Stepper Motor - Nanotec: it is a better motor or re-branded?

[metRo_]

Hi,
I'm using a stepper motor on an application that require to be silent as possible. Right now I'm using this motor http://www.exp-tech.de/stepper-motor-bipolar-200-steps-rev-35x28mm-10v-500ma and I was thinking if a motor with better construction could do less noise. So I found nanotec which looks good and following their catalog I selected this motor http://en.nanotec.com/products/185-st3518-stepper-motor-nema-14/ just to try if a better motor does less noise but then I found it  http://www.watterott.com/en/Stepper-Motor-Bipolar-200-Steps/Rev-35x36mm-27V-1000mA which looks exactly the same as the nanotec one but cost a lot less (BTW nanotec shipping cost is 50$).

So, nanotec motor has a better construction or is a Chinese stepper motor re-branded?
And could a better motor do less noise? I was thinking if better bearings make the motor to get less vibrations per example.

Thank you 

[coppice]

I think they make motors in their own Chinese plants. I could be wrong.

The noise from stepper motors has a lot to do with how you drive them. If you really let them chug from step to step they get pretty noisy. If you accelerate them, and then use microstepping when they are up to speed, they can be much smoother and quieter. Microstepping may work for you from rest, but it impacts the torque characteristics. You need to investigate how it will behave in your particular application.

[ajb]

At a certain point you'll need to look at the mechanics as well.  Things like mechanical resonances and large plates that are rigidly coupled to the motor that become sounding boards can have a big impact on the effective noisiness of the system. 

[metRo_]

At a certain point you'll need to look at the mechanics as well.  Things like mechanical resonances and large plates that are rigidly coupled to the motor that become sounding boards can have a big impact on the effective noisiness of the system.

So buying the motors directly from nanotechnology or other site shouldn't do difference?

I isolate the motor from the structure and that reduce a lot the noise. Another thing,I have it mounted on wood if I change to aluminium will it make difference?

[691175002]

The driver makes a huge difference.  In my experience anything with some form of current loop is dead silent at all speeds.

[ajb]

I'm no mechanical engineer, but I suspect that the quality of the motor only makes a significant difference at relatively high speed where things like bearings, rotor balance, and shaft runout can start to cause significant vibration.  I guess also the number of steps per rotation matters--at least it will affect the frequency of stepping noise at a given rotation speed.  Wood versus aluminum, I'd guess that whichever is heavier and/or thicker will provide better noise dampening.

[metRo_]

It is working at a relatively high speed. I don't mind to pay for a better motors to try even in the end the result is the same I just don't want to pay a lot more for a rebranded motors :s

[H.O]

If you accelerate them, and then use microstepping when they are up to speed, they can be much smoother and quieter.

No, you want to do the opposite. At low speed you want to use microstepping in order to reduce the energy wasted by the mechanical "ringing" introduced when fullstepping (which obviously also reduces the noise), reducing resonance issues etc. As the speed increases you can (if needed) switch to full-step mode since the benefits microstepping provides sort of dissapears.

If the motor does its work at a speed of more than a couple of revs per second not much is gained from microstepping it (except during the acceleration/deceleration phase) since the inertia will tend to smooth out the vibrations at that sort of speed anyway. Sometimes though it's impossible to get up to speed using full step mode since the vibrations at low speeds can cause the motor/load to resonate so badly that it drops out of sync.

Finally, it's not clear if you by "noise" means the noise caused by the vibrations of the motor or the noise from the current control chopper on some drives. Some drives are totally silent while others makes the motor "sing" and "chirp" at rather high frequencies.

Bottom line, use modern microstepping drive or switch to a real servo motor with feedback.

[coppice]

If you accelerate them, and then use microstepping when they are up to speed, they can be much smoother and quieter.

No, you want to do the opposite. At low speed you want to use microstepping in order to reduce the energy wasted by the mechanical "ringing" introduced when fullstepping (which obviously also reduces the noise), reducing resonance issues etc. As the speed increases you can (if needed) switch to full-step mode since the benefits microstepping provides sort of dissapears.

If the motor does its work at a speed of more than a couple of revs per second not much is gained from microstepping it (except during the acceleration/deceleration phase) since the inertia will tend to smooth out the vibrations at that sort of speed anyway. Sometimes though it's impossible to get up to speed using full step mode since the vibrations at low speeds can cause the motor/load to resonate so badly that it drops out of sync.

Finally, it's not clear if you by "noise" means the noise caused by the vibrations of the motor or the noise from the current control chopper on some drives. Some drives are totally silent while others makes the motor "sing" and "chirp" at rather high frequencies.

Bottom line, use modern microstepping drive or switch to a real servo motor with feedback.

That blanket statement is bad advice. Microstepping adversely affects the torque characteristics of these motors. If that's not a problem for you, microstepping from rest is great, which I said in the part of my previous post you edited out. If you need full torque from rest in your application, microstepping can lead to problems. Its not a magic cure for rough running.

[H.O]

I didn't edit it out I only quoted the part I was commenting on.
But you are of course correct that microstepping does have an impact on the torque but I'm sticking to my statement that starting with fullstep and switching to microstepping is counter producitve.

If you need "full" torque from stand still you're probably going to run into problems anyway since, unlike a servo-motor, the torque is inversely proportional to the speed (roughly). And since microstepping DOES reduce the torque (to about 70.7% (though some drives compensate at the cost of step linearity)) why would you want to switch from full step to microstepping once the motor is up to speed? That would reduce the "running torque" even further without gaining much "smoothness".

The theoretical reduction in torque introduced by the nature of microstepping is probably less in practice since less energy is wasted producing ringing and vibrations.

It's also important to understand that it's the holding torque at any given microstep that gets smaller and smaller as the step resolution goes up. If the rotational load on the motor shaft is higher than the holding torque at that step resolution then the rotor will be displaced from that position and issuing a "step" may not move the rotor exactly the expected distance (it may not even move it at all) but as you keep "stepping it" the torque increases and as the torque developed by the motor is higher than the load placed on the shaft it will move (up to a point of cours). Max torque will be developed when the equivalent of 2 fullsteps have been "accumulated" which is the point where the motor will de-synchronize and you have effectively lost position.

What I'm trying to say is that if you have a step motor capable of delivering 1Nm at 200rpm (when fullstepping) then it will deliver atleast 0.707Nm at 200rpm when microstepping.

You are of course correct that in order to engineer the "perfect" solution you need to take everything into account but if you can't afford the slight loss of torque introduced by the microstepping then selecting a slightly "stronger" motor - if at all possible - would be my advise. The pro's outweighs the con's IMO.