Welding stainless wire - Mass production. Need suggestions.

admin

Here at work we make fire rings out of various sizes of steel wire. Most of the parts that we make are out of 1006 or 1008 steel. However, there is one part that we make that uses 304 stainless steel. The wire diameter is 0.072"The wire is cut to length, bent into a rectangular shape, butt welded, then the weld area is ground and buffed down. Then the entire part is annealed, and sized to the correct diameter which is about 7.750" ID. The ring is then placed into a head gasket and seals the combustion chamber on a large diesel engine.We have to make a lot of these parts and it is very labor intensive. The cutting, welding, and sizing isn't a big deal, but the grinding and buffing is what takes a lot of time. Normally with regular steel we just weld the parts and then the weld area is placed into a small hydraulic press and compressed ("coined") back into the wire. We can't do this with stainless.The problem with stainless is that we need make a very large weld upset (as you can see in the pic) to get a good weld. Otherwise the weld will have a crack in it and fail either in the engine or before it even gets there. We can't "coin" stainless because it's too big and because the weld will not compress back into the wire. The hard weld area will just overlap the wire and cause a leak path. Therefore we are forced to grind off each weld by hand. And as we all know, people make mistakes and grind off too much material.Does anybody know of a way to weld stainless wire with a minimal upset? Can anybody think of a way to grind or remove the large weld from the ring that might eliminate operator error? Any suggestions are greatly appreciated. Attached ImagesLast edited by Carl26; 05-06-2008 at 03:45 PM.Lincoln AC/DC 225/125 Stick Linde HDA-300 MillerMatic DVI MIG Miller Dynasty 200DX Hypertherm Powermax 1000
Reply:More pics Attached ImagesLincoln AC/DC 225/125 Stick Linde HDA-300 MillerMatic DVI MIG Miller Dynasty 200DX Hypertherm Powermax 1000
Reply:You could use a clamp on orbital tig welder, but it will set you back about $23k.  We routinely weld stainless, hastelloy, kovar, and inconel wires to make jet engine igniters.  They range from .060" to .120" dia.
Reply:Do you weld in  a purged environment?  Pure argon.DavidReal world weldin.  When I grow up I want to be a tig weldor.
Reply:Me? No argon or shielding gas.Lincoln AC/DC 225/125 Stick Linde HDA-300 MillerMatic DVI MIG Miller Dynasty 200DX Hypertherm Powermax 1000
Reply:I am not the person to answer, I have never done that type of welding (resistance?), but stainless flows pretty good in pure argon.Might be able to fuse with a TIG.Thats a big freekin diesel.DavidLast edited by David R; 05-06-2008 at 04:48 PM.Real world weldin.  When I grow up I want to be a tig weldor.
Reply:Originally Posted by obewanYou could use a clamp on orbital tig welder, but it will set you back about $23k.  We routinely weld stainless, hastelloy, kovar, and inconel wires to make jet engine igniters.  They range from .060" to .120" dia.
Reply:Originally Posted by David RI am not the person to answer, I have never done that type of welding (resistance?), but stainless flows pretty good in pure argon.Might be able to fuse with a TIG.Thats a big freekin diesel.David
Reply:I am supprised that 304 SS would be any more difficult to resistance upset weld than low carbon steel.    I don't remember that electrical resistance of is very different, maybe higher for SS, but for sure the thermal conductivity of SS is much less than steel, so the heat will stay more concentrated around the joint and maybe this accounts for the different weld.What are the welding parameters you are using for the steel and the SS,  amperage, weld time, force, upset distance?As David R says, you could develop a production TIG fusion process.  The process would involve a fixture which clamped, precisely aligned, and applied pressure to the wire butt joint (similar to your resistance weld clamping maybe), a TIG or plasma torch mounted on a precision retractable pnenuatic slide, and a spot weld timer.  I have butt welded 0.030 SS wires on the bench top by simply holding them in contact and zapping the joint with a split second of current.As far as removing the big resistance weld flash, how about a clam shell tool steel die which clamps around the wire, then the wire and flash is pulled the die?  This would test the strengh of the weld as the flash was trimmed.
Reply:Thanks for the suggestions. Yeah, with low carbon steel I can get away with using much less spring pressure (force) and upset gap. If I remember correctly the heat and time is about the same. When we weld low carbon steel, a good weld is what we call a "bubble" weld. It looks like a small shiny or glossy metal bubble. A bad low carbon weld looks rough and dry similar to the stainless weld above. Except that you can actually see a line or crack in the weld through a magnifying glass.It's weird because stainless is just the opposite. If I try to go with lower spring pressure to make a smaller bubble weld, that weld is not strong at all and will usually break just by bending the wire at the weld. The thing that gets me mad about this whole thing is that we have a solution that will work which has been proven and is something that we do with almost all of our other parts. It is a thin (maybe .006" to .010") stainless steel flange or armor that wraps around the fire ring and gasket. This flange would eliminate the need for the fire ring to be perfect. But for whatever reason the customer is too cheap to do things right. So they would rather have gaskets fail in the field.Lincoln AC/DC 225/125 Stick Linde HDA-300 MillerMatic DVI MIG Miller Dynasty 200DX Hypertherm Powermax 1000
Reply:I spent most of my life solving these type of production problems for my bosses. I solved at least 30 problems like this, and the awnswer will surprise you! I saved THOUSANDS OF DOLLARS.The only thing that kept me going was I enjoyed being creative but when i have to go shopping for food or buy some gas I feel like a fool. While the wealthy get their divided checks i have almost no retirement. The awnswer to your problem IS not welding. The awnswer is to make a metal stamping. Also the ring could be fused with fusion welded when stamped. That is one of the 26 different welding processes.One of the best is in Los Angeles. Pacific metal StampingBut why re invent the wheel? Go to the Thomas Register or Google this and find the ring s pre made.OK....Go here. http://www.salpark.co.uk/products/wire-rings.phpLast edited by Donald Branscom; 05-07-2008 at 03:15 AM.
Reply:Thank you Donald. We will definitely look into those companies.Lincoln AC/DC 225/125 Stick Linde HDA-300 MillerMatic DVI MIG Miller Dynasty 200DX Hypertherm Powermax 1000
Reply:I think TIG would give the strongest smoothest weld.  If you are doing this in high volume, you would not want to use a conventional orbital welder.  You could have a system built that would adapt an orbital tig weld head to your needs.  It would be pricy.  AMET automated welding systems is a company that could build one for you.  It would be a dedicated weld cell with an automated open close and clamp on the weld head.  If  you are going to make thousands, it might be worth the investment, otherwise, you might want to outsource the part and buy it made to print.
Reply:Have you tried a spot welder.  Just hold the two pieces together step on a pedal and Zap.My last job used to use one when building rat cages.
Reply:Just want to point out, the wire Carl is welding is only 0.072" diameter, you will not need an orbital weld head for something this small.
Reply:I suppose the orbital might be overkill for his application.  For our electrodes, it is mandatory to maintain the correct weld profile.  We need 100% weld pen with no necking down.  Our electrodes are subject to a lot of stress and high cycle fatigue.  If they are not full pen, or are necked down, they break.  A break in an electrode weld can destroy a $6 million jet engine.  A weld failure in his seal, might result in a compression leak I suppose.  The best thing to do might be to contact an automation builder.  Maybe a simple stationary spot TIG would in fact do it.  The most complicated thing would be the clamping fixture.
Reply:A Tig arc between 2 tungstens in a gas pocket.  Push the ends of the wire together in the arc. Stainless fuses great.Just tig some filler wire together on the bench to see the idea.  7.2 amps?  DavidReal world weldin.  When I grow up I want to be a tig weldor.
Reply:Originally Posted by partagasHave you tried a spot welder.  Just hold the two pieces together step on a pedal and Zap.My last job used to use one when building rat cages.
Reply:Originally Posted by David RA Tig arc between 2 tungstens in a gas pocket.  Push the ends of the wire together in the arc. Stainless fuses great.Just tig some filler wire together on the bench to see the idea.  7.2 amps?  David
Reply:I'm not completely sure, but I think that these gaskets are used in one of these. Attached ImagesLincoln AC/DC 225/125 Stick Linde HDA-300 MillerMatic DVI MIG Miller Dynasty 200DX Hypertherm Powermax 1000
Reply:That picture would make R.G. LeTourneau happy - even though it does not have his name on it.
Reply:I also agree in a stamping and maybe taper the ends so they overlap then spotweld and do a little cleanup. Just my thought...BobBob WrightSalem, Ohio  Birthplace of the Silver & Deming Drillhttp://groups.yahoo.com/group/southbend10k/http://groups.yahoo.com/group/sawking/1999 Miller MM185 w/ Miller 185 Spoolmate spoolgun
Reply:I TIG Butt welded some 1/16" 308 wire on the bench top today.  Attached are some photos of my third try.  You can see the weld is wide on the top and narrower on the bottom.  It will take a little experimentation to ensure full penetration, but should not be difficult.  The bend specimen is a root bend and had a very slight lack of penetration at the root that opened up a bit.The settings were as follows, I used the start current feature with it's preset very short weld time.Lincoln Invertec 205, DCEN, 1/16" sharp 2% thoriated tungsten, arc gap about 0.020", Argon at 10 CFH, wire ends cut flat and square butted together, joint laid on copper block, start current set at 175 amps, weld time unknow (some fraction of a second preset in welder).This just shows it is feasible, you would need some good fixturing to hold the wires and the torch in position.  You could probably dial in the weld current and time settings in a matter of a few (20) practice welds.http://i56.photobucket.com/albums/g1...p/wire15X3.jpghttp://i56.photobucket.com/albums/g1...p/wire30X4.jpghttp://i56.photobucket.com/albums/g1...rebend15X2.jpg
Reply:Thanks Pulser  David Real world weldin.  When I grow up I want to be a tig weldor.
Reply:Thank you pulser. So it is possible. Very impressive! I'll show those pics to the boss.Last edited by Carl26; 05-07-2008 at 07:53 PM.Lincoln AC/DC 225/125 Stick Linde HDA-300 MillerMatic DVI MIG Miller Dynasty 200DX Hypertherm Powermax 1000Originally Posted by Donald BranscomBut why re invent the wheel? Go to the Thomas Register or Google this and find the rings pre made.OK....Go here. http://www.salpark.co.uk/products/wire-rings.php
Reply:No, I didn't miss it. We will be giving them a call tomorrow. Something tells me that it will cost way too much to ship them from England though. We have been in contact with some other companies here in the States as well.Lincoln AC/DC 225/125 Stick Linde HDA-300 MillerMatic DVI MIG Miller Dynasty 200DX Hypertherm Powermax 1000
Reply:The TIG welds look pretty good.  Almost as good as the ones we make with an orbital.  If it is not under high stress or vibration, it should do fine for your application.  TIG would probably allow you to make welds with no finishing.  Miller makes some pretty good inverter TIGs with simple spot weld timers.  You could probably afford to buy two even and to hit it from two sides.  I don't know how you would interface the two controls to a common start button, but that should not be a big deal.
Reply:Originally Posted by obewanYou could use a clamp on orbital tig welder, but it will set you back about $23k.  We routinely weld stainless, hastelloy, kovar, and inconel wires to make jet engine igniters.  They range from .060" to .120" dia.
Reply:Not sure I can post any pictures.  We basically have a modified/retrofitted small 2inch Hobart orbital weld head.  It is mounted on vertical thompson rail slides, and opens with a pneumatic solenoid.  It is a fully automated push the go button welding fixture.  We weld various sizes from .070" dia up to 1.25" dia.  The small diameters push the limits of the equipment.  We weld around 10-12 amps on the small stuff pulsed 3:1 ratio, and 9-10 ipm.  If we drop the amps any lower, the control is unstable, and we get voltage alarm aborts.  The equipment is not designed to weld anything less than .250 I think, so we have to lie to the control to "fake it out" and force it to do it's job.  The collets work fine on the small dia and are the key to making good welds.
Reply:Originally Posted by obewanWe weld various sizes from .070" dia up to 1.25" dia.  We weld around 10-12 amps on the small stuff pulsed 3:1 ratio, and 9-10 ipm.
Reply:Yes.  12 peak 4 background.   The pulse time is not in %, it is in secs.  We use something like .080 I think.  The rotation speed would be 9ipm if it was a .250 dia.  It is actually different because the part welded is .070" dia.  I would not use a long pulse time for a pps TIG unit if manual welding is planned.  Our operators here can not stand the flashing and use at least 100 pps.  Actually, when we are having trouble with welds being too hot, we push the travel speed up to 12-15ipm.  It really does not take much time on the part at all to weld 1/2 the dia.  We just use the rotation to get a consistent weld around the circumference.Last edited by obewan; 05-08-2008 at 03:55 PM.
Reply:Well,  I got the Linde HDA-300 running and I tried to TIG the parts. This is the first time I've ever TIG welded anything. I used 1/16 tungsten, DCEN, 10 CFH Argon, and about 50-75 amps (not sure). Weld time was controlled by foot pedal, I just barely touched the tungsten to the joint and let go of the pedal. I would say about half a second. If I held the pedal on too long, the part would heat up too much and just fall out. So it is possible. I just need to find a way to control the weld time and automate it. Maybe a new TIG welder.  Attached ImagesLincoln AC/DC 225/125 Stick Linde HDA-300 MillerMatic DVI MIG Miller Dynasty 200DX Hypertherm Powermax 1000
Reply:"I just barely touched the tungsten to the joint and let go of the pedal"You don't want to touch the tunsten to the joint, unless you have have not high frequency unit and have to "scratch start".  Scratch starting on this delicate weld is not the way to go.So, let's assume you have HF start, gas preflow and postflow.Position the tip of the clean sharp tungsten directly over the joint with a very small gap between the tip and the wire, as little as 0.020", no more than about 0.050", and rest the gas cup on the table to steady the torch.Close your eyes and turn your head (you don't need to try to see the weld, it happens too fast anyway), hit the foot pedal to the floor, the gas preflows for a second or two, the arc starts, immediately and fully come off the foot pedal, the arc goes out, the gas continues for postflow, move the torch away, look at the weld and adjust the current as needed for the next weld.If you don't have preflow, you have to hold the torch away from the table, hit the pedal on/off to start the gas, quickly position over the joint while the gas is still flowing, hit the pedal again on/off to make the weld, hold there until the postflow stops.Hitting the foot pedal on/off to control weld time works, but is inaccurate, so you could wire in a timed relay to control weld time, this might cost something like $50 - $80 new.  For that matter, wire in a time delay relay to delay the arc start and provide preflow time.Obviously, for consistent quality in production, you'll have to precisely clamp the wires close to the joint, and fixture the torch precisely over the joint.
Reply:Thanks pulser. My machine does have high frequency, but it was off. So are you saying I should use HF Start? Will that allow me to start an arc without touching part to be welded? Sorry for the dumb questions, I'm totally new to this. I know the machine has a postflow timer, but I'm not sure about preflow. I have the wire clamped in the copper jaws of a butt welder. I can control clamping/butting pressure with the mechanical foot pedal. You would laugh if you saw me. I'm holding down the butt welder pedal with my right foot while I control the TIG with my left foot. I hold my hand against the butt welder to steady the torch. So the torch itself is being held straight ahead; the tungsten is horizontal. I am using an auto-darkening helmet so I can see the whole time. Is a gas cup the same thing as a nozzle?I think I might need to go a little higher with the current because the parts broke at the welds when I bent them. Oh yeah, my tungsten grinder allows me to adjust the angle of the tungsten. What should the angle be for 1/16? I just used 40 deg. I can't remember what kind it is. I think I remember seeing the name Piranha on it.Last edited by Carl26; 05-16-2008 at 07:44 PM.Lincoln AC/DC 225/125 Stick Linde HDA-300 MillerMatic DVI MIG Miller Dynasty 200DX Hypertherm Powermax 1000
Reply:Yes to everything.The arc starts easier with a sharp point, but too sharp and it will melt/spit/degrade faster.Sounds like you have a good clamping setup, now just take care of better gas shielding (preflow/postflow), precise control of torch location and weld time, then dial in the combination of time and current.