About Stepper Motor Temperature Rise

I still remember that I didn't know how much high of the stepper motor temperature rise when I was a newbie of our factory. Once a time when our engineer was doing a test, I went there to have a look and wanted to acquire some knowledge but didn't know he was doing temperature rise test and touched the motor body without thinking. The result can be imaged is that I felt the motor is surprised hot. It was an unintentional joke, but for me it was especially memorable. Now let's discuss the knowledge of stepper motor temperature rise issue.

The motor temperature rise is the temperature difference between motor and environment which is caused by motor heating. The stepper motor starts running from normal temperature and the motor temperature keeps rising. When it is higher than the ambient temperature, one side the motor keeps absorb heat and temperature rise slowly. On the other side, It starts to release heat around. When the motor is in the heat balance state and the temperature not rises anymore, the difference between motor's temperature and ambient temperature is called motor temperature rise.

That is Temperature Rise= Motor Temperature - Ambient Temperature

The factors influence stepper motor's temperature rise includes the following points:

1) The motor silicon steel material. The higher of the silicon steel grade, the smaller of the heat loss and the temperature rise is much lower. I must tell you here that our THANK Brand stepper motor iron core is used Bao steel grade 470 silicon steel which temperature rise generated is much smaller than the market normal 600 and 800 grade silicon steel.

2) The silicon steel's thickness. The smaller thickness of the silicon steel for iron core, the smaller of the transformed heat which is generated from the iron loss and the lower of temperature rise. But the thinner of the silicon steel means the thickness of the iron core smaller at same length makes small holding torque. So we always use 0.5MM silicon steel plate for our stepper motor. If special requirement like low temperature rise by customer, we can adopt to use 0.35MM high grade 270 silicon steel. Correspondingly, the material cost will be approx 50% higher.

3) The saturation of stepper motor stator winding. The higher of winding saturation, the greater power output, and of cause the higher temperature rise.

4) The temperature rise has relationship with the current to stepper motor which is given by the driver. The bigger of the driver input current, the higher property of stepper motor under a high working state makes higher of the temperature rise relatively. But if the current keeps over limitation working long time, the motor is probably going to be broken because of the over higher temperature rise.

5) When the stepper motor is at phase locked state( means power on but no pulse state), the temperature rise will be speedily increase to make malfunction. So, the stepper motor driver will automatically shift to be half current when the motor is at phase locked state. This is a function settled to avoid stepper motor's overtop temperature rise.

Generally speaking, people's body temperature over 40℃ will feel very hot, and feel thorny it if is reaching 50 or 60 ℃. But Chinese standard permission temperature rise range of stepper motor is 80-85℃. In other words, If the ambient temperature is 20 ℃, when stepper motor is getting a heat balance working state, normally the motor surface temperature can get 100-105℃.

What kind of materials will be affected by the high temperature of the stepping motor? Will the motor be damaged? The stepper motor's main internal material basically has Magnet steel( permanent magnet), Wire rings( enameled round copper wires). Too high temperature will lead to irreversible demagnetization of magnetic steel which will cause the stepper motor to run feebly, melt the wire rings insulation layer, soften the frame, de-glue the bonding part and wear the bearing grease.

However, the design of silicon steel materials and winding parameters used in the stepper motor produced by CF electric Motor company ensures that the temperature rise of the motor is lower than that of other products under the same output power. In additional, the CF stepper motor internal materials and components configuration is as following:

1) magnetic steel heat-resistant grade 155 degree.

2) enameled wire heat-resistance grade 180 degree.

3) the stator frame heat-resistance grade 180 degree.

4) anaerobic adhesive using LOCTITE 680 which can get heat-resistance grade at 149 degree.

5) TPI and NSK bearing heat-resistance grade is 180 degree.

6) The leading wires are used 200 degree high temperature wires.

The minimum temperature resistance of all materials and parts can reach over 140 ℃. So we assure that such temperature rise will not affect the stepper motor if you choose CF Electric stepper motor.

Above is the brief knowledge of stepper motor temperature rise provided by CF Electric Motor Co., Ltd. We supply technique support, if you have any doubt, please call or email us.

CF Electric Motor Co., Ltd

www.cfemotor.com