The Old Chatter Issue

[pzzamakr1980]

This past three days I broke my two good 1/4in 3 flute Aluminum cutters because my motor on my x3 will bog down and stall whenever it feels like. And when the motor stalls, the cutter stops, but not the table, and you know what happens next. Anyways, I replaced the cutters at short notice with the only thing I could buy locally which was a 1/4in 4 flute solid carbide SGS uncoated cutter. The cutter's shank is 1/4in as well, the old ones and new ones. The issue I'm having is: the cutter will howl at such a high pitch that it will make my eardrums hurt. This was not the case with the 3 flute. There was noise, but not ear-popping screaming. The new cutter is being held in the same 1/4in end mill holder that the 3 flute was, and the workholding, DOC, and Feed Rate are all the same. I take lighter cuts; .06-.075 because the x3 is small and it doesnt like anything deeper. Also, as I was saying earlier, the motor will bog down at too deep a cut. I played around with feedrates, up and down, to no avail. I also did a quick check for excessive runout and no dice. Any suggestions. Thx

P.S. Yes Aluminum. 6061

[LeeWay]

Lighten up on the DOC about half. My mill likes .05 and a little less depending on cutter and aluminum type. I run my spindle at top speed of 6600 RPM and adjust feedrate to suit. Feedrates can vary from 30 to 60 IPM again depending on cutter and aluminum type. I do use coolant.
I can't bog my spindle motor down, so I could get your DOC easily, it's just not as quiet or as happy doing it. I mostly use 1/8" and 3/16" cutters both 3 and 4 flute HSS and cobalt.

A little trick I learned recently is using Mach 3 and bumping up the feedrate overide while cutting. Start with the lowest range of feedrate, then just hit the up arrow and it will incrementally increase the feedrate. Once you get the optimal for that process, you can then hardcode it or edit your Gcode.

Sometimes just reversing the direction of cut will change the decibels of the cut as well.

[MFassler]

remember too help with chatter reduce spindle speed,increase feed rate. Are you climb cutting, or conventional cutting? Also remember that the 3 fluter is going to be stronger because they have a larger web thickness.

[scadvice]

...it can be a problem. First thing to do is make sure that you are holding the cutter in the collet far in as possible the less hang out the better. The closest to the spindle the better even if you have to cut down the back of the EM.
Next, with a four flt EM you will have more teeth engaged in the cut and also chip loading is a real possibility. You will need some kind of coolant or mist. If you can, decrease you width of cut to 1/3 the diameter, so that you minimize the number of teeth engage. DOC should be decreased .05 to .035 and feed rate upped (I would say .003 to .004 per tooth, more if you spindle has the torque, and a feed rate of 92 in per min) If you cannot do the feed rate, decrease the RPM's until you can achieve a chip load of the .003 to .004. New carbides will tend to howl a little, but not like you described. Good luck...
Steve.