Originally emailed by Machine1
I am not 100% sure which inserts they are using. We kinda have a select few until monday. Do you have any suggestions. I believe that they are CPMT. What do you think we should go with? |
Hi Machine1
Sorry to not get back to you sooner. The nose shape of a CPMT is likely the culprit. The shape of this insert creates too wide of a cutting zone on the front, which increases the pressure requirement, and so the bar floats on top of the work to some extent, and results in chatter.
For best boring performance with a small, overhung bar, you need to go to an insert with a more acute point, like a T shape (60degree) or even more acute. The acute point tends to bring only a very narrow zone in contact, and will cut pretty good. I use a simple T221P insert and bar and have excellent results.
Hope this helps. Sorry if you spent big bucks on that other bar just for this job. Maybe you can return it and exchange it.
Sometimes the solution for chatter is to "really go at it". In other words, get the tool under a good chip. In aluminum, you should be running very fast (to get good chip flow), and at least .01" depth of cut. Take advantage of your insert shape by feeding at about .007" per rev. That is why you are using this insert, to reduce scallop height at an increased feedrate, so do it!
