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Followup -- What is the best speeds and feeds reference?

I spent a while today cutting aluminum at 2400 RPM with a 0.40 inch resharpened carbide endmill. I was just issuing G1 codes to see how things work.

Removed a pretty big pile of aluminum, trying to square off a big 1" thick cutoff piece, and learned a few things.

  1. At 2400 RPM and 0.40 inch 4 flute carbide cutter, with plenty of flood coolant, my mill is relatively happy cutting at 20 IPM in regular milling.

  1. At same parameters, but with climb milling, it squeals horribly, really loudly. I am not sure why. It may be some kind of a resonance thing, as I held a 12x6x1" piece vertically in the vise (so that it was 6" high, with 12" edge horizontal and 6" edge vertical, held at the bottom).

  2. I have a feeling, somewhat vague, that I need to pay closer attention to rigidity of my mill, and also take a second look at servo loop tuning.
i
Reply to
Ignoramus23408
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By the way, this supposedly needs 0.77 horsepower.

i

Reply to
Ignoramus23408

Your chip load was very low, about 0.002", and the end mill was likely rubbing more than cutting much of the time. Too low a feed rate is just as bad as too high a feed rate. You need to take the feed rate up quite a bit since what you were running was way below pretty much every recommendation out there. Even the very conservative chart you found at endmill.com recommends twice the chip load you were running. Try 40 IPM which would match their recommended 0.004" chip load starting point, and don't be afraid to push it harder in line with the recommendations on many other sites.

Reply to
Pete C.

I will try tomorrow. Sounds like a fun thing.

i
Reply to
Ignoramus23408

VERY odd! Climb milling, assuming the cutter is not pulling the work into the tool, usually sounds better. But, maybe you just need to turn up the feed. The chip load is .002" which sounds reasonable, but a large cutter can do more. This was originally a 1/2" cutter, ground down to 0.4"? That much regrinding would seem to remove most of the gullets between the flutes, thereby reducing chip clearance.

A long cutter tends to vibrate MUCH more than a shorter one. I got a 4" length-of-cut 1/2" end mill, and it is totally useless, the chatter could be heard by my neighbors.

That is not real likely to be the culprit, but maybe. Proper mounting of your vise will also make a big difference. The vertical fixturing of the part will make the flexibility of the part itself, and the mounting much worse. A 1" thick slab isn't real flexible, but it could vibrate in the vise.

Jon

Reply to
Jon Elson

I will try to to it again on my aluminum pieces, maybe it was the opposite. But clearly one direction worked great, and another did not.

i
Reply to
Ignoramus4403

Squealing from friction is more common in conventional milling. A vibration is more common in climb milling. If you're getting vibration, it implies looseness somewhere in your machine or your setup, or a lack of stiffness. Your machine is plenty stiff. Your tool shank or other parts of your setup may not be.

Reply to
Ed Huntress

What was the DOC? 1D is max I tend to go a bit lower but I'm running manual machines.

Climb milling is how it is normally done. Keep your passes down to 2/3 dia as far as width.

That chunk of metal hanging above and outside your vise wasn't a solid set up.

Wes

Reply to
Wes

Ayup.

Gunner

I am the Sword of my Family and the Shield of my Nation. If sent, I will crush everything you have built, burn everything you love, and kill every one of you. (Hebrew quote)

Reply to
Gunner Asch

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