Re: ATM Is micro facetting enough?

[Anthony Stillman <atmer@flash.net>]

>I disagree on the statement that there is NO edge effect.


Ken,

I accept your opinion and that it differs from mine.  You are not alone.
However, I stand by my previous post.


>The abrasive (polishing element)

Abrasives roll, fracture and gouge.  Polishing agents are not abrasives.


>.. migrates to the edge of the micro channels and
>is trapped there to perform the polishing action in a more
>agressive way

If this were so, then a thick paste would be more aggressive than a watery
thin suspension.


>Many think that the edges of the micro-channels do the
>majority of the polishing work as the pitch heats a bit more
>at the edge and expands a bit quicker than the facets.

Polishing models which match experimental results show that this is not so.
Assuming a well charged lap, there are basically three things which effect
stock removal: lap area, lap pressure, and the total distance the lap, in
contact, moves relative to the work piece.  Now I'll grant you, if the
facets are concave relative to the substrate, then only the facet edges
contribute to the lap area.  However, this condition will not persist for
long.


>Polishing is more efficient if a small amount
>of detergent is included in the mixture as the bubbles contact
>the glass surface during the strokes.

Detergent drives the pH basic.  The increase in pH is what makes the
polishing more efficient.


Anthony


Anthony