Editor"s Note: This article covers straightforward SMAW questions and answers. Preceding the SMAW section is the author"s opinion about the importance of retaining federal capital for vocational programs. If friend would prefer to express an opinionabout this topic, please feel complimentary to do so.

You are watching: When the welding machine is set to dcep, current flows

What are They Thinking?

As I compose this article, the rumors room flying native one end of the country to the other. I have heard President bush has considered cutting federal resources for vocational programs (the Perkins Act). Countless schools count on grants to subsidize their welding programs. I additionally have heard that President bush has denied speak he desires to cut these programs. I hope that is true.

Some in the political human being feel the our students must be in computer system labs quite than in vocational shops. I also believe students require to end up being computer-literate, however not at the price of vocational education. Many school districts have actually shut down vocational program to put in computer labs. Few of my partner in this districts have told me the this has been a regrettable actionbecause the dropout rate increased virtually immediately.

My skilled opinion is the cutting vocational programs is a bunch of bunk, as we speak in Texas. Shut under vocational education and watch the dropout rate and also skilled job shortage rise! recently a shipyard had actually to go to Ireland and also India trying to find welders. A decrease in craftsmen and also -women in every of the building trades is projected. Who the heck will construct thebuildings, planes, trains, and also automobiles?

Welding is component of our resides from the time we get up until we walk to bed in ~ night. Welded pipes lug us water come brush our teeth and remove ours sewage. Ours houses and apartments are full of welded appliances. Ours cars, trucks, and other transportation vehicles room welded. Our roadways go end welded bridges, and the traffic lights room fabricated and also welded. The structures we job-related in, defensehardware, automobiles, and the list goes on and also on.

So here"s a great idea some genius come up with: Don"t train any more welders. This idea gives the word lamebrain new meaning.

More than just a craft is learned in our vocational classes. Work ethics are developed, and also social an abilities are learned. I"ve taught number of female college student in the past few years, and it"s been great to check out them get in a male-dominated trade and find the end they can do really well. (I"ve written before about the women who built the planes, tanks, and ships that retained our country going duringWorld battle II.) It"s been wonderful the method the guys have embraced the women and also treated them through respect. Students learn to job-related cooperatively and develop friendships, while getting a basic idea of several of the various jobs available out there.

Now some could accuse me of gift biased (and ns am) due to the fact that of the reality that if vocational programs space cut, therefore is my job. Yep, the idea doesn"t specifically excite me, yet I dang sure ain"t worried around it either. I"ve remained in dire straits before, but if God"s willing and the creek don"t rise, I"ll be working somewhere else in the field in a flash.

Our vocational classes, what"s left of them, prepare students because that a abundant life even if castle never get in that certain craft. I know it since I"ve checked out it, and if we shut "em down, we space screwing up!

SMAW Basics – The Questions

Now that I"ve gained that off of my chest I believed I"d covering a couple of basic questions about shielded metal arc welding (SMAW or rod welding).

Give the best short answer because that the following:

In what direction does existing flow in DC electricity?In what direction does existing flow in AC electricity?What execute DCEP and DCEN stand for?What room the three significant weld defects in SMAW?Why shouldn"t you weld with exposed skin?How deserve to you tell if one unfamiliar machine is set right once welding?What is the difference between the ground and also the occupational clamp?You should constantly relax her hand and do what else when welding?What is spatter?List three factors you should never reduced or weld ~ above a supplied container.

SMAW Basics – The Answers

1. In direct current, electricity constantly flows from an unfavorable to positive. As with when you turn on her garden hose and also the water begins to flow, as soon as you weld with DC, the existing flows the end of the an unfavorable and earlier into the positive. This provides for a smooth welding current.

2. In alternate current, the electricity flows ago and soon from an adverse to positive and also positive to negative on a sine wave. This provides an erratic circulation for SMAW, producing an ext spatter and also a more unstable current. I offered AC for welding 6011 for a pair of years. The welds to be OK, yet give me DC anytime.

3. Direct current electrode positive (DCEP) is what we provided to contact reverse polarity. Direct present electrode an adverse (DCEN) is what we used to call straight polarity. I doubt the same human being who changed the indigenous library to the learning source center got a host of this terms.

In DCEP the electrical power flows into the tip of the welding rod and also concentrates around two-thirds of the heat, i m sorry gives good penetration. DCEP is usually supplied on more thickness steels.

In DCEN the electricity flows out of the rod, concentrating around one-third the the warm on the rod. Less penetration provides this a very good choice for diluent steels.

Right around now, some of you are hauling to your e-mail to tell me that I"m wrong around the penetration. Part journals say the DCEN gives better penetration. I had to look v three various journals prior to I uncovered one that agreed with me. Every agree that DCEP has the best weld characteristics. It additionally has cleaning activity that DCEN doesn"t have.

Its dubbed welding theory, and also my concept is that I"ve offered DCEP ~ above every dang point from high-rises, nuclear weapons facilities, dams, and a dam strength house! Not when did I ever before use DCEN. Like the journal that supports my theory, i say that the better weld characteristics and the two-thirds warmth at the end of the rod produce a force and "there is a jet action and / or growth ofgases in the arc in ~ the electrode tip. This expansion causes the molten steel to be thrust with good speed throughout the arc. The molten metal effects the base steel with greater force. This heavy influence on the base metal helps to create deep, penetrating welds." contemporary Welding 1997 Althouse, Turnquist, Bowditch, and also Bowditch." now that is precisely how i would"ve put it ... Well, much more orless.

The Hobart school of Welding"s Welding Guide additionally supports mine theory: "Electrode an unfavorable (straight polarity) regularly is used when shallower penetration is required. Electrode optimistic (reverse polarity) normally is supplied when deep penetration is needed."

We likewise conducted one experiment through dragging a 1/8-in. Pole on an 11-gauge shim. DCEP shed through after ~ one and one-half inches. DCEN did no burn with until about three and also a fifty percent inches. Now that I have backed up my theory with this highly scientific experiment, i am even more convinced!

I have actually no trouble accepting that DCEN penetrates much better in gas tungsten arc welding (GTAW). That"s a whole various ball game because of the tungsten electrode. Girlfriend can"t apply much heat on the smaller sized diameter tungsten rods through DCEP due to the fact that it melts far the tungsten. You can output more heat with DCEN, enabling for more penetration.

On some machines, a switch is available for transforming from AC to DCEP or DCEN; top top others, the leads have to be changed.

4. Porosity, slag inclusion, and also undercut, the cardinal sin that welding, room defects since they threaten the welded joint and also can reason it to fail.

Porosity is wormholes in the weld. It might be led to by humidity in the flux, i beg your pardon is turned right into tiny heavy steam explosions, or also minute traces that gas left in the steel as soon as it to be formed.

Slag consists occurs once the slag is not chipped and also cleaned properly and then welded over. A good welder will burn through any type of exposed slag, however sometimes the slag have the right to be skipped over, leaving that trapped under the bead.

Undercut is the cardinal sin since it occurs as soon as the base metal is penetrated, or reduced into, there is no leaving any type of filler metal. This normally happens once welders use the dorn rod angle, go as well fast, or use amps that space too hot.

5. Welding puts the end radiation with ultraviolet light rays. It"s like having actually a tiny sun at the finish of your rod. This rays have the right to sunburn her skin, and eyes and also even blister your corneas. Continually welding v your skin exposed have the right to lead to skin cancer, one of the fastest-growing cancers in our country. As soon as the skin is damaged over and over, the is feasible for among thehealing cell to be a poor one. Once it beginning multiplying, cancer may be present.

Often welders don"t want to wear hefty hot leathers or long sleeves on warm days. Execute it anyway! Melanoma can be deadly, and also even if it isn"t, you still could have to have actually lesions cut out of your skin.

6. I normally don"t pay attention to the numbers on the machine. I have eight devices of the very same brand in mine shop, and all eight that them run a little bit differently. I usually set the dial around halfway and then work from there. Run the maker until you gain a fluid, secure puddle, and then fine-tune the control.

7. In the field we always called the work clamp the ground, but the ground actually is what gives the power an escape path to the ground native the maker if miscellaneous malfunctions. The job-related clamp is the component of the circuit the clamps to the item being welded to complete the circuit.

8. as I"ve claimed before and also will say a million times again, relax her hand, and watch the puddle. I can still hear Phil Newell yelling in my ear as he was standing behind me stop my hand while to teach me to weld. I certain as hell couldn"t be sure then, however he dang sure acquired his suggest across! You need to relax your hand come get an excellent manipulation the the weld puddle. Even the slightestmovement will influence it. If you are tense, your movements will be jerky, and the weld pool will be erratic.

You must always watch the puddle to make sure you room feathering right into the steel evenly and also uniformly. You must see the puddle wash right into the steel, thus staying clear of undercut. ~ awhile, you have to even be able to feel that very subtle offer into the steel as the rod fuses right into the basic metal.

It"s OK come take your eyes turn off the pond to check out where you space as long as you conveniently return to watching it. Sometimes you can also lift her rod slightly and also lighten increase the area about the pond to watch where you"re going.

Along through relaxing your hand and also watching the puddle, monitor the stick angle, travel speed, and also temperature.

9. What is spatter? Spatter is the small molten droplets that stick come the steel roughly your weld. With 7018 girlfriend won"t get nearly as lot spatter just like 6010 or 6011. If the spatter chips off easily, every is OK. If the doesn"t chip off, you"re welding too hot.


See more: Ocean-Continental Convergence Produces _____., Parallel Belts Of Folded Mountains And Volcanic

Why execute I throw this in? since every year ns hear about a welder who gained hurt or killed from welding top top a supplied container. I never weld on supplied containers, and also I never will. You can get shed (flammable), blown up (explosive), or asphyxiated (toxicity) welding on the dorn container. Welding supplied containers reasons many, many accidents. Make it a preeminence to continue to be away fromthem. It doesn"t cost that much much more to use new steel.

How carry out You Score?

All correct—you space in the zone! Ask because that a raise.7 – 9 correct—not bad, girlfriend pretty much understand your stuff.4 – 6 correct—study up!Less 보다 4 correct—become a carpenter. (Just kidding, keep trying!)