porosity? help!

[SignWave]

Thanks W1,

Say...dont Disney engineers do things a little "mickey mouse"?
hehehehehe

[welder_one]

well, we all have do deal with close-minded dummies pretty much on a daily basis, just one of mine happens to be in charge of ordering...lol...i did put on a new flow meter (robbed off of the mm 350p) and i am about 33-35 cfh at the nozzle. the welds were cleaner and i can get back to a good travel pace, thanks. i only have one more week to deliver on these stobs, then the paintline gets to take over. and dfw international airport just put in some plans for a sign that is 14 foot 6 and 863 foot long built in 4 x 12 foot sections and a bottom row of 18 inch by 12 foot panels. it will be mounted together with splice plates to several stobs of i-beam. one pivot and a giant remote control motor. it will be used not only to tell the pilot "your'e about to run outta runway, dude" but also to help control windspeed on the runway. sounds like it might be a little fun. the panels are made of 2x2 squre tube mitered and filled with aluminum honeycomb then 0.80 sheet laminated to both sides. i am going to be busy, very busy for a while...i will post pics of the new pieces before and after paint. once i get a few of them done of course...

[SundownIII]

Bert,

I have been thinking the same thing. As I've said in several of my previous posts, when doing consulting, nothing is more frustrating when the response is, "well, we've always done it that way".

I wonder how much trouble and costly it's going to be if Disney rejects the delivered product. Just seems to me that, considering the numbers involved, that the company would want to use the best "tools" available.

Back to the gas coverage issue. 27 CFH at the nozzle sounds a little low to me. I'd (personally) rather see the flow at somewhere around 30-40 CFH when using straight Argon.

Just my .02

[Bert]

Change out the employee

"why, this is what we have always used here. we arent going to go and start changing things around because you want to"I'm shocked she can get away with that one! 'Specially working for Disney!!! I HATE those type of people that don't want to help people better themselves, or help the quality of the job!! I can go on a MAJOR rant over here...see your supervisor. Lot of people use a Argon/Helium mix for thicker aluminum!!! Just works better!!!
Glad you got it working though, and thanks for the pics and update!!!

[welder_one]

yeah, this set-up is used only for aluminum. i use a mm 350p for steel, or stainless. jws, you had mentioned how am i sure about 27 cfh? i use a flow meter that you hold to the nozzle and hit the purge button. the ball rises to tell you what your cfh is at the nozzle. handy little tool when your using bulk gas and machines are being run off of an orifice in the hose not a regulator or flowmeter. there are a couple heavy steel plants in little rock that are set up that way. the foreman will walk by and spot check a couple different machines with it. i dont remember who made the meter, think its esab, but i will try to find it later to post a pic or link...also when i said that pressure gets "lost" in a 30 foot hose, i didnt mean that it should dissapear. when you turn on the water hose the pressure and flow are dispearsed a little per foot of hose. i have a book here at the house that tells me exactly how much per foot and diameter,(someone had a little too much time i guess to come up with that one) it was a study that i did for mechanical engineering course. you are going to lose pressure and flowrate through that much hose and gun, not volume, just pressure and flow. anyway, got to go to work, im gonna be late. talk later

[man of steel]

re porosity

I would say the air flow from your fans or even too much pressure from your gun will cause turbulance coming straight from your nozzle(the turbulance tends to draw in contaminants from the air or an unkept or dusty work area)the only other thing i would have to ask (is your gun solely used for aluminum?I know a friend that changes up metals but neglects to remove the liner,which can also carry contamination.If i were you i wouldnt weld anything until i got your settings dead on perfect because it doesnt matter if you have one or a million pieces to do ,take your time and do them all like it was the only one with your signature on it in aluminum good luck

[jwsrep]

darmik, to answer your questions in order:
i have the meter pegged at about 60 cfh to get 27 at the nozzle. i did ask about that at first and i was told that pressure and flow gets lost in a 30 foot gun. maybe something there

i try to keep a 7 to 12 degree angle (push)at all times

about a 3/8 stick out

we have treating tanks for the aluminum, first tank is hot soap, #2 and #3 are rinse, #4 is etching:nitric and sulfuric acid mix #5 is rinse #6 is aladine and chromic acid, #7 is rinse. i run these parts through the tanks except for the last 2 the chrome and rinse tank. once dry, i use mek to cleanany oily residue, then stainless wire brush to remove "fresh" oxides immediately prior to welding

i keep 5 nozzles clean and rotate them out as they build up with spatter, when the last one is being used i will clean them all up real good again. it seems to keep production up that way. i am very a**l with keeping cleen consumables.

i dont use nozzle gel for aluminum, the wax cause poor welds. on steel i will though..

there is always a slight breeze where i weld. there is a huge exhaust fan above my tables and the plant is an open plant. it is about 400 yards long and about 100 yards wide. there is not really any way to keep breeze under control. i do use welding curtains and screens to block most of it.

that is an interesting point about travel speed too fast though, i dunno, i am "grabbing for straws here"

Allrighty then, let's take the first part of this post you said: "i have the meter pegged at about 60 cfh to get 27 at the nozzle."
How are you sure of this? Setting the fg at 60 CFH to get 27 CFH at the nozzle, are you measuring the flowrate with a gas flow indicator? Are you running a 100' hose? 200' hose? How can you be getting that much of a flowrate drop? Then you said " did ask about that at first and i was told that pressure and flow gets lost in a 30 foot gun." To which I say no way Jose. 30' of gas hose thru a torch will not affect the flowrate at all....nada.

See, SundownIII and I are of the same thought process on this. Porosity = gas flow/impurity problem....99% of the time.

After your post of setting the flowrate at 60CFH I almost have to draw the conclusion of 2 points.

#1) Too high of flowrate. You can create a turbulence effect when your flowrate is too high. The turbulence actually draws "air" into the gas column and the nitrogen, not to mention the oxygen creates porosity.

#2) You have a gas leak somewhere in the system and you are asperating the system.

As far as the fan goes, unless you have it directly blowing at your weld station I doubt this is the problem, unless it's a wind tunnel fan.
I have several customers that have fans blowing in their area and does not affect aluminum welding.

Ohh BTW the reason I asked about parameters is because welding at high voltage ranges (over doing it) can cause poor weldments. You at those ranges you mentioned are okay.

Like Darmik said about worm tracks, usually a flux core problem due to improper eso (electrical stick out) or improper voltage.

[Darmik]

Worm tracks

It is a typical problem with flux core.
You'll have a perfect weld and when you chip the slag you'll find in the center of the weld or just off to one side a surface crater about one inch long can be longer though then bareies it self at the end in the weld.

It's like when supermans metor hit earth that long surface crater that he created and then he came to a dead stop.the only difference is the worm hole goes down after the stop.

I hope this explains it.I wish I had a pic.the next time it happens to me I will take a pic of it.not very nice when your trying to pass a test.It's a fail if you get this.

I'm glad slowing your travel speed down helped out.

[welder_one]

Welder_One

Still think the problem stems from gas coverage. Wrong mix, not enough flow, or too much air movement. Seems like a lot of splatter in and adjacent to the bead. If I didn't know better, I'd almost say it looks like you're using C25 for a covering gas.

the shield gas used is 100% argon. i did try another piece today and brought the weld curtains close and turned off the fan. i did not change the porosity, it also didnt take long at all for the safety officer to threaten me with a write up for welding with the exhaust fan off...lol even in the dead of winter i have to run the fans. the spatter that is present on the weld bead and sides came of with a hand brush. i did slow my travel speed down and that seemed to kill the porosity. i have 790 of these stobs to make for disney in orlando. i was trying to move too fast i guess. i will post more pics of the new coupons, after they come back from x-ray.


i still dont know what worm tracking is though...

[BWS29128]

Now, SundownIII...don't go accusin' the poor guy of makin' one of MY mistakes!!!

[SundownIII]

Welder_One

Still think the problem stems from gas coverage. Wrong mix, not enough flow, or too much air movement. Seems like a lot of splatter in and adjacent to the bead. If I didn't know better, I'd almost say it looks like you're using C25 for a covering gas.

[aametalmaster]

[QUOTE=welder_one;16594]
there is always a slight breeze where i weld. there is a huge exhaust fan above my tables and the plant is an open plant. it is about 400 yards long and about 100 yards wide. QUOTE]

Now that's a shop....Bob

[welder_one]

Welder_One,

You mentioned that you had changed out your gas bottle but didn't mention what gas you were running. I'm assuming straight Argon.

You may want to try an Argon/Helium mix. As the metal thickness increases the helium will help provide more heat and wetting ability. I would recommend a flow rate in the range of 30-35 CFH with the helium mix.

i do use straight argon, the purchasing lady will not spring for another bottle though. i did ask her to order a 90/10 mix for steel so that i can spray transfer and was told "why, this is what we have always used here. we arent going to go and start changing things around because you want to"

[welder_one]

darmik, to answer your questions in order:
i have the meter pegged at about 60 cfh to get 27 at the nozzle. i did ask about that at first and i was told that pressure and flow gets lost in a 30 foot gun. maybe something there

i try to keep a 7 to 12 degree angle (push)at all times

about a 3/8 stick out

we have treating tanks for the aluminum, first tank is hot soap, #2 and #3 are rinse, #4 is etching:nitric and sulfuric acid mix #5 is rinse #6 is aladine and chromic acid, #7 is rinse. i run these parts through the tanks except for the last 2 the chrome and rinse tank. once dry, i use mek to cleanany oily residue, then stainless wire brush to remove "fresh" oxides immediately prior to welding

i keep 5 nozzles clean and rotate them out as they build up with spatter, when the last one is being used i will clean them all up real good again. it seems to keep production up that way. i am very a**l with keeping cleen consumables.

i dont use nozzle gel for aluminum, the wax cause poor welds. on steel i will though..

there is always a slight breeze where i weld. there is a huge exhaust fan above my tables and the plant is an open plant. it is about 400 yards long and about 100 yards wide. there is not really any way to keep breeze under control. i do use welding curtains and screens to block most of it.

that is an interesting point about travel speed too fast though, i dunno, i am "grabbing for straws here"

[SundownIII]

Welder_One,

You mentioned that you had changed out your gas bottle but didn't mention what gas you were running. I'm assuming straight Argon.

You may want to try an Argon/Helium mix. As the metal thickness increases the helium will help provide more heat and wetting ability. I would recommend a flow rate in the range of 30-35 CFH with the helium mix.