Re: Feeds and speeds for drilling
I am family with how horizontal feeds and chipload work, but does any of this apply to drilling?
hy it does not matter if it is a drill, a face mill, or a turning tool, etc : formula's apply to the cutting edge ( geometrical location )
let's calculate a few examples :
1) drilling ( on mill or lathe, rotating tool or rotating part ) a 32mm hole with 100M/min means that rpm has to be 100*320/32=1000 rot/min; feed may be 0.1mm/rot or 1000*0.1=100mm/min, depending if you like to use feed in mm/revo or in mm/min
Code:
G97 S1000 M03 M08
G00 X0 Z2.5
G01 Z-50 F0.1 G95 ( or F100 G94 )
Z-50+0.3
G00 Z2.5
2) face milling : tool dia 250 with 12 teeths; required rpm for 75M/min is 75*320/250=96 rot/min ( thus, this won't run on a cnc mill, but on a classical mill, because it has torque at low rpms ); feed may be 0.1mm/tooth, thus 12*0.1=1.2mm/rot or 96*1.2=115mm/min
depending on machine rigidity, you may start to increase ap & ae
3) turning diameter 90mm at 150M/min requires 150*320/90rot/min; feed may be, for example, between 0.05 - 0.70mm/revo
4) grinding calculations begin with computing rpm for the grinding wheel, and the part is simply feed ( moved or rotated under it )
1/8=cca3.2mm
in alu you may go twice as fast as in steel, or even higher; rpm for 100M/min is 100*320/3.2=10000 ... that's the math, at least theoretical
in reality, your tool may overheat pretty fast, and also depends how your machine spindle behaves at such speeds, and what is the machine limit and taper size
obviously, is better to have a low tir spindle and internal-coolant tool and an rpm limit > 20000, rather then a dull hss drill and a spindle limit of 9000 / kindly
ps : tsc : through spindle coolant
ps2 : i understand "chipload" as required spindle torque / cutting edge, while in reality it means feed/cutting_edge ... a proper name should be chipthikness ... you see, there is an adaptive okuma function, that is capable of delivering identical spindle torque by modifing chipthikness for each cutting edge : for example, if you use a face mill with 6 teeths that has tir, then each tooth will cut a different chipthikness because tir<>0, thus spindle torque for each tooth will be different; if the adaptive function kicks in, then feed will be automaticall adjusted ( with a rate of 6 times/revolution ), in order to stabilize the cutting, making it behave like the tool had low tir
Ladyhawke - My Delirium, https://www.youtube.com/watch?v=X_bFO1SNRZg