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Tried bumping my feed 40% on a 4140 job and blew through 3 inserts in one shift
Last month I got a rush order for 60 parts out of 4140 and the deadline was tight, so I cranked the feed way up past what I normally run to save time. I figured the inserts could take it since the book says the numbers are in range. Lost three inserts in about four hours, and one of them chipped bad enough to scrap a part that was almost done. Did the math after and the extra speed maybe saved me 20 minutes total across the whole run, but the inserts cost me $36 each. My old lead guy used to say the book is a starting point, not a promise, and I finally get what he meant. Now I write my real numbers on the setup sheet instead of trusting the catalog. Anyone got a feed and speed combo for 4140 that actually holds up over a full shift?
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linda_clark7d ago
Book numbers work fine if you're running the right grade insert for the material and not pushing a worn toolholder. Losing three inserts in four hours sounds more like a setup problem than a feed problem, because 4140 at catalog speeds shouldn't eat tooling like that. Plenty of shops run those numbers every day and make money doing it.
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