Newbie Qn on Servo

[Syphonics]

Hi all, I am new to servo.
Currently I intend to build a machine based on servos rather than stepper due to the precise positioning required.

I would required informations on servos, ie, what are the components requied? Driver? And what is a servo amplifier?
How do I connect the wires to the driver?

Any website on these informations?

Thanks

[YZF]

Steppers can be very accurate. It's just that they run in open loop, not closed loop.
Just to give you an example, one stepper system I worked on had an accuracy of about 5um (0.0002") over 3m of travel and the motor itself wasn't the limiting factor.

By the way, servo and stepper motors are not mutually exclusive, you can servo a stepper motor.

http://www.electricmotors.machinedes...bdeee4a_1.aspx

[Syphonics]

My application is to stamp out materials at a rate of 800 - 900 pcs / min.
Currently I am using pneumatic actuator, I am unable to reach that rate. But the pneumatic actuator is able to provide me with the sufficent punching force.
Is the stepper motor able to provide me that speed with the sufficent force? Or should I still considered servo setup?
Or is there any pneumatic setup with this speed?
My current pneumatic setup is at least 2000+ N of force but at a speed of not more than 200 stroke / min.

Originally Posted by YZF Steppers can be very accurate. It's just that they run in open loop, not closed loop. Just to give you an example, one stepper system I worked on had an accuracy of about 5um (0.0002") over 3m of travel and the motor itself wasn't the limiting factor. By the way, servo and stepper motors are not mutually exclusive, you can servo a stepper motor. http://www.electricmotors.machinedes...bdeee4a_1.aspx

[YZF]

How long is your stroke and what are those accuracy requirements again?

Moving something at 15Hz any significant distance/angle/load sounds like a challenge to either servo or stepper motors. Pneumatics aren't known for very fast response times so I'm surprised you can get this performance with a pneumatic actuator - maybe I'm missing something about your application.

Maybe you could use something like a crankshaft?

[Syphonics]

The stroke I required is very short say approximately not more than 6mm in length. I am thinking of using a crankshaft and servo or stepper but wondering could it produce that much amount of force.

Originally Posted by YZF How long is your stroke and what are those accuracy requirements again? Moving something at 15Hz any significant distance/angle/load sounds like a challenge to either servo or stepper motors. Pneumatics aren't known for very fast response times so I'm surprised you can get this performance with a pneumatic actuator - maybe I'm missing something about your application. Maybe you could use something like a crankshaft?

[YZF]

Well, motors are rated in torque, you need to convert this torque into force... With a screw you could have a huge mechanical advantage but you'd also have more mass to move. With a crankshaft you can also control your mechanical advantage somewhat and you can add some gear reduction as well.

Just to give you a rough idea, a NEMA 23 stepper or servo would be about 1.5 N-m, a NEMA 34, perhaps 5+ N-m, a monster cooled brushless servo, 150 N-m (peak)... You obviously need to consider the power ratings.

At the high end check out these guys:
http://www.baldor.com/products/servo...sm_nseries.asp

[YZF]

I don't know too much about crankshaft design but if you're 10mm off the axis of the motor your force would be x100 the N-m rating (1N at 1m is 100N at 10mm). So for 2000N you need a motor rated at 20N-m continuous that can run at 900RPM. Since the crank is going at (mostly) constant velocity it shouldn't matter. Sounds like that would work fine.
And you don't really want a stepper motor... Are you trying to synchronize the stamping with another axis?

[Syphonics]

Oh yes, because each time the mould stamp the material, new material is feed in. And I have to syn this two axis.

Originally Posted by YZF I don't know too much about crankshaft design but if you're 10mm off the axis of the motor your force would be x100 the N-m rating (1N at 1m is 100N at 10mm). So for 2000N you need a motor rated at 20N-m continuous that can run at 900RPM. Since the crank is going at (mostly) constant velocity it shouldn't matter. Sounds like that would work fine. And you don't really want a stepper motor... Are you trying to synchronize the stamping with another axis?

[YZF]

OK. So you could do this by mechanically gearing off the same motor or you can use something called electronic gearing to synch one motor to the other. Most commercial servo controllers support electronic gearing mode.

[Syphonics]

currently using my pneumatic i am controlling both the pneumatic actuator and the stepper motor for my feeder using a PLC.

Originally Posted by YZF OK. So you could do this by mechanically gearing off the same motor or you can use something called electronic gearing to synch one motor to the other. Most commercial servo controllers support electronic gearing mode.