Going to try and keep this short and to the point.

Using a Haas Mini Mill and have been running the exact same program for almost 2 years. Have ran 1000's of these parts. Aluminum has always been purchased from the same place (6061 T6). Same mixture and brand coolant. Also, same clamping and fixtures as I have always used.

I run 4 small pockets and 4 .130" slots .185" deep in 3 steps (.062 each pass) in each part. Feed is 19.5 ipm, RPM 6000.

I used to use a pretty cheap brand 1/8" 2 flt carbide end mill and was pretty happy with it. Then I switched to a high performance SwiftCarb 2 flt end mill and was extremely happy with it. I ran over 1500 parts with it in the last 4 months. It cut very quite and left a great burr free finish. Then it finally broke. Figured it was getting old.

I purchased two more of the exact same end mills that same day. Stuck one in the same tool holder and collet, made sure it extended out of the collet the same and started up my program.

The tool broke in the middle of the 2nd pocket. Clean break right at the collet.

Took my second tool, used a different tool holder and a brand new collet. Started the program and the tool sounded very loud while cutting. I stopped the machine after 10 seconds or so and checked the cut. There was a HUGE burr for an 1/8" EM.

I pulled this tool out of the holder, stuck in another new collet just to be sure, ran the tool again, and the cutter broke after a few inches of cut.

Back to the local shop, purchased a cheap double sided SGS carbide 1/8" EM, stuck it in the same tool holder (2nd one) with yet another new collet, and ran another 100 or so parts and it is still going strong. Though even with this SGS EM, it is leaving a very large burr (right off the bat). But at least it is not breaking. I run a .002" chamfer on all my parts, so the burr goes away, but the cut is still much louder than ever before.

Couple questions:

1. Could it be my aluminum? I did try another piece from the last batch of parts I ran a few months ago, and it did the same thing.

2. Trying two different tool holders and 3 collets with the same results. Don't think it can be that

3. And all my other tools are cutting just fine. 1/2", 1/4", couple drills, and 1/4" 90 deg. chamfer. Clean cut and finish.

I'm focusing on the fact that I broke my old EM, then 2 brand new ones, and the 3rd new SGS is still cutting, but loud with a large burr.

Anything obvious here that I may be overlooking? Just want to get the clean and quite cuts again with an 1/8" EM. Not sure what else to try.

Thanks!