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Ed Tipton
09-07-2006, 07:18 AM
I am looking for information on speeds and feeds as pertains to both lathes and mills. I know there are many charts and publications out there that provide these, but what I'm looking for is a "general" or "ball park" rule of thumb to be used in the absence of those charts. For example, I have been told that a cutting speed of 200 IPM is a good starting point when turning mystery metal. Is that an a reasonable starting point? And what about milling? I know there are many variables, but I am not looking for "absolutes" here. Just generalities. Any thoughts or comments are welcomed. I have both turned and milled, but I must confess that I do not fully understand why the differences in speeds and feeds. Other than multiple flutes on an end mill, why should the cutting speed be different for a mill than for a lathe? It's frustrating when you're self trained that you are forever fighting the "holes" in your knowledge. Once you venture outside the realm of your personal experiences, you are confronted with overwhelming complexities that cause no end of problems. And then, once again, I discover that the more I know...the less I know!!

Mcgyver
09-07-2006, 07:43 AM
you need some basics before rules of thumb will do much good...here's a good starting place

http://metalwebnews.com/machine-tools/fmt.html

ipm of 200 might be possible on wood router, but not a metal cutting machine machine. this is a feed rate and is determined by chip load per tooth.

maybe what you are after is cutting speed, ie surface speed, measured in say feet per minute. there is an optimal cutter speed for each combo of material - work and cutter. the spindle speed with change for different dia's but the surface speed should be maintained.

milling drilling lathe work, more or less doesn't matter, the cutting speed is a constant. do keep in mind its also an ideal, machine rigidity, setup, etc often means this ideal is not achieved and we use a slower speed

mild steel with a hss tool would be 75-100 fpm - the low end would be a good starting place for mystery metal

J Tiers
09-07-2006, 08:14 AM
ANY shop textbook will have a table of speeds and feeds for various metals. You need one....

http://img.photobucket.com/albums/0803/jstanley/books.jpg

As far as lathe vs mill, the fundamental difference is that teh same cutting tooth is always in contact with the work in a lathe. In a mill, there is about 20% cutting time, and 80% cooling time, so the temperature limited effects are different.

And, with many teeth, each can take a certain cut, the combination of all is the sum of the cuts, and ends up controlling feed speed, which is so much per tooth.

Dawai
09-07-2006, 08:23 AM
Evil nine headed poisonous snake.

Cutting Pressure, rpm, end mill type, end mill flutes, chip evacuation, coolant, ,climb milling, plunge milling and rigidity of the machine.

Change any of the above and you need to modify your IPM feed drastically.

Dawai
09-07-2006, 08:25 AM
For some reason Materiel is not on that list... UHMW cuts a lot faster than D2.

Millman
09-07-2006, 09:40 AM
All I can say is; read your Bible. If you don't have one, get one. The old timers had this figured out alot of yrs. ago. Mine was new in 1946 and the formulae stay the same.