trochoidalpath
Cast Iron
- Joined
- Jan 17, 2016
I had an expensive day today and I am trying to figure out why.
This 6061-T6 part has a number of 0.196" wide slots, either 1.417" or 3.346" long, 0.127" deep. Roughed them out with a ramp down at 2 degrees to full depth, leaving 0.005" per side for a finish pass later on. I was using Helical H40ALV-3 1/8" end mills in either Kaiser NBC with on-size collets, MST shrink-fit collet holders, or ER collet chucks. Running on a Speedio. Very good chip evacuation with flood coolant (Trim 690XT).
I blew up no less than six end mills. Even for me this is egregious.
I kept backing off the speed and feed, and ended up at very conservative full slotting numbers (16000 rpm, 19 in/min, 0.060" ramp depth). The broken end mills were pristine -- no broken tips, no visible wear, no chip welding whatsoever. Four of the six broke inside the nose of the collet, which trashed two collets and two shrink-fit collets.
That ran me out of 1/8" aluminum-specific end mills, and I needed to get the part done, so I grabbed a random 1/8" 4-flute and ran that. It finished the job without complaint.
Maybe a bad batch of carbide from Helical? Those were all ordered at the same time, and have sat in my drawer until today.
I'm just pissed at scrapping a bunch of tooling and I'm trying to figure out why.
This 6061-T6 part has a number of 0.196" wide slots, either 1.417" or 3.346" long, 0.127" deep. Roughed them out with a ramp down at 2 degrees to full depth, leaving 0.005" per side for a finish pass later on. I was using Helical H40ALV-3 1/8" end mills in either Kaiser NBC with on-size collets, MST shrink-fit collet holders, or ER collet chucks. Running on a Speedio. Very good chip evacuation with flood coolant (Trim 690XT).
I blew up no less than six end mills. Even for me this is egregious.
I kept backing off the speed and feed, and ended up at very conservative full slotting numbers (16000 rpm, 19 in/min, 0.060" ramp depth). The broken end mills were pristine -- no broken tips, no visible wear, no chip welding whatsoever. Four of the six broke inside the nose of the collet, which trashed two collets and two shrink-fit collets.
That ran me out of 1/8" aluminum-specific end mills, and I needed to get the part done, so I grabbed a random 1/8" 4-flute and ran that. It finished the job without complaint.
Maybe a bad batch of carbide from Helical? Those were all ordered at the same time, and have sat in my drawer until today.
I'm just pissed at scrapping a bunch of tooling and I'm trying to figure out why.