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HOT METAL SKILLS

8609-C

ARC WELDING – BASIC STEPS

GETTING STARTED

As with any other skill, arc welding takes timeto learn and master. Basic fundamentals mustbe learned and practiced repeatedly in orderfor one to become proficient at arc welding. Itis necessary to understand the basiccomponents of the arc welding process,however, for a person to really learn the tradeit is necessary to have vast amounts ofexperimentation and experience. Industry isalways searching for certified weldors. Theagricultural science laboratory is a great placeto learn the skills necessary to be AmericanWelding Society (AWS) certified aftergraduation. Patience and determination are keycharacter traits to keep in mind while learningthe skill of arc welding.

PREPARING METAL FOR WELDING

In order to increase the efficiency of the welding process, it is necessary to prepare the metal beforehand.Stronger, cleaner, and more attractive welds will result if proper preparations are made. Another reason forpreparing metal is that fewer electrodes will be needed, saving both time and money.

If welding unprepared metal, more heat will be needed to perform the welds, therefore amperage should beincreased an additional 20 amperes.

There are several methods of preparing metal. Using a steel brush, filing, scraping, and grinding are allproven techniques. Using a grinder is the quickest method for preparing metal for welding.

Weld surfaces should be ground to ensure that all metal burrs and rough spots are removed. This is especiallyneeded for sheets of metal less than 1/4 inch thick.

Metal that is more than 1/4 inch thick should be beveled* at a 30-degree angle. To bevel means to inclineor slant an edge. The two pieces of prepared metal placed with the beveled edges together to form a 60-degree angle.

* Underlined words are defined in the Glossary of Terms.

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Metal sheets that are 1/4 to 1/2 inch thick should be spaced 1/32 to 1/16 inches apart before welding. Thisspacing will provide for maximum heat penetration during the welding process and ensure quality welds.Heat penetration is the depth at which the base metal is sufficiently heated and melted in order for fusionto occur.

DETERMINING CORRECT AMPERAGE SETTING

Ensuring that the welder is set to the correct amperage is critical to the overall success of any weldingoperation. Amperage setting is crucial to forming strong beads, allowing for proper penetration and producingminimum spatter. Most welding suppliers provide charts and information that show the proper amperagesettings according to electrode size and thickness of metal. These charts are available at many weldingsupply stores. Amperage setting is determined by the following factors:

Metal ThicknessSize and Type of ElectrodeSpeed of TravelPosition of Weld

Several scenarios can occur when the amperage is improperly set.

Amperage too High – the bead will be flat with increased porosity, excessive spatter will occur andthe electrode will burn too hot.

Amperage too Low – striking an arc will become very difficult, as well as maintaining correct arclength. The metal will pile up, forming a high narrow bead. Proper penetration will not occur.

Correct Amperage – weld ripple will be uniform and the weld deposit will be equal to the depth ofpenetration.

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The following chart is an example of one that might be found in a welding supply store. It suggests theamperage setting according to electrode size and metal thickness.

AMPERAGE ELECTRODE SIZE METAL THICKNESS

65 3/32” 1/16”80–100 3/32” 3/32”80–120 1/8” 1/8”115–130 5/32” 3/16”130–150 5/32” 1/4”140–150 5/32” 5/16”160–175 5/32” 3/8”175–200 5/32” 1/2”

USING CORRECT WELDING POSITION

A key component in developing proficiency inwelding is finding a welding position that iscomfortable and will allow for less fatigue. Thereare several different types of welding positions thatwork for different people. Welding can be donewith one hand or two, and an individual can weldeither standing up or sitting down. An example ofone type of welding position is the following:

To start welding, hold the electrode holder in theright hand and use the left hand as a support forthe right hand. Strike the arc and weld from left toright. (Left handed weldors should do theopposite.) Tilt the electrode toward the directionof travel, always keeping it at a 15-degree angle.After striking the arc, maintain a correct arc lengththroughout the entire process.

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STRIKING THE ARC

To begin the welding process, it is necessary to learn the skills involved in striking or starting an arc. An arcis formed when the electrode is brought into contact with the base metal and then withdrawn slightly, thusopening the circuit. The result of this action is that electric current jumps the gap and makes an arc thatproduces enough heat to melt the base metal and the electrode. Striking an arc is a challenge for mostintroductory weldors; it takes time and practice to become adept at the procedure. The following is anexplanation of two methods of striking an arc commonly used in the field today.

The tapping method of striking an arc:

Set the amperage correctly prior to beginning welding. Hold the electrode directly over the desiredstarting point. Bring the electrode straight down and tap the metal. After the arc is established,hold the electrode about 1/8 inch above the bottom of the crater. Tilt the electrode towards thedirection of travel.

The scratching method of striking an arc:

Set the amperage correctly. Bring the electrode down diagonally across the work as if striking amatch. After the arc is established, hold the electrode about 1/8 inch from the metal. Tilt the electrodetowards the direction of travel.

Arc length is an important factor to consider in producing quality welds. The arc length, or distance betweenthe electrode and molten metal, should be equal to the diameter of the bare end of the welding rod orelectrode. It is necessary to maintain a correct arc length throughout the entire welding process to producehigh-quality welds. Excessive spattering and porosity will be eliminated if a proper arc length is maintained.

The correct arc length may also be determined by sound. If the arc is too long, a blowing sound will beproduced. If the arc length and amperage are correct, the arc produces a continuous crackling or fryingsound. When the arc length is too short a popping sound will be the result.

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Most beginning weldors will experience difficulties causedby electrodes sticking to the work. If this happens, releasethe electrode from the electrode holder by squeezing thelever. Turn the welder off and while wearing welding gloves,grab the electrode with a free hand and bend it back-and-forth. This back and forth action should break the electrodefree. After breaking the electrode free, check to see if theflux on the end of the electrode has been removed. If theend is free of flux, discard the electrode and begin with anew one. Electrodes that have lost their flux on the end arevery difficult to strike, especially for a beginning weldor.

CAUSES OF DIFFICULTIES IN STRIKING AN ARC

There are many obstacles that most beginning weldors will face as they learn the techniques and methodsinvolved in the welding process. Striking an arc is the first major skill that any weldor must develop. Someof the causes for increased difficulty that an introductory weldor might encounter in striking an arc are:

The flux coating may be absent from the end of the electrode. Discard electrodes in which the fluxis removed and begin with a new one. A fast scratching technique is also recommended to helpalleviate this problem.

The work may be improperly grounded. Arcing may occur where the ground clamp is attached tothe metal. The metal should be clean where the ground clamp is attached. Check the groundclamp and reapply the clamp to the metal, ensuring that proper contact is made. In some instances,it may be necessary to make a tack weld in order to get a good ground.

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The electrode may not be making proper contact with the electrode holder. Look for a weakspring or foreign materials. Be certain that the electrode holder is not clamped on the flux coating.The bare end of the electrode should be held in the electrode holder.

The electrode and amperage setting may not be correctly matched in relation to the metal or jobto be done. Check the metal thickness, electrode being used, speed of travel, and position ofweld. Consult a chart that gives correct amperage settings for different situations and make theproper adjustments.

The connections between the cables and welder terminals may be loose. Loose or dirty connectionswill reduce the electrical efficiency of the welder. Check and tighten any loose connections. Cleanany dirty connections prior to resuming welding.

RUNNING A BEAD

After learning to strike an arc, the next step for any weldor is to learn how to run a bead. This is anotherprocess that will take time and practice to master. Beginning weldors should first learn how to run a bead inthe flat position. The following steps will guide a beginning weldor through the process.

Adjust the amperage according toelectrode size and type and the thicknessof the metal. Consult an amperage chartfor correct specifications.

The second step is to hold a long arcuntil the base metal begins to melt, andcontinue to watch the puddle instead ofwatching the arc. It is suggested thatyou hold the arc for a count of threeseconds to allow the base metal to meltbefore actually running the bead. Thispractice is known as preheating.

After the metal begins melting, theelectrode should be maneuvered to theproper arc length and tilted correctlytoward the line of the weld. The correctarc length should be maintainedthroughout the process.

Maintaining a good puddle is one of themost important steps in making a goodweld. The puddle should be about 1.5times as wide as the width of theelectrode. The weld puddle is the areathat is being heated and melted to a hotliquid state during welding.

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To maintain a good puddle, the speed of travel must be adjusted to permit a desired bead height.Welding heavy plate requires a slower speed than welding thin metal. You must learn to adjustyour travel speeds for different types and sizes of metal.

Sometimes the arc will have to be broken while running a bead. This can happen when the weldorfinishes one electrode and must start another. The bead should not be restarted in the same place(the crater of the interrupted bead). The bead should be started on the metal behind the crater. Bydoing this, the weld will pass through the crater toward the bead and then over the same path in theline of the weld. This process is known as tying in or tying the beads together.

To fill a crater, push the end of the electrode down into the crater and pull it away quickly to breakthe arc.

ELECTRODE MOVEMENTS FOR RUNNING A BEAD

The main movements that a weldor must perform and master in order to become skilled at the craft arefeeding the electrode to maintain the proper arc length and moving the electrode along the weld line. Downwardmotion is necessary to compensate for the area of the electrode that is being consumed. The electrodemovement is also vital to the quality and strength of the weld.

Several types of electrode movements are utilized and the exact type that is used is the weldor’s personalchoice. Electrode movement is very important because it controls the penetration, porosity, width, andbuildup of the bead that is produced. The following are some common movements or weaves that are usedtoday. The drawings are self-explanatory.

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USING BEADS AND WEAVES IN PADDING

Practice is the key to becoming a polished weldor. It is necessary to work repeatedly at running a straightbead on a flat metal plate. This is used to practice and gain experience, and is often referred to as runningstringer beads. This type of bead is most beneficial to students who are working on maintaining arc length,practicing weave patterns, and achieving proper electrode angle. There are many different ways to practicerunning beads. The following is one set of directions for running stringer beads.

Begin the stringer bead at the upper left cornerof the plate and move from left to right keepingthe bead flush with the top edge of the plate.

Be sure the bead runs in a straight line flushwith the top of the plate and fill the crater at theend.

Chip and wire brush the bead until it iscompletely clean before running another beadalong its side.

Place the second bead so that it will fuse with20% (1/5) of the first bead.

Repeat each step until the entire surface of the plate is completely covered with deposited metal.

It is important to realize that there are many possible weld positions. The flat, horizontal, vertical, andoverhead positions are just a few. The American Welding Society (AWS) has come up with a set of codes toidentify different welding positions. In order to become a (AWS) certified entry-level weldor, the weldormust be able to perform welds in many different positions. The following is a good practice method tobecome more skilled at welding in a variety of different positions.

Without changing the position of the practice plate, begin at the lower left hand corner and run thebead away from the body. Cover the entire plate and brush it clean for the next layer.

Deposit a third layer without moving the plate, moving the arc from right to left. Cover the entireplate and brush it clean for the next layer.

Add the fourth layer with the steel plate in the initial position. Clean the plate so that all the beadsmay be examined.

Numerous practice exercises exist and it is the weldor’s personal choice as to which one he/she uses to learnthe craft. Keep in mind that patience and determination are very important character traits to possess whenlearning the arc welding process.

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One learning tool that is available for purchase from the Instructional Materials Service (IMS) is a videocassette# 9779 Stick Metal Arc Welding I. This video is an excellent learning tool for introductory weldors andexplains the basic processes and skills involved in arc welding.

For arc welding activities related to your SAEP, refer to IMS #RB-221, Activities for Agricultural Science221. After completing an activity, be sure to record the entry in the journal page of your Internet recordbook, and click on 221-H for the Course and Unit of Instruction.

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Acknowledgements

Jared Doughty, Graduate Technician, Department of Agricultural Education,Texas A&M University, revised and organized this topic.

Kirk Edney, Curriculum Specialist, Instructional Materials Service,Texas A&M University, reviewed this topic.

Vickie Marriott, Office Software Associate, Instructional Materials Service,Texas A&M University, prepared the layout and design for this topic.

Christine Stetter, Artist, Instructional Materials Service,Texas A&M University, prepared the illustrations for this topic.

REFERENCES

Alexander, R., E. Bohnart and R. Witcraft. Welding, The Fundamentals of Welding, Cutting, Brazing,Soldering, and Surfacing of Metals. John Deere Publishing, 2000.

Jefferson, T. B. and Gorham Woods. Metals and How to Weld Them. 2nd ed. Cleveland, OH: TheJames F. Lincoln Arc Welding Foundation, 1990.

Jeffus, Larry. Welding: Principles and Applications. 4th ed. Delmar, 1999.

Morford, V. J, T. Hoerner and W. Anderson. Metals and Welding. Hobar Publications, 1988.

New Lessons in Arc Welding. 2nd ed. The Lincoln Electric Company, 1976.

Sosnin, H. A. Arc Welding Instructions for the Beginner. 6th ed. Cleveland, OH: The James F. LincolnArc Welding Foundation, 1970.

Sosnin. H. A. Arc Welding Instructions for the Beginner Teachers Manual. Cleveland, OH: The JamesF. Lincoln Arc Welding Foundation, 1964.

“Welding Made Easy.” [On-line]. Available: http://www.lincolnelectric.com/knowledge/articles/tips.asp [2002, June]

GLOSSARY OF TERMS

Bevel – To incline or slant an edge.

Heat penetration – The depth at which the base metal is sufficiently heated and melted in order for fusionto occur.

Porosity – Permeable to liquids.

Preheating – Holding the arc for a count of three seconds allowing base metal to melt before running a bead.

Spatter – Fragments of metal that are thrown onto the metal surrounding the actual weld area.

Stringer bead – A type of flat bead that is used as a practice technique for introductory weldors.

Weld puddle – Area that is being heated and melted to a hot liquid state during welding process.

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SELECTED STUDENT ACTIVITIES

SHORT ANSWER/LISTING: Answer the following questions or statements in the space provided or onadditional paper.

1. List three reasons for preparing metal prior to beginning a welding job.____________________________________________________________________________

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2. Explain in detail the two effects that can occur if amperage is improperly set.____________________________________________________________________________

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3. List the types of sounds for an arc length that is too long, too short, and one that is correct.____________________________________________________________________________

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4. List three causes for increased difficulty in striking an arc for beginning weldors.____________________________________________________________________________

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5. List five types of electrode movements for laying a bead.____________________________________________________________________________

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ADVANCED ACTIVITIES

1. Research the American Welding Society (AWS) for information concerning the certified weldorprogram. Find out the expectations and requirements for becoming an AWS certified weldor. Presentyour findings to the class.

2. Search for innovative ways to instruct other beginning weldors in arc welding. Present a demonstrationto the class and test the ease of use for others. Discover ways to implement your instructions into theagricultural science laboratory.

3. Construct a display of welding rods used at proper and improper amperage settings on the samepiece of metal. Present this display to the class along with an explanation for each completed weld.

ALL RIGHTS RESERVED

Reproduction prohibited without written permission.Instructional Materials Service

Texas A&M University2588 TAMUS

College Station, Texas 77843-2588http://www-ims.tamu.edu

2002