The Home Machinist!

Hi to all Dear industrial men



can you please help me for calculate feed rate and rapid travels of CNC machine?

i have a Servo motor with :

Rate speed : 2000 RPM
Max speed : 2800 RPM

I use ballScrew with 5 mm lead.

Does the maximum feed rate is : 10000 mm/min
Does the Maximum Rapid travels : 14000 MM/min

I read ballscrew catalog and the ratio of maximum speed and max rotation for select lead is :
15000 mm/min and 2800 rotation
Then we select 5 mm lead.


Can you please help me if i must consider any other ratio ?
What parameter i must use for select feed rate and rapid travels?


Thank you

Your maximum rapid feed rate is accomplished by tunning your servos. Somewhere there should be a "set-up" feature in you machine software. You need to find the maximum speed and the maximum acceleration.

This is quite easy to do. You simply increase your maxiumum speed and maximum acceleration untill your servo motors make a grinding noise. The noise are the magnets inside the motor not gears. When you find the maximum speeds have been exceeded slow the motors down about 20% and then test them again. You want to run the motors as fast as possible without missing steps.

This is what I do with stepper motors. I assume servos are the same.

Finding feed rates while machining is another subject.

Jim

_________________
Tool & Die Maker/Electrician, Retired 2007

So much to learn and so little time.

www.outbackmachineshop.com

Jim

Servos are a totally different aniamal than steppers.
Since servos have feedback and go to a position and do not just respond to pulses they will eventally get to the commanded position. Its how they get there that gets tuned, Max speed of the motor is the name plate speed but you have to tune gains and offsets to minimize following error / repsonse , over shoot etc . A typical cnc control for servos monitors the following error (difference between commanded error and actual position while the system is in motion) if the error is exceeds a preset amount then a error in the system is produced. Some systems have tuning tools built into the setup software where you can monitor the gain and following errors and make adjustments. Sorry for rambeling about hope this makes some sense

_________________
Rick

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