Any ideas?
I have a piece of 2.5" 6061. I drill a 1" hole 2.3" deep. Then I bore the entire thing to 1.25", then I bore the top 0.75" to a width of 1.9".
The main problem I am having is that when I am boring out the hole, I am getting long stringy bits of aluminum that fly around, curl up around the boring bar, get all wrapped up and lead to a crap-tastic surface finsh as they all get in the way of the boring bar.
Specs are...
2500RPM
0.100 depth of cut
0.005IPR
1/2" boring bar (I know I could use larger but I need this for some other jobs)
21.51CCMT insert that's positive rake and polished (made for aluminum)
I do not have coolant through the boring bar.
It seems the problem is that it's just not effectively breaking the chips. If the chips were breaking I could mess with the coolant nozzle to make sure it's blasting into the bored cavity and flushing the chips out, but when it turns into a bit string and wraps around the bar, it turns into a big ball that looks like steel wool and impedes the coolant flow as well.
I am thinking maybe its insert wear (doubt it - almost brand new insert)
Possibly my feed/speeds are off?
Maybe I am taking too big a cut? Too small a cut?
Any opinions are welcome!