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Up Topic Welding Industry / General Welding Discussion / Help...mig welding on high vacuum chambers
- - By gonzo (*) Date 05-09-2008 09:54
Need advise....(help)..I'm  trying to make an argument with the president of the
company I work for. I've been welding large and small high vacuum chambers using the gtaw process
and never used mig on the vacuum side or inside of chambers always use the mig for tacks
or frames the owner has hire a supervisor that has promissed to increase production by 40 percent and wants to use mig on
everything and I mean everything ..hes made some coments about welding that has led me to belive that hes blowing hot air
and doesent really know a lot about vacuum welding .and he cant tig to good either but I'm open minded if there's a right way
will you please help me and guide me the right way to discus this polightly ... with the boss. I need to know before the headaches start
I just cant see the benefit sprayarc or mig for vacuum welding ....help
Parent - - By MDG Custom Weld (***) Date 05-09-2008 14:08
I guess it could work if you had the proper welding prodecures and procedure qualifications to back them. 
Parent - - By Lawrence (*****) Date 05-09-2008 14:48 Edited 05-09-2008 15:23
I'm with MDG

I've been consulting with a maker of Stainless vessles who is using procedures with a 1970's date on the paper...  Now they work just fine...  If it worked then it will work now.

However... Technology has certainly improved... and these guys are making GTAW the process of choice on material as thick as 5ga.

There are several power supplies on the market that will run GMAWP on fillets as thin as 18ga with no burn thru at about 5x the production rate as GTAW and quality that will satisfy any code body.

GMAWP can also reduce fillet size in vs spray transfer mode.  Here is an example:
Lets say your drawings call for a 3/16 fillet size but the welders pretty much produce 1/4 inch fillets because it's pretty hard to get stainless to spray small fillets... No big deal right?  it's only a 16th; extra strong eh!

But the increase in weld volume from a 3/16th fillet to a 1/4 in. fillet is 33% !!!!!!!!!!!!

Lot's of folks are paying $300 for a 25lb roll of stainless solid wire...  Thats $12 per pound.

Lets say your company is rather small and only uses 10,000 pounds of wire every year. So $120,000 per year on wire....  Those 1/4 inch fillets cost the company over $39,000 just in filler wire above what they could have spent to make the 3/16 fillets as designed..

It also takes 33% more arc time to make that oversized fillet... Bringing the overhead even higher..

Not to mention the often ignored distortion issues that slow production when fillets are oversized.

Thats money that could be given to you!

Nothin wrong with haveing a listen to the new tech guys with an open mind.......  Make them prove it in trials before you even consider changing practices on the floor...

But know thare are some good things happening with welding power supplies these days and they can have a really big impact on the bottom line *if* they are managed with intellegent process control.
Parent - By gonzo (*) Date 05-11-2008 17:58
thank you lawrence this will help me out in understanding
what it really takes to build the chambers (specially all the wasted welding were doing
once again thank you.....gonzo
Parent - - By 803056 (*****) Date 05-09-2008 14:49
Spray mode transfer is deep penetrating due to its high heat input. As long as you are in the spray mode it should be a viable alternative to manual GTAW.

Quality welds depend on proper preparation and precleaning to ensure welds that will perform as expected. Likewise, it is important to follow a proven welding procedure to ensure the properties are going to meet your expectations.

There is plenty of literature available from manufacturers and AWS to help you get started.

Best regards - Al
Parent - - By MDG Custom Weld (***) Date 05-09-2008 16:23
I think in theory that any process could make an adequate weld on any given application.  Sure some processes are much better suited for certain applications, but they are not the only process that you could use to get the required weld.  This just comes down to proving out how successful any given process is for the application.  That's where procedures and procedure testing comes into play.  You can do it however you want, but you better be able to produce records that show the success level is adequate per the job requirements.

I'm always open to looking at different ways to get the job done faster, but just because someone says they've done it that way before doesn't mean it will work for you.

BTW Lawrence, good analysis on the cost of over welding.  That's a daily battle we fight here, and the welders just have a hard time to understand the overall cost impact.
Parent - - By Lawrence (*****) Date 05-09-2008 17:40
I am addicted to the books of Jack Barckhoff

Jack authored  Total Welding Management and was also a contributing author to Certified Welding Supervisor Manual for Quality and Productivity Improvement

These great works have really informed me when it comes to consulting and process control work.

They are full of excellent proven statistics.
Parent - By darren (***) Date 05-09-2008 19:19
agree with mdg, awsome response lawrence. it definatley slapped me with reality. our shop has a tendency to whatever the drawing calls for as a weld dimension, we put one size bigger so there is no under size weld ncr's by the customer. it must be costing the company a fortune. i will definatley expose the powers that be to these concerns. thanks
darren
Up Topic Welding Industry / General Welding Discussion / Help...mig welding on high vacuum chambers

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