Rack and pinion in an Ultra-High Vacuum

[LaunyO]

TL;DR

Rack and pinion mechanism in UHV

Hi everybody, I have a question with no clear answer so far.

Does the rack and pinion mechanism work in UHV ?

I have to translate an object in very confined scace (less than 10 mm), all in UHV.

Any response is welcome :)

 

[phinds]

1) How are you going to get a rack and pinion into 10mm ? Might be possible (I'm not familiar w/ micro-machines) but seems unlikely.

2) I see no reason why it would not work in a less confined space. Presumably the drive mechanism would have a sealed lubrication system.

3) What does "translation" mean in this context?

 

[Vanadium 50]

Presumably the pinion is in a region of rougher vacuum.

what is your concern? Cold-welding of the rack to the pinion? Materials choice should solve that, no?

 

[LaunyO]

Thanks for your answer phinds.

1) Yes it is possible. I am working on a prototype with elements from 0.1 to 6 milimeters.

2) I was afraid that some air could be blocked between the rack and the pinion.

3)I have a rod and inside it I have another one that must be able to move perpendicularly to the axis (100nm to 500nm)

 

[Baluncore]

2) I was afraid that some air could be blocked between the rack and the pinion.

The rack and pinion is mechanical and does not require air to operate.

Out-gassing from a metal component may be a problem, depending on the material and foundry process. You have not identified the materials.

You do not mention contact forces, the number of cycles, or lubrication requirement. The steel ball bearings for the rotating anode X-ray tube motors were lubricated with lead dust because it did not evaporate.

 

[LaunyO]

Thanks for your answers.

I read about out-gassing and looked at materials that can be used in UHV but my other constraint is that it must be non-magnetic. Even slightly magnetic is out of the question.

You do not mention contact forces, the number of cycles, or lubrication requirement. The steel ball bearings for the rotating anode X-ray tube motors were lubricated with lead dust because it did not evaporate.

I do not fully understand what you mean. (Btw I am French, so I get by in English but it is not my native language...)

 

[Baluncore]

Use Google translate ...
"Vous ne mentionnez pas les forces de contact, le nombre de cycles ou les exigences de lubrification.
Les roulements à billes en acier des moteurs à tube à rayons X à anode tournante ont été lubrifiés avec de la poussière de plomb car elle ne s'est pas évaporée."

Ask specific questions. Posez des questions spécifiques.

 

[LaunyO]

Use Google translate ...
"Vous ne mentionnez pas les forces de contact, le nombre de cycles ou les exigences de lubrification.
Les roulements à billes en acier des moteurs à tube à rayons X à anode tournante ont été lubrifiés avec de la poussière de plomb car elle ne s'est pas évaporée."

Ask specific questions. Posez des questions spécifiques.

Yeah thanks I know google translate... I still do not understand your last sentence, even translated in French.

 

[LaunyO]

Do any of you know with certainty a non-magnetic metal that can be use in UHV.

On some websites they say Brass or 304L Stainless steel are good and on others they say that they can be slightly magnetic...

 

[Baluncore]

Do NOT use stainless steel.
Use brass or bronze.

 

[Baluncore]

Pure zinc from electrolytic refinery.
Zinc can be machined, or cast into a high temperature silicon rubber mold.

 

[Vanadium 50]

How much vacuum are we talking about? 10^-7 Pa? 10^-9? Lower?

 

[Nik_2213]

Would NASA or cube-sat sites have advice on compatible non-galling, non-outgassing materials ?

 

[LaunyO]

How much vacuum are we talking about? 10^-7 Pa? 10^-9? Lower?

1 E-8 mbar to 1 E-7 mbar

 

[Vanadium 50]

That's not crazy high (much softer than the LHC vacuum). I'm not an expert, but see no reason 316L stainless wouldn't work.

 

[LaunyO]

That's not crazy high (much softer than the LHC vacuum). I'm not an expert, but see no reason 316L stainless wouldn't work.

Because 316L can be slightly magnetic.

 

[Baluncore]

I'm not an expert, but see no reason 316L stainless wouldn't work.

When you machine non-magnetic stainless steel the surface and the swarf become magnetic. Then the magnetic state changes over time as the crystal structure evolves.

 

[LaunyO]

When you machine non-magnetic stainless steel the surface and the swarf become magnetic. Then the magnetic state changes over time as the crystal structure evolves.

That's why I am not going to use stainless steel at all. I will use brass or beryllium copper.