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Tried bumping my feed rate 15% on a finish pass and the insert lasted 3 times longer
So last Tuesday I was running a batch of 4140 steel pins on the Haas and getting annoyed because I was burning through inserts on the finish pass. I kept backing the feed down thinking I was being gentle on the tool, going slower and slower, and the chips were coming off thin and stringy and the insert was just rubbing itself to death. Out of pure frustration I said forget it and cranked the feed up about 15% over what the book said. The chips started breaking nice and blue, the finish came out better than before, and one insert ran the whole 40 piece run when I used to swap inserts every 12 or 13 parts. I stood there feeling dumb because I had it backwards the whole time, slow feed just rubs the coating off, you gotta get under the material and cut. My lead guy Dale laughed and said he ran into the same thing his first year and everybody thinks slower is safer. Now I want to mess with the speed too but I'm not brave enough yet. Anybody else find out the hard way that you were babying your tools instead of actually cutting?
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karenh5629d ago
15 percent is the magic number that saved me too, on 304 stainless last spring. Everybody in the shop told me to slow down for finish passes and all it did was polish the flank wear right into the insert. Once you get the chip to curl and break instead of string out, the heat leaves with the chip instead of soaking into the tool. Dale is right, it happens to almost everybody in their first year, the book numbers are just a starting point not gospel. Get brave on the speed next, bump it 10 percent at a time and watch your chip color, when it goes light blue you are right where you want to be.
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