WLD 217

Diesel Welding

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INDEX

Welding Worksheets

3-8

Math on Metal 9-16

Oxyacetylene Welding and Cutting 17-28

Braze Welding 29-39

Shielded Metal Arc Welding

40-53

SMAW Cast Iron

(Science on Steel)

54-60

CAC-A and PAC

61-69

Flux Cored Arc Welding

70-91

Gas Metal Arc Welding

92-97

Gas Tungsten Arc Welding 98-101

Glossary

102-104

Course Assessment Break Down 105

This project was supported, in part,

By the

National Science Foundation Opinions expressed are those of the authors

And not necessarily those of the Foundation

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Welding

Worksheets The welding worksheets are “sprinkled” throughout this training

packet. The student is expected to complete all worksheets to earn a

grade for the course. Use the following information to answer the

questions.

Welding Principles and Applications by Larry Jeffus

Welding Fundamentals of Service by Deere & Company

(See Tool Room Technician for a copy if you’re a welding student)

WLD 217 Training Packet Information Sheets

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Introduction to Joining and Cutting Metals

(Chapter 1 John Deere)

Name: _________________________ Date: _____________________________

1. Name two metal cutting processes used in metal fabrication.

2. What arc welding process stands for SMAW?

3. What type of welding process is Gas Metal Arc Welding (GMAW)?

a. Manual

b. Semi-Automatic

c. Automatic

4. What type of metal can be cut using the oxyfuel process?

5. At what temperature do soldering alloys and brazing alloys melt?

6. Soldering and brazing rely on the principle of ________________________ for the

soldering or brazing alloys to flow into the space between two or more tight-fitting parts.

7. What cutting process is used to cut stainless steel and aluminum?

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8. What are two ways to increase the heat when using the Oxyacetylene Welding (OAW)

process?

9. When increasing the heat in arc welding, you increase the ________________________.

10. Name the five parts of a fillet weld.

11. List the five basic joints in welding fabrication.

12. The size of a fillet weld is measured by _________________________.

13. A fillet weld gauge measures ___________________ and __________________.

14. What weld test position is identified by 4F?

15. Name the weld defects that can be visually inspected on fillet and groove welds.

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Welding Safety

(Chapter 13 John Deere)

Name: _________________________ Date: ____________________________

1. List protective equipment for welders.

2. List protective clothing for welders.

3. Never use ___________________________ for ventilation.

4. Personnel welding on containers should be with what standard?

5. When welding on containers which have held gas or liquid which will readily dissolve in

water, clean thoroughly and fill with an inert gas because…..(complete the sentence).

6. How far can flying sparks travel?

7. Thirty minutes after the completion of a welding job the work area should be inspected

for ________________, _____________________, and ____________________.

8. What can result from using oxygen to dust off clothing?

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9. Keep ____________________ and _____________________ away from cylinders.

10. Transport, store and use acetylene cylinders in the _______________________ position

to avoid “splitting” the acetone.

11. Oil and grease in the presence of oxygen may do what?

12. A notch or groove in the nut on a gas fitting indicates a ________________-hand thread.

13. Standard hose connection are threaded _______________-hand for oxygen and

______________-hand for acetylene or other fuel gases.

14. Before connecting regulators to cylinders, ____________________ the cylinder valve

carefully to blow out any foreign matter that might harm seats, clog orifices or become

ignited.

15. Stand to ______________________ ______________________ of the regulator gauge

when the cylinder is opened.

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16. How many turns should an acetylene cylinder be opened?

17. Open oxygen cylinder valves _____________________________.

18. When arc welding avoid ___________________ areas and keep hands and clothing

________________ at all times. Dampness on the body may cause an ______________.

19. Avoid breathing ___________________ when welding galvanized metal, paint, or zinc.

20. Never strike an arc on a ______________________ gas ____________________.

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Math

on

Metal

The Welding Fabrication Industry needs qualified welder fabricators who can deal with a

variety of situations on the job. This portion of the training packet explores math as it

relates to industry requirements.

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UNDERSTANING FRACTIONS

The welding fabrication industry requires the everyday use of fractions. Besides simple tape rule

measurement, it is often necessary to add, subtract, multiply and divide fractions. Before

practicing performing these kinds of calculations, it’s a good idea to know a few other fraction

skills.

Look at this bar. Notice that it has 4 sections. Three of the sections are shaded, the fourth is

white

Take a look at this fraction: 3/4

The number on the bottom always represents the number of parts that an object has been divided

into. In this case it is 4.

The number on the top tells you how many parts you are concerned with. In this case 3.

An inch on a ruler may be divided into 8 parts, 16 parts or 32 parts. Sometimes they are divided

into 64 parts.

If your inch is divided into 8 parts, then each fraction of that inch will have an 8 on the bottom.

Examples are 1/8, 3/8, 5/8, 6/8

This bar represents 5/8ths, because 5 of the 8 sections are shaded

If your inch is divided into 16 parts then each fraction of that inch will have 16 on the bottom.

Examples are 4/16, 8/16, 11/16

In each case the numbers on the top of the fraction let you know how many parts of the whole

thing that you have. If you had 8/8 or 16/16ths, you would have the whole thing or one (1). If

you had 4/8 or 8/16ths you would have half (1/2) of the whole thing.

If you have two bars that are the same size and one is divided in thirds, 3 pieces, and the other is

divided into 4ths, 4 pieces, which is bigger 1/3 or 1/4th

?

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Measuring with Fractions

When we measure with a measuring tape or ruler of some kind, we need to be able to read

the marks on the tape or rule correctly. If we are counting the marks that divide the inch into

8 equal slices, we are counting "eighths." If we are counting the marks that divide the inch

into 16 equal slices, we are counting "sixteenths," and so on. It is easier to measure and to

visualize eighths and sixteenths than it is with 32nds and 64ths. Therefore, if we get

something in 32nds that can actually be simplified to eighths, we jump on the chance. The

next practice sheet "Reducing Common Fractions" deals with exactly that.

The 2nd

practice sheet, called "Expressing Common Fractions in Higher Terms" works with

doing the exact opposite of reducing fractions. We often need to "expand" fractions in order

to be able to add them together or subtract them from each other, a skill that is frequently

needed when figuring layout. Follow the examples and see how easy it is to convert those

fractions back and forth to lower and higher terms.

The pages following these first two practice sheets deal with actually reading the tape

measurer or ruler. The first of these pages shows an expanded one inch ruler with equivalent

(equal) fractions for 1/4 "(2/8 and 4/16), '1/2 "(2/4, 4/8, and 8/16) and other common

fractions. The second of these pages shows a ruler marked off in sixteenths. For each letter A

- O, count off how many 16ths or how many whole inches* and how many additional

sixteenths. Then, if they can be simplified, use your reducing skills to write these

measurements in inches with fractions of lowest terms.

*Note: Make sure that you don't give answers, like for letter "F " that look like 21/16. If the top number of your f action is larger than the bottom number, you need to simplify. Fractions with a larger top number are called improper fractions, and they are hard for people to read and even harder to measure off on metal! Make that one inch and 5/16 - or -- 1 5/16 inches. Same with "K" - that's 2 ?/16's Start counting after the inch mark!

Do the exercises on this second ruler page and the following two pages as well. All of the

rules are either in eighths or in sixteenths.

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Reducing Common Fractions Example 1: Express 30/32 in lowest terms.

Solution: Find the largest number that will go into each number. Divide that number into

each number of the fraction. 30 ÷ 2 =15

32 ÷ 2 =16 Ans. = 15/16

Example 2: Express 12

/16 in lowest terms.

The largest number that will go into each number is 4.

12 ÷ 4 =3

16 ÷ 4 =4 Ans. = 3/4

Notes: If both numbers are even, the fraction is always reducible by 2.

In example 2, what if you could not see that 4 was the largest number and you reduced by 2?

12 ÷ 2 = 6

16 ÷ 2 = 8 Ans. = 6/8

6 ÷ 2 = 3

8 ÷ 2 = 4 Ans. = 3/4

Practice:

1. 4/8 2. 8/16

3. 14/16 4. 8/32

5. 6/16 6 . 2/8

7 . 2/4 8 . 6/8

9 . 10/16 10 . 24/32

11 . 16/32 12. 4/16

They are both still even and

must be reduced again.

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Expressing Common Fractions in Higher Terms

Example 1 Express 3/8

as 16ths

3 /8 = ?/16

Solution: Divide the smaller denominator (bottom #) into the larger denominator.

3/8 =

?/16 16 ÷ 8 =2

Multiply that answer times the first numerator (top #) and place over the larger

denominator.

2 x 3 =6 =6/16

Practice:

1. 3/4=?/16 2 5/8=?/16

3. 3/4=?/32 4: 7/8=?/16

5. 1/2=?/8 6. 1/4=?/16

7. 3/4=?/8 8. 1/2=?/16

9. 1/4=?/8 10. 7/2=?/32

11. 3/8=?/16 12. 1/8=?/16

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NSF-ATE Project - Advanced Materials Joining for Tomorrow’s Manufacturing Workforce

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NSF-ATE Project - Advanced Materials Joining for Tomorrow’s Manufacturing Workforce

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Hand Cutting

Beveling and Piercing

Combination Cut Project #1

Material Size 3/8" to 1/2" by 6” by 8”

Practice on Scrap Metal First

Example of a Bevel Cut

Example of Piercing

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0Hand Cutting Flushing Project #2

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Track Torch

Bug-O-System Information Sheet

1. Turn power on with in line switch.

2. Disengage drive lever so Bug-O carriage is in neutral gear.

3. Turn motor direction knob to point to desired direction of travel.

4. Turn ball valves for oxygen and acetylene on.

5. Set fuel and oxygen pressures according to tip chart.

6. Adjust torch angle for straight or bevel cut, by using protractor or use triangles for bevel cut.

7. Align material with torch for cut.

8. Light and adjust cutting torch to a neutral flame.

9. Roll the Bug-O-carriage to locate the cutting tip halfway on the metal and half way off.

10. This will allow for a cleaner cut starting point.

11. Preheat metal to the kindling temperature (Cherry Red).

12. Actuate the oxygen-cutting lever to start the cut.

13. Engage the drive lever to continue the cut.

14. Once cut is complete:

a. Disengage the drive lever

b. Turn off cutting oxygen

c. Shut torch down

15. Once completed with all your cutting projects ensure needle valves are off and turn the in-line

electrical switch off.

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Bug-O Track Torch (Use material sizes from cutting projects in this packet.)

Straight Cut Project #3

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Oxyfuel Welding (OFW) Process

(Chapter 2 John Deere)

Name: _________________________ Date: ___________________________

1. Name the safety device on an acetylene cylinder.

1. What is the purpose of the cylinder cap?

2. What is the maximum pressure in an oxygen cylinder at 70o F (20

o C)?

3. What type of valve is on the oxygen cylinder?

4. What is the maximum pressure in an acetylene cylinder at 70o F (20

o C)?

5. What is the procedure for opening the oxygen cylinder valve?

6. Free acetylene should never be used at pressure above ____________________.

7. What is the purpose of the oxygen and acetylene regulators?

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8. How is the size of a welding tip determined?

9. When cleaning a welding or cutting tip, you should always start with the

___________________ size tip cleaner.

10. When connecting the welding tip to the torch body, how tight should the tip be tightened?

11. List three things that will cause the tip to backfire.

12. List two things that will cause a flashback.

13. List two ways the fuel gas hose connections can be identified.

14. What color is the oxygen hose?

15. When setting up the oxyacetylene cylinder system, what position should the cylinders be secured

in?

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16. All hose connecting nuts, regulator connections, and cylinder connections are made of what kind

of metal?

17. List six areas to check for leaks on the oxyacetylene cylinder system.

18. List the types of oxyacetylene flames.

19. What fuel gas produces the hottest flame in the oxyfuel process?

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OXY-ACETYLENE WELDING NOZZLE FLOW DATA

Metal

Thickness

Tip Size

Drill

Size

Oxygen

Pressure

(PSIG)

Min. Max.

Acetylene

Pressure

(PSIG)

Min. Max.

Up to 1/32” 000 75 (.022) 3 5 3 5

1/16” – 3/64” 00 70 (.028) 3 5 3 5

1/32” – 5/64” 0 65 (0.35) 3 5 3 5

3/64” – 3/32” 1 60 (.040) 3 5 3 5

1/16” – 1/8” 2 56 (.046) 3 5 3 5

1/8” – 3/16” 3 53 (.060) 4 7 3 6

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OAW Open Root Butt Joint 1G Project #4

Technique: Both plates should be preheated to form a keyhole. Move torch side-to-side and add filler directly into

the puddle. A slight keyhole should be maintained to ensure complete penetration. The weld should

completely fuse into side of joint and completely penetrate to form a root reinforcement of 1/16”. Bead

width on face should be ¼”.

Tips:

Tack plates together at both ends, place one or more tacks in middle to hold spacing and to prevent

warping during welding.

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Braze Welding

Braze Welding does not need capillary action to pull filler metal into the joint. Brazing and Soldering

are both classified by the American Welding Society as a Liquid-solid phase bonding processes. Liquid

means that the filler metal is melted: solid means that the base material or materials are not melted. The

phase is the temperature at which bonding takes place between the solid base material and the liquid

filler material. The bond between the base material and filler metal is a metallurgical bond because no

melting or alloying of the base metal occurs. If done correctly, this bond results in a joint having four or

five times the tensile strength of that of the filler metal itself.

Soldering and brazing differ only in that soldering takes place at a temperature below 840oF (450

oC) and

brazing occurs at a temperature above 840oF (450

oC). Because only the temperature separates the two

processes, it is possible to do both soldering and brazing using different mixtures of the same metals,

depending upon the alloys used and their melting temperatures.

Brazing is divided into two major categories, brazing and braze welding. In brazing, the parts being

joined must be fitted so that the joint spacing is very small, approximately .0251in. (.6mm). This small

spacing allows capillary action to draw the filler metal into the joint when the parts reach the proper

phase temperature.

Some advantages of soldering and brazing as compared to other methods of joining include:

� Low temperature-since the base metal does not have to melt; a low-temperature heat source can

be used.

� May be permanently or temporarily joined. Since the base metal is not damaged, parts may be

disassembled at a later time by simply reapplying heat. The parts then can be reused. However,

the joint is solid enough to be permanent.

� Dissimilar materials can be joined. It is easy to join dissimilar metals, such as copper to steel,

aluminum to brass, and cast iron to stainless steel. It is also possible to join nonmetals to each

other or nonmetals to metals. Ceramics are easily brazed to each other or to metals.

� Speed of Joining

o Parts can be pre-assembled and dipped or furnace soldered or brazed in large quantities.

o A lower temperature means less time in heating

� Less chance of damaging parts. A heat source can be used that has a maximum temperature

below the temperature that may cause damage to the parts. With the controlled temperature

sufficiently low, even damage from unskilled or semiskilled workers can be eliminated.

� Slow rate of heating and cooling. Because it is not necessary to heat a small area to its melting

temperature and then allow it cool to a solid, the internal stresses caused by rapid temperature

changes can be reduced.

� Parts of varying thickness can be joined. Very thin parts or thin part and a thick part can be

joined without burning or overheating them.

� Easy realignment. Reheating the joint and then repositioning the part so you can easily realign

parts.

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Physical Properties of the Joint

Tensile Strength The tensile strength of a joint is its ability to withstand being pulled apart. A brazed joint can be made

that has a tensile strength four to five times higher than the filler metal itself.

Shear Strength The shear strength of a joint is its ability to withstand a force parallel to the joint. For a solder or braze

joint, the shear strength depends upon the amount of overlapping area of the base parts. The greater the

area that is overlapped the greater the strength.

Ductility Ductility of a joint is its ability to bend without failing. Most soldering and brazing alloys are ductile

metals, so the joint made with these alloys is also ductile.

Fatigue Resistance The fatigue resistance of a metal is its ability to be bent repeatedly without exceeding its elastic limit and

without failure. For most soldered or brazed joints, fatigue resistance is usually fairly low.

Fluxes

General � They must remove any oxides that form as a result of heating the parts.

� They must promote wetting.

� They should aid in capillary action.

The flux, when heated to its reacting temperature, must be thin and flow through the gap provided at the

joint. As it flows through the joint, the flux absorbs and dissolves oxides, allowing the molten filler

metal to be pulled in behind it. After the joint is complete, the flux residue should be removed.

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Brazing Methods

General Soldering and brazing methods are grouped according to the method with which heat is applied: torch,

furnace, induction, dip, or resistance. It is preferable to use one of the fuel gases having a higher heat

level in the secondary flame. This is where acetylene brazing comes in. The oxyacetylene flame has a

higher temperature near the inner cone, but it has little heat in the outer flame.

Advantages of using a torch

� Versatility o Using a torch is the most versatile method. Both small and large parts in a wide variety

of materials can be joined with the same torch.

� Portability o A torch is very portable. Anyplace a set of cylinders can be taken or anywhere the hoses

can be pulled into can be soldered or brazed with a torch.

� Speed o The flame of the torch is one of the quickest ways of heating the material to be joined,

especially on thicker sections.

Disadvantages of using a torch

� Overheating o When using a torch, it is easy to overheat or burn the parts, flux, or filler metal.

� Skill o A high level of skill with a torch is required to produce consistently good joints.

� Fires o It is easy to start a fire if a torch is used around combustible materials.

JOINT DESIGN General The spacing between the parts being joined greatly affects the tensile strength of the finished part. As

the parts are heated, the initial space may increase or decrease, depending upon the joint design and

fixtures.

The strongest joints are obtained when the parts use lap joints where the joining area is equal to three

times the thickness of the thinnest joint member. Parts ¼” in (6mm) thick should not be considered for

brazing or soldering if another process will work successfully.

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Braze Welding Information Sheet

When brazing, apply flame to the joint area, heating either edges or surfaces to a dull red color. Do not

over heat the base metal. If the base metal becomes to hot, the zinc in the brass filler rod will burn off

and this may produce toxic fumes. Too much heat is indicated when the joint area turns copper in color.

Some brazing flux compounds are specially formulated so they melt when proper brazing temperature is

reached.

While heating the metal, keep the end of the brazing rod in or near the torch flame to preheat the rod.

This helps the rod melt more easily when touched to the hot material that you are going to apply filler to.

When the base metal has been heated to a dull red color bring the brazing rod into contact with the dull

red area. Maintain uniform heating in the base metal by using a smooth, uniform torch motion. The

brazing rod will quickly melt and flow over or between the joint surfaces.

The width of the braze welding bead is determined by the width of the portion of the base metal that is

heated enough to melt the filler metal. The filler metal will only flow on and adhere to the base metal

surface that is free of oxides and is at the correct temperature. Moving the torch flame in a particular

direction causes the filler metal to flow in the same direction. As a guideline, the width of the braze

weld bead should be just a little wider than a normal fusion weld on the same thickness of metal.

When braze welding, move the weld bead along the joint at a uniform rate of travel, as you would the

molten puddle when gas welding, increase travel speed slightly. Do not hold the flame as close in weld

brazing as you would in gas welding. Holding the flame to close will cause the base material to become

to hot and will increase the width of the weld bead. Flashing the torch away from the weld puddle the

metal cools and the bead will narrow. You may move and change the work distance as necessary to

obtain the desired bead width. The finished welded joint should have the appearance of adequate

adhesion to the base metal. The filler metal should seep all through the brazed joint and appear

underneath. On braze welded joints, the filler metal should completely fill the joint area and have a

smooth appearance.

A white deposit (like white soot) along the toe of the brazed joint indicates an overheated joint.

Discoloration of the braze filler metal in the joint also indicates overheating. A good welded joint

should show the color of the filler metal itself.

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Fluxes

Various metals require different types of fluxes. Most fluxes fall into one of several chemical

groupings, which include borates, boric acid, alkalis, fluorides, and chlorides. Manufacturers have their

own trade names for fluxes to be used with different metals. For the best results follow the

manufacturer’s recommendations for selection and application. Fluxes are available in many forms,

such as solids, powders, pastes, liquids, sheets, rings and washer. They are also available mixed with

the filler metal, inside the filler metal, or on the outside of the filler metal.

Purposes of Fluxes: � Chemically cleans the base metal.

� Prevents oxidation of the filler metal.

� Floats and removes the oxides already present.

� Increases the flow of the filler metal

� Increases the ability of the filler metal to adhere to the base metal.

� Brings the filler metal into immediate contact with the metals being joined.

� Permits the filler metal to penetrate the pores of the base metal.

Braze Filler Rods

Characteristics of filler rods for braze welding:

1. Filler rods consist of copper alloys containing about 60% copper and 40% zinc which:

a. Produce a high tensile strength.

b. Increase ductility

2. Filler rods contain small quantities of tin, iron, manganese, and silicon which help to:

a. Deoxidize the weld metal.

b. Decrease the tendency to fume.

c. Increase the free-flowing action of the molten metal.

d. Increase the hardness of the deposited metal for greater wear resistance.

3. Filler rods [bare] should be cleaned with emery cloth before use.

4. Filler rods with flux coating can be used as they come from the manufacturer.

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Trouble Shooting Tips for Brazing

IF BRAZING ALLOY DOESN’T WET

SURFACES, BUT “BALLS UP” INSTEAD

OF RUNNING INTO THE JOINT TRY:

IF BRAZING ALLOY DOESN’T CREEP

THROUGH THE JOINT, EVEN THOUGH

IT MELTS AND FORMS A FILLET, TRY:

1. Increase amount of flux

2. Roughened surfaces by shot blasting,

pickling, etc.

3. Removing surface oxides by machining or

grinding

4. Placing the assembly in a different position

such as on an incline, to encourage brazing

alloy to run into joints.

Look for:

Impurities in the acid used for pickling, grit

from shot blasting, lubricant from various

machining operations, etc.

1. More time for heating

2. Higher temperature.

3. A looser fit, or a tighter one.

4. Flux applied to both alloy and parent

metals within and around joint.

5. More thorough cleaning of parts before

assembly.

Look for:

1. Interruption of capillary action within

the joint, such as by a gap.

2. Line contact within the joint instead of a

uniform fit.

3. Freezing of brazing alloy caused by

excessive pick-up of the parent metal.

4. Flux breakdown due to too much heat.

5. Improper or insufficient cleaning.

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IF JOINT OPENS DURING BRAZING,

ALTHOUGH IT WAS TIGHT WHEN

ASSEMBLED, LOOK FOR:

IF BRAZING ALLOY MELTS, BUT

RETAINS ITS ORIGINAL FORM

WITHOUT FLOWING, TRY:

IF BRAZING ALLOY FLOWS AWAY

FROM, INSTEAD OF INTO THE

JOINT, TRY:

1. Excessively tight press fit, which

stretches outer member beyond its

elastic limit.

2. High coefficient of expansion.

3. Unequal expansion of parts due to

unlike metals or sections.

4. Release of residual stresses (stresses

from cold-working) in certain parts.

5. An unsupported section, which might

sag at high temperatures.

6. Porosity in parent metals caused by

burning through it when tack welding

parts together.

1. Coating the brazing alloy with flux

before using and applying flux

generously to parent metals within and

around the joint.

2. Mechanically or chemically cleaning the

brazing alloy, if noticeably oxidized

before using.

1. Providing a reservoir at the joint into

which brazing alloy can flow.

2. Placing the assembly in a different

position, such as on an incline, to

encourage flow.

3. Placing brazing alloy in a strategic

position above the joint, if axis is

vertical, or against the shoulder if axis is

horizontal, so it will creep into the joint.

1. Look for burrs at edges of punched

holes, or other obstacles over which the

brazing alloy might not creep.

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Soldering, Brazing and Braze Welding

(Chapter 9 John Deere)

Name: _____________________________ Date: _________________________

1. How does braze welding differ from regular fusion welding?

2. In some instances, why is braze welding preferred over fusion welding?

3. Why is a flux required for brazing?

4. What three types of heating devices may be used for brazing?

5. In brazing with the carbon arc, how does the carbon electrode for DC current differ from the one

used with AC power supply?

6. What is the difference between braze welding and regular brazing?

7. When is soldering not recommended for joining metals? Give one example.

8. Most solders are alloys of ______________________ and ________________________.

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9. What does tinning a copper mean?

10. How does sweat soldering differ from seam soldering?

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TB Lap-Joint 2F (Braze Welding) Project #5

Technique: Hold the torch at approximately 45deg. work angle and a 45deg. travel angle and move down until flame

is about 1/8 of an inch from surface at the very corner of joint. Concentrate heat on lower plate and then

move to the upper plate in a circular motion until both plates have reached a dull red. Insert filler rod

into flame, drop a portion of filler into dull red area, start circular motion of flame, move torch in

direction of travel adding additional filler as needed.

Tips:

Control heat input on plate. Flashing torch will aid in controlling heat input. Add filler in middle of

puddle. Flashing and adding filler will help control size of weld bead. Weld bead should not be larger

than 3/8”in. in width.

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Shielded Metal Arc Welding (SMAW) SMAW is a process where a power sources converts high voltage and low amperage into low voltage

and high amperage current used to melt the base metal through the electrode arc to make a weld. The

power source depending upon quality will produce either alternating current or alternating current and

direct current.

The electrodes that are used with SMAW are approximately 14 inches long and will be consumed into

the weld. These electrodes are flux covered and it’s this flux that distinguishes its arc characteristics and

its ability to weld out of position.

The electrode flux has several functions. These include:

• Gas shielding

• Controls Penetration

• Helps remove oxides

• Alloy additions

• Provides Arc Stabilizers

• Increases deposition rates

If flux is missing from the rod, the electrode should be considered useless and discarded.

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Components of a SMAW Unit

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SMAW EXX10 and EXX11

Fast Freeze Electrode Information

General Uses � Welding carbon steel (mild steel)

� General purpose fabrication and maintenance welding

� Out of position welding

� X-ray quality

� Pipe welding – cross country, in-plant, and non-critical small diameter piping

� Best choice for the following steel conditions:

o Galvanized

o Plated

o Dirty or painted

o Greasy material

� Joints requiring deep penetration

Arc Characteristics � Truly all-purpose: particularly good for vertical and overhead

� Light slag with little slag interference for easy arc control

� Deep penetration with maximum admixture

� Appearance: flat beads with distinct ripples

Welding Techniques Polarity

Unless otherwise specified, use DCEP, with EXX10 and DCRP or AC with EXX11. The

EXX11 electrodes can also be used with AC. Always adjust current for proper arc action and

control of weld puddle.

Flat Position Hold a 1/8” or shorter arc or touch the work lightly with the electrode tip. Move fast enough to

stay ahead of the molten pool. Use currents in the middle and higher portion of the range.

Vertical Position Use 1/8” or smaller electrodes. Vertical down drag techniques are used by pipeliners and for

single pass welds on thin steel. Vertical up is used for most plate welding applications. Make

the first vertical-up pass with the whip and pause technique. Apply succeeding passes with a box

or straight weave, pausing slightly at the edges to ensure penetration and proper wash-in. Use

currents in the lower portion range.

Overhead and Horizontal Butt Welds Use 1/8” or smaller electrode. These welds are best made with a series of stringer beads using a

whip and pause technique.

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Common EXX10 and EXX11 Electrode Oscillation Techniques

Technique Diagram Typical Application

Whip and Pause

Used with fast freeze

electrodes to make

welds in all positions

Whip and Pause (Using a side to side

motion in the crater)

Used with fast freeze

electrodes primarily

in the vertical

position.

Straight side to side

weave

Used with fast freeze

electrodes to make a

fill pass in the vertical

position.

Triangular Weave

Used with fast freeze

electrodes for the root

pass on fillet welds

and groove welds

Circular Motion

Used with fast freeze

electrodes to make

overhead welds. A

Whip and Pause

technique can be

incorporated into this

technique too, to help

control the puddle.

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Shielded Metal Arc Welding (SMAW)

(Chapter 3 John Deere)

Name: _________________________ Date: __________________________

1. Shielded metal arc welding is also known as __________________ welding.

2. What is the main factor that determines the type of electrode to be used?

3. During arc welding, the welder and all persons around must be protected from

_________________ of the welding arc.

4. What type of power source is needed for Shielded Metal Arc Welding (SMAW)?

5. What determines the size of the electrode holder, ground clamp and welding cable to be used?

6. Referring to Fig. 18, what size welding cable is recommended for 125 feet at 150 amps?

7. What are two reasons that will cause cable connections, the electrode holder and cable to become

hot?

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8. What types of shoes, (footwear) are not recommended when welding?

9. What type of eye protection should be worn when welding or working in a welding area?

10. What shade lens is recommended for welding at 150 amps?

11. What first safety step should be taken before setting up Shielded Metal Arc Welding (SMAW)

equipment?

12. What is the recommended root opening for a single V groove with a back up strip?

13. What is the recommended root face (land) for a single bevel groove?

14. What do the first two numbers in the American Welding Society (AWS) electrode identification

system indicate?

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15. What type of stainless steel electrode is recommended for welding dissimilar metals?

16. Shielded Metal Arc Welding (SMAW) electrode size is measured by the

______________ of the ________________ __________________?

17. What electrodes need special heated storage containers?

18. What is the approximate bead width after the slag has been removed?

19. Name two ways to start the arc in Shielded Metal Arc Welding (SMAW)?

20. Sketch the bead sequence on a multi pass “T” joint.

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E7018 (Low Hydrogen)

The E7018 electrode is known as low-hi and is designed to weld high tensile steel. This electrode has a

heavy slag, a medium to soft arc, and a fast deposit rate. It produces an exceptionally smooth weld

deposit. It is a low hydrogen rod that contains little hydrogen in either moisture or chemical form and

has outstanding crack resistance, little or no porosity and quality x-ray deposits.

The E7018 should be stored in a heated rod oven. This oven provides for dry heat to keep the moisture

out of the flux. This is an essential pre-welding step to produce a low hydrogen weld.

The coating consists of up to 30% iron powder (by weight) plus various alloys and should be operated

with the "drag" technique like the E7024. This electrode also works very well on mild steel and is often

preferred because of the higher deposition rates than other electrodes like E6011.

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Corner Joint 1F E7018 Project #6

Technique: Use a stringer bead with tight arc. Center the weld in the first pass (root pass) so that it is equally

distributed on to each piece of metal. This is accomplished by adjusting the work angle so that the bead

centers itself. The additional passes should then be laid down to allow the weld deposits to flow equally

on the previous passes and to the parent material. Desired outcome is to make each individual pass tie

into the previous pass (es) and/or parent metal so that a convex weld is achieved.

Welding Sequence Alternate directions of welding for each pass.

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E7018 T-Joint 2F Project #7 Technique: Use a string bead technique with a tight arc length. When running the first pass (root weld) it is

important to center the weld so that it has equal distribution onto each piece of metal. This is

accomplished by adjusting the work angle so that the bead centers itself. Additional passes should then

be laid down to allow the weld deposits to flow equally on the previous passes and to the parent

material. The key is to make each individual pass tie into the previous pass(es) and or parent metal so

that a flat to convex surface is obtained.

When welding any of the passes in the T-joint it is critical to not let any of the slag float ahead of the

electrode. This will cause slag inclusions because the arc is not forceful enough to remove the slag (see

helpful hints section for technique in dealing with this problem). Corners must be wrapped.

Welding Sequence Weld the root pass on all four sides of the joint. Rotate the work so that all the welding is completed in

the horizontal position. Notice bead placement starting at the bottom and “stair stepping” towards top of

parent metal.

“Stair Stepping”

Do Not Weld Like Photo Photo Only Shows Bead Placement

VT Criteria Student Assessment Instructor Assessment

Reinforcement (0” –1/8”)

Undercut (1/32”)

Weld Bead Contour

Penetration

Cracks (none)

Arc Strikes (none)

Fusion (complete)

Porosity (none)

Grade Date

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E7018 T-Joint (3F) Project #8

Welding Sequence Vertical up welding requires special attention to heat control. See Vertical Up Info Sheet for helpful

hints.

For multi pass welds first deposit a fillet weld bead by using a slight weave continue up over the top for

a wrap. Deposit additional layers with a slight side-to-side weave hesitating at the sides long enough to

minimize undercut. When “ wearing,” do not spend time in the middle of the puddle. It takes care of

itself. Do not use a whip technique or take the electrode out of the molten pool. Travel slowly enough

to maintain the shelf without causing metal to spill. Use currents in the lower portion of the range. You

can use a weave or a straight stringer bead.

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Science

on

Steel

The Welding Fabrication Industry needs qualified welder fabricators who can deal with a

variety of situations on the job. This portion of the training packet explores science as it

relates to industry requirements.

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Diesel Repair Welding: Cast Iron Welding with the

Shielded Metal Arc Welding Process

Contents of this Packet include - Types of Cast Iron

- Metallurgy of Cast Iron Affects Weldability

- Weld Metal Metallurgy

- Ni-rich Filler Metal to Weld Cast Iron by SMAW

- Heat-Affected Zone Metallurgy

- Two Ways to Weld Cast Iron by SMAW using Ni Electrodes

Types of Cast Iron Welding of cast iron is very difficult and should only be attempted when all other means of joining are

exhausted. There is a wide variety of cast irons in common use throughout the world. They are

extremely popular because they are very economical, very castable, and have high damping capacity.

This is why cast irons are used for engine blocks, bases for milling machines and lathes, and many other

applications. In fact, there is more cast iron produced in the world than all other cast metals combined.

The most common types of cast iron are:

- Gray Cast Iron

- White Cast Iron

- Ductile Cast Iron

- Malleable Iron (converted from white iron by heat treatment)

However, common to all cast irons is a very high carbon content from approximately 1.8%-4.3%. The

table below provides the approximate ranges of compositions for common types of cast iron.

Table 1- Typical Composition Ranges for Cast Irons.

Element Gray Cast Iron White Cast Iron Ductile Cast Iron

Carbon

Silicon

Manganese

2.5 – 4.3

1.0 – 3.5

0.1 – 1.0

1.8 – 3.5

0.5 – 1.8

0.3 – 0.8

3.0 – 4.0

1.7 – 2.9

0.2 – 0.9

Despite the fact that cast iron is not recommended for welding, there are times when it must be done.

For example, gray iron antiques, old engine blocks, crank cases, cylinder liners, bells, and many other

casting applications. To weld cast iron, it is helpful to understand the metallurgy of the different types of

cast iron to appreciate why certain techniques are used.

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Metallurgy of Cast Iron Affects Weldability Regardless of the type of cast iron, the weldability of cast iron is generally very poor. There are many

reasons for this poor weldability, but the most important reason is the extremely high carbon content.

Unfortunately, high carbon content is vitally needed for the production of cast iron. Compared to steel

castings, the high carbon content in cast irons provides:

• Reduction of melting temperature to only approximately 1150°C for cast irons, compared to

approximately 1510°C for steel;

• Solidification to a mixture of graphite (carbon) + austenite, compared to Fe3C + ferrite for steel;

• Excellent cast ability because solidification to graphite + austenite is without significant

shrinkage

• Machinability

• Dampening capacity

• Inexpensive castings compared to steel

Thus, cast iron castings are always in great demand when high strength and high fracture toughness are

not required.

Generally, for all the reasons that make cast iron desirable (listed above) to a user, they also make

welding of cast iron a very poor choice. The primary reason for its poor weldability is its very high

carbon content. Although weldability of cast irons is poor, some types of cast iron are more weld able

than others, because of the shape of the graphite (carbon) in the casting. For example, the following is a

list of cast irons in order of weldability, with ferritic ductile iron having the best weldability and white

cast iron having the poorest weldability:

Table 2 Relative Weld abilities of Different Types of Cast Iron

Type of Cast Iron Microstructure Weldability

Ferritic ductile iron

Pearlitic ductile iron

Ferritic gray iron

Pearlitic gray iron

White iron

Ferrite + nodular graphite

Pearlite + nodular graphite

Ferrite + flake graphite

Pearlite + flake graphite

Fe3C + pearlite

Best

↓

↓

↓

Poorest

Ductile and gray cast irons contain a large volume of the graphitic form of carbon in the microstructure.

The shape of the graphite in gray iron is in the form of sharp flakes, while the graphite shape in ductile

iron is spherical. Since the graphite does not contribute to the strength of the casting, the shape of the

graphite has a great effect on the mechanical properties of the cast iron. The round shape provides the

least stress concentration, so ferritic ductile iron has properties that are almost as good as pearlitic steel.

However, because of the high stress concentration effect of flakes, the mechanical properties of ferritic

gray iron are poor compared to ferritic steel. For example, the % elongation of ferritic steel is about

50%, but the % elongation of ferritic cast iron is less than 1%.

The weldability of cast irons is even more difficult, because when gray or ductile iron melts during

welding, it resolidifies as white iron. White iron is the most brittle form of cast iron because it contains

a majority of brittle iron carbide, which is also known as cementite and Fe3C. In addition to iron

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carbide, white iron contains pearlite. The % elongation of white iron is nil or 0%. The heat-affected

zone is also susceptible to brittleness as a result of welding because of the formation of brittle high-

carbon martensite. So, in order to understand the metallurgy of welding cast iron, the weld metal and

the heat-affected zone need to be addressed separately.

Weld Metal Metallurgy using Cast Iron Electrodes Weld metal metallurgy of melted gray iron or ductile iron always results in the resolidification of brittle

white iron, because of the naturally fast cooling rates associated with welding. Fortunately, the weld

metal brittleness problem is the easiest to remedy by using the appropriate filler metal. The three

generally classes of filler metal for cast iron are:

Cast iron electrodes

55% Nickel electrodes and

Nickel electrodes

Cast iron electrodes are specially alloyed to contain high carbon and high silicon for maximum

graphitization potential during solidification. In addition, it is important to help the electrode

solidification as graphite + austenite by slowing down the weld cooling rate. This can only be done by

using high heat input and high preheating temperatures. The combination of high heat input and high

preheat must always be used to ensure such a slow weld cooling rate that the weld metal solidifies as

graphite + austenite, instead of the very brittle mixture of Fe3C and pearlite, or a mixture of Fe3C and

martensite (when the cooling rate is not slow enough). The primary advantage of using cast iron

electrodes is economy, but welding must be performed with high heat input and preheating temperatures

above 600°F to promote the formation of graphite + austenite during solidification.

From a metallurgical point of view, oxy-acetylene is the ideal way to weld cast iron with cast iron

electrodes. Because of its very slow heating and cooling rate, the oxy-acetylene process is a naturally

slow-heating and slow-cooling welding process, which is perfect for cast iron with cast iron electrodes.

Oxy-acetylene has such a low energy density that virtually the entire casting has to be heated before the

weld joint melts. As a result, cooling rates are very slow. In addition, preheating above 600°F must still

be used to ensure that solidification is free of carbides.

Ni-rich Filler Metal to Weld Cast Iron by SMAW Although Ni (nickel) type electrodes are very expensive, they do have one outstanding advantage over

cast iron electrodes. Ni is such a powerful graphitizer that the weld metal will always solidify to the

desirable graphite + austenite. That is, the Ni electrodes will not permit brittle carbides to form in the

weld fusion zone. So, SMAW with Ni electrodes can now be performed much more quickly than with

oxy-acetylene. The two major types of Ni electrodes include:

• Iron-55% Ni electrodes, and

• Pure Ni electrodes

Compared to the pure Ni electrodes, most welders prefer using the iron-55%Ni electrode because it is

cheaper and provides stronger welds. Pure Ni electrodes are very expensive, but Ni has the ability to

convert all of the carbon in the weld metal into graphite during solidification. As a result, the weld

metal will be virtually free of cracking.

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Heat-Affected Zone Metallurgy Question: If Ni electrodes prevent cracking in the weld metal, why then is cast iron

so difficult to weld?

Answer: The heat-affected zone is now the weak link in the welding of cast iron. Because of cast

iron’s high carbon content, the heat-affected zone is very susceptible to cracking because of:

• The formation of high carbon brittle martensite

• Presence of flakes (in gray iron) or nodules (in ductile iron), which act as stress concentrators to

promote cracking

• The narrow unmixed zone located between the weld fusion zone and the heat-affected zone

always solidifies as brittle white iron despite the use of a Ni electrode.

Using Table 2 as a guide, the heat-affected zone of ferritic ductile iron will be the best suited to provide

a crack-free heat-affected zone. The reason why the heat-affected zone of ferritic ductile iron is least

sensitive to cracking is because:

• The ferrite in ferritic ductile iron contains no carbon, and

• All of the graphite is in the shape of spheres, which have the lowest stress concentration

When the heat-affected zone is being created during welding by SMAW, the graphite spheroids do not

change significantly while that ferrite transforms to carbon-free austenite. Upon cooling to room

temperature , the graphite still remains unchanged and the austenite transforms to ferrite. So, the only

heat-affected zone difficulties in welding ferritic cast iron are the (a) the stress concentration effects of

the spheroids, and (b) the presence of the thin unmixed zone of brittle white iron between the Ni weld

metal and the heat-affected zone.

The worst case for welding cast iron is the welding of brittle white iron or pearlitic gray cast iron. Since

so many parts in automotive industry are made of gray cast iron, the metallurgy or the heat-affected zone

needs to be discussed. The reasons by the heat-affected zone of pearlitic gray cast iron is so sensitive to

cracking when SMAW (even with Ni electrodes) is because: (a) the pearlite transforms to austenite upon

heating and then transforms to brittle martensite upon cooling to room temperature, martensite expands

substantially during cooling while the weld metal is contracting to produce a complex state of high

stress, (c) sharp-edged graphite flakes act as potent crack initiators, and (d) the ever-present white iron

layer in the unmixed contributes to the brittle of the gray iron heat affected zone.

Two Ways to Weld Cast Iron by SMAW using Ni Electrodes Based on the above discussion on weld metal and heat-affected zone metallurgy of different types of

cast irons, there are only two ways to effectively weld cast iron with nickel filler metal using SMAW.

The first and preferred method is to preheat the cast iron to at least 600º F and then weld with either

55%Ni electrode or pure Ni filler metal. Using high heat input combined with preheating will help slow

down the weld cooling rate to prevent the formation martensite in the heat-affected zone and help relax

stress concentrations around graphite flakes in gray iron or graphite nodules in ductile iron. Blankets

can be used to cover the hot weld immediately after welding in order to slow down the cooling rate

further.

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The second method is more susceptible to cracking. In this second method, SMAW is used with either

55%Ni or pure Ni electrodes, but with NO preheat and low heat input. This method is more prone to

cracking than in first method, but is more economical. Usually, cast iron comes in massive sections like

engine blocks, heavy counter weights, etc. By welding with no preheating and low heat input passes,

the brittle zones in the heat affected zone and the unmixed zone will be small. It is hopped that these

brittle zones will be so thin that cracking will not take place. In fact, in order to assure the fastest

cooling possible, many welders cool down the area around each pass to ensure that the brittle zones are

minimized.

Although both methods are used by welders, the first method (SMAW with Ni electrodes, high heat

input with preheating) is metallurgically the safest method. With the second method (no preheat, low

heat input), only ferritic types of cast iron would have the best chances for welding without cracking.

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SMAW/CAST IRON_____________ ______ Project # 10

The diesel mechanic is often confronted with the task of welding cast iron. Make sure that the material

is cast iron by grinding lightly and observing the spark pattern. Refer to your textbook to interpret the

spark patterns. Cast iron and cast steel look similar but they require different welding procedures.

To prepare the casting for welding, first locate the crack as follows:

Swab the damaged area with a kerosene or cleaning solvent soaked rag to remove grease and dust.

Allow the liquid to penetrate any cracks then wipe dry. Immediately chalk over the area with common

blackboard chalk. After a few minutes, even cracks not visible to the naked eye become evident by the

liquid bleeding back through the chalk. Commercial dye-penetrant procedures may also be used but

since there are many different kinds it is essential that the manufacturers instructions be followed

closely.

Locate the ends of each crack, mark and then drill a small hole to prevent the crack to create a V-groove.

Be sure the groove exits to the bottom of the crack. On sections more than 3/16” thick, bevel the edges

so that the root of the Joint is 1/8” to 3/16” wide. If the crack extends through the section, leave about a

1/8” gap and a 1/16” land. Remove surface scale by grinding wherever welds are to be made.

There are a number of electrodes that can be used for cast iron; but the one most used has a high nickel

content (45% to 99%) and is often referred to as “Ni-rod”.

The primary goal when welding without preheat is to keep the casting as cool as possible. Use small

diameter electrodes and low currents. Deposit welds no more than 1” long, spaced apart so that one may

cool while the other is being deposited. Peen (lightly hammer) the weld immediately after depositing,

before it has a chance to cool and contract. This causes the weld metal to stretch, thus relieving much of

the stress caused by the welding process. The principal reason for keeping the temperature down is to

prevent stresses from uneven heating and cooling.

Obtain a piece of cast iron, prepare the crack, select the appropriate size rod and repair.

APPROVED: ___________________________ DATE: ______________________

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NSF-ATE Project - Advanced Materials Joining for Tomorrow’s Manufacturing Workforce

Air Carbon Arc Cutting (CAC)

Air carbon arc gouging (often referred to as Carbon Arc) is the transfer heat through a

carbon/graphite electrode with a high velocity blast of air to rapidly remove metal. This process

is very useful to remove old welds or to gouge a groove in order to gain full penetration. Sparks

from this process may travel as far as 35 feet, therefore it is extremely important that all

flammable material be protected or removed from the area.

The air carbon arc-cutting torch is designed differently than the shielded metal arc electrode

holder. The major differences between an electrode holder and an air carbon arc torch are

� The lower electrode jaw has a series of air holes.

� The jaw has only one electrode-locating groove.

� The electrode jaw can pivot.

� There is an air valve on the torch head.

By having only one electrode locating groove in the jaw and pivoting the jaw, the air stream will

always be aimed correctly. The air must be aimed just under and behind the electrode and

always in the same direction. This ensures that the air stream will be directed at the spot where

the electrode arcs to base the metal.

Torches are available in a number of amperage sizes. The larger torches have greater capacity

but are less flexible to use on small parts.

The torch can be permanently attached to a welding cable and air hose or it can be attached to

welding power by gripping a tab at the end of the cable with the shielded metal arc electrode

holder. The temporary attachment can be made easier if the air hose is equipped with a quick

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disconnect. A quick disconnect on the air hose will allow it to be used for other air tools such as

grinders or chippers. Greater flexibility for a workstation can be achieved with this arrangement.

Unlike the oxy-fuel process, the air carbon arc cutting process does not require that the base

metal be reactive with the cutting stream. Oxyfuel cutting can only be performed on metals that

can be rapidly oxidized by the cutting stream of oxygen. The air stream in this process blows the

molten metal away.

Electrodes Air carbon arc cutting electrodes are available as copper-coated or plain (without a coating). The

copper coating helps decrease the carbon electrode overheating by increasing its ability to carry

higher currents and improves the heat dissipation. The copper coating provides increased

strength, to reduce accidental breakage.

Electrodes come in round, flat, and semi round. The round electrodes are used for most gouging

operations, and the flat electrodes are most often used to scarf off a surface. Round electrodes

are also available in sizes ranging from 1/8 to 1 inch in diameter, with ¼ and 5/16 inch being the

most common. Flat electrodes are available in 3/8 and 5/8 inch sizes.

Electrodes are available to be used on both direct-current electrode positive and alternating

current. The DCEP electrodes are the most commonly used, and they are made of carbon in the

form of graphite. The AC electrodes are less common; they have some elements added to the

carbon to stabilize the arc, which is needed for the AC power.

To reduce waste, electrodes are made so that they can be joined together. The joint consists of a

female tapered socket at the top end and a matching tang on the bottom end.

The connection of the new electrode to the remaining setup will allow the stub to be consumed

with little loss of electrode stock. This connecting of electrodes is required for most track-type

air carbon arc cutting operations to allow for longer cuts.

Power Sources Most shielded metal arc welding power supplies can be used for air carbon arc cutting. The

operating voltage required for air carbon arc cutting need to be 28 volts or higher. This voltage

is slightly higher than that required for most SMA welding, but most welders will meet this

requirement. Check the manufacturer’s owner’s manual to see if your welder is approved for air

carbon arc cutting. If the voltage is lower than the minimum, the arc will tend to sputter out, and

it will be hard to make clean cuts.

Because most carbon arc cutting requires a high amperage setting, it may be necessary to stop

some cuts so that the duty cycle of the welder is not exceeded. On large industrial welders this is

not normally a problem.

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Air Supply Air supplied to the torch must be between 80 and 40 psi. The minimum pressure is around 40

psi. The correct air pressure will result in cuts that are clean, smooth, and uniform. The airflow

rate is also important. If the airline is too small or the compressor does not have the required

capacity, there will be a loss in air pressure at the torch tip. This line loss will result in a lower

than required flow at the tip. The resulting cut will be less desirable in quality.

Application Air carbon arc cutting can cut a variety of materials. It is a relatively low-cost way of cutting

most metals, especially stainless steel, aluminum, nickel alloys, and copper. Air carbon arc

cutting is most often used for repair work. Few cutting process can match the speed, quality, and

cost savings of this process for repair or rework. In repair or rework, the most difficult part is the

removal of the old weld or cutting a groove so a new weld can be made. The air carbon arc can

easily remove the worst welds even if they contain slag inclusions or other defects. For repairs

the arc can cut through thin layers of pain, oil, or rust and make a groove that needs little, if any,

cleanup.

Never cut on any material that might produce fumes that would be hazardous

to your health without proper safety precautions, including adequate

ventilation.

The highly localized heat results in only slight heating of the surrounding metal. As a result,

usually there is no need to preheat hardenable metals to prevent hardness zones. Cast iron is a

metal that can be carbon arc gouged to prepare a crack for welding without causing further

damage to the part by inputting excessive heat.

Air carbon arc cutting can be used to remove a weld from a part. The removal of welds can be

accomplished with such success that often the part needs no postcut cleanup. The root of a weld

can be back gouged so that a backing weld can be made ensuring 100% weld penetration.

The electrode should extend approximately 6 inches from the torch when starting a cut, and as

the cut progresses, the electrode is consumed. Stop the cut and readjust the electrode when its

end is approximately 3 inches from the electrode holder. This will reduce the damage to the

torch caused by the intense heat of the operation.

Gouging Gouging is the most common application of the air carbon arc cutting processes. Arc gouging is

the removal of a quantity of metal by completely consuming that portion of the metal removed to

form a groove or bevel. The groove produced along an edge of a plate is usually a J-groove. The

groove produced along a joint between plates is usually a U-groove. Both grooves are used as a

means to insure that the weld applied to the joint will have the required penetration into the

metal.

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Washing Washing is the process sometimes used to remove large areas of metal so that hard surfacing can

be applied. Washing can be used to remove large areas that contain defects, to reduce the

transitional stresses of unequal-thickness plates, or to allow space for the capping of a surface

with a wear-resistant material.

Safety In addition to the safety requirements of shielded metal arc, air carbon arc requires several

special precautions, such as

� Sparks The quantity and volume of sparks generated during this process is a

major safety hazard. Extra precautions must be taken to ensure that the spark stream

will not affect other workers, equipment, materials, or property in the area.

� Noise This process produces a high level of sound. The sound level is high

enough to cause hearing damage if proper ear protection is not used.

� Light The arc light produced is the same as that produced by the shielded metal

arc welding process. But because the arc has no smoke to defuse the light and

amperages are usually much higher, the chances of receiving arc burns are much

higher. Additional protection should be worn, such as thicker clothing, a leather

jacket, and leather aprons.

� Eyes Because of the intense arc light, a darker welding filter lens for the helmet

should be used.

� Fumes The combination of the air and the metal being removed result in a high

volume of fumes. Special consideration must be made for the removal of these fumes

from the work area. Before installing a ventilation system, check with local, state,

and federal laws. Some of the fumes may have to be filtered before they can be

released into the air. It is advisable to wear approved respiratory protection.

� Surface contamination Often this process is used to prepare damaged parts so that

they can be repaired. If the used parts have paint, oils, or other contamination that

might generate hazardous fumes, they must be removed in an acceptable manner

before any cutting begins.

� Equipment Check the manufacturer’s owner’s manual for specific safety information

concerning the power supply and the torch before you start any work with each piece

of equipment for the first time.

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PLASMA ARC CUTTING

(FYI -- The other cutting and gouging process)

Pictured here are two PAC units that are rated for different thick nesses of material.

Plasma arc cutting is one of the most effective processes available for cutting both ferrous and

nonferrous metals. Advantages of the process include no preheat. Cuts can be started instantly.

The heat-affected zone from cutting is minimal. High travel speeds are possible because it is a

thermal process rather than an oxidation process like oxygen cutting. It can be used for cutting

almost any material that will conduct electricity and, in many situations, at faster speeds than any

other process. A plasma torch has the ability to cut metals such as aluminum, copper, brass, cast

iron, carbon steel, nickel, stainless steel, and other ferrous and nonferrous metals.

Typical PAC torch and Ground clamp

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Cutting And Gouging

This section of the training packet compares the three cutting and gouging processes that are

commonly used in industry today.

Compare and Contrast Three Cutting and Gouging Processes

Process Name Oxyacetylene

Cutting

Air Carbon Arc

Cutting

Plasma Arc

Cutting

AWS

Abbreviations

OAC CAC-A PAC

Heating

Mechanism

Heats metal via gas. Heats metal via electric

arc (electrode is made

of graphite and coated

with copper for strength

and conductivity).

Heats metal via

ionized plasma gas.

Metal removal

mechanism

Removes metal/dross

with industrial grade

oxygen.

Removes metal/dross

with compressed air.

Removes metal/

dross by the

secondary gas (air).

Capability Cuts only ferrous

metal (relies on the

rapid oxidation of

steel).

Will cut any conductive

metal (will deposit

carbon and this may be

detrimental).

Cuts any conductive

metal.

Equipment Cylinders

Regulators

Flashback arrestors

Hoses

Torches

Tips

Power Source

Compressed air

Arc Air Torch

Electrodes

Power Source

Compressed air

Torch consumables

Safety Cylinder care/storage

#5 filter lens

Flying sparks

Flashbacks/backfires

Ventilation

Electrical shock

#12 filter lens

Flying sparks

UV/IR

Ventilation

Noise

Electrical Shock

#10 Filter lens

Flying sparks

UV/IR

Ventilation

Noise

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Cutting and Gouging Metals

(Chapter 6 John Deere)

Name: _______________________ Date: _________________________

1. What are three processes that use heat for cutting metals?

2. How does cutting with the SMAW process compare to the processes in Question 1?

3. What is the difference between cutting and gouging?

4. Give the function of the orifices at the “outlet” end of a cutting tip.

5. What can happen if a cutting flame or hot metal comes in contact with a cement surface

like a floor?

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6. List the 3 types of oxyacetylene flames and tell how to recognize the difference between

them. Also tell which one should be used for cutting.

7. What is the proper distance to hold the cutting flame from the workplace?

8. How can the proper depth of the groove needed for removing a fillet weld be recognized

when using an arc air torch?

9. How can the proper depth of the groove needed for back gouging a groove weld be

recognized when using an arc air torch?

10. What is dross?

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Air Carbon Arc Straight Cut in the Flat Project #11

Using an air carbon arc cutting torch and welding power supply that has been safely set up in

accordance with the manufacturer’s specific instructions in the owner’s manual and wearing

safety glasses, welding helmet, gloves, and any other required personal protection clothing, you

will make a 6-inch-long straight U-groove gouge in a carbon steel plate.

1. Adjust the air pressure to approximately 80 psi.

2. Set the amperage within the range for the diameter electrode you are using by

referring to the box the electrodes came in.

3. Check to see that the stream of sparks will not start a fire or cause any damage to

anyone or anything in the area.

4. Make sure the area is safe, and turn on the welder.

5. Wearing a good dry leather glove, to avoid electrical shock, insert the electrode in the

torch jaws so that about 6 inches is extending outward. Be sure not to touch the

electrode to any metal parts, because it may short out.

6. Turn on the air at the torch head.

7. Lower you arc welding helmet.

8. Slowly bring the electrode down at about a 30o angle so it will make contact with the

plate near the starting edge. Be prepared for a loud, sharp sound when the arc starts.

9. Once the arc is struck, move the electrode in a straight line down the plate toward the

other end. Keep the speed and angle of the torch constant.

10. When you reach the other end, lift the torch so the arc will stop.

11. Raise your helmet and stop the air.

12. Remove the remaining electrode from the torch so it will not accidentally touch

anything.

When the metal is cool, chip or brush any slag or dross off of the plate. This material should

remove easily. The groove must be within + 1/8 inch of being straight and within

+ 3/32 inch

of uniformity in width and depth. Repeat this cut until it can be made within these

tolerances. Turn off the CAC equipment and clean up your work area when you are finished

cutting.

Instructor sign off ______________________________________

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Equipment for Shielded Flux Cored Welding Process

Power Sources The flux-core process utilizes the same basic equipment as any of the other gas metal arc

welding processes that incorporates a power source, wire drive-control, gun, and a system for

supplying a shielding gas.

A constant voltage type power source is required to obtain the maximum efficiency from the

flux-core

process. This type of power source automatically supplies the correct amperage to maintain

constant arc voltage.

Since most constant voltage welding machines are rated for 100% duty cycle at rated current,

they provide power for automatic and semi-automatic welding equipment. This factor provides a

safety margin when the welding machines are operated for short periods of time at currents

above their rated capacity.

An outstanding advantage provided by constant voltage welding machines is the simplicity of

welding operation. The electrode feed speed is adjusted to give the desired welding amperage

that is automatically provided by the constant voltage-welding machine.

Electrode Feed Controls

Wire Spool

The purpose of the electrode feed control is to supply the continuous electrode (wire) to the

welding arc at a preset rate. The electrode feed speed controls the welding amperage from the

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constant voltage power source. Flux-core electrodes used in the process require V-grooved feed

rolls of correct size so that the electrodes are not flattened or distorted.

Welding Guns Welding guns used in the flux-core process serve the purpose of providing transfer of the

welding current to the electrode, shielding gas coverage, and control of the arc. The guns may be

air-cooled or water-cooled depending upon the service conditions. Contact tips are subject to

wear and should be changed periodically to insure correct size and reliable current pickup.

Inside diameter tolerance on the contact tip is important to assure reliability of the process.

The welding gun parts consist of the Gas

Diffuser. The Contact Tip which electrically charges

the wire electrode. The Nozzle, which directs the

cover gas over the weld zone. And the Insulator,

which isolates the Nozzle from the electric current.

Insulator

Gas

Nozzle

Contact

Welding

Connector

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PRINT OF FCAW EQUIPMENT

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Wire Conduit Installation SINCE YOU WILL BE USING THE "TWECO MIG-GUNS" ON THE EQUIPMENT, IT IS

ESSENTIAL THAT YOU BE ABLE TO REPLACE PARTS AS NEEDED, THE WIRE GUNS

FROM MOST OTHER MANUFACTURERS ARE SIMILAR; BUT, IF DIFFICULTY IS

ENCOUNTERED, YOU SHOULD READ THE APPROPRIATE INSTRUCTION SHEET.

Installing a New Wire Conduit in Tweco Mig Guns The procedure for removal and installation of a wire conduit in either the No. 4 AN or the No. 6

MIG GUN is identical. The No. 6 MIG GUN wire conduit stop has two O-ring gas seals. The

No. 4 AN MIG GUN wire conduit stop has a sleeve type gas seal only.

1. Be sure the MIG GUN is stretched in a straight line free from twists when removing or

installing a wire conduit. To remove old wire conduit, first remove the MIG-GUN

nozzle, contact tip, and nozzle insulator. No. 4 AN MIG GUNS have a sliding adjustable

style nozzle (see drawing) and the No. 6 MIG GUN has a fixed threaded style nozzle (see

drawing). Loosen the Allen screw in the Gas Diffuser (see drawings) and remove the

Gas Diffuser. Loosen the Allen screw in the MIG KWIK Connector Plug (see drawings)

and pull the old wire conduit out of the Cable hose at the MIG KWIK Connector end.

2. To install a new Wire Conduit Liner, first inspect the gas seal O-rings or sleeve type gas

seal for cuts or damage. Start from the MIG KWIK Connector end of the assembly and

begin pushing the conduit through the MIG KWIK Connector Plug, the Cable hose, and

into the gun. If the conduit should lodge along the way, gently whip or work the Cable

hose to aid forward movement.

3. When the wire conduit stop meets the end of the MIG KWIK Connector Plug (see

pictures), the small Allen screw in the Connector Plug must be securely tightened onto

the conduit to prevent its backward movement.

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4. IMPORTANT: When the conduit is fully inserted into the Cable hose and the

conduit stop is firmly against the Connector Plug, the "raw end" of the conduit will

protrude out of the open end of the gun conductor tube (see picture). Cut the conduit end

off squarely outside the conductor tube according to dimensions in (see picture). The cut

end which seats in the Gas Diffuser must be filed and reamed perfectly smooth on the

inside and outside radii so that the wire feed will not be obstructed.

5. Seat the smoothed end of the wire conduit into the end of the Gas Diffuser and screw the

diffuser into the conductor tube. When the Gas Diffuser is fully tightened, remove the

small Allen screw to make sure that the conduit is visible through the screw hole. This

inspection will assure that the wire conduit is fully seated in the Gas Diffuser.

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START-UP AND SHUTDOWN-PROCEDURES In order to insure a minimum amount of down time replacing parts or troubleshooting and

performing quality welding, it is necessary to use a sequential start-up procedure. Neither your

Instructor nor an employer is impressed with needless destruction of parts, excess gas

consumption, or poor quality welds due to lack of proper maintenance.

A sequential start-up procedure will be used in school at the start of your class. On the job, it is

recommended that you use this procedure first thing in the morning and immediately after lunch.

The gas nozzle and contact tip will be cleaned as required.

The shutdown procedure is necessary to eliminate unnecessary costs for power, loss of shielding

gas, damage to equipment, and to conform to OSHA regulations. This procedure shall be

followed at the end of each class period. On the job, it is recommended that you use this

procedure before you leave for lunch and at the end of the shift.

START-UP PROCEDURE

1. Remove gas nozzle.

2. Clean gas diffuser and contact tip with wire brush. Be sure the holes in the gas

diffuser are not clogged.

3. Check gas diffuser, contact tip, and nozzle insulator for wear and tightness.

Replace and tighten as necessary.

4. Inspect and clean gas nozzle as needed.

5. Replace gas nozzle.

6. Lightly spray or dip inside and outside of nozzle with anti-spatter compound.

7. Turn shielding gas on. Note regulator to make sure there is ample supply. In case

of a Manifold system, this may not be possible. Be certain you have the proper

gas.

8. Turn power source on.

9. Depress trigger, note gas flow, and adjust flow meter to 45 cubic feet per hour.

Examine wire for excessive marking caused by the feed roll tension being too

tight. Adjust as necessary. See Information Sheet.

10. Run practice bead on scrap and make adjustments as required for the project.

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SHUTDOWN PROCEDURE

1. Hang gun so that neither the power cable nor the gun can be walked on.

2. Shut off power at the ON-OFF switch on the power source. DO NOT TURN

OFF power by throwing the breaker switch.

3. Turn gas off at the tank or outlet from the manifold system.

PROCEDURE TO REPLACE WIRE SPOOL

1. Depress gun trigger until wire no longer moves. Turn power source off!

2. Pull remnant of wire through the power cable from the gun end.

3. Remove gas nozzle and contact tip.

4. Release feed roll tension by opening the wire feed rollers.

5. Loosen the keepers on the wire roll and remove the remainder of the wire spool.

Release tension on the wire by releasing the

feed rolls. On this type of wire feeder you

simply turn the black knob ½ turn and the rolls

will pop open.

Wire feeds into

rolls through a

tube located here

This keeper knob must

be removed to take the

wire roll off of the

feeder

Wire roll brake

adjustment

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6. Install new wire spool. Make sure loose end of new spool will feed from the

bottom in the direction of the feed rolls. DO NOT CUT ties on the new wire

spool.

7. Cut the tie that the end of the new wire spool is attached to and cut the wire

square with wire cutters, manually feed the wire through the guides and feed rolls,

and feed the wire at least 6 inches into the wire conduit. Cut the second wire tie if

necessary.

8. Replace feed rolls and/or tension screws and adjust moderate tension on the wire.

9. Cut remaining ties.

10. Turn power source on.

11. Grasp the electrode between the input guide and the wire reel and depress gun

trigger. You should be able to cause the wire to slip on the wire feed only with a

very firm grip. Adjust feed roll tension as needed. Tension rolls adjusted too

tightly may flatten the wire causing it to offer excessive resistance when traveling

through the wire guides, wire conduit, and the contact tip. Tension rolls adjusted

too loosely will cause the wire to slip excessively, resulting in sporadic electrode

feed. This will contribute to low quality welds and poor operating efficiency.

12. Depress and release the gun trigger several times while observing the wire roll.

There should be a very slight amount of slack in the wire between the input guide

and the reel. If there is tension on the wire, the brake adjustment on the wire reel

is adjusted too tightly. If the reel continues to revolve with the trigger off, it can

cause the wire to become unraveled resulting in wasted electrode. Adjust the

tension as needed.

13. Depress trigger until wire emerges from the gas diffuser. Replace the contact tip

and

gas nozzle.

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Gas Metal Arc Welding and Flux-Cored Arc Welding (GMAW and FCAW)

(Chapter 4 John Deere)

Name: _________________________ Date: ___________________________

1. Gas Metal Arc Welding is also known as ___________________________ welding.

2. When doing Semi-Automatic welding, what two things does the equipment control?

3. GMAW and FCAW have been replaced by what two other processes for many

fabrication and repair jobs?

4. What does GMAW-S stands for?

5. A “buzzing” or sharp “crackling” sound best describes what type of metal transfer?

6. The maximum thickness that is typically welded with GMAW-S is ______________

inches.

7. A “hissing” or “whispering” sound best describes what type of metal transfer?

8. What type of Power source is used for all the processes and metal transfer methods listed

in Chapter 4?

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9. Because these processes use a “continuous wire”, the duty cycle for industrial power

sources should be _________________% duty cycle.

10. Most 300-amp air-cooled welding guns are rated at this amperage at what duty cycle and

with what gas?

_______________% duty cycle, __________________ gas.

11. In Fig. 24, which gas produces the deepest penetration?

12. The wire sticking out of the gun end presents what two hazards?

13. In GMAW and FCAW, amperage is set by which control?

14. The longer the arc the ________________ the voltage, and the shorter the arc the

_____________ the voltage.

15. The distance from the contact tube to the arc for GMAW-S is _______________ inch.

16. When shutting down the equipment and draining the shielding gas by pushing the gun

trigger, what two hazards must be guarded against?

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17. What four corrective actions will help eliminate porosity in the weld?

18. When trouble shooting, break the situation down into these three areas:

__________________, __________________, ____________________.

19. List two gun parts that need to be inspected frequently.

20. When adjusting drive roll tension, hold the end of the gun several inches away

from a _____________________ and adjust the _________________ ________________

until slippage stops.

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E71T-1 T-Joint (2F) Project #12 Welding Sequence E71T-1-- Root Pass Single pass technique with slight weave to ensure the weld metal is

fusing

into both pieces of metal.

E71T-1—Fill Use the split bead technique with stringer beads ensuring even fill.

E71T-1—Finish Beads Use stringer bead technique keeping the electrode in the puddle at

all times.

The weld joint pictured above is what is known as a 2F or Horizontal Fillet Weld. Notice that

the joint has been securely tacked at each end prior to starting the weld. Make sure your project

is tacked on all four sides before you start to weld. If you do not tack your piece before you start

welding, or if your tacks are too small the parts will pull or move while you are welding them.

Begin the weld at one end of the joint and continue to weld at a constant even speed all of the

way to the other end without stopping. After you finish the first root pass have your instructor

check your work.

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E71T-1 T-Joint (2F) Project #12 Information Continued

Notice the desirable fillet weld

profiles.

Acceptable fillet weld profiles will

have an equal amount of weld on

each of the legs of the weld.

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E71T-1 T-Joint (3F) Project #13 Welding Sequence E71T-1-- Root Pass Single pass technique with slight weave to ensure the weld metal is

fusing into both pieces of metal.

E71T-1—Fill Use the split bead technique with stringer beads ensuring even fill.

E71T-1—Finish Beads Use stringer bead technique keeping the electrode in the puddle at

all times.

The weld joint pictured above is in the 3F or Vertical position. This weld will be started from

the bottom of the joint and weld to the top. It is important to remember while you are welding

this type of a joint that one side of the weldment is the edge of the plate and the other side of the

weldment is the center of the plate. The reason this is important is the edge of the piece being

welded will be effected by the heat of the weld much sooner then the piece you are centered on.

Once you begin the weld watch for the puddle to form. When you see the puddle form and fill

out into a circle begin to move upward slowly keeping the wire electrode in the center of the

puddle. If you move to quickly and get ahead of the puddle the wire electrode will burn a hole in

the metal.

VT Criteria Student Assessment Instructor Assessment

Reinforcement

Undercut

Bead Contour

Cracks

Arc Strikes

Fusion

Porosity

Bend Test

Grade Date

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SELF SHIELDED FLUX-CORE PROCESS AND WELDING VARIABLES

The self-shielded flux-core process involves welding with a flux core fabricated electrode.

Welding current is supplied from a constant voltage power source. Normally, direct current with

electrode negative (straight polarity) is used. This process offers many advantages, the greatest

of which is no gas cover making it ideal for outdoor use.

The self-shielded flux-core process results in a deeply penetrating arc. This deep penetration has

great economic advantages. It reduces edge penetration for butt joints to a minimum, allowing

considerably less weld metal with less welding time. The greater penetration of the arc permits

small fillet welds, which require much less welding time to have comparable strength and

load-carrying capacity.

High deposition rates of weld metal are available with the flux-core process. High current

density on the electrode and continuous welding make the high deposition rates possible. The

greater amounts of weld metal deposited in a given length of time result in remarkable cost

savings in the finished weldment.

All-position electrodes are available in .045", 5/64” and 1/16" diameters. These small diameter

electrodes have been developed to produce excellent welds in out of position work with very

little spatter.

JOINT DESIGN

The self-shielded flux-core arc welding process is capable of producing weldments with great

savings of time and weld metal. Part of the savings results from the continuous welding with

high deposition rates, which are inherent to the process. The other part of the savings is achieved

from the proper design of the weld joints to make full advantage of the deep penetration of sound

weld metal.

Reducing the root opening, by increasing the root face, and by using smaller bevel angles can

effectively reduce the volume of weld metal required to complete a butt joint.

Because of the deep penetration of the arc, fillet welds can be reduced in exterior size and retain

comparable or greater strength.

SELF SHIELDED FLUX-CORE WELDING VARIABLES

When the variables by which the process is operated are understood and controlled, consistently

good welds throughout a wide range of welding conditions are easily obtained. Each variable

listed below is important in obtaining a balanced welding condition.

Metal thickness, types of joint, and joint geometry must be taken into consideration when using

the following variables:

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EFFECT OF WELDING VOLTAGE

Arc voltage determines the arc length. The best or balanced arc voltage for the self-shielded

flux-core process is achieved when the arc length is such that the tip of the electrode is about

level with a flat plate surface. The weld metal transfer across the arc is confined (or buried)

below the plate surface, resulting in a spatter-free welding condition with good penetration, and

weld bead appearance. A balanced arc condition is referred to as "Zero-Arc Length.”

Higher arc voltage results in a longer arc. The tip of the electrode and a portion of the arc stream

are above the surface of a flat plate when the arc voltage is high. The arc stream is cone-shaped

with the vertex at the electrode tip. The base of the arc stream cone is larger with a longer arc.

A larger area of the base metal is heated, resulting in a wider and flatter weld bead. Excessive

arc length contributes to heavy spatter and gives an irregular weld bead appearance. This arc

condition is called "Plus Arc Length."

Lower arc voltage results in a shorter arc. The tip of the electrode and the arc stream are below

the surface of a flat plate when the arc voltage is low. The base of the arc stream cone has a

smaller area and heats less base metal, which gives a narrower and higher weld bead shape. This

shorter arc is prone to weld metal spatter that splashes out of the molten pool and has a cutting,

knife-like action at the leading edge of the arc. This arc is referred to as "Minus Arc Length."

EFFECT OF WELDING CURRENT

The electrode feed speed is the variable that controls the welding current from a constant voltage

power source. The power source supplies the amount of current (amperes) necessary to melt the

electrode at the rate required to maintain the preset voltage and resultant arc length.

An increase in the electrode feed speed (all other normal welding variables constant) requires

more electrodes to be melted to maintain the preset voltage and arc length. Higher current is

automatically supplied by the power source and the deposition rate (lb./hr.) increases. More

weld metal and more heat in the base metal are applied per unit length of weld, resulting in

deeper penetration with larger weld beads.

A decrease in the electrode feed speed (all other welding variables constant) results in less

electrode to be melted to maintain the preset voltage and arc length. Less current is

automatically supplied by the power source and the deposition rate (lb./hr.) decreases. Less weld

metal and less heat are applied per unit length of weld, resulting in less penetration and smaller

weld beads.

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EFFECT OF WELD TRAVEL SPEED

The relative speed between the electrode and the work surface is the "Weld Travel Rate" and has

a marked effect on the weld penetration and bead appearance.

Slower travel rates give proportionally larger weld beads and more heat input in the base metal

per unit length of weld. The longer heating time of the base metal increase the, depth of

penetration and the increased weld deposit results in a higher and wider bead contour. The

increase of weld metal and heat input continue until the speed is reduced to a point where the

volume of the molten weld metal and slag becomes so great that the molten materials flow into

the crater beneath the arc and give an insulating effect between the arc and the base metal. The

heating of the base metal beneath the arc is reduced and the molten weld metal heats a wider area

of the base metal, resulting in a wide bead with shallow penetration. This effect is readily visible

during welding.

Progressively increased travel rates give opposite effects. Less weld metal is deposited with

lower heat input per unit length of weld. This gives a narrower weld bead and less penetration.

Excessively fast travel rates result in ropy, irregular bead shapes with difficult slag removal and

undercut.

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EFFECT OF GUN ANGLE

Picture shows a push gun technique

WELDING GUN ANGLES

Drag angle is the angle the welding gun is tilted from perpendicular in the direction of travel

with the top section of the gun in advance of the point of welding.

Push angle is the angle the welding gun is tilted from perpendicular to the direction of travel

with the top section of the gun behind the point of welding. The arc stream plays ahead on the

cold base metal when a pushing gun angle is used and reduces the intensity of the heat on the

work. This lowers the penetration and helps to prevent burn-through on thin gage metals.

Dragging gun angles are usually desirable because the operator has a better view of the arc and

better control. A dragging gun angle of 2 degrees to 15 degrees is recommended on heavier

weldments.

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EFFECT OF CONTACT TIP-TO-WORK DISTANCE

The contact Tip-to-Work Distance, or "Electrode Stick-Out" is the length of the electrode

extending from the end of the contact tip to the work surface. This extended length is the part of

the electrode that carries the welding current, and is subject to resistance heating, sometimes

called "electrode preheat." In the case of Self Shielded Flux Cored Electrodes the pre

heating process is very important. Without pre heating of the electrode you will have weld

defects.

Low resistance and electrode preheat are encountered with 5/8” electrode stick-out (minimum

recommended). A 1" stick out (maximum recommended) causes high resistance and electrode

preheat. The constant potential power source, however, continuously supplies the correct

amount of current to maintain the preset constant arc voltage and arc length at any fixed

electrode feed speed

Penetration is slightly affected by the stick out length the deposition rate is constant, provided the

electrode feed speed is unchanged. The same amount of electrode is melted per unit length of

weld, and there is little or no change in the weld bead shape.

Reducing the electrode stick-out to5/8" will require more current (amperes) that is automatically

supplied by the power source to melt the electrode and maintain the preset arc length. The lower

welding current and smaller amount of weld metal deposited results in lower heat input (base

metal heating) per unit length of weld and a smaller weld bead with reduced penetration.

Increasing the electrode stick-out to ½ " results in:

1. More preheating of the extended electrode

2. Less current required to melt the electrode while maintaining the preset arc length.

The electrode feed speed was increased to give the original current value of bead 2.

Increased electrode feed speed results in a higher deposition rate (lb./hr.). Increased deposition

and heat input (base metal) per unit length of weld results in a larger weld bead with greater

depth of penetration.

Proper electrode stick out makes it possible to take advantage of the electrode preheating

on the length extended. Proper attention to these dimensions will assure maximum weld

quality, penetration, and deposition rate with a given set of balanced conditions.

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E71T-8 Horizontal T-Joint (2F) Project #14 Welding Sequence E71T-8-- Root Pass Single pass technique with slight weave to ensure the weld metal is

fusing into both pieces of metal.

E71T-8—Fill Use the split bead technique with stringer beads ensuring even fill.

E71T-8—Finish Beads Use stringer bead technique keeping the electrode in the puddle at

all times.

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Gas Metal Arc Welding Horizontal T-Joint Project #15

• To weld the Horizontal “T” (which is shown in the picture above and also in the print on

the following page) you will need to first tack the three pieces together as indicated in the

print. Make sure all of the parts are at a 90º angel in relation to each other. Once you have

the project tacked together take it to your instructor for his approval of the fit up before

you weld the project.

• As you are welding the project the nozzle of the Welding gun should be at a45º angle to

the perpendicular and the travel angel should be about 15º. The key to a quality weld is

consistency. As you travel across the plate, be consistent in the distance from the nozzle

to the work. Be consistent in the travel speed, and keep the Welding gun at the same

angel from the begging of the weld to the end of the weld.

• If you are not sure what some of the prints are weld symbols mean you will find more

information relating to this subject in the “Welding Principles and Applications” textbook

in chapter 18.

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Gas Metal Arc Welding Plate to Pipe T-Joint Project #16

• When making the pipe to plate weld in the 2-F position (as shown) it is important to make a

weld that is consistent in size and shape and to make smooth tie-ins where you do your

starts and stops.

• Keep your welding gun and your travel speed and angel the same as you travel around the

pipe allowing the weld to be equally distributed on the plate and the pipe.

• When Welding pipe it is usually “tacked” in four places. Once at each of the four

quadrants of the pipe. Do not start or stop your Weld on the tacks as this will leave a high

area in the Weld Bead. Start the Weld next to the tack, make a quick back motion to tie the

tack into the Weld and then continue with your Weld pass. When finishing the Weld stop

Welding before you run up on the tack, allowing the Weld metal to flow over the tack as

you stop.

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Gas Metal Arc Welding Vertical T-Joint ____ Project #17

• The Vertical Down position is often used when welding material that is thin gauge. By

using the downward travel motion the welder applies less heat to the pieces being

welded.

• With the Welding gun pointed upward as shown in the picture, start the weld and travel

from top to bottom. Watch the weld bead and the pieces being welded for signs that you

are moving to slowly. If it appears that the metal is about to melt through pick up the

travel speed.

• The Short Circuit Transfer (SCT) Welding method has a very low heat input and in most

cases Vertical up is the preferred method of Welding with this process. However in

some cases Vertical Down will be required due to a part being very thin or the need to

control heat distortion.

• Once you have successfully completed this project in the Vertical Down do the same

project again, this time starting from the bottom and going up. This is the Vertical up

Welding position.

• When running the first pass (Root Pass) of the Vertical up Weld you should move the

gun slightly from left to right as you Weld to better spread the Weld to both sides of the

Weld joint.

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Gas Tungsten Arc Welding (GTAW)

(Chapter 5 John Deere)

Name: _________________________ Date: ____________________________

1. Gas Tungsten Arc Welding (GTAW) is the AWS correct terminology for the process. List two

other common names that describe it.

2. DC ____________________ is a very common setting to use with GTAW.

3. What kind of a wire brush should be used for cleaning aluminum?

4. The ____________________ is the torch part that must be of the proper size to hold the tungsten

electrode.

5. An ____________________ gas is used with GTAW.

6. Which type of inert gas creates the hottest arc – helium or argon?

7. The flow rate for helium must be ______________ times greater than argon because it is so light

it floats as it leaves the gas nozzle.

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8. When using a filler metal, the end not being melted presents what safety hazard?

9. When welding carbon steel, give one kind of filler metal, which should not be used.

10. Argon and the cylinders it is supplied in present what two safety hazards?

11. A good system to follow when setting up the equipment is to start at ________________

and work back to the __________________.

12. According to Fig. 39, welding a 3/16” thick stainless steel fillet weld requires

_______________ maximum amperage.

13. According to Fig. 40, welding a 3/16” thick stainless steel fillet weld requires

_______________ maximum amperage.

14. The arc length should be ___________________ times the electrode diameter.

15. If the electrode becomes contaminated, _________________ before continuing to weld.

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Properties of Metals

(Chapter 11 John Deere)

Name: ___________________________ Date: _________________________

1. What are the two major groups of metals?

2. Which melts at a high temperature, cast iron or mild steel?

3. What is the difference between an iron and steel?

4. Match the items on the left below with the correct item at the right.

a. Tensile strength-- 1. Ability to resist penetration

b. Ductility-- 2. Ability to resist pulling apart

c. Malleability -- 3. How easily a metal fractures

d. Hardness-- 4. Ability to be stretched

e. Brittleness-- 5. Tendency to be hammered into shape

5. If you chip a metal with a cold chisel and it curls, would it be a mild steel or a cast iron?

6. Annealing is the ______________________ of metals by heat treatment.

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7. How does malleable iron differ from cast iron?

8. What does the “L” after a stainless steel mean?

9. What is the first step in identifying a metal that has a plating or painted surface?

10. What is another name for “pot metal”?

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Glossary of Common Welding Terms

Alternating Current The electrons change direction back and forth, (first flowing

(AC) one-way, then reversing flow in the opposite direction).

Amperage A measure of current. Current measures the rate of flow of electrons in a

circuit. In Welding we study current flow from negative to positive.

Arc Length The distance the electrode is above the work.

Autogenous Weld A weld made without the addition of filler metal.

Backfire The momentary recession of the flame into the welding tip or cutting tip

followed by immediate reappearance or complete extinction of the flame.

Usually caused by a dirty tip, air leak, damaged tip, or poor mixture

adjustment.

Base Metal The metal to be welded, soldered, brazed or cut.

Carburizing Flame Also called reducing flame. A gas flame containing an excess of fuel gas.

Crater In arc welding, a depression at the end of a weld bead or in the molten weld

pool.

Direct Current (DC) Current that flows in only one direction.

Electrode A component of the welding circuit through which current is conducted to

the arc, molten slag or base metal. In the case of SMAW (stick welding) the

"Stick" or welding rod is the electrode.

Electrons Negative charges that can move about freely in a circuit.

Ferrous Descriptive of a metallic material that is dominated by iron in its chemical

composition.

Fillet Weld A weld of approximately triangular cross section joining two surfaces

approximately at right angles to each other in a lap joint, T-Joint or corner

joint. See types of joints at the end of this glossary.

Flashback A recession of the flame into or back of the mixing chamber of the torch.

This can be very dangerous and the torch must be turned off and allowed to

cool immediately.

Flux Material used to prevent, dissolve, or facilitate the removal of oxides and

other undesirable surface substances.

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Gage Number A numbering system used to express the thickness of wire or sheet metal.

GTAW Gas Tungsten Arc Welding. Sometimes referred to as TIG (Tungsten Inert

Gas).

Kerf The width of the cut produced during a cutting process.

Non-Ferrous A material lacking iron in sufficient percentage to have any dominating

influence on the properties.

Overlap A weld defect caused by the weld extending beyond the toe of the weld

without fusing into the base metal. Also known as Cold Lap or Roll Over.

Parent Metal Non-standard term for base metal.

Plate Material thicker than 3/16".

PSIG Pounds per square inch gage pressure.

Reverse Polarity (RP) Electrode positive, work negative.

Ripple The surface pattern on a weld bead. Also known as chevrons,

Freeze lines or convolutions.

Sheet Metal Material .18"-(3/16") or less usually measured by gage number. Shielded

Metal

Arc Welding: (SMAW) an arc welding process, which produces joining of metals by

heating them with an arc between a covered metal electrode and the work.

Shielding is obtained from decomposition of the electrode covering. The

filler metal is obtained from the electrode.

Slag A nonmetallic solid material deposited on a weld during the welding

operation.

Straight Polarity (SP) Electrode negative, work positive.

Travel Speed The amount of time it takes to weld a given distance.

Undercut A groove melted into the base metal adjacent to the toe of a weld and left

unfilled by weld metal.

Voltage The force that pushes the current through the circuit.

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Weave Bead A type of weld bead made with a transverse (side-to-side) oscillation

movement.

Welding The melting, flowing together, combining, and freezing of two materials

under controlled conditions.

Welding Rod The filler metal used in oxyfuel welding or brazing, and in GTAW.

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Final Grades - WLD 217 Name: _________________ Instructor: ___________________ Date: __________________

Welding Projects = 40%

Out of Out of Out of

Out of Out of Out of

Out of Out of Out of

Out of Out of Out of

Out of Out of Out of

Out of Out of Out of

A Total Project pts. ________ / Total pts. Possible _______ X 40 = _______ %

Written Work = 20%

Out of Out of Out of

Out of Out of Out of

Out of Out of Out of

B Total Project pts. ________ / Total pts. Possible _______ X 20 = _______ %

Safety = 15% Each day of attendance is worth 3 points earned. Any safety violation will result in 0 points for the day.

Out of Out of Out of Out of Out of Out of

Out of Out of Out of Out of Out of Out of

Out of Out of Out of Out of Out of Out of

C Total pts. earned ________ / Total pts. Possible _______ X 15 = _______ %

Employability Skills = 15% The following attributes will be assessed - attendance, attitude, time management, team work,

interpersonal skills, etc.. Daily points (there are no excused absences, hence no points earned for days missed ) 3 pts =

present and working for the entire shift; 2 pts = late; 1 pt = late and left early; 0 pts = no show.

Out of Out of Out of Out of Out of Out of

Out of Out of Out of Out of Out of Out of

Out of Out of Out of Out of Out of Out of

D Total pts. earned ________ / Total pts. Possible _______ X 15 = _______ %

Final Exam 10%

Written Exam Out of

E Total Project pts. ________ / Total pts. Possible _______ X 10 = _______ %

Add Lines A + B + C + D + E. This will give you your Final Grade TOTAL % _________

FINAL GRADE _________