We are machining 4140 Steel. Our stick out has to be 3.5 inches. We are taking about .750" depth of cut and stepping over .030". Feed rate is about .0025 per tooth on a 5 flute 1/2" carbide end mill. End mills don’t last very long before they break. Any suggestions???
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@BrianCusick what RPM ate you running? Look into your lead in and outs. Try less feed .0015 more side load .045 or more.
More information from you can let us help you.
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I would go with a Harvi 1 four flute.
You can get them with cleared neck, if that helps.
I suspect, with 5 flutes the chip elimination is not great and you gem pack your flutes with chips, then break the endmill. Also, 3.5" hanging out, I’d always go for reduced RPM and chip per load, because at such length in .5 diameter you are making the tool chatter way more than it needs to. Hope this helps
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We are running 2200 RPM. 275 Surface feet. Any suggestions on feed and speed?
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Definitely in the future step down with your endmills. Have a tool to stick out 1”. Then another go to 2” then 3.5”(just and idea). The less you have to use with that much stick out the better and faster it will go. Gradually slow speeds and feed rates the more you stick out your tool
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