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speedsport
01-25-2008, 03:36 PM
Using 200A AC/DC Tig/Stick inverter welder. How to determine when to use AC when to use DC?. Using 6011 5/32 Lincoln welding rod on mild steel, what amps would you expect to use?

macona
01-25-2008, 03:37 PM
Always use DC. AC is for aluminum tig.

5/32 will be somewhere around 140 amps.

speedsport
01-25-2008, 03:43 PM
always use DC for welding mild steel?, then why can you buy a AC/DC stick welder?

NickH
01-25-2008, 03:45 PM
Because metal is not always plain old mild steel,
funnily enough :rolleyes:
Nick

JoeFin
01-25-2008, 04:11 PM
Check the Lincoln Knowledge base

http://www.lincolnelectric.com/knowledge/articles/list.asp

Kinda of like an infomercial you 'll have to weed through to get some good information but they do have lots of good information.

As for your welder sounds like you got a good 1. I use a variety of AC/DC and TIG welding depending on the job.

As for your 6011 on mild steel feel free to use AC or DC 30 - 60 amps depending on the thickness of the steel you are welding

pcarpenter
01-25-2008, 05:41 PM
I think the reason you got the "always use DC on steel" advice was under the assumption you were tigging it.

With stick welding, I generally find that I get a smoother weld with DC with any rod for which it is an option. AC tends to offer deeper penetration, but does not seem to produce the same quality weld otherwise. Its been a couple of decades since my welding classes, so I don't even remember the general cases under which AC is considered desirable.

All my DC experience has been with welders I don't own. I took several semesters of welding in high school.....almost 25 years ago. I only own an AC buzz box (beside my MIG welder) personally. I would probably use stick more if I had DC as it seems to make for better looking welds. As it is, if I don't need to weld something fairly thick (beyond the abilities of my 170A MIG), I end up using the MIG (which is inherently DC).

Paul

R W
01-25-2008, 06:22 PM
Always use DC. AC is for aluminum tig.

5/32 will be somewhere around 140 amps.

Amps for a 5/32(8gauge.4mm) rod would up to around 180 depending on the
thickness metal of the steel.Could even go higher on thick sections.
AC can be more suitable on small jobs where thin material is utilised,as it
dosn't get the job as hot as DC. A 1/8 or smaller rod with a lower amp setting
is easier to use in this situation, a 5/32 at 140 amps will be hard to start in
many cases.

macona
01-25-2008, 06:26 PM
In general even in stick if you have DC use it. I prefer 7018 for pretty much anything.

John R
01-25-2008, 06:30 PM
What about reverse DC ? When is it to be used ?
John R

macona
01-25-2008, 06:43 PM
That can depend on the rod. You can look at the manufacturers specs. 7018 runs reverse polarity. 60 series usually straight. Cant remember for sure. I avoid stick like the plague.

loose nut
01-25-2008, 07:21 PM
What about reverse DC ? When is it to be used ?
John R

Reverse polarity for stick, straight polarity for tig, except aluminum.

wierdscience
01-25-2008, 07:33 PM
6011 you can go either way.Use DC for clean new metal use AC for rusty painted crap.The AC will dig in and cut through the rust and dirt better than on DC. AC will also allow better arc control in inside corners.

5/32" rod huh?What you welding a battleship?3/32" is more than enough for most things up to 1/4",plus on a 200 amp machine 5/32 will put you towards the short end of the duty cycle.

You might also try some 7018 or 7024 low hydrogen rod,better quality cleaner welds,just a suggestion though hope this helps.

fishfrnzy
01-25-2008, 09:43 PM
In my limited welding experience I would have to agree with Wierd and Mancona. If you are doing general garage welding and fabricating Try the 7018 on dc stinger positive. This should do you well up thru 1/2 plate. 1/8 rod on my machine runs well at 120-140 and 3/32 at 75-90 amps. Way smoother beads, less spatter and doen't smell nearly as bad as 6011.

BTW I have heard but not tried yet that 6010 is the best (this is by a full time 25 year welding friend).

torker
01-25-2008, 09:55 PM
Guys...Holy smoke! OK...you don't run 5/32 6011 at 30 to 60 amps. If you are a really well schooled old pro....you MIGHT be good enough to run it at 180 amps. Run this or 6010 at around 150 amps for 5/32".
Yup...6011 is ok for AC or DC. It was actually made more for AC. It handles a little nicer than 6010 but I prefer the extra hard "dig" from 6010 DC.
Don't forget..this is a "Whipping Rod"...not a dragging type rod. You have to "whip" it back and forth or use little circles or the "J" hook to run the fast freeze rod. That is how it's meant to be run. I can't believe how many people run this rod the same as 7018...as a dragging rod. Don't!
This rod actually takes a lot of practice to use it right.
7014 (NOT all position) is a far better rod for the begineer. 7018 is also a good choice but most begineers have a hard time lighting it up/ You can screw up a 7018 weld a hundred ways til Sunday and you still have a pretty strong weld.
BTW...I prefer DC welding to AC anyday. A far smoother arc and a better looking weld.
Russ
(Come over for coffee...I give free lessons to HSM members!)
Oh ya..Darin is right about Ac and arc blow in dead end corners....it is better. For DC...keep your rod straight up and down...it helps in corners.

Flatwins
01-25-2008, 10:26 PM
http://www.millerwelds.com/education/calculators/

macona
01-25-2008, 10:58 PM
Oh yeah, inverters tend to run a little hotter than a transformer because of the purer DC output. Thats why I said 140 amp for 5/32.

torker
01-25-2008, 11:34 PM
Oh yeah, inverters tend to run a little hotter than a transformer because of the purer DC output. Thats why I said 140 amp for 5/32.
I agree wit ya! As long as the inverter is in good shape. A good inverter is an animal in a different world. I've used many, many Miller 304's. Great machines...just don't gough with them.....they aren't near as tough as the old transformer machines when put to the (goughing)test.

speedsport
01-25-2008, 11:54 PM
well, I've tried everything except reversing the polarity and I just can't get this thing to act correctly, hard to explain but it just acts weird, doesn't seem to want to deposit any metal down.

wierdscience
01-25-2008, 11:58 PM
Try electrode (rod) negative,that should work.

Forrest Addy
01-26-2008, 12:39 AM
I use AC when I want a little less penetration with stick welding as for thinner material. AC 6011 or 7011 (or XX18) will work on AC and DC. I prefer it for welding rect tube and stuff 1/8" and thinner. TIG is nice and civilized but it lacks both fluxing action and it's time consuming. Consumable costs for TIG can be double or triped those of stick welding. MIG is great especially for clean material but it doesn't have the penetration and fluxing action of stick - unless you're using flux core or duo-shield. If you get the 2% O2 shielding gass you can MIG plasma transfer with MIG (if your machine is up to it) which makes for good deposition and penetration minimizing distortion. But that can be expensive.

No one process is universal. Each has strengths and disadvantages. You have to look as the options and select the process that best solves the existing problem. Sooner or later the choice comes second nature. Newbs and people of limited experience can be overwhelmed by too many choices. A little study when the pressure is off makes these lessons come easier and better decision made if the info is already is in your head.

Welding is a whole trade. You don't have to learn it all to produce sound welds in your home shop but you should have awareness of the refinements and know where to find the information when you need it.

That's words of wisdom from a fair to middling amateur welder having the benefit of contact with some pretty good welders, a metallurgist, and weld engineers.

torker
01-26-2008, 12:59 AM
well, I've tried everything except reversing the polarity and I just can't get this thing to act correctly, hard to explain but it just acts weird, doesn't seem to want to deposit any metal down.
Speedy...you running it on straight or reverse polarity? I always run 6010/11 on reverse polarity.
Are you DRAGGING the rod? Don't. I can build up 60 series rods as thick as I want...they are fast freeze.

R W
01-26-2008, 05:11 AM
Straight Polarity = Electrode Negative.
Reverse Polarity = Electrode Positive.

macona
01-26-2008, 07:18 AM
Dont need O2 in the mix for spray transfer mig. 95/5 ArCO2 works just fine. Just one more specialty gas for the weld shop to sell you! Just like those stainless tri-mixes. Waste of money.

Forrest Addy
01-26-2008, 01:08 PM
My reference to O2 was for plasma transfer a process that promotes greater penetration. Spray transfer is a bit different because of the intraction of the gas with the arc. Then there's short arc. Each has specific advantages.

You're correct that a proliferation of shielding gasses can eat up a chunk of money. I probably shouldn't have mentioned plasma transfer but my intent was to illustrate the many processes as a sidebar to addressing AC Vs DC in welding technique.

Scishopguy
01-26-2008, 06:56 PM
What about reverse DC ? When is it to be used ?
John R

John,

If I remember correctly, DC reverse is used for 6010 rods on root passes. 6010 is a fast freeze rod (meaning you have to make the little ripples by moving it back and forth as you advance.) It has been years since I took welding at trade school but I remember cussing 6010 rods. They are the stickingest buggers you will ever strike an arc with.

best regards,

macona
01-27-2008, 05:07 AM
The only plasma transfer welding I know of is the system that is like a plasma cutter crossed with a tig machine. Like the Thermal Arc Ultima. Ran like tig with a filler rod. There is a plasma spray process as well where a plasma arc is used to adhere coating to the substrate. But these processes all use pure Argon.

There are only three modes of MIG transfer that I know of. Short Arc, Globular Transfer, and Spray Arc. Different manufacturers called the process by their own names. Airco called Short Arc "Dip Transfer".

Its commonly thought for spray you need a 98%Ar/2%O2 mix. When in reality spray arc can even be achieved with 75/25 and .035 wire. Although it is mich easier to get into spray with something like 95/5.

Anyway, back to the original topic..

speedsport, what kind of welder is this? All you have said is inverter.

Philip in China
01-27-2008, 10:54 AM
AC DC I don't know the theory but........... use DC. It is a lot easier and gives a better weld! What else do you need to know?

speedsport
01-27-2008, 04:49 PM
OK, heres the deal, my previous welding experience is mostly O/A, which I think is the most versatile welding equipment one can own, I also own a Hobart Handler mig machine. I have used the basic crackerbox welders on and off for a long time. When I retired I sold a 1973 Ducati Sport motorcycle which I bought new in 1973, it was completely dis-assembled, engine taken apart, wheels unlaced, etc, to a guy in Australia for $15K, thats what I had to work with. Not wanting to spend a big portion of the life I have left looking for good deals on old American iron I decided to buy Chinese, the best China made stuff I could find, direct from the factories in China. I bought a 6x26 mill, a 12x36 gearhead lathe, lots of tooling, I bought everything I thought I would need/want, milling vises, rotary table, cutters, endmills, measuring tools, welding machines, plasma cutters etc, everything and anything I wanted. Built a new 20'x24'x10' building in my backyard, completely insulated with heat and AC. Did all that with a little money left over.
The welding machine is a Mitech AC/DC Tig/stick. I bought some 7018 1/8" rod yesterday and have been playing today, it runs this rod great, AC or DC, reverse polarity @ 125amps. Maybe it is just my inexperience that I couldot get the 6011 to work. If this machine turns out to be a POS I will buy a Miller or Lincoln when I can find a good deal on a used one. I will continue to look for old American lathe and mill, when and if a good deal turns up I will buy it, until then I will make chips on the China made tools, which ain't all that bad, better than I expected by far.

R W
01-27-2008, 05:25 PM
What about reverse DC ? When is it to be used ?
John R

Reverse Polarity.EP Gives better Penetration.
Straight Polaririty. EN Gives less Penetration.

Bob Ford
01-27-2008, 06:58 PM
Speedsport

With 6010 dc or 6011ac or dc you start the weld, get the molten puddle hot, then lift the rod out about 1/2 inch above the weld.
Watch the weld puddle just as it solidifies re- introduce the rod. These rods are about the only ones that you can break the arc and restart and still get a good weld. Using this technique you can fill holes, and wide gaps. 1/8th rod runs from 80 - 130 amps depending on metal thickness and temperature. The normal circle or J move works well. Almost never is the rod dragged.

Bob

Roy Andrews
01-30-2008, 01:16 AM
6010 and 6011 are good general repair rods and good for root passes and burning first passes thru paint, rust or dirt/oil. they can be hard to run and tend to burn thru on thin material if you are not very skilled. 7018 is an excelent all position rod for clean metal. if you want to run out of position run 3/32 at around 70-85 amps. 7024 is a fast fill rod used flat on clean metal where you want to deposit a lot of metal quickly. try to run 6010 and 11 by holding the rod almost straight up and down and twisting your wrist so that the rod tip moves upward and in the direction of the weld creating a long arc then twist back. keep doing this long arc,short arc. then when you look at your weld you will be able to see each time you short arced the weld deposit and then its just a matter of getting the right frequency of "whip". on thinner you stay out longer. i always stick weld dc reverse.

camdigger
01-30-2008, 12:44 PM
So far I read about polarity, DC vs AC, and current settings, but something that I've found in addition to all these factors that has a big influence on weld success is the general type of weld Uphand (up hill) vs down hand (down hill). I've used some 7018 - usually in 3/32 and 1/8 and have found that up hand or flat work well, but welding down hand or down hill can trap slag under the weld bead. The 6010 and 6011 rods will weld uphand and give spectacular penetration by comparison to 6013, 7014, or 7018 but with huge issues with burn through on thin material. It is widely accepted to weld down hand with either 6010 or 6011 and often the only way relatively thin pipeline pipe ( 1/8 wall) is welded. I've witnessed pressure tight/ Xray quality welds done overhead outdoors in harsh conditions with mobile equipment welding 3/16 wall pipe to a 4140 flange 1 1/2" thick with a little preheat and 7018 rods too. Rarely does anyone I've watched weld 7018 downhill.

My $0.02
Cam