I've been making these parts for a while, but never been too happy with cycle time, tool life, etc.. I'm formulating the next approach, but want to see what you guys think.
Small parts held in very rigid fixture, held with mitee-bites and self-made talon back-up bars. I've broken 2 1/2" carbide roughers in them, and the parts don't move. Tool is a Lakeshore Carbide 4-flute rougher, 5/8" flute length / 0.75" stickout in a solid endmill holder held with a set screw. Running at 220 SFM (1680) and .002 ipt (13.4 ipm).
They start out as 0.75" x 1.0" x 1.0" blocks, and are stood up on the 0.75' side. I've been peeling from between 0.070" to 0.135" per pass, at a depth of 0.600". The .135" radial cut required 2 passes, but I backed down to the smaller bite and did it in 4. I never broke an endmill in this op, but thought I should give it as background.
In the next op, the parts are put in another fixture to face off the bottom that was held in op 1, and they are even more secure than the first setup. Here I have to remove almost 0.250". The first go around had me taking a 0.400" pass twice to clean up the total width of 0.75". The endmill snapped on one of these passes. Got a replacement (thanks Lakeshore), and reduced the radial DOC to 0.250", making it 3 passes instead of 2.
So last night it decides to take a crap again and snap in the middle of a part. I kind of thought it was getting a little louder, but let it go. I'm wondering if this is just the cutter getting duller and then work hardening until failure. Really wondering if I'm doing something blatantly wrong, or is this normal tool life. I think I've got about 50 parts done before failure.
Wanted to try HSM, as it seems that burying the tool so much radially is just letting the heat build up, even with really good flood coolant. I also wonder if the fact that the 1st op doesn't seem to have as much of a problem is because the tool is being used along its entire length, reducing the bending moment when using just the last .250".
I'm trying to give this as much thought before going in for round 3. Any recommendations for speeds and feeds, and would you use a rougher when utilizing HSM, or stick with the rougher.
Sorry for being long-winded. Just trying to get all the facts out before I forget them.
Thanks,
Burt
Small parts held in very rigid fixture, held with mitee-bites and self-made talon back-up bars. I've broken 2 1/2" carbide roughers in them, and the parts don't move. Tool is a Lakeshore Carbide 4-flute rougher, 5/8" flute length / 0.75" stickout in a solid endmill holder held with a set screw. Running at 220 SFM (1680) and .002 ipt (13.4 ipm).
They start out as 0.75" x 1.0" x 1.0" blocks, and are stood up on the 0.75' side. I've been peeling from between 0.070" to 0.135" per pass, at a depth of 0.600". The .135" radial cut required 2 passes, but I backed down to the smaller bite and did it in 4. I never broke an endmill in this op, but thought I should give it as background.
In the next op, the parts are put in another fixture to face off the bottom that was held in op 1, and they are even more secure than the first setup. Here I have to remove almost 0.250". The first go around had me taking a 0.400" pass twice to clean up the total width of 0.75". The endmill snapped on one of these passes. Got a replacement (thanks Lakeshore), and reduced the radial DOC to 0.250", making it 3 passes instead of 2.
So last night it decides to take a crap again and snap in the middle of a part. I kind of thought it was getting a little louder, but let it go. I'm wondering if this is just the cutter getting duller and then work hardening until failure. Really wondering if I'm doing something blatantly wrong, or is this normal tool life. I think I've got about 50 parts done before failure.
Wanted to try HSM, as it seems that burying the tool so much radially is just letting the heat build up, even with really good flood coolant. I also wonder if the fact that the 1st op doesn't seem to have as much of a problem is because the tool is being used along its entire length, reducing the bending moment when using just the last .250".
I'm trying to give this as much thought before going in for round 3. Any recommendations for speeds and feeds, and would you use a rougher when utilizing HSM, or stick with the rougher.
Sorry for being long-winded. Just trying to get all the facts out before I forget them.
Thanks,
Burt