise machine and holder must be used. I have seen this tool perform wery well in some material that was 53-55HRc. The part was well fixtured, the tool was in a hydraulic holder, and the machine was fairly new. It may work for you or it may not. I've had good luck with OSG tools and their technical support.

[bob1112]

And that could be some of our problem since we are doing this work with a 30 taper machine. We don't do too much hard material machining so just curious as to how much runout you can have and why it is so important to minimize it? Does this just come down to vibration and cutter breakage? thanks

Brandon