Does The Calorification Of Stepping Motor Effect Its Service Life?

- Aug 31, 2017 -

  Stepping motor is one important part of laser engraver. What’s the reason that cause the calorification of stepping motor in operation. Does the calorification effect its service life?


1. The reason for the calorification of stepping motor.


All stepping motors are composed of iron core and winding coils inside. Winding coils have electric resistance that causes current loss after being electrified. The loss is in direct proportion to the electric resistance and current squared. This phenomenon is often called as copper loss. The nonstandard direct current and sine wave can further lead to harmonic loss.  Hysteresis eddy effect often occurs on iron core, which can result in the current loss in alternating magnetic field. The loss degree is related to materials, electric current, electric frequency and voltage. We called this phenomenon as iron loss. Copper loss and iron loss will display in the form of calorification that has influence on the efficiency of electric motor. Stepping motor is designed for the precise location and torque output. With low efficiency and large current, stepping motor usually radiates much more heat than Ac motor due to much harmonic wave and the alternate electric frequency altering with rotate speed.


2. The effect of Calorification


Because the calorification has little effect on the service life of stepping motor, it is unnecessary for most of customers to worry about. However, severe calorification can lead to negative effect. For example, the different expansivity of motor parts can lead to the change of structural stress and small alternation of interior air space, which will effect dynamic response of motor and cause out-of -step of motor. Stepping motor is not allowed to generate much heat in circumstances where it is applied in medical devices and High-precision testing equipment. So it is necessary to deal with the calorification of stepping motor.


3. The reasonable range of heating of stepping motor


The extent to which motor heating is allowed depends mainly on the internal insulation level of the motor. Internal insulation is destroyed at high temperatures (above 130 degrees). So as long as the interior is not more than 130 degrees, the motor will not be damaged, and the surface temperature will be below 90 degrees. Therefore, the stepper motor surface temperature is normal at 70-80 degrees. Simple temperature measurement methods can use digimite, can also make a rough judgment: Touch more than 1-2 seconds with your hands, the surface should be no more than 60 degrees; Just touch it once with your hand, about 70-80 degrees; A few drops of water quickly vaporize, then 90 degrees above.


4. Stepper motor heating varies with speed


When the constant current drive technology is adopted, the current will remain constant at the static and low speed to maintain the constant torque output. When the speed is high to a certain degree, the internal anti-electric potential of the motor will increase, the current will gradually decrease, and so is torque. Therefore, the heat caused by copper loss is related to the speed. High fever at static and low speed, low heat at high speed. But the changes of iron loss (although the proportion is smaller) is not exactly so, and the whole heating of the motor is the sum of the two, so above is only a general case. Therefore, the heating of the engraving machine’s stepper motor will not affect the service life, but if it is serious heating, it will bring some negative effects.


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