Post By hobbyman
Post By Ciszewski
Post By dave powelson
Post By SND
Lack of MIG Fusion on Small Parts & Shop Attitude
We are a custom machine builder shop with Fabrication and Machining capabilities.
Been seeing a problem with the Mig welds on the smaller parts.
MIGs is 250 amp 3 phase machines.
Steel is A36, cut on plasma table.
Welds not adhering on the edges.
Fabricators (that weld) usually running the machines in short-arc mode.
Fillet welds. Gas is 75-25.
The Mill Scale is NOT ground off the pieces before welding.
I highly suspect this is the root of the adhesion problem.
You can take a razor blade and pick at the edges of the weld that do not adhere to the plate.
The real problem seems like a culture problem.
The pieces with the weld problems are not life critical.
The shop is busy.
There is time to BS and goof off.
I was told there was no time to grind off the mill scale.
Historically I have seen there is no time for the fabricators to grind off the Mig spatter.
The paint department does not think it is their job to clean Mig spatter.
So we make parts and paint over the Mig spatter.
In many cases, this seems acceptable.
So I am asking a Welding question and a Shop management question.
How can I get our shop culture to care about weld prep?
I am an engineer who has some say in part quality.
The shop manager does a pretty good job of things,
but changing shop attitudes on issues of having a quality mindset
is a monumental task, and I can't expect him to go it alone.
Any advice? I know it is a difficult subject. Thanks.
Oh boy ... changing attitudes is very difficult once a particular culture has been setup. One thing I will say though, it has to start at the top and it absolutely cannot be a "do as I say not as I do" thing. The guys at the shop level must see the guys in the office taking it to heart FIRST - as in it pertaining to their own job functions. If they come out on the shop floor and start acting in a condescending way forget it.
I agree with Joe - you have your hands full to change both attitude and acceptable welding practice. You don't say what material thickness that you typically weld, but in my experience, you should not have to grind off normal mill scale or typical oxy-fuel / plasma dross. I assume by your mention of short arc mode that you are dealing with thin stock, say 1/8" or less. If your weld parameters are correct (wire size, wire speed, gas mixture, voltage, travel speed, wire stick-out, wire angle and position, etc) for the material and position in which you are welding, you should be able to easily obtain 100% fusion in all but exceptional circumstances. Also, excessive spatter should not be a problem if you are welding new material and all your parameters are correct.
If I were to guess, your welders have learned "short cuts" to increase speed at the expense of sound welds. Changing that will require someone in authority, ideally someone who already has the professional respect of your welders, to become very knowledgeable about the welding that you do and determine the root cause of your problems. The solution will likely require a combination of teaching your welders and very close but sustained supervision and QC, among other things. Somehow, your welders must be made to believe and accept that their job is to make sound welds, every time, all the time. If they don't already have them, the welders must be given the right knowledge, right equipment, proper procedures, adequate time and a sense of responsibility to make consistently good welds. The latter will likely be the toughest given the conditions that you describe.
As Joe correctly points out, it will take someone (several someones) to get serious about it, consistently demonstrate that they are really serious and get right in there with the welders to show the company's commitment. The latter is the hardest part. My guess would be that there are some peer leaders within the welders that could become part of the solution if the situation is handled right. If the lack of fusion and spatter are really a problem for your product, you should be able to clearly demonstrate it through sectioning samples to show the problem and/or bending the welds.
Additionally, my personal view is that spatter and/or its removal is part of the welding operation. If it is a problem and needs to be removed, the welding operation is not complete until that is performed. Sounds like you have finger pointing between the welders and the painters - I would put the onus on the welders to completer their operation. If you don't have some clearly defined standards for all aspects of the welding, those should be developed and become the baseline. They don't have to be especially detailed but cannot be entirely left up to the welder's judgement.
Change gas to a high argon mix designed for spray transfer. That will allow an huge increase in heat as well as eliminating spatter. Using higher amperage and voltage in spray transfer will get rid of cold lap and make the job go faster. Short circuit transfer is for light gauge work and out of position..... or for welders who want to stretch their time out.
tell them your going to switch to flux core and they will have to clean up slag instead of mill scale and mig splatter. that should get them more excited about prepping the parts properly.
What material thickness ?
Hobbyman summed it up pretty good.
Here should be an attached pix of a spray weld I did last night, material thickness
.216 for the pipe. Note lack of spatter, but good tie in.
Personally, I would call in Ed Craig (weldreality.com) and pay for a visit the shop.
Fire the lot of them & hire a crew that takes pride in the work that they do.
Steel MIG in shop with no process controls?
1-What various thicknesses are you using?
2-If the toes have LOF (lack of fusion), it's pretty certain that the inside
corner of fillets will have LOF. You can verify this by sawing thru sections,
rough, finish sand and halfway polish with fibertex to SEE what's what.
It's wholly easy to still have LOF when spraying, pulse spraying, using flux core or dual shield, depending on parameters, thicknesses, fitup, torch attitude, etc.
3-LOF is highly common in mfg.--and is ignored.....until field failures point this out.
Management addresses the issues either on the shop floor or in the courtroom.
You need to establish some process controls, procedures, qualifications.
4-The prepping of steel is a no-brainer, comes with the job. Welder machine selection,
welder parameters, gas selection, consumables, splatter control, etc.---are a management area. 20 years ago, I bought Ed Craig's book and video on steel
MIG machine setup and applications--had every welder in the shop, watch it,
study and discuss. That took the controversy and individual quirks out of how
we were going to setup and run. Saves time, money, hassle.
Craig and his current biz-Weld Reality is a good, unbiased place to start,
as opposed to an LWS (local welding supply) who will gladly sell you gas, consumables,
and equipment--that still may not do what you really need done.
Doozer, if the shop manager does a good job and they are a busy shop, just what really is your position and relevance in all this ? Does shop ownership and the shop manager agree with your thoughts ?
Alot of production fab stuff is sold across the world just as you described----- if it sells why spend more time and money ? Not bashing you--- just trying to read WHY things need to change and for what reasons ?
Have a manufacturing and weld procedure that has to be stuck to, anyone who doesn't agree and wants to keep doing it half assed gets fired.
Anyone who doesn't want to do a little extra and fix the things that slip(spatter and such) to make sure the final product is perfect, fire them too.
It's a big problem when everyone sees an issue and nobody thinks it their responsibility to fix it and it goes out wrong.
OK- My involvement in the quality side of this.
Company I work for is owned and makes machines for a large international company.
Engineering (I am part of engineering) is part of this larger company.
My boss's objective is to reform the old ways of the shop and make us would class, like the rest of the company.
One of my (multi-year) objectives is to help organize things and lead the way in establishing what world class manufacturing is.
Right the first time is part of this. Like engineering (good drawings) and the shop (good quality machinery and parts). Lots of things contribute to this. Good packing and shipping, projects done on time and on budget, so many things that make a business first class. The shop manager is very knowledgeable in mechanical things, and we often collaborate on machine issues, shop issues, and people issues. And of course everyone needs to have a part in quality. So are some of the reasons I am interested in helping figure out this welding issue.
The shop manager was out this week, so I am starting on this weld issue myself. I asked our fabricator in the shop, who is our dye penatrant weld inspector to look at the welds. He agrees lack of fusion. The attitude part of what I received was that some welds have always been like this, and no time to prep the parts (but time to BS).
The steel is 1/4 to 3/8" thick mostly. The 1/2" steel they seem to burn in pretty well.
I forgot about Ed Graig. That is a good idea.
I talked to my direct boss abut the weld situation, and since our company is so large, we have our own learning school. He suggested we send some of the weldors to our training school and use company resources that way. Ed Craig's video might be a start though. As to changing the culture, I am working with the shop manager on that. It seems sometimes my job is more working with people than working with engineering and drawings.
PS- I like the 85-15% gas idea.
Sound to me like the welders are dragging the weld bead downhill (down hand ) . Bead will look great but not have any penetration and is real fast to do just my opinion . Someone needs to set up a weld procedure and set weld parameters , if set up correctly there will be no need to grind weld spatter there won't be any. Short arc,Spray, pulsed spray , gas shielded , gas-less flux core, if parameters are correct and procedures are adhered to LOF or spatter will be a non Issue. Only my opinion only been doing this for thirty odd years seen all the "Shortcuts and time-savers "
getting dialed in
1-To repeat--the only way to check for fusion is to slice thru, rough polish the coupons--
Originally Posted by Doozer
--that's the way the grownups do it. Takes maybe 2 minutes. A weld looking like it's 'burned-in'
pretty good, even in spray can easily have LOF in the fillet, etc.
If you really intend on becoming 'world class', it's going to take some studied, documented effort on
your part, which has been outlined by myself and others.
2-84 Ar-16 CO2, aka 'steelmix'--airgas brand was a mix developed by Ed Craig for Airgas.
It's a compromise between 75-25 and higher Argon content mixes, allows for both spray and short arc. You probably would be better served by using a spray mix of higher Argon content---but
first you need to outline and document your own, in shop problems/practices with some drudgery
work on coupons.
There's a decent amount of free info on Craig's website--some of which may be wholly contrary
to the opines of your in house experts. Craig focuses on cost effectiveness--not glitz; and
he can be rather hard-nosed about that--telling one things they need to hear but don't wish to hear!
Were i am currently has a zero tolerance for parts with splatter leaving the shop. Its easily achieved with good mig settings, the right gas use of a good anti splatter spray (what little splatter there is chips of easy not ground off :-) and some skill on the welders part. Im no welder but mig is easy. Problem comes with welding down hill. If your settings are right you can do it and make a perfectly sound weld. If you don't know what your doing you can lay a bead of metal that will damn near fall off! Problem is they will both look good unless you know what to look for. Lack of joint cleanliness makes a technique that's already border line worse, a lot worse.
Changing these attitudes is hard. But if you want to ship better product you need to. If you want to complain about the Chinese undercutting you in cost, you at least need to better them in quality!
Making good welds, making clean welds does not need to take much if any extra time. Removing all the splatter on a properly prepared and weld splatter release pre sprayed weld is like two swipes running a cold chisel up and down the work piece. Say 3 seconds of weld splatter spray a foot of weld and anouther 3 secounds to swipe the cissel along. Easily sub 10 seconds per foot of weld.
Previous postings have covered the welding pretty well, although I'm not fond of spray arc for 1/4 to 3/8 thick workpieces. Thats a lot of heat for a small part and may lead to more warping. As far as cleaning spatter, my favorite tool is a masons or cement chisel. At 4" wide, it covers a lot of spatter in one swipe.
Ahhh...now more info comes out.
I wouldn't worry about gas mixes, uphand, down hill or anything.
The culture needs changed (as posted above) to WANT to provide
The fact the weld whop is internal to a machine design shop that's internal
to a large international leads me to this.
The next job that comes thru the shop, farm it out to a local job welding shop.
There are so many welding job shops around, that will go from "art to part",
Some in Erie (specializing in very heavy fab) get business from around
your area. Custom Engineering, Erie press to name a few.
Not the machining part, JUST the welding part. (if machinist's arent' part of the problem,
no reason to punish them)
Have the weldment brought in to the machining department, and make sure
the internal welders see it, know what the cost's vs internal welders cost's, and how much
better the job is.
In my experience threats and negative things will make things worse what helps is some competition
Perhaps a bonus for the team that produces the best weld every week in a competition voted on by all.
Also if the welders want better weld prep maybe you need to help them.
Spray weld and some pride should fix this if not automation will.
I'm not advocating all out outsourcing the whole welding department.
Originally Posted by Heavey Metal
The welders have pushed back to making improvements.
Probably not all are bad, but seeing how it should be done
will probably get the conscientious welders to have a little talk
with the problem welders to "straighten up, or your gonna blow
it for all of us"
It's a very fine line to walk. A local large fab shop (50-100 employees)
son takes over, calls all welders in, threatens to go to mexico
(the beating will continue until moral improves talk)
Got just what he wanted, dis-gruntled employees quit, replaced
"craftsmen" welders (high time, high pay who worked very well) with young rod burners
for half price.
I'm not advocating this at all.
But I must ask, how much crap do you put up with before making a hard decision ?