[djstylexx]

hello everyone!

I'm fairly new to the cnc world ( right under a year) and I'm looking to speed my processes up, while prolonging tool life if possible. Production is priority, but I know I have to be burning inserts running at the rate I am now.

Keep in mind I am an operator, and I may not be using the correct terminology. I'm far from a machinist but I do try to research and make educated decisions. I have the leeway to change programs and run the machine how I feel is most productive, so any and all input is appreciated.

Now. For the real question.
I'm currently using a mazak 650 ultra. I mill water main pipe flanges from 2"-20" in diameter, but my focus is on the larger fittings (12"-20" dia).. They are made out of ductile cast iron.

Currently I run a 6" sandvik milling head ( 14 inserts) and r365-1505zne-km k20w inserts ( I believe that's coated carbide, but again. Could be wrong) they specify fz as .011in and vc as 445sfm. This is extremely slow ( I believe it's around 3in/min feed rate) and from what I read, rated for .125" cuts. I need to take off closer to .100" ( sometimes less) but I'm not within a strict tolerance. I have the mazak programmed to take .04" cuts 2-3 times at 80in/min and 656sfm.

Is is there any chance someone could divulge some information that might help? I've read smaller fast cuts work better by taking the hard layer off seperate from the soft metal, and I've heard digging deep on the first pass to cut soft and hard at the same time will save on tool life.

*edit for clarity*.
Finish doesn't matter. I'm looking for the quickest/most efficient rough cut possible.

Any experience? All input is greatly appreciated. Thank you.

[ERUS]

A 6" cutter with only needs to go 283 rpm for a SFM of 445.

A FPT of 0.011 (w/14 inserts) comes out to a feedrate of 43.5 IPM. Which is really isn't super slow.

3.0 IPM comes out to a FPT of about 0.0008", and that will just burn up the inserts faster than it will cut the metal.



Honestly your numbers don't seem too bad. You're doing a 0.013" FPT with your feeds and speeds.

I would do almost the full DOC if you can. If you have to go 0.100", try going 0.09" and leaving 0.01" for cleanup, of if its truly just a rough then go the full depth. Its going to wear out the inserts the same if you go in steps or full DOC.

If you tried 1 pass at full DOC, 445 SFM with a 43.5 feedrate, its still faster that doing 3 cuts at 650 SFM & 0.013 FPT.

[djstylexx]

I'm not sure where I got that 3in/min feed rate now. ��

So to verify. .09" on a single pass at 445sfm and 43.5 in/min federate. This isn't too large of a cut for a single pass? We have done .08 on a single pass but it always sounds horrible. But We used to run it around 500-1000 rpms at 8-15 in/min. I started researching and changed it to smaller passes and different feeds and speeds. But no one here has had proper training on machining. It's just ran by ordinary guys that change things if it sounds weird haha.

Thank you for your advice. I will try it on my next part in a few minutes!

[djstylexx]

Hopefully this photo shows up.

This is why I remember 3 in/min.. Any idea why it's calculating like that? My sandvik calculator comes up with the same numbers as you. But my mazak doesn't agree haha.


*edit*

im assuming I messed up and should multiple .011 by my number of teeth. Told you I'm a newb...

[djstylexx]

Sounds amazing. Thank you for the help and quick reply!

[ERUS]

You got it.

There should be a setting somewhere in the machine for the number of teeth. Also the diameter of the tool is critical to the sfm calculation so there should be a input for this as well.

If you dont have a setting for this then multiply the fpt by the number of teeth. .011 x 14 = 0.154 fpt. That should give you a correct feed rate.

I use this. Its helpful. - Speeds/Feeds Conversions Calculator | American Machinist
And this - https://www.carbidedepot.com/formula...oubleshoot.htm

[ERUS]

You're in front of the machine so you experience what is happening. You cant beat that. Machines are different.

In cast iron I think you could get away with .095 depth. Specially since you're using a 6", 14 tooth face mill, but its putting a lot of force on the machine.

I wouldn't go above 275 - 300 rpm with that large a cutter, but try 20 ipm @ 0.09 doc, .01 finish. I think its doable. Adjust your fpt, or ipm based on how it sounds and how your inserts are wearing out.

[djstylexx]

I tend to always run it at 656sfm and adjust my feed to what sounds best. But I don't have shop experience outside of this job to know what it "should" sound like either. So I just use trial and error. haha.

The 445sfm at .154in/rev seemed to work nicely on the smaller stuff ( more rigidity?) but chattered on the larger parts. Just wondering if it's something simple i could easily fix. I've thought about my overhang, but it seems to be ok. And I can't really make a difference with climb cuts or conventional cuts since my part face is round. Unless I'm being totally oblivious to something else idk what would spend things up. Just seems like it -should- be able to handle more.

Thank you again for your help! I appreciate it.