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Spot Welding Machine for MIG Welded Stainless Door

Spot Welding Machine for MIG Welded Stainless Door

Welding Automation for MIG Welded Stainless Door

laser Welding Machine for MIG Welded Stainless Door

Welding Automation for MIG Welded Stainless Door

Welding Automation for MIG Welded Stainless Door

Platform Spot Welding Machine for MIG Welded Stainless Door

Platform Spot Welding Machine for MIG Welded Stainless Door

MIG Welded Stainless Door


Tue, 31 Aug 2021 14:29:29 GMT
I recently finished my first stainless steel door (one of many to come) and had a few questions to ask as well as some (hopefully) useful information to share. Some background on this project:My family is currently in the process of building a meat processing facility for our farm and one of my tasks is the fabrication of stainless  furniture for our new building. The basic design mentality here is to maximize ease of cleaning and long term durability.First, some photos of the finished product installed on it's frame. Some of the pictures are broken in half since the rooms are small and I could not stand far enough back to get a full height image of the door.Hallway side:http://sugarmtnfarm.com/blog/uploade...iewTop0161.jpghttp://sugarmtnfarm.com/blog/uploade...ottom0162w.jpgBathroom side:http://sugarmtnfarm.com/blog/uploade...InTop0206w.jpghttp://sugarmtnfarm.com/blog/uploade...ottom0198w.jpgThe louvre fins:http://sugarmtnfarm.com/blog/uploade...ouvre0176w.jpgHall side handle:http://sugarmtnfarm.com/blog/uploade...leOut0174w.jpgHinges:http://sugarmtnfarm.com/blog/uploade...ngeIn0194w.jpgInside handle with latch bolt:http://sugarmtnfarm.com/blog/uploade...dleIn0185w.jpgThe biggest problem that I encountered while building this door was a slight difference in thermal distortion between one sheet face and the other (inside of room vs outside). I believe this was caused by the fact that I used a thinner sheet of steel on the bathroom side (20 gauge) and a thicker sheet for the hallway (16 gauge). Here is a brief description of the welding process:First, the skins (20 gauge and 16 gauge sheets) were tacked around their perimeter to the already welded structural skeleton (16 gauge x 1" x 1" square tube) and plug welded every 5-inches to this frame of box beams. The square tube frame was argon back-purged whenever it was being welded on.First sheet tacked with 16-gauge 1" square tube structural skeleton still visible:http://sugarmtnfarm.com/blog/uploade...cture0013w.jpgPlug welds with clamped AL angle fixture/heat-sink:http://sugarmtnfarm.com/blog/uploade...amped0023w.jpgEdge welding began with the top and bottom seams by clamping the edges between two aluminum angles (1/4" thick x 3" leg x 3" leg) to act as restraints and heat-sinks. Once preperation was complete, I began making ~4-inch long intermittent welds in mirrored pairs (side by side) to try and balance the distortion. After the first pass of intermittent welds, I sanded the weld ends with a flap disk to assure fusion with the next pass, then went over it again filling in all the sections between my earlier welds to create a fully sealed edge.Picture of bottom edge clamping setup:http://sugarmtnfarm.com/blog/uploade...dEdge0056w.jpgAs I began preparing the door's latch side for welding, I clamped it in a similar fixture, checked with a laser line and adjusted the fixture it so that the long edge was held perfectly straight when I began welding. Again using mirrored pairs of welds as described above. However, after the weld was finished and the clamps were removed, the door appeared to have a 3/16-inch bow in the middle towards the thicker 16 gauge skin side.Now, this particular door does not require a perfectly straight edge, since it does not need to be insulating or air tight. Nevertheless, I attempted to remove the distortion by clamping the edge to a beam of 2x6 boards and then using wooden shims in the middle to bend the edge back to straight.Although I was not able make any progress correcting the bow, it did demonstrate a surprising degree of resilience in the door, since it deflected by a full inch in the opposite direction and continued to spring back to where it began.At this point, I decided to leave the problem alone and focus on how to finish the other long edge, preferably without adding further distortion.I prepared several test pieces designed to mimic the thermal distortion effects on the door. Cladding a 12-inch long square tube (identical to those used in the door skeleton) with a strip of 20 gauge sheet on one side and 16 gauge sheet on the other.Welding on these test pieces consistently displayed the same distortion pattern as I had seen on the door edge. Always bowing towards the 16 gauge side, while the two sides of the square tube without the added sheets generally ended up balanced and straight after all four edges of the tube had been welded.I made several attempts using unbalanced welding sequences to correct for the differing thermal expansion, but was unable to come up with a solution, I think there may be an answer in this direction, but I would need to preform more tests to ferret it out. A pre-distortion, created by clamping the piece in a counter-bowed shape by 1/32" per foot in the opposite direction, was the only solution I have found so far. Using this information, I prepared the last remaining door edge for welding. This edge already had some bowing in it due to distortion from the already-welded edges. While the counter-bow that I applied was not able to bring this line perfectly straight due to it's pre-existing condition, it does seem to have prevented additional distortion, since the edge was left with the same curve after welding as before.Picture of edge clamped and pre-distorted:http://sugarmtnfarm.com/blog/uploade...eDist0066w.jpgThe next door I am planning to build will have the same thickness sheets on both sides, as well as a stronger frame of 2" box beams, so hopefully I will have less difficulty in keeping the edges perfectly aligned.If I had to make another door with different skin thicknesses, I would probably be able to practice on a few test pieces, then pre-distort or change my welding sequence to create something closer to straight edges.On a side note, one useful little trick that I found when making the 16 gauge louvre fins on my homemade sheet metal break was to use a wooden wedge to set the precise angle of folding.http://sugarmtnfarm.com/blog/uploade...eFold0109w.jpghttp://sugarmtnfarm.com/blog/uploade...eFold0110w.jpgI am currently constructing a pair of cabinets for protecting electrical breaker boxes, but after finishing those I intend to begin building my second full size door and would be interested in getting some feedback before I start.Cheers,Will
Reply:Welding that much ss sheet is a bugger, no two ways about it. Only suggestion I could make is design the door with minimal welding. Resistance weld whatever you can. You can also brake the sheets so they fit together like a box, the plug weld them together, then caulk the seams with SS colored silicone. Good luck,
Reply:nice looking work. i like the louvers in the doors. what kind of hinges did you use? do the stainless doors have a mild steel tubing frame and do you think  there's going to be a corrosion problem with the rust exerting pressure on the stainless sheet causing them to bulge and or not close properly?i.u.o.e. # 15queens, ny and sunny fla
Reply:That's a lot of welding for sheets of SS. It doesn't need to be welded solid. Tack the seems and like walker suggested chaulk the rest with SS/Aluminum colored silicone. I did a lot of restraunts in the Casinos in Las Vegas and the industry uses silicone for most seems if the stainless is just the skin and not structual. I would not have plug welded the SS to the frame. Those welds are most likely no longer corosive resistant. Spray some water on it, and see what happens. Next time just lay a bead of silicone or contruction adhesive between the skeleton and SS sheet.For the edges I would have a sheet metal shop brake up some 20ga channel with an I.D. that of the tubing O.D. with 3/8 flanges place these along the border than lay the skin down, tack and silicone. Done.Grinding/Sanding causes a lot of heat too. I have done flat welds on 20ft+ counter tops that were pefectly flat, hit it with the sander and it bowed. The heat from the sander can be used to take the bowing out. Use a worn out sanding pad(fine grit) heat the area annd spray with a water bottle for the side that you want shrunk, the side with the depression. Something like the how the samurais get the curve in their sword.You may what the louvers made as a seperate assembly and screwed/riveted on to allow for cleaning. Just checking, everything that you use for stainless, is only used for stainless right? Like sanders and wire brushes.Last edited by toolbox; 06-03-2014 at 08:51 AM.
Reply:Regarding the materiel used in construction: The entire structure is 304 (304L wherever possible) stainless steel, welded using 308LSi wire.All Abrasives used for finish work are kept exclusively for use on stainless steel only and any clamps have either plastic shoes, aluminum spacers or at the very least, a layer of gorilla tape to reduce the chance of scratches/contamination.The stainless steel hinges are called weld-on bullet or barrel type hinges.http://www.hingesandhardware.com/wel...el_hinges.htmlTwo things that I forgot to mention earlier about this design:We intend to fill many of these doors with a spray-in-place polyurethane foam for insulation and sheet impact support. The doors will be clamped in a flat fixture to prevent bulging while the foam expands.Also, there are a few small slits in the top of the louvre opening and bottom of the door to allow all interior areas to drain moisture and equalize pressure/temperature changes.@Toolbox:Regarding plug welds, I might take your advice about leaving those out next time, however I did sprayed down the door after finish work was done and saw no corrosion problems. Is there something about plug-welds that tends to make them more susceptible?The idea of using intermittent welds with either silicone or epoxy filler does seem to be a common solution in door construction, but from what I have seen the filler is liable to crack and fall out eventually (A big no-no in a sanitized food processing environment) and according to the door manufacturers who offer this feature, fully welded edges are also much more durable, which is another very important attribute for us.Here is one such company:http://www.nvsdoor.com/If I am still having problems with bowing after the next door (with same-gauge skins this time) then I might consider less edge welding. But after all the work of cutting, cleaning, fit-up, etc, welding only intermittently vs welding the entire seam is a very small difference in effort for me and the results (if I can balance the distortion) are beautiful and permanent.Folding both sheets to make a single line for welding would be another interesting possibility, although some of my future doors will need to use thicker sheets (for high impact) and I would not be able to bend those.High pressure hoses using hot water and sanitizing chemicals are planed as our primary cleaning method. Therefore, louvre fins welded in place can be easily sprayed out, whereas the crevices created by screws, rivets and a louvre frame assembly would be impossible to wash thoroughly without removal (which means extra effort each time we clean).I did notice the distortion you mentioned during grinding and finish work, but had not thought of heating+quenching to straighten. I might try that on one of my test pieces and see if I can make it work for me. Although with stainless steel you have to be careful because excessive heat from sanding can also make it more susceptible to corrosion (excessive surface oxide buildup).Thanks for the ideas and feedback.
Reply:The use of silicone is unavoidable. I assume your counters, sinks, wall flashing, walk-in refrigerators will all be made out of stainless. There will be seems that can't be welded, like where a sink butts up againgst the wall or where wall flashings butt/lap. And this is where silicone comes in. I don't see how the can allow it in some areas and not others, ecspecially a door where cross contamination is lower. I've done comercial kitchens in Las Vegas, the worlds leader in dining and processing/handling of foods. That's how they do it. Blah, blah... Anyway, I couldn't find the regulations or code that they reference in their recommendation of a fully welded door.I'm stuck on using silicone. So here's another suggestion. Lap the joints, and silicone both in between the lap and on the edge. This way the silicone is sandwiched in-between and won't come out.I am currently building a stainless toolbox using Tig out of 18ga 304. I too wanted fullly welded edges, just to show off to my buddies. Bad idea, the warping is getting out of hand. I can't imagine the distortion you're getting using mig. I may be using 20-30 amps (machines on 150 with a peddle). Ill post a pic later.As for the plug welds, I assumed the tubing was mild steel and not stainless, and impurities would work its way to the up to the surface.
Reply:Oh I forgot to mention a trick I use while doing flat (butt welds) on counters. Wet a rag and lay it around the few inches about to be welded. Works great. I can get 3ft of welding with little distortion. I just fuse it really quick, it doesn't have to be fully penetrated.
Reply:An interesting idea with the wet-rag heat sink. The aluminum angles that I clamp on either side of my welds are intended to serve a similar purpose while also adding rigidity and I have found them to greatly reduce rippling distortion. Another similar trick that I have sometimes used when the aluminum angles would not fit is a heat-sink paste called Anti-Heat, which is basically a moist clay that can be spread on either side of your weld to absorb heat.http://www.amazon.com/Tempil-Anti-He.../dp/B003T0QKTSA wet rag would probably work too, as long as it will stays in place and does not drip moisture into the weld zone.Last year, I welded up a small stainless cooler which sounds somewhat like your toolbox. I found that using short sections of aluminum angle firmly clamped on either side AND behind the sheets to be welded greatly reduced the distortion ripples. Outside corner welds with this setup generally had very little distortion. Inside corner fillet welds had more problems, but were still much better with the aluminum clamping than without. The setup takes some getting used to and adds prep time, but it definitely helps reduce distortion and keep everything aligned.Since these stainless sheets on the door are clamped tightly to a stainless square tube beam and bracketed by aluminum, the localized rippling distortion has actually been almost nonexistent along the edges, although I did end up with some around the plug welds, which is where I would more readily consider using an adhesive next time. Along the sheet edges, the only distortion problem I have had is a gradual, long distance bow, always towards the thicker 16 gauge side, away from the 20 gauge side both in my tests and as applied in the door.I will probably use an adhesive like you suggested to attach the sheets in the middle of their frame instead of plug-welding. But, I would like to make at-least one more attempt at the fully welded edges, since the distortion is only a simple bow and I am hoping balanced gauge sheets will solve that problem. Before starting the next door, I am planning to weld up some tests on square tube with two 16-gauge sheet strips and will let you know how the results turn out.There are a few places in the building that will need adhesive seals such as sinks and ventilation grates, however we are trying to minimize these as much as we possibly can. Our meat processing facility is actually a bit different in construction from what you may be used to. The entire structure has been built in layers of insulation and reinforced concrete, which will then be sealed with a layer of polyurea (think truck-bed liner materiel). Walk in coolers are concrete rooms with stainless doors, and there are no wall panels or flashing that I am aware of. We have shown our designs to several USDA officials and they have been very enthusiastic about the sanitation advantages of this construction method over conventional wall paneling. Better sanitation design with fewer crevices means lower odds of a recall, less effort to clean and lower maintenance costs.I would be interested in hearing more about your experiences in commercial kitchens and will keep you posted regarding the results of my next experiments on sheet-clad square tube, although I may have a few other projects to finish before I get to those.

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