motor sizing vertical slide EDM

Brad,

Could you help me with some motor sizing?
( Mariss, I'm using some calculation you posted long ago )

The calculations I used to size my motor were:
Watts = InchPerMin * Weight / 531
Torque oz-in = 2.55 * Weight / TPI * efficiency
RPM = IPM * TPI


The mechanics:
I have vertical slides that weigh near 700 pounds ( 300kg)
and, since this is for an ZNC edm slide,
the immediate reversals make the load seen by motor much larger,
I estimate 5x ( I've read it was RATED near 10X )
so the 'weight' is now 3500 lbs ( 1500 kg )
WEIGHT = 3000

The system uses ground ballscrew(HiWin/Star)
0.2" or 5mm pitch,
1.25 to 1.5" dia.
. Schneeberger roller bearings,
gear ration to be determined, but Gates wide toothed belts (0.8 to 1")
TPI = 5

I want to move them at 120 inches / minute ( 3 m / min)
IPM = 120

The Math:
Watts = 800
= InchPerMin * Weight / 531
= 120 * 3500 / 531 = 790 W, say 800 W to 1 kW
Watts = 800

Torque oz-in = 2.55 * Weight / TPI * efficiency
= 2.55 * 3500 / 5 * 0.9
= 1983 oz-in
TorqueNm = 14Nm ( 1983 oz-in * (7.062 * 10 ^-3 ) )

RPM = IPM * TPI = 120 * 5
= 600 rpm

The Conclusion:
so a belt drive ( like 1" wide GATES power belt ) with a 5:1 gear ratio
would allow use of a 3000 rpm motor, and add torque,
maybe reducing the Toque requirement to near the 3 Nm mark
( 600 * 5 = 3000rpm at 5:1 )

This also keep the motor rpm up,
out of the dead area area where the EDM spends most of it's time,
but keeps the acceleration and velocity available for when it needs to be
QUICK ( neccesary for EDM ).

So, I'm thinking a 1Kw motor at 3000 rpm and >3Nm torque.
This is WAY bigger than any system I've seen, so I'm asking for opinions.

If I use 5:1 gearing and wide belts, this make for a pretty big pulley on the
screw, but allows for that low speed toque, and uses the whole range of motor
rpm. The system should respond immediately to unit (bit) changes from the DAC.

I'm thinking Yaskawa, Panasonic, Fujitsu type drives
( motor/encoder/brake plus amplifier pkgs)

Any thoughts?

thanks,
TomP