End Mills

[GlennW]

Did a little comparison test yesterday and got the results I sort of suspected. I needed to cut some parts from 6061 T6 Alum flat, 1/2 x 4". Tried a 2 flute HSS, a 2 flute high helix Crbide, a 4 flute high helix carbide, and a 3 flute high helix carbide (for aluminum). All at 1/2" DOC, slot milling, flood coolant. CNC Knee mill with 3200 rpm spindle max which isn't much, but that's why I'm loking for optimization! Started with the 2 flute HSS and ran the feed rate up to where the cutter produced a low frequency humming vibration and stopped there. I left an acceptable finish, but not great. Next the 4 flute carbide under the same conditions and it chattered and left a chattered finish!(what a surprise) Threw in the 2 flute Carbide and it acted about like the HSS which was no surprise given the spindle speed. Last was the 3 flute which went through it effortlessly like it was butter , was absolutely silent, and left what I would consider to be the best finish possible on this machine with a single pass. Very impressive and reasonably priced at $19.00 just to give an idea. Made by Accupro, on sale from MSC.

I'm sure this isn't big news, just an FYI for anyone that has not tried them!

Glenn

[JimGlass]

I'm sure this isn't big news

Oh yes it is. That is very interesting. I have never used a 3 flute endmill in my 35 year career.

My advice, is keep testing and let us know what you find out.

Jim

[GlennW]

Hello Jim,

They slot on size too. There are no opposing flutes so the cutter deflects to the small side. Re-cutting chips does not seem to effect size either as the deflection does not cause the opposing flute to go oversize. Think about it!

Next test will be the $19.00 Accupro 3 flute vs the $10.00 Hanita 3 flute HSS vs a $24.00 OSG Blizzard 3 flute Carbide end mill. All above are specifically for aluminum.

I've gone a little over the top on my end mill purchasing!

Stay tuned.......

Glenn

[Bill Shields]

one reason I shy away from 3 flute end mills is that they are sort of tough to measure with a mic to set your offsets.....

or at least with the mics that I have...

[GlennW]

Due to stack up of other influencing factors, I try to interpolate a hole or make two parallel cuts, gauge it, and then set cutter comp acordingly.

Glenn

[seal killer]

Glenn--

Since you are testing in aluminum, you might try one of those Lakeshore Carbide three flute, ZrN end mills specifically designed for aluminum. I have a couple, but am too inexperienced to make a judgement.

However, when I used the 0.375" end mill, I thought it zipped through aluminum far better than my TiN end mills. (I did not have any HSS end mills at the time. I do now and love them.)

I will keep track of your testing.

Thanks!

--Bill

[toastydeath]

Low frequency hum is not chatter, or even related to chatter (except maybe in a once-removed cousin sense). That's just what a cutter sounds like when it takes an acceptable roughing chip load.

Any particular reason you stopped at that hum on the two flute? Was the test sort of a "first noise" kind of thing?

[GlennW]

Didn't say it chattered. I was profiling parts out of the 1/2 x 4 flat and was looking for the best finish and speed on a single pass with my machine. Finish started to deteriorate at that speed with the two flute. Probably would have cut at a much faster feed but I was looking for good finish. Didn't see the point in increasing the speed until they broke. Different machines will produce different results. Unfortunately I don't have a 40 hp Matsuura

[toastydeath]

Different machines will produce different results. Unfortunately I don't have a 40 hp Matsuura :cry:

Now accepting donations!

[GlennW]

Even 30 hp would be acceptable

[GlennW]

Used some Hanita (Kennametal) 3 flute HSS end mills today. Only a few bucks cheaper than the carbide equavilent but work just as well. Actually, I like the smaller sizes a little better as they come with 3/8 shank as opposed to shank = cutter size on the carbides. R8 machines wouldn't have a problem, but my machine is 30 taper, and I use collet holders and the scientists that design them recess the collet in the holder so you have to stick the tool out an extra 1/4 to 3/8" so you lose rigidity. Anyway, like 'em, will order more!

Glenn

[Metalcutter]

That's a nice test Glenn. I too like 3 flute endmills. They don't bang like a two flute does, and they don't chatter like a four flute. Four flutes are ok for steel type machining because you don't go as vertically deep in the cut, and you run the rpm a lot slower. However, three flutes are good for everything unless you have a darn good reason to buy something else.

When I was a young guy I told and old machinist I didn't like three flute tools, because I couldn't measure them.

He said you don't need to measure them. It says on the box what size they are. grin.. What do you do after they are resharpened, I asked.

He says you don't grind the outside, you grind off the worn end and repoint. That way you always have the same diameter and you don't ruin the flute geometry for cutting.

Best regards,

Stan-