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Found out from a 1968 machinist's handbook that my old shop was running feed rates 40% too slow on aluminum
I was killing time at the library last Saturday and grabbed a copy of a 1968 machinist's handbook off the free cart. Flipping through the aluminum section, I saw a chart listing surface speeds around 800 to 1000 feet per minute for carbide tooling. My old shop in Dayton always ran 500 max on the same 6061 stock, and the foreman swore that was pushing it. So I pulled up the numbers from our last production run and the parts were coming off hot with a bad finish after 3 passes. I ran a test coupon at 900 and the chips came off silver and clean with no chatter. Has anyone else looked up old reference books and found their shop was decades behind on speeds?
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river_bailey29d ago
Wait, your foreman was running 6061 at 500 surface feet and calling that pushing it? That is wild to me. We run 6061 on a little Haas at my shop and even the old guys there would laugh if you tried to baby it like that. The part about the chips coming off silver at 900 is the real tell too, hot blue chips and a bad finish mean you were rubbing the tool more than cutting.
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