"Face milling" with end mills (workpiece is smaller than end mill dia.)
Hi,
I am currently reducing the width of 1/4in stainless 304L bar from 1.5in to 1.3in. I am accomplishing this by holding the bar on it's side and using a 3 flute 5/8 HSS end mill to "face" it down by a 0.1in pass, turning the piece over, and making another 0.1in pass. The cutter is centered over the .25in width of the bar.
I'm not sure if this is the best way to do this, whether I should use an actual face cutter, or something else. I'm definitely a newbie, but I figured a face cutter wouldn't be able to make this deep of a pass. Anyways after 15 of these 11" bars (I have 60+ to make), the 5/8 end mill sheared off at the collet. Prior to this, it was also getting dull. I don't have a powerfeed so I can't really give an estimate of my feed speed but the chips are not discolored in any way. My spindle speed is 500, and I'm running flood coolant.
I am trying to do this operation in a decent amount of time, and currently it takes 15min per piece including work holding setup etc.
So my questions are: Should I continue using an endmill for this? (If so, what type), Would a different size work faster?, Is this too deep of a pass?
Re: "Face milling" with end mills (workpiece is smaller than end mill dia.)
Perhaps rough it by using Z axis moves using the end of the endmill, like boring. A good start might be 0.030" cuts on the X axis. Then a finish cut in the current method using a fresh part of the endmill.
Re: "Face milling" with end mills (workpiece is smaller than end mill dia.)
high speed steel end mill is good but you need to run it about 40 to 45 surface feet per minute. It can take a fairly heavy cut, about 0.0015 per tooth. is this on a manual Bridgeport style or a CNC with ball screws? on a Bridgeport you will want to run off center and conventional mill, on a CNC you will run off center and climb. tool life will be better climb milling. are you holding these bars in 1 or two vices? A rigid set up is of most importance to stop vibration and reduce chipping of the cutting edge. You need to run a Hot coolant concentration 10% or higher to lubricate the cutting edge to keep from having built up edge. A carbide end mill would result in higher production only if you have absolutely no vibration. A TiAln coated endmill will last longer than an uncoated one, but you need to consult Mfg on speed and feed. 304 stainless is very gummy and the correct feed and speed are very critical to good tool life. too low of feed will result in work hardening of the material, to high of feed will overload the cutter body and shank, you can almost not go to slow on High speed steel, but too fast and you will smoke your cutting edge even with coolant flooding on it.
Good Luck on your endeavor.
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"Face milling" with end mills (workpiece is smaller than end mill dia.)
