Cnc Polishing

[doubleboost]

(05-04-2013, 07:37 PM)wrustle Wrote: This was something I have never done before (Cnc polishing, and no....it's NOT and ethnic thing!), but when your biggest customer tells you "We don't want tool marks in the pocket", you find a way to satisfy them!

So......we set out to do just that.

This was a prototype piece we made for our customer.

The part is roughly .750" x 6" x 8.400" lg. 6061 aluminum.

The pocket is .250" deep and 5.700" x 7.780" lg.





When you look at the picture, you think to yourself (well at least I do) that looks really rough, when in fact it is actually flat within .001".

The problem is though, my customer, after seeing the prototype, does NOT like the looks of the toolmarks as it is a visible surface to the end user (lab technician) and aesthetics are just as important as tolerance when it comes to laboratory equipment.

Sooooo......customer says, ok.....we approve the design, let's make 50 units......but no tool marks in the pocket.

Ummm......that's cool, and glad we got the order but,....how the hell am I supposed to do that?? Ok, just thinking out loud there.......you ALWAYS want to give your customer the impression you can walk on water for them.......however, if you tell them you can, you best be able to back it up.

So, I made some phone calls, talked with my tool rep., posed this very question on another forum......"How do I mechanically polish the floor of a pocket to remove tool marks?"

Well, someone somewhere knew exactly what I needed to do and got me turned and headed in the right direction.

Placed a call to a couple different brush manufacturers and got in some tools to try out.

Ended up going with an Osborn Brush (mfr) which is a Nylon brush infused with silicon carbide.

For the pocket shown above we used a 2" brush.

Though it would not get into the corners entirely, the finish tool path around the perimeter of the pocket was done with a .500" Carbide EM so no need to get all the way into the corners with the brush.

Here's a pic of the brushes. A 2" brush and a 1" brush for doing the multi-pocket opposite side.




Here's a picture of the 2" brush all mounted up in the tool holder ready to go!




Here you can see two of the parts in the machine all finished to size and depth just needing to be polished.




In this pic the Osborn is working its magic......we hope anyways!

Not a fast process by any stretch of the imagination.

2,500 RPM 18 IPM .020" DOC




But as you can see the results are outstanding!!

Pockets polished to remove toolmarks. Don't let the brush tool path fool you......it is smooth as glass!!




Here's a pic of the backside all finished up.






More pics of the front all completed. Next stop, clear anodize.





I was very happy with the outcome and my customer was especially happy......a win, win for sure!!

Best Regards,
Russ

Very nice
It is hard to tell what shape it is with the brush marks
John