Stick Welding - DC Polarity
By highwaystar
Stick Welding Technology - how to select the best welder!
What type of portable stick welder works best for all-around use?
A portable welder with an AC/DC output, whether its an electric arc machine or a gas engine drive...
Bear in mind the duty cycles, which means the number of minutes out of a 10-minute cycle a welder can operate.
For example, a machine that creates a 200 amp DC output at 20 percent duty cycle. It can weld continuously at 200 amps for two minutes...
And then must cool for eight minutes to prevent overheating.
Duty cycle and amperage are in general, relative to the work load.
Operating at 90 amps, with a 100 percent duty cycle, means you can weld without stopping.
In my experience DC welding offers advantages over AC for most Stick applications, including:
Easier starts
Fewer arc outages and sticking
Less spatter and much better looking welds
Easier vertical up and overhead welding
Easier to learn with and a smoother arc...
DC reverse polarity (electrode positive) provides about 10 percent more penetration at a given amperage than AC...
On the other hand DC straight polarity (electrode negative) welds thinner metals better.
However AC output does have its advantages too.
Like if you need to weld farm equipment or material that's become magnetized from friction...
For example; when hay, feed or water constantly rub against a steel part.
A DC output won't work because of "arc blow," where the magnetic field blows the molten filler metal out of the weld puddle.
The advantage of AC, because an AC output alternates between polarities, it enables you to weld magnetized parts.
The type of surface being welded can also affect weld characteritics including strength of welded parts and finish...
Should you remove rust or oil before welding?
Stick welding because of its very nature is more forgiving on unclean surfaces...
TIP: It never hurts to clean parts with a wire brush or grind off excess rust.
Sometimes...even great welding skills cannot overcome poor surface preparation, as it can lead to cracking, lack of fusion and slag inclusions.
In general...if you get into the habit, prepare well and have average welding ability, you can make just about any job seem quicker and easier.
And if you select the right type of rod, half the work is already done.
For general purpose welding work on steel, a common electrode used include 6010, 6011, 6013, 7018 and 7024, each of which has specific properties.
6010 electrodes penetrate deeply...
While 6013 electrodes penetrate less.
For much better bead appearance and work on higher strength steels (for a hitch), use a 7018 rod.
For better penetration on thick material, grind the joint to a 30 degree bevel (leave a nickel-width land on the bottom of the groove) and make multiple passes.
Alternatively, make the first pass with a 6010 rod, then make a "cap" with a 7018.
The 7024 rod is perhaps the easiest to use. Also known as a "drag rod," this electrode's thick flux automatically maintains the correct arc length...
Which allows you more control over draging rod directly along the work piece.
What determines how big of machine do you need?
Usually and this depends on the specific requirement, a good rule of thumb is to go for a range from 225 to 300 amp...most modern machine can handle almost anything you'll encounter...
Most Stick welding procedures require 200 amps or less.
To weld material thicker than 3/8 inch., simply make multiple passes - this is what professionals do, even when welding on 1 inch structural steel...
Comments
Maybe... what kind of info are you refering to?
Good article btw.
Lincoln welding electrodes ie 6010- can use DCEN? if no then tell me other elctrodes using negative polarity
Lincoln welding electrodes ie 6010- can use DCEN? if no then tell me other elctrodes using negative polarity
Lincoln's electrode Fleetweld 5P E6010 (DC+) great for welding on dirty, rusty, greasy or painted steel (ideal for vertical or overhead) or Fleetweld 5P+ E6010 (DC+) ideal for steel less than 100% clean for pipe welding, vertical-up and overhead plate welding...
what rod should i use for 1/4 mild steel
Jon, generally 3/32 will be about as good as it gets for most 220v machines. Some run 3/32 and others handle 1/8 (7018) very well. Tip: Go to weld shop and ask for 1/2 dozen 1/8 rods, just say you wanna see if your machine will run it, (if you plan on doing business with them, they'll give you test rods to run, so it really depends on your machine...here's to your continued welding success!
I have a old Miller Roughneck gas driven stick welder. It is a DC plug in lead model. It has one recep for WORK, and the rest of the recp. are your heat range settings.What is considered the POSITIVE recep and what is the NEGATIVE recep? Example, If I have my electrode holder plugged into one of the heat settings, is that straight or reverse polarity??? Thanks
Ken, electrode (stick) is negative (DCEN - Direct Current Electrode Negative) into your workpiece or ground clamp which is positive. Negative to positive or straight polarity :)
I am a veteran downhill pipe welder and use a sa200 Lincoln. I had a hard steel cutting edge to put on a tractor bucket and ran my root pass with 5p+ and hot filled with 8010g. I ran 7018 for position and vertical welds and ran 7024 where I could. The 7024 produced nice blues and gold colors and the flux peeled. Welds appear to be nicely fused. I ran the 7024 reverse polarity at the 190-240 range and 60% or so which is 210-220 amps or so. (That's where I run a 3/16 8010 to cap pipe) the 7024 doesn't seem to dig much in charcteristic. Any thoughts or hindsight?
By the way I failed to mention the 7024 was 1/8 diameter and I was welding 3/4-1" hard steel preheated well and beveled. Thank you for your insight. I pass knowledge of downhill pipe SMAW to anyone humble enough to ask. :)
Hey Beau, how are you...thanks for sharing your knowledge and experience in both penetration & appearance, your description of weld is "text book". 7024 is perhaps the easiest rod to use for higher depositions in flat or horizontal positions. keep in mind, there are a lot of variables. You need a very good DC transformer or inverter to run the above rods effectively. Sometimes I use the horse-shoe shaped weaving, slightly increase travel speed or steeper upper electrode slant about 10 degrees:)
Hi, how u doing?
Is there any guide to select electrodes for different materials?
Hey manpreetsin88, thanks for asking, doing fantastic.
Here's a guide for amperage calculations:
Range: 77 - 150
Fine tune dial: 0 - 10
Desired amperage: 105 amps
150 - 77 = 73
73 / 10 = 7.3
105 - 77 = 28
28 / 7.3 = 3.836
Range: 77 - 150
fine tune dial: 0 - 10
dial set at: 6
150 - 77 = 73
73 / 10 = 7.3
7.3 x 6 = 43.8
43.8 + 77 = 120.8
Also, I've put together a powerpoint slide for SMAW welding techniques if you're interested let me know.
Is it advised to x-ray any 7024 welds?
Mike, thanks for your feedback. Does the job require X-ray inspection? Most types of welds will be evaluated with respect to specific X-ray radiography (used to detect internal defects such as porosity or inclusions) as for E7024 electrodes, clean slag from every bead on multiple pass welds to prevent slag inclusions which would appear on X-ray inspection. Hope that helps...cheers!
7018 rod do you run dc+ or dc- ?
highwaystar 4 years ago
Does anyone want additional info on welding?