I am using stepper motor for my CNC machine. Its model number is EM284 STP-42D221-01 by Shinani Kenshi. I don't know any specs of this motor; neither voltage rating nor current rating. I don't even know its RPM. I am using IRF640 MOSFETs to drive stepper motor along with 817B optocoupler.
I am running my stepper motor at 12 V. I have to do diagonal motion so I am running two stepper motors simultaneously.
Problem is when I use 12 V power supply with 4.2 A current rating, my motors are getting hot and also driver circuit is also getting hot. But the motors are running smoothly and are not missing the steps.
When I use 12 V supply with 2 A current rating, both motors are missing the steps but this time both driver and motor are not getting hot.
I don't know where is the problem? What should I do? Either there is a problem in my driving voltage or problem in driving current, or some other issue.
The driver circuit for both motors are in parallel. That means if I use 2A source, then 1A current is going in each driver means in motor.