[bebob1]

Im trying to make Al alloy molds with small 0.01" and smaller features. The depth can also be equally small. I want to be able to have the mold be essentially mirror finished and smooth so I can cast clear plastic and that it remains optically transparent.

However I cant use conventional methods like use a buffing wheel etc that you can do on larger mold parts.

So whats the way to get good mirror finishes on these molds?

Also critical is that I want the mold to maintain geometry, e.g. 90degree straight edges should remain 90 degree after polishing, so say buffing techniques are sometimes not suitable because they round out edges.

[txcncman]

What do you consider a mirror finish in numbers? 16 RMS?

Yes, you can polish features as small as 0.010". There are tools made for doing it.

Have you considered burnishing?

You location is listed as "c". Where is "c"?

[underthetire]

We routinely do small profile stuff with less than an 8 finish. Sometimes even in sub nano finishes. All depends on the machine, tooling, and the guy running it. Just cause the part is mirror, doesn't mean the finish is actually good btw.