Surface finish for glass

[vidon]

I have a question- my company is producing with measurement glass that has to be grinded very precisely. Now I've measured that we need additional treatment to get from 15 um (0,015 mm) to 10um (0,01 mm) without doing any damage to the surface. We are talking about mass production - this isnt a one time job.
What kind of surface treatment do you recommend. The only thing I came up was etching, but frankly I just dont like the idea.

Thanks

Vid Golob
Research and developement
Iskra Tela d.d.
Cesta dveh cesarjev 403
1000 Ljubljana
Slovenia

 

[ykee]

Have you tried fluid jet polishing? Something like what these guys have might work, depending on what your throughout requirement etc. are.

http://www.lightmachinery.com/Fluid-Jet-Polishing.html

 

[IRstuff]

What kind of overall flatness?

TTFN

FAQ731-376

 

[vidon]

Within +/- 10 um (0,01 mm).

 

[vidon]

One more thing - length is 2000 mm.

 

[IRstuff]

A conventional optical grinding/polishing machine can handle that size.

How many per day do you need?

TTFN

FAQ731-376

 

[vidon]

About 10-15 per day - it takes us about half hour to do one right now

 

[IRstuff]

Well, truth be told, optical polish seems to be gross overkill, since the objective to achieve submicron roughness.

Fluid jet likewise seems to be overkill, but there are examples of large subtrates, but not quite the level you're talking about:

http://www.qedmrf.com/orgMain.asp?orgid=338&storyTypeID=&sid=&

TTFN

FAQ731-376

 

[vidon]

I couldnt agree more. I tried to tell my boss that the problem lies with the glass we originally get, but he seems to disagree so I have to find a diferent solution. thanks anyway

 

[IRstuff]

I am confused by how you manage to get glass that has 15 um roughness. Seems to me that it should almost be impossible to get that. Standard window glass has sufficient smoothness to make reflections, which requires way better than 15 um roughness.

TTFN

FAQ731-376

 

[vidon]

Heres the thing - we grind the glass to get 15 um roughness.
But for our buyer that just isnt enough - this glass serves as reading glass ( sort of a pathway ) for a measuring device which means that a reading unit is driving on it and that reading unit requires +/- 10 um roughness.
Before you ask - I dont know why they dont change the reading device etc.

 

[IRstuff]

My perplexion wasn't about your grinding, but how you could buy glass that was rougher than that.

Again, standard window glass is way smoother than that, why not use that?

TTFN

FAQ731-376

 

[vidon]

Standard window glass wont do because we put chrome into glass (lets say its in the middle of it) so our glass is custom made ( only with the addition of chrome is this glass proper reading glass ). Because no glasshouse in our country can provide this kind of service, it is done in a laboratory. I think the problem lies there, but it looks like were going to have to live with that and find another solution.

 

[IRstuff]

OK, but why can't you get this lab and a suitable manufacturer to convert it into a viable production process?

TTFN

FAQ731-376