Joining of Stainless Steel Without Welding

Proper welding and finishing can produce a sheet with no visible seams and no rough areas. I don't think any other method can do as well.

I don't think there is any way of butt joining two thin sheets which will have sufficient strength to stop a crack opening up in service.
I think you need to have it welded and the joint ground flat if it has to be seamless.
Del

This is a shot in the dark, but I wonder if you could use silver solder quick enough to prevent burning the substrate.

http://www.youtube.com/watch?v=fV0aLDxlvXk

ye its good but its really difficult and laborious job to get them straight, specially when you cut sheet from shearing machine(as there is a little chance of sheet slip during cutting and its really cumbersome job to grind SS). well still i`ll try it. Aesthetic is important, i have to check availability of this epoxy.

Thanks for guidance :-)

This is exactly what I thought of when I first read this post. It is simple, direct and definitely seamless.

Coil stock is the way to go. Have your supplier stretch it so it will be flat. There will have to be a allowance on both ends of the unrolled stock for the stretcher to grab that will be trimmed off as scrap when finished.

Doug

32' long coil could not be used. Actually SS has to be pasted on 1.5" thick MDF wooden sheet with silicon, so it has to be bend from front to cover the MDF sheet. 32' long sheet could not be bend. Also welding is not a good option as it sometimes cause swelling when Silicon is used.

Expanding on answer #2 (tee hee, see what I did there, expanding... oh never mind)

Assuming a temperature shift of 10 degrees C, you can expect each 8' panel to change it's length by about 0.015" I don't think any rigid adhesive (over such a small area as a butt joint) will hold the plates together. A flexible filler may disguise the gap, but I don't think an adhesive will do it long term... but hey what do I know I just a cat?
Del
_{(A thousand Quatlous on the crack opening up!)}

Like Kramarat said. Use coil stock.

Buy a 10 Ton Coil? Cranes-decoiler!

Cut at lab with Scissors by hand?. All 32' + 2 ends ---in a single piece?

End up with a messy wavy ,bubbly tabletop?

Neat Job?

No!!

Unless the laboratory is at a constant temperature the linear expansion is going to beat you. All that extra length has to go some where and you can bet it will go wrong unless you design it to go where you want it.

What about a design rethink of four tables/benches of 8 foot. Think of the flexibility of lab layout that this could provide in the future. Long Lab benches are a pain if you ever have to relocate.

BAB

The only way is welding, grinding and finishing. 2mm is quite thick for a table top and is easily welded and finished without there being any visible marks. Commercial kitchens are done like this all the time. I run a workshop that does this type of work all the time so I can tell you it does work and is your best option

We just finished a custom kitchen, all stainless, with a 60" wide hood, at the above stove height, by 12' tall with multiple vertical angles, going into a 2' flue--All done with metal cutting, and filled welds--You cannot see a single seam--It all all polished to the same finish, before and after the welds--Three dimensions included--I asked the constructors about the difficulty--"We do this all the time--no big deal"--Take a look at some of your large commercial kitchens---Somebody does these--Do not try to re-invent the wheel--The technology is out there, and it is NOT silicon--

Bend down1" at ends and tackweld the hidden downside ends. Even fasten/screw at ends.Take help of a Press Brake.

7'10"x4=31'-4" -- Should be OK?

I agree with the previous posters: welding and finishing or coil stock.

I think your choice will come down to whether you can have a 32' sheet delivered and installed or whether the top has to be made insitu. If the latter then you'll have to go for the welding and finishing option.

If you want to go for the off-coil option, have a chat with your local steel mill as they'll have the facilities to unroll the material and (probably) cut to length.

Good luck and let us know how it goes.

If you went for coil stock, but had to have the thickness: could you glue two or three sheets on top of each other?

Stock coil is available in 2 mm thick.....we buy it off coil and cut to a specific sheet size for our lasers.

I think the changeover is around the 4 - 5 mm mark, but I could be thinking of something else...

The primary issue with this application is the use of MDF, never a good idea on 32' table. I would suggest the use of double layer interior grade 3/4 BC Plywood. use an epoxy style glue spread with a 16th notch trowel.

Sand the seams of the plywood proir, and back fill the screw holes.

The glue application should keep the joint stable to butt without a weld. You will have expansion in the plywood but the glue will keep it stable and the control of expansion can be dictate by the layering of the double plywood ie; each joint offset and 1/2 the distance. The seams in the metal offset 1/2 from all seams in the plywood, use a silicone bead at the joint only if your joint is not but within the correct tolerance.

Coil seems to be the way to go but whatever method you chose don't forget to also bond a balancing layer to the underside of the MDF or ply to stop it warping.

What type of laboratory? The use of MDF and wood can grow "critters" that may not be wanted in certain laboratory environments.

If you are going to use a MDF base for the table I would use a brand Called Medex made by Plum Creek and then use 3M 5200 sealant to hold the Steel in place. Medex is a water proof type off MDF and the 5200 is a much better sealant than silicon.

Bruce

I did some reading about MDF, and I believe insitu welding is a bad idea.....MDF will release toxic gasses. Welding enough sheets together to get a 32 foot length will not work either.....you will not be able to keep them flat enough to make a useful table top when you try to maneuver it and bond it to the MDF substrate. I think that leaves coil stock as your best bet if you insist on one 32 foot long piece.

So how will you handle a 32 foot long coil or sheet of material?

I ask this because: how do you plan to move it into an existing laboratory? Can you get a 32 foot long piece in existing doorways? That implies you must build in place too, and we have discussed some serious problems with doing that. Even if you get a coiled piece through the doorwys, how will you do the necessary processing to the coil to get it to lay flat?

Why not four 8 foot long tables carefully lined up, with the seams sealed? Much easier to fabricate and move into place, and if edges are not quite aligned, they can be ground smooth and even in place (as long as you do NOT grind the MDF but wear respirtory protection anyway) prior to applying a service-appropriate sealing compound.

Use a sheet roll and s-lock the seams or folded seam and roll flat. This will give you a bit of room for expansion and contraction.

As far as MDF in a lab did you know they still use formaldehyde in the glue. Thats going to be a bit yucky down the road out gassing.

Soft solder would provide a continuous metal bridge with gap filling properties. So would TIG/MIG.

Soft soldering can be performed after gluing to the MDF. The MDF won't burn at soft soldering temperatures. Correct fluxing and strict adherence to surface preparation protocol will provide an easy to implement, reasonably aesthetic and fairly durable joint. It is repairable in situ. Use lead free soft solder if the bench is for food or medicine and such.

TIG/MIG welding has to be done prior to being glued down or you will burn the MDF and glue badly. Achieving really nice welded butt joints can be easily achieved if the two butt ends are clamped onto a conductive rigid backing plate during the welding process. This allows any gaps to pool up with liquid weldment on the first pass on one side. If you use a piece of copper busbar as a backer you may not even have to perform a second pass on the opposite side. Really nice welds. Surface preparation is less critical for welding than soldering. Once finished (grinding et al) it will be almost invisible and as durable as the parent material. It is not repairable in situ but will most likely never need to be.

Is easy disassembly an issue in this application?

If using coil stock, possible problems are 1) difficulty in flattening, and 2) bending any flanges that may be desired, such as down in front and up for backsplash.

Consider this: Use 4 pieces of flat sheet, formed as desired. Beneath the SS seams, rabbet the MDF substrate to accommodate brass or copper back-up bars. You need only a shallow seal weld, not a full-penetration strength weld. The back-up bars will keep the "meat" of the SS from being distorted, and will limit thermal transfer to the MDF. The welds can then be ground/sanded/brushed/polished to be (nearly) invisible, and certainly smooth enough to prevent contamination.

There wont be a temperature issue. it will maintain to room temperature. moreover 32' coil could not be used as it has to be bend from front and also from the back.

@Tornado: hmm sounds good. will c if its possible for us.

Hello Shoaib:

A 32' long table sounds serious enough for a lab spending the money necessary to aquire it, contact these guys and have them modify their designs to fit your needs.

Don't be cheap, you're not stablishing a crapy meth lab, are you?

Regards

It's really begging for a nice mechanical flush jointing system IMO.

The practicalities of fabrication, transport and getting it into the room and possibly out again should be considered.

It wouldn't be the first bit of in situ stainless jointing that's been done. Plenty of it around the place. The successful ones weren't done on the cheap either, your right there.

Look, it if it was a meth lab then the cost would be irrelevant. Itwouldjusthavetobedonefast.

Time for developing the electrically morphing metals? that might be another approach.

But you're correct, specially your last sentence.

Route for draw bolts on the underside of the mdf and join the ends to be seamed with a spline joint.

Sand smooth with a belt sander, then laminate the steel sheets to the mdf with contact cement.

This can then be taken apart for transport, and re-assembled in the field.

Once again as I stated at the start the weak link here is the MDF it would be good to loose this plan, once you choose the correct substrate, you can fit it as you.....see fit...