Rated and working voltage of a stepper motor

Hello,
I've got a stepper motor Mitsumi M42SP-6TE that I interface with Arduino Uno and the IC L293D (4 chan motor drive + diode 16). I use the 3 sketches from the examples available on arduino.cc (stepper_oneStepAtATime, stepper_OneRevolution and stepper_speedControl).
Fantastic, it's all working!
When looking at the datasheet of Mitsumi, I see that the Rated voltage is DC 12V or 24V and the working voltage is between DC 10,8 and 13.2 or 21.6 and 26.4 V.
However, the 3 interfacing projects are working with the voltage of Arduino, DC 5V.
So, my question 1 is :what is the meaning of the voltage mentioned on a datasheet? Why does it work with a lower voltage?
Question 2, if a higher voltage is recommended, how can I know if I need to use 12 or 24 V?
Thanks for helping my.

A simplified example: Use a 12V lamp and put 5 volts on it. It will light but dimly. The Stepper is doing the same thing it is rotating but it does not have the rated torque (brightness). There is no way for you to know this unless you measure it; you measured the light with your eye. You will need to supply enough voltage to do the job you want plus some reserve. That stepper is designed for commercial applications. The data sheet I looked at was for 24 Volts so it would need to be operated from a 24V DC system for maximum performance.

jack-69:
When looking at the datasheet of Mitsumi, I see that the Rated voltage is DC 12V or 24V and the working voltage is between DC 10,8 and 13.2 or 21.6 and 26.4 V.
However, the 3 interfacing projects are working with the voltage of Arduino, DC 5V.

Please post a link to the datasheet for your stepper motor.

Does the last sentence, above, mean that you are only supplying 5v for the motor power? If so, I'm surprised that it works at all. In general stepper motors work better with higher voltages but if you use a voltage higher than the rated voltage you must use a specialised stepper driver such as a DRV8825 which can limit the current to protect the motor.

Your last sentence also implies that you are deriving the 5v power for the motor from the Arduino 5v pin. If so, then that is a bad idea for any motor. It is likely to overload the Arduino and may damage it. Motors should have a separate power supply.

...R
Stepper Motor Basics