Stepper motors getting HOT!!!

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Flash
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Stepper motors getting HOT!!!

Post by Flash »

I just installed the Nema 34s on the X and Y axis.
On the Y I have 2 running each ball screw with The Y axis mirrored to the N axis. I just did a test piece and the system seems to be working very well, however the stepper motors are getting hot even when there's no movement. The power supplies are 60 volt... And right now I have the voltage set to about 57. They are 6 amp stepper motors... But I have the amperage set slightly lower to that right now because I was afraid the the higher amperage was causing them to get hot. I'm not sure what the issue is here. Any ideas?
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Miamijerry
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Re: Stepper motors getting HOT!!!

Post by Miamijerry »

Are there dip switches on the Stepper Motor Drivers?

If so what is the #4 switch set to?
Richards
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Re: Stepper motors getting HOT!!!

Post by Richards »

Stepper motors run hot, especially when stopped. Many stepper drivers reduce current to the motors about one second after the motor stops. The insulation on the stepper motors that I have is designed to handle a temperature rise of 80-degrees C over ambient. That's hot enough to blister.

Also, check to make sure that your power supply voltage matches the needs of your motors. The formula is SquareRoot(inductance) X 32 = MAXIMUM voltage. For instance, if the motor is rated at 4.5mH, then SquareRoot(4.5) X 32 = 67.8 Vdc. A 60VDC power supply could be used with that motor.
-Mike Richards
Flash
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Re: Stepper motors getting HOT!!!

Post by Flash »

Miamijerry wrote: Sun Nov 28, 2021 8:03 pm Are there dip switches on the Stepper Motor Drivers?

If so what is the #4 switch set to?
There are no dip switches on these motors.
Flash
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Re: Stepper motors getting HOT!!!

Post by Flash »

Richards wrote: Sun Nov 28, 2021 8:04 pm Stepper motors run hot, especially when stopped. Many stepper drivers reduce current to the motors about one second after the motor stops. The insulation on the stepper motors that I have is designed to handle a temperature rise of 80-degrees C over ambient. That's hot enough to blister.

Also, check to make sure that your power supply voltage matches the needs of your motors. The formula is SquareRoot(inductance) X 32 = MAXIMUM voltage. For instance, if the motor is rated at 4.5mH, then SquareRoot(4.5) X 32 = 67.8 Vdc. A 60VDC power supply could be used with that motor.
Thanks for the input, I just wanted to be sure. I'm positive that the power supplies are the proper ones for these motors. I double and triple checked my stats before I even ordered them. So what you're saying is even though the motor is rated for 60 volts DC, based off that calculation they can accept 67.8vdc? And the temperature the motors get while in standby is all normal?
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Re: Stepper motors getting HOT!!!

Post by tblough »

It's hard to say it's "normal" without knowing the temperature. What is the max temp rating on the motor datasheet? It the operating temperature of your motors less than that?
Cheers,

Tom
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Re: Stepper motors getting HOT!!!

Post by vw_chuck »

Yea mine get hot just sitting. I run big ass Nema 23's. Touchable but still pretty warm.
rk9268vc
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Re: Stepper motors getting HOT!!!

Post by rk9268vc »

Steppers just run hot, and that's fine. The amount of current directly correlates to how hot they get.
They are made to run hot. I use a lot of nema 23 and 34 steppers at work for various projects. Running hot will shorten their life in theory, but I have steppers that run so hot you cant have your fingers on them for more than a few seconds, and they run 3 shifts for over a year and are still going strong.
If you are too worried, you can get stick on heat sinks off of amazon to help dissipate the heat. Here is a picture of one little rotary project I did that on.
IMG_20211129_095243565.jpg
IMG_20211129_095222274.jpg
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Re: Stepper motors getting HOT!!!

Post by Muzzer »

The pain threshold for most people is around 50C / 120F, so "very hot" may actually equate to a fairly modest temperature rise. Those non contact IR thermometers are fairly cheap these days and can give a quick and easy measurement of the case temperature.

Many motors these days are designed for hot spot (internal) temps around 130C (Class B), 155C (Class F) or 180C (Class H), which will result in a case temperature of around 30-40C or so below that. You could seriously burn yourself on a motor housing at 100C but it may well be happy to sit like that for the entirety of its service life.

Servo motors only drive the current required to generate the torque required to keep the motor in position, so the steady state temperature rise is typically a lot lower. Conversely you might say they are more efficient, as all that heat in the steppers at zero torque represents lost energy.
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Re: Stepper motors getting HOT!!!

Post by Flash »

tblough wrote: Mon Nov 29, 2021 9:09 am It's hard to say it's "normal" without knowing the temperature. What is the max temp rating on the motor datasheet? It the operating temperature of your motors less than that?
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