on feed and speed rates

[andy.collyer]

Hi, I am trying to cut some alluminium sheet, which is 0.457mm thick with a 2 flute 1mm carbonised cutter, have tired using settings of 24000 rpm with a feed rate of 400mm/min and plunge rate of 300mm/min, and also 19000 rpm with the same feed and plunge rate however the cutter keeps breaking. I can't use a bigger cutter as the items that I'm cutting are quite intricate.... If anyone can suggest any other ideas it would be much appreciated.

Thanx

[cnc-fred]

To start I would use a 2 flute high speed steel end mill, I don't know what a carbonised cutter is. You will need your work clamped good, no movement. You may need to clamp your work on a soft plate and move your clamps as you cut. If it picks up any you can kiss your mill good by. No slop in your spindle or in your X Y and Z axis. I would use coolant too, air if you don't have coolant. With that said, if your mill is loading up drop your RPM's. Then start dropping your feed till your mill stops breaking. Hope this helps you.

[DMF_TomB]

Hi, I am trying to cut some alluminium sheet, which is 0.457mm thick with a 2 flute 1mm carbonised cutter, have tired using settings of 24000 rpm with a feed rate of 400mm/min and plunge rate of 300mm/min, and also 19000 rpm with the same feed and plunge rate however the cutter keeps breaking. I can't use a bigger cutter as the items that I'm cutting are quite intricate.... If anyone can suggest any other ideas it would be much appreciated.
Thanx

1mm Diameter End mill cutting 12mm deep??

end mills come in different lengths 1.5x, 3x, 5x, 7.5x diameter.
a medium length 1 mm diameter end mill is 3 mm long flutes
carbide end mills are more rigid and can stick out farther but are also more brittle, when they break they snap suddenly.

....... when stickout (flute length + extra out of collet) is
2x longer then depth of cut is reduced to 1/4 and feed to 1/2
3x longer then depth of cut is reduced to 1/9 (1/3 x 1/3) and feed to 1/3

basically 3x longer reduces metal removal rate by 3x3x3 or 1/27

this is one of those laws of the universe cutting 12mm aluminum with a 1mm diameter end mill is beyond normal recommendations

[riche543]

I've been cutting 12mm Ali recently with a 3mm 2 flute bit, using air heres my settings gcode feedrate is at 120mm per min 1.5mm per pass rpm in range of 21k-22k if I change rpm too 24-25 I can double feed too 240. Lots of others could & would go quicker if your machine is ridged enough , in the process of building better machine as mine is a mdf machine & there is movement when cutting things harder than soft plastics. Hope this helps, 1mm bit for 12 deep, could be bit too much to ask but good luck , let us know if it works out
Cheers
Riche.