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Feed Speeds, RPMs, and Bit Life
Question
My concern is the bit seems to be getting too hot, so life is an issue. I just cut 16 sheets and by the time I got to the 11th sheet, the bit sounds a little dull and I had to slow down to 200ipm feed to keep it going without bogging down. The tool is from Integra and they tell me I should spin at 18000 rpm and feed at 600ipm. I can do that if cutting 1/4" deep dados, but not on the through cuts. What am I doing wrong? Should I be using a different type of tool, smaller diameter, maybe a 1/4" bit instead? Forum Responses
From contributor P: If the bit is getting too hot, I think you need to increase the feed rate. You should increase it until you start to see the cut quality start to degrade, then back it off a little. The larger the chips you form, the more heat you take off the tool. Going too slow causes the tool to heat up. If cut quality is not critical, use a single flute or a chipbreaker. Let us know how it goes. From contributor T: Here's a formula to help get your speeds and feeds dialed in. (chipload) x (# of cutting edges) x (rpm) = feed rate From contributor A: Try a 3/8" 2 flute cutter. The smaller diameter may allow you to boost the cutting speed to keep the bit from burning. I cut mostly 3/4 ply at 600ipm and 16000rpm, getting 100 plus sheets per bit. From contributor J: I'm having the same problem that the questioner is having with burning, and when the bit gets dull, it starts slipping inside the collet. I think that I am probably cutting too slow also. I'm using a 2 flute 3/8" straight bit making 2 passes at about 200ipm and cutting 3/4 birch and maple running a 8hp hsd spindle. Are you using a straight flute upcut or compression, and what size router are you running? Are you making more than 1 pass? From contributor G: You are burning up your tool, because you are recutting the chips. Reduce your RPM to 12K. Longer tool life will be the result. At 600 IPM, your RPM should be 15-16K. Most firms (and I do mean most) reduce the feed speeds; they should increase feeds or reduce RPM. Remember, make chips, not dust. Would you like to add information to this article? Interested in writing or submitting an article? Have a question about this article? Have you reviewed the related Knowledge Base areas below? 
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