I have a hobby CNC machine running with three cd drive stepper motors in it using a 2amp supply for all of them, it is run by Arduino uno and EasyDrivers. Suddenly I noticed them getting very hot, I am worried it might get damaged, please help I am new to this and cannot seem to find any answer. Also my old pc power supply got damaged which I was using to power the setup with I replaced with a 12 volt 2 amp power adapter, could this change be the reason for the overheat ?
The motor current is controlled by the driver. You can set the pot on the driver board to set the current as shown in the datasheet:
This is accomplished inside the driver chip by driving the coils with a PWM signal. If the coils were powered continuously from the 12V they would burn out because usually they're only rated for a couple of volts continuous. A 12V rated stepper would be objectionably sluggish.
In some applications the stepper current is automatically reduced when it is "holding" position, which helps keep the motors cooler. I don't know if your setup has that ability. In any case if you keep the surface temperature below 60°C you should be fine. If you intend to operate at higher temperatures you should consult the datasheet for the motor.
The obvious reason for motors to get too hot is that too much current is being run thru them for too long a time.
Several possible fixes follow from the above:
- Run less current thru the motors.
- Run the current at a lower duty cycle, with the cycle period small relative to the thermal time constant of the motors.
- Use bigger motors that can handle the current without overheating.
That said, make sure the motors are really getting too hot, not just simply hot. Some elevated temperature is normal. I'd say anything you can keep your finger on for 10 seconds without getting hurt is not too hot.
How did you decide that it was OK to run 2 A thru these "CD drive stepper motors"? I expect they didn't come with a datasheet. Perhaps they just aren't meant for that much current. The dissipation goes with the square of the current. At 1.4 A, the rise above ambient should be half what it is now.