Stepper motor running continuously? 1

[loughnane]

I was looking to by a ball-screw driven linear drive module from Oriental and was told that their stepper motors are not recommended to run continuously. Considering my application was a back-and-forth motion with a period of ~1s and no rest, this was concerning.

I have never heard of such a limitation for stepper motors before, and am having trouble finding documentation regarding it.

Any thoughts?

Chris Loughnane - Product Design

http://www.pdnotebook.com

http://www.twitter.com/_chrisloughnane

 

[IRstuff]

So long as there's no excessive temperatures, it should be fine.

TTFN
faq731-376

 

[zekeman]

They mean at full load.
At full load continuous the winding temperatures could get excessively high.
Some mfrs give a table of maximum allowed housing temperature as a function of ambient temperature which by higher mathematics infers the limiting winding temperature.
You could ask the mfr if such a table exists.
However, absent such a table, if you are able to touch the housing without
scorching yourself, I would say it is OK.

 

[mikekilroy]

They mean at full load.
At full load continuous the winding temperatures could get excessively high.

This is a conflict or terms and ratings. by definition, a stepper mfgrs speed torque curve shows the area under which it can run continuously without overheating. to show a curve that is not possible is misleading and of no value to a user.

If you know from experience with Oriental brand that their speed torque curves are wrong, that is good to know - and the reason of course. But I wonder if they really would publish a speed torque curve that is unachievable on their motors?

It may be that the model stepper they use on that actuator uses steel bushings instead of bearings so life would be too short for continuous use. Rather than guess, you need to ask them the next question: WHY?

 

[benta]

They mean at full load.
At full load continuous the winding temperatures could get excessively high.

Am I missing something here? AFAIK, stepper motor coil current is not influenced by the mechanical load, but purely by the controller.

Benta.

 

[IRstuff]

"stepper motor coil current is not influenced by the mechanical load, but purely by the controller"

That should only be true from a transient perspective. If the stepper motor is being run at a "constant" velocity, one would expect the power consumption to correspond to the frictional and parasitic loads, while a stepper motor always starting from a dead stop should see a stall load.

TTFN
faq731-376