Servo Motor Selection

John Elson and All on the list,

I solved the cogging problem with my Ametek servo, like you said it was a funny brush and the more I run it the better it gets. The other problem as you said was actually a dud encoder connection.


I am in the process of selecting servo's for a full size machining center. I want to run the machine with 700ipm max rapids and 600ipm Max Feedrate. The wieght of the x axis table is 200kg (441lb) and the wieght on the yaxis with the saddle is 300kg (661lb)

The xaxis travel is 500mm and on the y is 400mm, I am using 1" dia ballscrew with a .250 lead. I am designing for a cutting force of 2000lbs (8896N) max.

My calculations say that for my ballscrew to reach 2000lbs thrust I require 9.06nm at the screw or 80lbin.

That I need around 2900rpm at the screw.

That the x axis given 2000lbs of thrust constant will accel at 45ms^2

And will accel to 700ipm in .0067 seconds. I dont think this is right.

By my calcs I require motor 2?

The motors I have to choose from are as follow, in order of price:

These are all AC brushless servo's.

Motor 1
Cont. Stall Nm : 7.8 (69lbin)
Peak Nm: 23.3 (206.2lbin)
Rated Torque at 2000rpm: 7.46Nm (65.5Lbin)
Rated Torque at 4000rpm: 6.8Nm (60.2lbin)
Max revs: 6000rpm
Vrms/Krpm: 45.9
Nm/A:0.76

Motor 2
Cont. Stall Nm : 12 (106.2lbin)
Peak Nm: 56 (495.6lbin)
Rated Torque at 2000rpm: 11.42 (101lbin)
Rated Torque at 4000rpm: 11(97.4lbin)
Max revs: 3000rpm
Vrms/Krpm: 45.6
Nm/A:0.75

Motor 3
Cont. Stall Nm : 17 (150.5Lbin)
Peak Nm: 81 (716.9Lbin)
Rated Torque at 2000rpm: 16.57 (146.7Lbin)
Rated Torque at 4000rpm: 13 (115Lbin)
Max revs: 6000rpm
Vrms/Krpm: 44.3
Nm/A:0.73

Could you please help me select which motor is required for industrial use. The motors vary hugely in price so I would like to get the cheapest possible, ie. Motor 1!

Thankyou so much for your help, it is appreciated greatly.

Regards,

Jason Cox


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