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Linear Stages Working in Vaccum 1Bar

06/27/2015 7:15 AM

There are 3 stages X and Y combined. Z axes separate. All motorised by stepper motors. Load remains same and working cycle also same. Now whole system is enclosed In a chamber. During the working cycle air is sucked and vaccum is created to 1 bar.

Do we have to change motor holding torque? Reduce or increase.

Can lubrication in linear guide n ball screw interfere vaccum process? What shall be the solution for lubrication In vaccum?

What sensors are recommended?

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#1

Re: Linear stages working in vaccum 1bar

06/27/2015 7:32 AM

I am working on a modification to a similar system - X, Y, Z and rotation stages operating at 10-6 Torr. Stages supplied by Thor Labs. Motor torque not affected. Lubrication may be a problem if you need a very "pure" hard vacuum - suggest you contact the stage suppliers.

Mechanical contact switches or maybe Hall effect sensors for limits. The Thor Labs products include incremental encoders, which work fine, but I don't know what technology they employ.

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#5
In reply to #1

Re: Linear stages working in vaccum 1bar

06/27/2015 11:34 AM

Thanks a lot For getting my views cleared.

And feel more confident to go about my project.

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#2

Re: Linear stages working in vaccum 1bar

06/27/2015 8:31 AM

There are a few lubricants (Apiezon) rated to work in vacuum. They are mostly intended to fill voids in attachment screws and gasket seals not the large surface areas of a stage screw. However, 1 bar is not much of a vacuum when one considers 1.01325 bar is atmospheric pressure.

As for the current in your motors if you use high vacuum grade motors that are designed to handle bake out temperatures you probably will not have to change your current settings. If you are using a stepping motor designed for mostly air cooling then reducing your current is probably a good idea. Reducing the running current may cause steps to be lost if you do not change your acceleration profile. Depending on how intelligent your software (closed loop, dynamic current, etc.) this maybe trivial to compensate or impossible.

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#4
In reply to #2

Re: Linear stages working in vaccum 1bar

06/27/2015 9:08 AM

I was assuming that the OP meant "-1 bar g". As you point out, 1 bar absolute can't really be called a vacuum. Clarification from the OP would be nice.

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#6
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Re: Linear stages working in vaccum 1bar

06/27/2015 11:44 AM

Thanks a lot. Please give manufacturer name.

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#7
In reply to #6

Re: Linear stages working in vacuum 1bar

06/27/2015 1:06 PM

Of what? The grease! The underlined blue word is a hyperlink. If you click on it...

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#8
In reply to #2

Re: Linear stages working in vaccum 1bar

06/29/2015 9:37 AM

Please give the lubricant manufacturers name.

Thanks for your apt reply.

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#9
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Re: Linear stages working in vaccum 1bar

06/29/2015 9:41 AM

Thanks. I got the site and details.

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#3

Re: Linear stages working in vaccum 1bar

06/27/2015 9:04 AM

look up prevention of vacuum self welding This was noticed with certain metals in orbit in the 60's.

Adsorbed air and water would desorb in the vacuum and if those metals touched they would contact weld. Under thermal cycling some of the oils used as lubricants would also evaporate. A large area, like a nut and thread, could impede operation, if welded.

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