Cnc Polishing

[wrustle]

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

[EdK]

Russ,

Is there a slope to that tray or is it flat? Interesting pattern the brush leaves.

Ed

[Mayhem]

So - off to Tom for the anodizing?

Interesting process Russ, thanks for posting this.

[Tony Wells]

You can get a lot from using brushes like that. A sub of mine did a lot of plastic mold work for another customer and they had tons of polish work in those molds, because they product comes out a perfect replica of the mold, right down to the feedlines. The used mostly tooling from BRM on theirs, but also some fancy electro-chemical process. I checked into it for deburring some wireways in an unreachable area on some parts I used to make. I had a hollow wand that you used kind of like a mini die grinder, but an electrolyte was pumped out if it and when current passed from the part through the electrolyte back to the wand, a process similar to reverse plating took place and the burrs simply "washed" off, leaving a perfectly smooth, radiused edge.

Your work looks very good. Anodizing will give it a more uniform appearance generally.

[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

[wrustle]

(05-04-2013, 08:35 PM)EdK Wrote: Russ,

Is there a slope to that tray or is it flat? Interesting pattern the brush leaves.

Ed

Hi Ed,

No slope at all, they are indeed flat. The brush toolpath ramps down into the middle and spirals out with the last path being around the edges before ramping up out of the piece. It looks the way it does because of the way the light reflects off the surface, and the flash from the camera really enhances that effect.

Below is a pic of the same piece without the flash and the same view with it.

I always take several shots of each image both with and without flash. Then when viewing full screen on the computer I can choose the best ones and toss the rest.

Every time I take just ONE picture, it's inevitably a tad blurry, or the flash masks a part of the shot I wanted, or an area I really wanted to look good and make "pop" off the screen when viewing is just not happening.

For example the shiny face on the orange anodized piece to the right literally grabs your immediate attention when viewing.

This photo is going on my website for sure!





Here's an example of what I was talking about above.

No flash on this pic.




Same pic with flash.



Best Regards,
Russ

[stevec]

(05-05-2013, 04:29 AM)doubleboost Wrote: Very nice
It is hard to tell what shape it is with the brush marks
John

Pardon my ignorance John but why would you quote wrustle`s entire post just to say what you did?
I don't mean to start anything but just curious.
Steve

[John S.]

We have had good success having the parts bead blasted using peanut shells as a media. Leaves a matt finish that looks nice because it doesn't reflect light.

[wrustle]

(05-04-2013, 10:55 PM)Tony Wells Wrote: You can get a lot from using brushes like that. A sub of mine did a lot of plastic mold work for another customer and they had tons of polish work in those molds, because they product comes out a perfect replica of the mold, right down to the feedlines. The used mostly tooling from BRM on theirs, but also some fancy electro-chemical process. I checked into it for deburring some wireways in an unreachable area on some parts I used to make. I had a hollow wand that you used kind of like a mini die grinder, but an electrolyte was pumped out if it and when current passed from the part through the electrolyte back to the wand, a process similar to reverse plating took place and the burrs simply "washed" off, leaving a perfectly smooth, radiused edge.

Your work looks very good. Anodizing will give it a more uniform appearance generally.

Thanks Tony, and you're right about the anodize, it does "soften" the look of some parts while enhancing it on others.

A lot depends on the type of anodize and the amount of etch (if any) the part endures. A typical commercial anodize will get an etch of about 10-30 seconds depending upon the vendor and how they run their line.

Once a specification is attached to the drawing the process becomes more involved as documented procedures with regard to process and lengths of those processes is adhered too.

Any time you want to have a consistent look and color to any part going for anodize, a specification part will always come back looking the same from any vendor......well, it should anyways, if they're doing their job properly.

Here's a couple of pics of the parts after Clear Anodize. These were done to a Military Specification. MIL-A-8625 Type 2, Class 1.

The silk screened customer name and logo have been edited out.





By requiring the parts to have this specification finish, I can come back, make these parts, and they will look exactly the same as ones done previous from the anodizer.

Here's a link to the specification for those who find this stuff interesting;

http://www.anodizing.org/Publications/bulletin_3.html

Now, here's some other pieces we did for another customer.

These are some (approx. .250" thick x 3" x 3" 6061) aluminum covers that go on the front of some high end 3D Surround Sound Processors by Krell......as in $30K.....yes.....$30,000.00!



These were highly polished and black anodized.

In the picture you have the finished part accompanied by pieces out of the tumbler ready for polishing before anodize.




These were the same part, however these needed to be Clear Anodized and had to have visible grain lines going horizontally across the face to match the grain lines on the face plate of the product. See the link below the picture for the final product view.



http://www.krellonline.com/evolution707.html

Best Regards,
Russ

[EdK]

Gorgeous work Russ!

Ed