Anyone have experience polished lengths of stainless tubing/bar stock?

[Econdron]

I'm looking for ways to do this very quickly. I was told a Timesaver would be the best investment for what I'm doing, and it's been great for brushed finishes, but doesn't give repeatable results trying to get up to a #7 or #8 finish. I'm polishing lengths of stainless bar stock ranging from 1/4" x 2" up to 3/8" x 4". Then tubing ranging from 1x1 up to 3x3 (all square and rectangular sizes in-between).

Currently, we run the material through the Timesaver with a 120 grit belt to take out all the pits and mill finish. Then we run the material through again with a Trizact grit, A160, then A45. That's about all we can do on the Timesaver. Then we're using hand burnishers with small Trizact pads with A16 and finally A6. Then we make what we need to make with the material, then buff with some polishing paste from NuVite.

Results are OK. Scratches still visible, but I haven't had anyone complain. Currently, it takes us about 6-8 man hours to complete an order. Making the equivalent item from steel takes about 45 minutes for reference.

I'm really hoping someone out there has experience with this sort of thing and can either give me some pointers to speed things up, or can tell me I'm doing this all wrong, and can give some detailed advise on what to do differently.

EDIT - I'm currently getting pricing on pre-polished materials, we'll see what that comes back as. I had it quoted before, and it wasn't very cost effective. But that may have been for a one off, I can't remember. Also electro-polishing is not an option. Results look like garbage when done on raw material.

 

[Milland]

Don't some mills offer polished materials? Risk of damage during your processing makes that a no-go?

Have you tried Scotch-Brite belts in the Timesaver? Maybe the extra cushioning would smooth deeper scratches? What's the belt size of your machine?

Heh - you edited your post as I was writing mine.

 

[Econdron]

The Timesaver works great when it works. Comes out nearly perfect. The problem is when we get to the A16 and A6 belts, the belts tend to load up so fast they just smear the surface of the stainless. If we take a lighter cut, it doesn't get the deeper scratches out. Like I said, sometimes it works great, but most of the time it just smears and causes more work, so we stopped using the A16 and A6 belts. It's a 19" model, so belt size is 19x60. I have some of the scotchbrite belts, but I've never tried them during the polishing process. Usually just for brushing aluminum, or smoothing out a rough brushed stainless finish.

 

[Ries]

Where I live, stainless boat railings are a big item.
I have friends who build them, they order all their tubing prepolished, each stick comes wrapped.
But I have never seen square, or flat bar, this way- only round tubing.
They generally have to order a fair amount at a time- 100 sticks, 20' each, or so.
Their regular steelyard gets them in.
Boat rails are generally round, 14 gage or so up to 1/8" wall, in sizes from 3/4" to 1 1/2". Those sizes are pretty commonly available.
They electropolish all the prepolished tubing after assembly.
The electropolish will keep it from rusting in salt water environments, but they use pre-polish, then buff it all out before electropolish.

I have ordered pre-polished plate before- they dont use an ordinary Timesaver- they use a dual head machine like these german ones.
I had 3/8" thick 4'x8' sheets done by a place in San Francisco- it added an extra $500 to the cost per sheet, but, for that project, was well worth i.
FINISHING and DEBURRING


I have gotten good results electropolishing flat bar and square tubing- but only after I sand it first.
I usually just use a 4 1/2" angle grinder, with very fine flap wheel and a very light hand (I usually have to do this myself, not have an employee do it_ then use random orbit sanders with finer and finer grits, then with scotchbrite pads on the random orbits.
I also have scotchbrite belts for a few of my different sized belt sanders, from Klingspor.

Basically, I figure stainless costs five times as much as steel, and thats just fabbing.
Five times total finished price- not five times materials.
Polishing adds a lot more on top of that.

have you tried talking to these guys?
http://www.aaa-metals.com/polishing.html

This bench, for example, is 1/4" x 1" flat bar, electropolished.
The tops, where it tapers and wraps around the round bar, are forged, and the texture up there is as forged, so its rougher. But the main body, that is just flat bar, was just sanded then electropolished, and it looks nice.
I didnt want a high mirror finish- it shows scratches too much, and this is at a high school.
So I stopped at maybe 150 grit on the random orbit, so its a slight matte finish.

 

[Milland]

There might be a lubricant you can use with the sanding to minimize loading and smearing. Check with Timesaver to see if there's anything they recommend, or you could experiment (if you don't mind the mess) with a dilute coolant mix dripped onto the belt. I'm thinking coolant for rust protection of the machine, and the lubricity. A small aquarium pump, a bucket, and a length of perforated plastic tubing for delivery. Maybe a valve to regulate flow.

 

[Econdron]

There might be a lubricant you can use with the sanding to minimize loading and smearing. Check with Timesaver to see if there's anything they recommend, or you could experiment (if you don't mind the mess) with a dilute coolant mix dripped onto the belt. I'm thinking coolant for rust protection of the machine, and the lubricity. A small aquarium pump, a bucket, and a length of perforated plastic tubing for delivery. Maybe a valve to regulate flow.

It's a wet machine. The parts and the belt are soaked with coolant as it runs through, comes out dry through a squeegee system. Though I never thought to check and see if there were different lubricants that were recommend for this application. I'll call and ask.

And Ries, I think you hit the nail on the head with the electropolishing issue. I have to basically polish the parts before sending them out in order for electropolishing to look good. Kinda like chrome plating. It's got a lot of benefit to it for pharmaceutical and saltwater applications, but I don't see it's benefit in my application. My local electro polisher agreed to do a sample piece for me and this was the result:


Definitely shiny, but far from mirror finish.

 

[Milland]

It's a wet machine. The parts and the belt are soaked with coolant as it runs through, comes out dry through a squeegee system. Though I never thought to check and see if there were different lubricants that were recommend for this application. I'll call and ask.

I'll be curious what they say, please update the thread. You mentioned a few belt types you've tried, you could ask some of the belt manufacturers if there's a specific abrasive or coating that would be best for your needs.

It's been ages since I've been in a shop with a Timesaver, and that one was dry.

 

[Whetstone]

We polish a lot of brass and stainless. I have found that there is no way to compete with pre polished if you don't have good buffing equipment. While I don't have a timesaver I do have a stroke sander and a few big belt sanders with grits up to a16.

For stainless under 2" I'll use the Space Saver belt sander to a a16 and then move to a buffer. You will need at least a 5hp buffer and a good selection of wheels/compound to get to a true mirror. As with anything the right prep is everything and if you are not removing all prior scratches with each grit change you will never get great results.

Below is a 6" cube that took at least 5-6 hours to finish. Now we use pre polished and cut finishing in half. Still way too long.

Edit- can't find the image on my phone, I'll post later from my computer.


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[Whetstone]

How long is your longest length?


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[Econdron]

How long is your longest length?


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I guess it's encouraging to know I'm not doing this completely wrong. Brass is easy, I would love if all I had to polish was brass!

And lengths range from 12' to 20', so not really feasible to use conventional buffing equipment.

 

[Whetstone]

Your finished cut to length parts are that long? When we have do do it I usually cut my parts a inch or two longer, sand and buff then cut to length.


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[Whetstone]

If you guys are producing more than a polished table a month you really should look into pre polished.


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[Whetstone]

Here is that cube that took forever. I polished this about a year ago. I've stepped up my polished game since then the mirror frame was a couple months ago and took maybe 2 hours total from rough material to full polish.

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[stephen thomas]

What alloy are you using when a full polish is requested?

I make small hardware items in stainless. 303 sometimes, a lot of 17-4 lately. Only do a matte finish so far (Through scotch brite red). Polish is too sensitive and time consuming.

I have a widebelt sander but don't use it on metal. I have run a dry one on metal in the past. I do use a stroke sander when the parts get large but usually not necessary for my stuff. Scotch brite belts are available for stroke sanders, too.

smt

 

[solidworkscadman]

We have a older beta sander it like a centerless grinder but sanding or polishing.

We do 4" tubing in 10ft legnths

 

[Whetstone]

We have a older beta sander it like a centerless grinder but sanding or polishing.

We do 4" tubing in 10ft legnths

But that's for round tube? It's a lot more difficult to wield a 10' length of square tube.


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