First, you need to define what "super precision", "mini", and "no vibration" mean (no vibration will have to be restated as an allowable vibration level since nothing is perfect), then someone might be able to provide useful suggestions.

This mini conveyors dimention is 250x100x10 mm.
The super precision means that, this is a scaling conveyor and the scale tolerance is 0.1 gram.
It means that any unwanted vibration affets on scaling precision.
I khow that nothing is perfect but I want to reach smooth movement as much as possible.

What is the size and weight of the items being weighed?
What is the conveyor speed, and is it variable speed and/or incremental start-stop?
What is the motor and drive?
What is the power transmission?
What is the conveyor belt, and how is it driven by roller or sprocket?

Don't forget about torsional vibrations! Don't forget to preload the precision ball bearings!

Walt

It's a belt conveyor and does not desing yet. I prefer to use a DC motor with geabox.
The speed can be variable.
My problem is how to choose bearings for it?
Ball bearing? needle bearing? or something else?

The weight is not matter. It is vory low. Maximum 200 grams. The vibration while moving is important. It can affect on load cell measurement.

What do you mean by backlash in the bearings? I've never heard backlash used in relation to bearings, only gears and such... Do you mean radial/axial play? This can mostly be removed with adequate pre-load. I'd recommend that you pick a bearing manufacturer and talk to their technical sales or applications engineering department, this is what those guys are there for.

I wanted to know is there any other way for rotation without ball bearings?
The ball bearings are some unsteady.(or radial/axial play as you said)
It's very low but it is and preload can't remove it perfectly.
I was thinking about grinding shaft and use submersible Brass bush or something like this instead of ball bearings.
Do you have any experience about that?

HI MH500

I suggest you tell us everything you know about the project on a single post and then we might be able to help you.

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein

If you don't know the solution , there is no need to post a comment.
Try to find out and learn new things...

I'd check out hydrostatic bearings.

Hi MH500,

I understand there is probably language and possibly cutltural differences at play here.

"If you don't know the solution , there is no need to post a comment."

Like others, I respectfully submit that a "solution" requires first knowing, and defining "the problem."

Do you believe you have defined your problem ?

https://www.nasa.gov/audience/foreducators/best/ed...
"The NASA’s BEST Engineering Design Model serves as a foundation for all BEST activities. BEST Activity Guides were designed to teach students the Engineering Design Process (EDP) as an iterative process that engineers use to guide them in problem solving. NASA Engineers ask questions, imagine solutions, plan designs, create and test models, and then make improvements. These steps all contribute to mission success and may be described as follows:

ASK: Students identify the problem, requirements that must be met, and constraints that must be considered..................."

My question is simple
HOW CAN MAKE A BEARING JOINT FOR ROTATING A SHAFT WITHOUT ANY VIBRATION?
I think, i defined every thing about this, very well.
The hydrostatic bearings need power pack to supply hydraulic pressure.

Anyway thank u

Good luck with that, try talking to a bearing manufacturer with the information you have and you will see how little info you have.

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein

The answer to the current question is just simple: No, you cannot do it. Elastic materials with imperfections always have some vibration when they are in motion. Fluid film bearings also have sources of vibration. Just as we can't *eliminate* friction, we can't *eliminate* vibration in moving parts.

You could try to describe the actual vibration limits (.0001", .00001" displacement peak to peak for example). Or you could try to describe the existing attempts and we can try to offer relevant suggestions to improve on it. Or you could hire a consultant with precision machine design to assist.

This is the answer that I was looking for.
So there is no way to eliminate vibeartion totally.
It seems l have to use high precision series of ball bearings.
This project is prototype and I don't know the the allowed limit of vibration yet.

Thank u and the others for your help

New Way Air Bearings

https://www.newwayairbearings.com/

Vibration during movement is important. It affects the measurement of the load cell.

Supply Forever Global Industry Co., Ltd.
https://www.supplyforever.com/

This is the answer I have been looking for.
Thank you and others for your help.

Supply Forever Global Industry Co., Ltd.
https://www.supplyforever.com/