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Unpopular opinion: I was climb milling every finish pass on 4140 and wondering why my inserts kept chipping
Figured this out 6 months ago on a batch of 4140 shafts, running a .015 finish pass at 800 SFM and burning up a corner every 3 parts. A guy named Rick at the shop down the road in Toledo asked if I was conventional or climb on the finish and I just stared at him, because I never thought about it at all. Switched to conventional on that last pass and got 40 parts off one corner instead of 3. Has anyone else had a finish pass habit that was quietly eating inserts for months?
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dianawilson5d ago
Man, that Rick guy saved you a pile of money! The climb vs conventional thing on finish passes gets people because the chip gets thin at the end of the cut, and climb milling pulls that thin chip right under the insert edge so it rubs instead of cuts. Flip it to conventional and the chip thickens as it leaves the cut, so the heat goes out with the chip instead of into the corner. Bet if you checked your finish readings after the switch they were just as good too, since 4140 at .015 doesn't really need climb to hit a decent Ra.
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