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Up Topic Welding Industry / Technical Discussions / Need help choosing process
- - By swsweld (****) Date 03-25-2007 03:28
    I need to find the best process and set up to weld a tube (approx. 1" ID .200 wall thk) to a magnet encased in a steel shell. The magnet is about 5" dia. and 14 gage material. The tube lays paralell to the magnet not perpendicular. There is no PQR or WPS, I will need to develop these. I have a few thousand to assemble so speed is critical but I cannot distort the magnets case or affect the magnets pull. It does not have to be welded full length both sides probably 2" each side, no certian weld size is necessary.I am thinking pulsed GMAW or P GTAW for lowest heat imput. GMAW for speed. We do mostly field pipe work but have this opportunity for this shop work. I also need consistant results so manual welding is not preferred. I have done mechanized welding on pipe in field applications a decade ago but not up to date with mechanized or automated shop equipment to do this project.
    Thanks in advance for any imput.

     SWSWELD 
Parent - - By CWI555 (*****) Date 03-25-2007 03:48
SWS,

The first thing that comes to my mind is the potential for magnetic arc blow given your welding to a magnet. Can you tell us something about the magnets themselves? gauss readings in particular in the areas to be welded, also polarity
Parent - - By swsweld (****) Date 03-25-2007 04:30
CWI555,

A partner w/company used manual GTAW to weld tube to magnet shell. He didn't mention any problems w/arc blow or anything unusual. But he only did one. That is a good thought as arc blow can be big trouble. We were awarded the contract yesterday so we will order about one hundred magnets to do R & D to find the best process ,parameters,etc. We can remove and reinstall magnets if necessary, but do not want to if any way around it. The magnets have an 85 lb pull each. I do not have any more info on mags at the present. I didn't do any leg work for contract. Since we have the job I will be involved now. I can get more info Monday. I have recently obtained my AWS CWI and was going to try to do PQR and WPS for project. We are not required to just think that we need to for several reasons.  I have not been employed as CWI nor do I have experience at this position. Was wondering if this material falls under D1.1 or sheet metal code?

SWS
Parent - - By CWI555 (*****) Date 03-25-2007 05:14
14 gauge is .083" thick. You've mentioned the other being .200" wall.
Underneath 1.2 of D1.1 it states that 1/8" thick and up are applicable to D1.1
Base materials less than 1/8" D1.3  should apply. It later says when used in conjunction with D1.3 conformance with the applicable provisions of this code shall be required. Key words are should apply. and Shall. My interpretation is you will need to cross over both. I am a little more than curious about what form of structural welding code involves welding magnets? Or is it just for exercise?
Parent - By swsweld (****) Date 03-25-2007 16:40
Thanks for help on applicable codes, D1.1 I have  D1.3 I do not.
These magnets are for military use. They are for quick connect and disconnect of the material and or hardware to be attached.

I have used similar magnets (not as powerful) in the nuclear industry to attach fire cloth to a vessel (steam generator, pressurizer,etc) so that welders will not strike an arc on the shell that would require NDE every occurance.

We want to deposit enough weld to hold the magnets to the tube steel, not adversely affect the magnets,  
produce fast and repeatable welds.
Parent - - By billvanderhoof (****) Date 03-26-2007 00:13
If you could somehow get the parts before the magnet is in the case your problem would be solved.  You might even get something for assembling the magnet into the case.
Bill
Parent - - By DaveBoyer (*****) Date 03-26-2007 04:23
Bill makes a good point. By the way, what temperature can the magnets be heated to without degrading them?
Parent - By js55 (*****) Date 03-26-2007 13:41
Dave's on to something here. If you could heat them to above the Curie point you could then weld them. I think. Never done it myself. Where would the Curie point be? Might be pretty high.
Parent - - By ssbn727 (*****) Date 03-26-2007 19:44
Can you show us a rough drawing or sketch at least so we have a better idea as to how the shell is assembled/joined to the magnet and the tube and visa versa???

This might just help us in giving you some better informed suggestions. Btw, type of specific metals would also be helpful.

Respectfully,
Henry
Parent - - By swsweld (****) Date 03-27-2007 02:36
Thanks for the replies.
I will get magnet manufacturer to send specifications and forward info on heat affects on magnets.
The magnet casing will be zinc plated carbon steel and the tube will be carbon steel. Sorry for lack of specific base metals but until I get specs I can only be general on info.

The weld detail will be a double flare bevel groove weld if that helps you visualize the joint configuration. Also if you can imagine a frying pan w/o the handle 5" in diameter, that would be the casing. I have not seen the magnet yet but pretty sure this is accurate.

My partner has done the precontract work but I will be involved now. I will try to get sketch soon. He said the mock up demo weld (manual GTAW) showed no signs of arc blow or magnitism.

I was incorrect on material thickness, both members are less than 1/8". My question is if we do PQR,WPS and WPQR should I buy D1.3 Structural Welding Code Sheet Metal or D9.1 Sheet Metal Welding Code? I'm thinking the latter. Probably no prequalified WPS for this?

As previously stated I'm a new CWI. Many years experience in pipe and steel. 0 in sheet metal. We are a small company and I'm trying to get us headed in the right direction i.e.code compliant. We have no SCWI to oversee things. So your input, ideas and advise is appreciated.

Regards,
Tim
Parent - - By DaveBoyer (*****) Date 03-27-2007 03:09
However You do it, take all the proper precautions regarding the zink fumes. My suggestion about heat and the magnets is coming from the direction of the magnets loosing strength from heat, or becoming detached from the housing from heat. Too much heat ruins magnets.
Parent - - By swsweld (****) Date 03-28-2007 00:23
Thanks for the advise. Still waiting on specs from manufacturer but will do test on magnets after welding to check for strength or cracking. We will try to use a pulsed process to minimize heat imput to magnets. If it can't be done we will see if they can be bought seperately , weld them then adhere the magnets per manufacturers recommendations. Several thousand to do,but better to do that than damage the product.
Parent - - By Sourdough (****) Date 03-28-2007 01:15
very curious about the outcome, this one.
Parent - - By swsweld (****) Date 03-28-2007 02:12
I will update with results when we get some material in to do mock up and R&D.

Leaning towards buying pulse mig for lowest heat imput. Anyone with other thoughts are for equipment are welcome. Probably will call Miller and Lincoln. I'm sure they will be happy to sell us their best product.

Still not sure which code book to buy D1.3 or D9.1 for WPS, etc info.

Thanks
Parent - - By DaveBoyer (*****) Date 03-28-2007 03:08
If considering buying a pulsed MIG You might wamt to look at Ed Craig's website, "WeldReality.com" He has some pretty strong opinions about these machines.
Parent - - By swsweld (****) Date 04-16-2007 03:03 Edited 04-16-2007 03:33
Thanks for the link to Weldreality.com Got a lot of useful info there. Magnets are adversly affected when heated above 400F. I scrapped the idea to weld directly to the casing. I do not want to risk the integrity of the magnet. We will add an additional piece of hardware between the magnet and the tube and preweld those two pieces before attaching them to the magnet. The actual magnet is donut shaped allowing us to use the middle of the magnet for bolt up. 
   The welds are nothing unusual, the only absolute is that we cannot penetrate the I D of the tube. A rod is inserted into the tube and there is very little tolerence. I misstated the wall thickness earlier, it is .065. That is why I thought a pulsed process might be better to have a cooling affect on the puddle. I am much more informed on PGTAW than on PGMAW. However we will be using a GMAW process.
   We are leaning towards getting a Bug o System and putting two mig guns on it and program it for a skip weld sequence. The welds are only 5/8" long but there will be 32,000 welds in six weeks and we want repeatability. Bug o has a carriage that slaves the welding source with the carraige utilizing contactors. i.e. welds the skip sequence without operator initiating and terminating the arc. We need to get equipment this week. Any comments on this set up or weld process are welcome. We are not a large manufacturing shop mostly do field piping jobs.
   I am trying to upload a sketch of this configuration. Hope it helps.

Thanks in advance,
Attachment: magnet.jpg (0B)
Parent - - By DaveBoyer (*****) Date 04-20-2007 05:09
Sounds like You have a pretty good handle on everything, My only concern at this point would be distortion of the tube interfering with the rod, how much clearance is there?
Parent - By swsweld (****) Date 04-21-2007 02:57
We do not have the composite rods that insert into the tubes. I was told it was only .010. We ran some today with the new mig welders and the Bug O system and can make good welds without any distortion on ID as long as the guys don't play with the numbers. Thanks for the thought on the affects of heat on the magnet. Except for the module on the Bug o system arriving damaged (they are sending another one tomorrow) the biggest problem I have now is the lack of burnback on the mig wire. I just added a new post on this topic. I'm glad we have a smart guy or two with the company. Trying to program the Shape Module to do what we need it to do is not for the simple.
Thanks,
Up Topic Welding Industry / Technical Discussions / Need help choosing process

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