Brush finishing aluminum tubing in quantity

[mxtras]

I have a nearly constant need to surface finish ("brush") quite a quantity of rectangular extruded aluminum tubing.

The method currently employed is to use three pads of relatively coarse Scotch-Brite edge clamped to a flat surface and then the cut lengths of tubing are manually rubbed back and forth - about 8-12 times per side to achieve the desired finish. This method is effective but requires a lot of time and labor, as you can imagine. The finish it leaves is what I am after but there has to be a better way to go.

I am looking to either mechanize or automate the process in a cost effective way. I need to be able to 'brush' all sides of pieces that range from a few inches to about 36" long with a uniform finish.

My current thought is to mechanize a small table that will oscillate in a straight line - not randomly - to basically duplicate exactly what I am currently doing. I want the brushed look, not the random appearance produced by a DA mechanism.

The use of something like a belt sander with a Scotch Brite belt is a possibility, but I think the contact patch is too small to eliminate the witness marks of inconsistant manual motion, so it too would have to be mechanized. Attempts in the past were less than successful - small pieces are very difficult and many times end up on the floor several feet away.

A motorized, oscillating table will save quite a bit of time and effort but might not be the ultimate solution but unless a better idea comes and smacks me in the face, it's the direction I am heading.

So, before I begin construction of this oscillating contraption, I wanted to see if any of you have any better ideas?

How are aluminum pieces brush finished in industry?



Scott

[mxtras]

Another idea just rushed through my foggy mind -

I could stack 4 or 6 of the pictured discs on a rotating shaft and use a motorized traction conveyor to shuttle the pieces under or over the spinning wheels.

The issue would be how to accomodate the differing heights of the tubing - the switch from one dimension to the next would have to be quick and reliable which would add some complexity. These wheels are also a bit pricey.

Another issue would be that the leading edge of the tubing would have to be at least clipped in place to keep the disc from grabbing it - many of the pieces are mitered so the leading edges might present a problem. I could poisition a leading edge clip or ledge on the belt to rectify this but again, it's adding a bit of complexity. I would also be concerned about balancing issues and wheel life.

Still thinking....

Scott

[mxtras]

Here is a decent looking piece of equipment that is in the ballpark:

http://www.millermotorsports.com/mbo...ead.php?t=6753

Scott

[Sparky John]

Think of this as a poor man's Timesaver. Check out:

http://www.max-ind.com/m_catalog9.asp

[mxtras]

Thanks for the link, I had not run across that site.

Obviously not a popular topic.......

I think I have chosen a direction. Follow up shortly.

Scott

[mxtras]

After reviewing all of the replies to this thread , I have formulated a direction.

Now, if you guys are really, really, super nice to me I will share details of the machine as it is being constructed.



I was hoping for a little more input but the input recieved so far was helpful in selecting a direction - which is many times the most difficult part of any task.

More later..

Scott

[Unabiker]

I've obtained a pretty nice brushed looking finish on aluminum using a pneumatic body file like this: http://www.harborfreight.com/cpi/cta...emnumber=91773
I used a roll of this: http://www.wttool.com/product-exec/p..._Sanding_Rolls

The finish left was pretty nice. The down side is that the body file is pretty loud, and my little old air compressor couldn't keep up very long. If you're work bench is of normal height, you'll end up with a black belly, too.

[mxtras]

Ok. Another thought has crossed my congested grey matter:

I refuse to spend $4K for a fairly simple machine when I could easily construct it for $5k.



I am now thinking about utilizing a stainless, rotary brush or two. I am just now digging into it (cost and complexity), but I am thinking of setting up a tunnel arrangement with a powered conveyor or traction roller feed and "brushing" two surfaces of the rectangular tubing per pass.

This thread needs a bit more enthusiasm, guys......

Any other thoughts?

Scott

[Stuff-Builder]

Hey Scott,

I've pondered doing the same thing myself, from time to time.

What if you started a fine abrasive sleeve like p/n 4657A34 from McMaster. You could set one pair vertically to do the sides of your material, and one pair horizontally down the way a little to do the top and bottom. If you mounted these to spring loaded arms then they could open or close to accomodate different sized stock. Finish could be adjusted by changing the abrasive type and the spring pressure.

As far as feeding goes, you could probably either push the part through by hand or use a pneumatic cylinder to push the tube. A set of drive rollers would work too - perhaps one set in front of the sanding sleeves and one on the other side. Kind of a push-pull arrangement.

I hope that helps some!

(Another) Scott

[mxtras]

I have tried the air file (straight line sander) as suggested by Unibiker several years ago and gave up on it - I think I am going to dust it off and try it again.

I am still undecided. I had given some thought into the sanding drums using a pneumatic bladder - not only would this allow the abrasive drum to be changed quickly, but this would also allow contour of the belt contact patch to be adjusted (I think). I am just not sure I really want to sand the material for fear of losing thickness. I guess that's a function of the grit and pressure. Might need to play with that a bit..... And I might try a Scotch Brite drum - depending on availabilty of similar sizes as sanding drums - I don't want to invest a bazillion bucks in bladders.

The wire brush method is a definate no-go. The finish it leaves is not what I am looking for - i did a test this evening and was not happy with the results. The surface is left very open and rough - it snags cloth and leaves the surface fuzzy. Not good. Not to mention, the brushes are a bit pricey.

For now, I am going to continue to use an electric DA with a Scotch brite pad. The finish it leaves is not all that bad and it doesn't take long to achieve a randomly uniform appearance that does a good job of hiding imperfections. It also doesn't make all that much dust. The finish it leaves looks like the finish left on aluminum parts that have been tumbled. Heck - the appearance is beggining to really grow on me now - especially after having such a difficult time choosing a direction on how to get the brushed finish. Once the method is selected, I then feel the need to at least partially automate the procedure.

If anyone has any addition things that they think I should try, please contribute and save my sanity. Thank you. Thank you very much.

Scott

[mxtras]

Originally Posted by Stuff-Builder Hey Scott, .....As far as feeding goes, you could probably either push the part through by hand or use a pneumatic cylinder to push the tube. A set of drive rollers would work too - perhaps one set in front of the sanding sleeves and one on the other side. Kind of a push-pull arrangement. I hope that helps some! (Another) Scott

Yup! Having the ability to run the tubing through a process once and finish all sides simultaneously has some major advantages that would justify spending the time to figure out the arrangement.

Scott

[Mitsui Seiki]

See if these guys have what you are looking for.

http://www.weilercorp.com/