Grinding down and polishing over welds on stainless steel sheet metal

h about welding outside of what information a chapter in my Manufacturing P rocesses textbook gave me. So please keep that in mind if I don't give enou gh information or don't understand the terminology.

doing an internship at a small business. My main job is to get the the mac hines they make built faster. Part of the machine is a stainless steel shee t metal shroud that we have made by another company. They are not made from one piece so there are a few welds on it. Since this is an external compon ent the welds are quite noticeable. The boss wants to make these machines a bit better looking, and part of that involves making the shrouds as shiny as polished chrome. The guys in the shop have been working on grinding down the welds then polishing over them using (insert name of tool that looks l ike an angle grinder but has a drum instead of a disk). I've noticed that t his takes a good amount of time to complete and I was wondering if anyone h ere knew how to accomplish this in an easier, less time consuming method.

A good place to start would be to minimise the number of welds, and to mak e the welds as small & neat as possible - less to grind off. Don't think you can avoid it altogether.

@Phil: As I said it is not something we are doing in house. The shrouds are being made by another company that we have no control over. However that i s something I will suggest to the boss. Perhaps he could talk to our suppli er and try and make them out of fewer pieces of sheet metal. It wouldn't su rprise me though if they couldn't, as you'd need a pretty big water jet cut ter to do so.

The boss wants to make these machines a bit better looking, and part of th at involves making the shrouds as shiny as polished chrome. The guys in the shop have been working on grinding down the welds then polishing over them using (insert name of tool that looks like an angle grinder but has a drum instead of a disk). I've noticed that this takes a good amount of time to complete and I was wondering if anyone here knew how to accomplish this in an easier, less time consuming method.

I would use a flap disc in an angle grinder.

Dan

Since we don't have a picture or even dimensions it is hard to tell you what would work best. If I were you I would contact an abrasive maker and ask for advice. Try Pferd for example. For sure the fastest method will involve different grits of abrasive. You will want to remove as much of the weld as possible as fast as possible without leaving big scratches or overheating the sheetmetal and warping it. Then use progressively finer or less aggressive grinding media to get finer and finer finishes. Merit and Norton may also be able to help. Be prepared to email some pictures of before and after so the abrasive supplier or maker can give you good advice. Eric

Assuming that "you" designed the shroud and are having it manufactured by another company to your specifications it might be possible to redesign it for spot welds rather than a continuous bead of welding, It would look prettier that way, take far less polishing and more important it would take less time to make which I would imagine must be important to the manufacturer.

A simple way to do this is to convert flat butt seams into flanged joints and spotweld the hidden inner side of the flanges. Another is to lengthen and "joggle" one side so they overlap.

jsw

Thanks for the advice guys.

@Gunner: There isn't any way to cover the shroud so that wouldn't work. But what do you mean by 'powder coating'? We don't want to paint the metal oth erwise we wouldn't be polishing it in the first place

@Eric: I haven't used google groups before so I'm still getting used to its features. The weld itself is about a foot long on 1/16 -1/8 thick stainles s steel sheet metal (though there's a good chance I'm off as I can't judge quantitative measurements worth a damn). Already we are using a process lik e you mentioned. However unless you have a row of grinders with the differe nt disks you need in a row in front of you, this process seems pretty time consuming if one has to switch out the disk frequently and to do this proce ss for 4 - 6 welds on just one shroud.

@John: I believe either the company I'm working for designed it, or gave th e supplier the dimensions and had them figure out the best way to have it b uilt. However these shrouds are for concrete floor grinders and polishers s o they take quite a bit of punishment. I don't think a simple spot weld wou ld hold up.

@Jim: For where the shrouds are any flange that would be used to weld the p ieces together would have to be sticking out, making it look worse than it does with just the unpolished weld.

If they only have one grinder then thay should rough grind all the parts first, then medium grind all the parts, then finish grind all the parts. They would probably be better off if they bought a few more grinders. I have two, one for grinding discs and the other for flap discs. It doesn't take very long for the time saved by not changing discs to pay for another grinder. I'm surprised the business owner hasn't realized this. Eric

These are butt welds? Then they damned well better be full penetration welds! Grinding them flush and not full pene will fail. What are the consequences of failure? Better to look at a nice weld, eih?

I have no idea what kind of welds they are. Since the OP hasn't posted links to any pictures, and since the description is vague, the type of weld and the weld quality is anybody's guess. But we here on usenet still try to help as best we can. Eric

On Thursday, May 29, 2014 9:24:17 AM UTC-4, Jim Wilkins wrote: it might be possible to

You might also try to find a vendor that can seam weld. Seam welding is like spot welding in that it is a resistance weld. But continuous. Should be as strong as the metal being welded and look nice.

Dan

Not mine, I read about joggling sheet and angle in a WW2 aircraft fabrication manual. You might know it better as flanging or panel crimping.

jsw