welding terms & techniques

8/6/2019 Welding Terms & Techniques

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USEFULWELDING

INFORMATION

TERMS &TECHNIQUES


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Welding Glossary

A

Air Carbon Arc Cutting (CAC-A)- A cutting process by which metals are melted by the heat of an arc using acarbon electrode. Molten metal is forced away from the cut by a blast of forced air. To remove large amounts ofmetal, look for a welder that can use carbons of at least 3/8 in diameter. Consumables: carbon electrodes,

compressed air supply.

Alternating Current (AC)-An electrical current that reverses its direction at regular intervals, such as 60 cyclesalternating current (AC), or 60 hertz.

Amperage-The measurement of the amount of electricity flowing past a given point in a conductor per second.Current is another name for amperage.Arc-The physical gap between the end of the electrode and the base metal. The physical gap causes heat dueto resistance of current flow and arc rays.

Arc Force-Also called Dig and Arc Control. Gives a power source variable additional amperage during lowvoltage (short arc length) conditions while welding. Helps avoid "sticking" stick electrodes when a short arclength is used.

Auto-Link -Internal inverter power source circuit that automatically links the power source to the primaryvoltage being applied, without the need for manually linking primary voltage terminals.

Automatic Welding-Uses equipment which welds without the constant adjusting of controls by the welder oroperator. Equipment controls joint alignment by using an automatic sensing device.

C

Constant Current (CC) Welding Machine-These welding machines have limited maximum short circuitcurrent. They have a negative volt-amp curve and are often referred to as "droopers". The voltage will changewith different arc lengths while only slightly varying the amperage, thus the name constant current or variable

voltage.

Constant-Speed Wire Feeder-Feeder operates from 24 or 115 VAC supplied by the welding power source.

Constant Voltage (CV), Constant Potential (CP) Welding Machine-"Potential" and "voltage" are basically thesame in meaning. This type of welding machine output maintains a relatively stable, consistent voltageregardless of the amperage output. It results in a relatively flat volt-amp curve as opposed to the drooping volt-amp curve of a typical Stick (SMAW) welding machine.Current-Another name for amperage. The amount of electricity flowing past a point in a conductor every second.

D

Defect-One or more discontinuities that cause a testing failure in a weld.

Direct Current (DC)-Flows in one direction and does not reverse its direction of flow as does alternatingcurrent.

Direct Current Electrode Negative (DCEN)-The specific direction of current flow through a welding circuitwhen the electrode lead is connected to the negative terminal and the work lead is connected to the positiveterminal of a DC welding machine. Also called direct current, straight polarity (DCSP).

Direct Current Electrode Positive (DCEP)- The specific direction of current flow through a welding circuitwhen the electrode lead is connected to a positive terminal and the work lead is connected to a negativeterminal to a DC welding machine. Also called direct current, reverse polarity (DCRP).

Duty Cycle-The number of minutes out of a 10-minute time period an arc welding machine can be operated atmaximum rated output. An example would be 60% duty cycle at 300 amps. This would mean that at 300 ampsthe welding machine can be used for 6 minutes and then must be allowed to cool with the fan motor running for


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F

Fan-On-DemandTM

-Internal power source cooling system that only works when needed, keeping internalcomponents cleaner.

Fixed Automation-Automated, electronically controlled welding system for simple, straight or circular welds.

Flexible Automation-Automated, robotically controlled welding system for complex shapes and applicationswhere welding paths require torch-angle manipulation.

Flux Cored Arc Welding (FCAW)-An arc welding process which melts and joins metals by heating them withan arc between a continuous, consumable electrode wire and the work. Shielding is obtained from a fluxcontained within the electrode core. Depending upon the type of flux-cored wire, added shielding may or maynot be provided from externally supplied gas or gas mixture. Consumables: contact tips, flux cored wire,shielding gas (if required, depends on wire type).

G

Ground Connection-A safety connection from a welding machine frame to the earth. Often used for groundingan engine-driven welding machine where a cable is connected from a ground stud on the welding machine to ametal stake placed in the ground. See Workpiece Connection for the difference between work connection andground connection.

Ground Lead-When referring to the connection from the welding machine to the work, see preferred termWorkpiece Lead.

H

Hertz-Hertz is often referred to as "cycles per second". In the United States, the frequency or directional changeof alternating current is usually 60 hertz.

High Frequency-Covers the entire frequency spectrum above 50,000 Hz. Used in TIG welding for arc ignitionand stabilization.

Hot StartTM-Used on some Stick (SMAW) machines to make it easier to start difficult-to-start electrodes. Used

for arc starting only.

I

Inverter-Power source which increases the frequency of the incoming primary power, thus providing for asmaller size machine and improved electrical characteristics for welding, such as faster response time and morecontrol for pulse welding.

K

KVA-Kilovolt-amperes. The total volts times amps divided by 1,000, demanded by a welding power source fromthe primary power furnished by the utility company.

KW-Kilowatts. Primary KW is the actual power used by the power source when it is producing its rated output.Secondary KW is the actual power output of the welding power source. Kilowatts are found by taking volts timesamps divided by 1,000 and taking into account any power factor.

L

Lift-ArcTM- This feature allows TIG arc starting without high frequency. Starts the arc at any amperage withoutcontaminating the weld with tungsten.

M

Microprocessor-One or more integrated circuits that can be programmed with stored instructions to perform avariety of functions.

MIG (GMAW or Gas Metal Arc Welding) An arc welding process which joins metals by heating them with an


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Another method of MIG welding, spray transfer moves a stream of tiny molten droplets across the arc from theelectrode to the weld puddle. Consumables: contact tips, shielding gas, welding wire.

O

Open-Circuit Voltage (OCV)-As the name implies, no current is flowing in the circuit because the circuit isopen. The voltage is impressed upon the circuit, however, so that when the circuit is completed, the current willflow immediately. For example, a welding machine that is turned on but not being used for welding at themoment will have an open-circuit voltage applied to the cables attached to the output terminals of the welding

machine.

P

Plasma Arc Cutting-An arc cutting process which severs metal by using a constricted arc to melt a small areaof the work. This process can cut all metals that conduct electricity. Miller Spectrum cutters are completepackages that contain all required equipment and torch consumables. Consumables: torch consumables, gas orcompressed air supply.

Pounds Per Square Inch (psi)-A measurement equal to a mass or weight applied to one square inch ofsurface area.

Power Efficiency-How well an electrical machine uses the incoming electrical power.

Power Factor Correction-Normally used on single-phase, constant current power sources, to reduce theamount of primary amperage demanded from the power company while welding.

Primary Power-Often referred to as the input line voltage and amperage available to the welding machine fromthe shop's main power line. Often expressed in watts or kilowatts (KW), primary input power is AC and may besingle-phase or three-phase. Welding machines with the capability of accepting more than one primary inputvoltage and amperage must be properly connected for the incoming primary power being used.

Pulsed MIG (MIG-P)-A modified spray transfer process that produces no spatter because the wire does nottouch the weld puddle. Applications best suited for pulsed MIG are those currently using the short circuit transfermethod for welding steel, 14 gauge (1.8 mm) and up. Consumables: contact tips, shielding gas, welding wire.

Pulsed TIG (TIG-P)-A modified TIG process appropriate for welding thinner materials. Consumables: tungstenelectrode, filler material, shielding gas.

Pulsing-Sequencing and controlling the amount of current, the polarity, and the duration of the welding arc.

R

Rated Load-The amperage and voltage the power source is designed to produce for a given specific duty cycleperiod. For example, 300 amps, 32 load volts, at 60% duty cycle.

Resistance Spot Welding(RSW)-A process in which two pieces of metal are joined by passing currentbetween electrodes positioned on opposite sides of the pieces to be welded. There is no arc with this process,

and it is the resistance of the metal to the current flow that causes the fusion. Spot welding requires thefollowing equipment: air- or water-cooled spot welder, set of 2 tongs and set of 2 tips. Consumables are notrequired to spot weld.

RMS-Root Mean Square. The "effective" values of measured AC voltage or amperage. RMS equals 0.707 timesthe maximum, or peak value.

S

Semiautomatic Welding-The equipment controls only the electrode wire feeding. The welding gun movementis controlled by hand.

Shielding Gas-Protective gas used to prevent atmospheric contamination of the weld pool.

Single-Phase Circuit-An electrical circuit producing only one alternating cycle within a 360 degree time span.


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Spot Welding-Usually made on materials having some type of overlapping joint design. Can refer to resistance,MIG or TIG spot welding. Resistance spot welds are made from electrodes on both sides of the joint, while TIGand MIG spots are made from one side only.

SquarewaveTM-The AC output of a power source that has the ability to rapidly switch between the positive andnegative half cycles of alternating current.

Stick Welding (SMAW or Shielded Metal Arc)-An arc welding process which melts and joins metals byheating them with an arc, between a covered metal electrode and the work. Shielding gas is obtained from the

electrode outer coating, often called flux. Filler metal is primarily obtained from the electrode core. An AC/DCwelder is recommended for Stick. For most applications, DC reverse polarity welding offers advantages overAC, including easier starts and out-of-position welding, smoother arc and fewer arc outages and sticking.Consumables: stick electrodes.

Submerged Arc Welding (SAW)-A process by which metals are joined by an arc or arcs between a bare metalelectrode or electrodes and the work. Shielding is supplied by a granular, fusible material usually brought to thework from a flux hopper. Filler metal comes from the electrode and sometimes from a second filler rod.

T

TIG Welding (GTAW or Gas Tungsten Arc)- Often called TIG welding (Tungsten Inert Gas), this weldingprocess joins metals by heating them with a tungsten electrode which should not become part of the completed

weld. Filler metal is sometimes used and argon inert gas or inert gas mixtures are used for shielding.Consumables: tungsten electrode, filler metal, shielding gas.

Three-Phase Circuit-An electrical circuit delivering three cycles within a 360 degree time span, and the cyclesare 120 electrical degrees apart.

Torch-A device used in the TIG (GTAW) process to control the position of the electrode, to transfer current tothe arc, and to direct the flow of the sheilding gas.

Touch Start-A low-voltage, low-amperage arc starting procedure for TIG (GTAW). The tungsten is touched tothe workpiece; when the tungsten is lifted from the workpiece an arc is established.

Tungsten-Rare metallic element with extremely high melting point (3410o

Celsius). Used in manufacturing TIG

electrodes.

V

Voltage-The pressure or force that pushes the electrons through a conductor. Voltage does not flow, butcauses amperage or current to flow. Voltage is sometimes termed electromotive force (EMF) or difference inpotential.

Voltage-Sensing Wire Feeder-Feeder operates from arc voltage generated by welding power source.

Volt-Amp Curve-Graph that shows the output characteristics of a welding power source. Shows voltage andamperage capabilities of a specific machine.

W

Weld Metal-The electrode and base metal that was melted while welding was taking place. This forms thewelding bead.

Weld Transfer-Method by which metal is transferred from the wire to the molten puddle. There are severalmethods used in MIG; they include: short circuit transfer, spray arc transfer, globular transfer, buried arctransfer, and pulsed arc transfer.

Wire Feed Speed-Expressed in in/min or mm/s, and refers to the speed and amount of filler metal fed into aweld. Generally speaking the higher the wire feed speed, the higher the amperage.

Workpiece Connection-A means to fasten the work lead (work cable) to the work (metal to be welded on).Also, the point at which this connection is made. One type of work connection is made with an adjustable clamp.


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MIG Welding Tips

1. Keep a 1/4 to 3/8 in stickout (electrode extending from the tip of the

contact tube.) (Refer to Diagram 1. Electrode Extensions)

2. For thin metals, use a smaller diameter wire. For thicker metal use

a larger wire and a larger machine. See machine recommendations

for welding capacity. (Refer to Diagram 4. Welding Wire Thickness

Chart)

3. Use the correct wire type for the base metal being welded. Use

stainless steel wires for stainless steel, aluminum wires foraluminum, and steel wires for steel.

4. Use the proper shielding gas. CO2 is good for penetrating welds on

steel, but may be too hot for thin metal. Use 75% Argon/25% CO2 for

thinner steels. Use only Argon for aluminum. You can use a triple-mix

for stainless steels (Helium + Argon + CO2). (Refer to Diagram 2.

Penetration Patterns for Steel)

Diagram 1

Argon + CO2 CO2

Penetration Patterns for Steel

Diagram 2


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5. For steel, there are two common wire types. Use

an AWS classication ER70S-3 for all purpose,

economical welding. Use ER70S-6 wire when

more deoxidizers are needed for welding on dirty

or rusty steel. (Refer to Diagram 6. Welding

Wire)

6. For best control of your weld bead, keep the wire

directed at the leading edge of the weld pool.

7. When welding out of position (vertical, horizontal,

or overhead welding), keep the weld pool small for

best weld bead control, and use the smallest wire

diameter size you can.

8. Be sure to match your contact tube, gun liner, and

drive rolls to the wire size you are using.

9. Clean the gun liner and drive rolls occasionally,

and keep the gun nozzle clean of spatter. Replace

the contact tip if blocked or feeding poorly.

10. Keep the gun straight as possible when welding,

to avoid poor wire feeding.

11. Use both hands to steady the gun when you

weld. Do this whenever possible. (This also

applies to Stick and TIG welding, and plasma

cutting.)


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Diagram 3

Diagram 10: Recommended Fillet Weld Thickness

Diagram 5: Example of Good and Bad MIG Welds

Good

Weld

Travel

Too Fast

Travel

Too Slow

Voltage

Too Low

Voltage

Too High

WFS

Too Low

WFS

Too High

12. Keep wire feeder hub tension and drive roll pressure just tight

enough to feed wire, but dont overtighten.

13. Keep wire in a clean, dry place when not welding, to avoid picking

up contaminants that lead to poor welds.

14. Use DCEP (reverse polarity) on the power source.

15. A drag or pull gun technique will give you a bit more penetration

and a narrower bead. A push gun technique will give you a bit less

penetration, and a wider bead. (Refer to Diagram 3. Effect of

Electrode Position and Welding Technique)

16. When welding a llet, the leg of the weld should be equal

to the thickness of the parts welded. (Refer to Diagram 10.

Recommended Fillet Weld Thickness)

17. Compare your weld to our photos to determine proper adjustments.

(Refer to Diagram 7. Example of Good and Bad MIG Welds


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Aluminum MIG Welding Tips

1. The best feeding of wire for aluminum is done with a spool gun. If you cant use a spool gun, use the

shortest gun possible and keep the gun as straight as possible. Use Argon only for shielding gas. Only use apush gun technique when welding aluminum.

2. If you are having feeding problems, one thing you can try is a contact tip that is one size bigger than your

wire.

3. The most common wire type is ER4043 for all-purpose work. ER5356 is a stiffer wire (easier to feed), and is

used when more rigid, higher-strength weld properties are needed.

4. Clean the aluminum before welding, to remove the oxide layer. Use a stainless steel wire brush used onlyfor cleaning aluminum.

5. Fill the crater at the end of the weld to avoid a crack. One way to do this is to dwell in the weld pool for a

second at the end of the weld.


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Self-Shielded Flux Cored Welding Tips

1. Use a drag (pull) gun technique.

2. Keep the wire clean and dry for best weld results.

3. The weld is similar to Stick welding, in that a layer of slag must be removed from the weld after welding. Use

a chipping hammer and a wire brush.

4. Self-shielded Flux Cored does not need shielding from an external cylinder of shielding gas. (The shieldingis in the wire.) This makes it good for outside work, where external shielding gas could be blown away.

5. Self-shielded Flux Cored is generally harder to accomplish on thin metals than MIG welding.


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TIG Welding Tips

1. Use Argon shielding for steel, stainless, and aluminum.

2. Use DC-Straight Polarity (DCEN) for steel and stainless. Use AC for

aluminum.

3. Always use a push technique with the TIG torch.

4. Match the tungsten electrode size with the collet size.

5. Aluminum - use a pure tungsten, AWS Class EWP (green identifying

band). Will form a balled-end in AC.

6. Steel and stainless steel - use a 2% thoriated tungsten, AWS Class

EWTH-2 (red identifying band). Prepare a pointed-end for DCENwelding. (Refer to Diagram 11. Tungsten Preparation)

7. When welding a llet, the leg

of the weld should be equal

to the thickness of the parts

welded. (Refer to Diagram 10.

Recommended Fillet Weld

Thickness)

1. Stable Arc

2. Flat

3. Grinding Wheel

4. Straight Ground

Note: Do not use wheel for other jobs or tungsten can

become contaminated causing lower weld quality.

1. Arc Wander

2. Point

3. Grinding Wheel

4. Radial Ground

1

4

2

3

2

3

1

4



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Stick Welding Tips

1. Take precautions with ying

materials when chipping slag.

2. Keep electrodes clean and

dry - follow manufacturers

recommendations.

3. Common steel electrodes: (Refer

to Diagram 8. Recommended

Stick Electrodes)

4. Penetration: DCEN - Leastpenetration, AC - medium (can

be more spatter also), DCEP -

most penetration.


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5. When welding a llet, the leg of the weld should be

equal to the thickness of the parts welded. (Refer toDiagram 10. Recommended Fillet Weld Thickness)

6. To set your amperage control, rst determine

recommended amp range for your electrode type and

diameter. Then pick an amperage within the range

based on your metal thickness (thinner metal, less

amps). (Refer to Diagram 7. Example of Good and

Bad Stick Welds)



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7. Electrode Polarity and Amperage


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Plasma Cutting Tips

1. Clean, dry, oil-free air is important.

2. Stay at recommended air pressure (more air is not necessarily better!)

3. Touch torch tip gently to workpiece.

4. When initiating a cut, start on the end of material to be cut and ensure arc has completely penetrated metal

before proceeding further.

5. When completing cut, pause at the end to assure severance.

6. Torch should be perpendicular to workpiece.

7. Work cable should be attached as close to workpiece cut as possible.

8. If you can see the arc coming through the bottom of the cut metal, it will eliminate guessing if your travel

speed is correct.


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Resistance Spot Welding Tips

1. Resistance welding is not recommended for aluminum, copper, or copper alloys. Use for steel and stainless

steel only.

2. For more heat (amperage output), use shorter tongs.

3. For units without a heat control, tong length can be used for a control. For instance, for thin metals where

you want less heat, longer tongs can be used.

4. Keep in mind that longer tongs can bend, and you may lose pressure at the weld.

5. For the metals being welded, make sure there is no gap between the pieces - this will weaken the weld.

6. Keep the alignment of the tongs straight, so that the tips touch each other exactly. Also, maintain a proper

pressure adjustment - not too much or too little pressure.

7. When you need one side of the weld to have good appearance, you can atten (machine) the tip somewhat

on that side.

8. Clean the tips on a regular basis, or you will lose output (amperage). Dress the tips with a proper tip dresser.

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