Very basic milling question about depth of cut

Mikey- can you make one addendum to your very useful post above- can you recommend a high helix roughing end mill for aluminum? I haven't been able to locate a ZrN coated, high helix, roughing end mill.

[EDIT]- I probably should have googled better. I found this one which looks quite nice (a 1.5 LOC version is also available)

ZrN Coated 1/2 dia 3 Flute High Helix Carbide Rougher X 2.0 loc MariTool

www.maritool.com www.maritool.com

[EDIT x2]- I'll create a separate thread. See here.
 
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Hey Wildo. I use a 3-flute coarse pitch roughing end mill, Niagara Cutter N75201 , for aluminum. This is a cobalt cutter with a 36 degree helix angle so it works good for both slotting and profiling in aluminum. They come in various diameters and flute lengths. I usually go for a 3/4" flute length to keep deflection down unless I need to deep; then I have to use a longer one. My most used one is a 3/8" diameter and it will HOG! Imagine a Sherline mill taking 3/8" depth of cut in a pocket. Chips all over the place!

I prefer coarse pitch roughers in aluminum. Makes a mess but the chips are bigger and easier to clear with a vacuum or blast of low pressure air. Fine pitch is okay but the chips tend to pack up at the feeds and speeds I can use so I use these mostly for steel and other harder non-ferrous stuff.

Hope that helps.
 
Here is a video of what a 1/2 inch endmill will actually take..... If you have enough machine to drive it. Most of us are not going to be able to run a machine this hard, but it really shows how strong a quality endmill actually is. It also helps to have a ~15,000 lb machine with a 30HP spindle

 
wildo said:
That was really incredible. And they doubled the RDOC on today's video:
Click to expand...

That was chattering the whole time. I do not no anything about the cnc world and watching the video was amazing to see material getting mowed off but left me a lot of questions.
Why sparks when plunging the holes? No sparks on any of the other movements.
Why are they climb milling on all movements? All movement was in clockwise rotation.
Wouldn't you conventional while hogging out then go to a climb on your finish passes?
Why not use a 3/4 or 1" and go even bigger cuts?
Like said idk about cnc so I'm curious as to their mindset.
 
Cadillac said:
That was chattering the whole time. I do not no anything about the cnc world and watching the video was amazing to see material getting mowed off but left me a lot of questions.
Why sparks when plunging the holes? No sparks on any of the other movements.
Why are they climb milling on all movements? All movement was in clockwise rotation.
Wouldn't you conventional while hogging out then go to a climb on your finish passes?
Why not use a 3/4 or 1" and go even bigger cuts?
Like said idk about cnc so I'm curious as to their mindset.
Click to expand...

I am certainly no expert, and I also wondered about the sparks.

For the rest of it though, here are my guesses:
-I have read that for roughing end mills, they can be more effective in a climb pattern since the swarf is shot out of the way. In conventional milling, the swarf is pushed ahead of the tool and recut. Plus they have a rigid machine unlike old clapped out mills.
-In HEM, I think that they don't have a need (well... a regular need) for large end mills like in manual shops. They use very, very high feed rates with smaller cuts in order to achieve significantly faster MMRs.
-I suspect that the surface finish could have been improved with coolant, but then we wouldn't have gotten to see anything in the video. Not to mention that the video was more about testing the end mill to capacity. Then again, I think it's fair to make the claim that perhaps surface finish doesn't matter as much with your rougher, and you'll come in with a finishing tool to address the surface finish.
 
Cadillac said:
That was chattering the whole time. I do not no anything about the cnc world and watching the video was amazing to see material getting mowed off but left me a lot of questions.
Click to expand...

The chatter would be no problem for a roughing pass. It's all about removing material as fast as possible. I think the MRR was a bit high in the last video, but this was just a test of the endmill.

Why sparks when plunging the holes? No sparks on any of the other movements.
Click to expand...

Good question, and the only thing I can think of is that when plunging the cut depth/tooth (chip size) was smaller than the side milling and thus putting more power into a smaller mass.

Why are they climb milling on all movements? All movement was in clockwise rotation.
Wouldn't you conventional while hogging out then go to a climb on your finish passes?
Click to expand...

Normally on a CNC you climb cut for everything because you normally have little to no backlash because of the ball screws. When climb cutting the endmill is actually taking a nice big bite of the material as the tooth enters the material then the chip thins out as the tooth continues around. Less rubbing and more cutting, much better heat transfer. You can't do this on a manual machine with acme screws because the cutter is being pulled into the work, and the backlash in the system causes the cutter to grab too much material and you can't control it.

Why not use a 3/4 or 1" and go even bigger cuts?
Like said idk about cnc so I'm curious as to their mindset.
Click to expand...

In this case they were testing the end mill, but yes, they could have used a bigger cutter. At some point you run out of horsepower driving a larger end mill. In another video they actually stalled that 30 HP spindle with a large (3 inch?) face cutter.[/QUOTE]
 
Thank you Jim for the responses. Specific to this scale of machine. As for climb milling wouldn’t conventional be able to chew through the material easier because the EM helix is directed into to material. Idk if that makes sense? The chip would still shoot just in a different direction. Idk
 
It's a bit counter intuitive, but climb milling produces less cutting forces than conventional so it's a bit easier on the equipment and tooling. You can take a much bigger bite climb cutting, but does require a rigid machine and minimal backlash else it will try to bite off more than it can chew.
 
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