Personnel from Boeing's Research & Technology group recently answered readers' questions. One reader asked the following. To see the list of experts taking questions from readers right now, see our Ask An Expert page.
I am roughing Al 7000-series material at around 30,000 rpm using a 1-inch solid carbide uncoated end mill with 2 flutes at an axial DOC of 0.200 inch and a radial DOC of 50%. I am using an HSK80 toolholder, coolant through, with a good machine and stable setup.
At this speed, there is no surface finish difference if I climb or conventional mill. But is there a difference between the two methods in terms of tool life?
Response from Boeing’s Research & Technology group
With 7000-series aluminum on our own 24,000-rpm spindle, we achieve 200+ hours of tool life using carbide cutters. We do both climb and conventional milling and we do not see tool life being affected. For us, the key to long tool life and good part finishes is dynamically testing all of our cutting tools first before high speed machining aluminum. By doing so, we find what is called the "sweet spot," which is the optimal rpm and depth of cut the cutting tool will run with no chatter regardless of step-over, full slot cutting or corners. Once we have these parameters, we program to them—confident that we will not have any cutting tool chatter issues. The system we use for this dynamic testing is called "Metal Max” from Manufacturing Laboratories, Inc.