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INTRODUCTIONOur business is welding and we offer this handbook to both the handyman and industry in general, in an earnest endeavour to assist all those engaged in MIG welding.

We have not covered all phases of welding, but present briefly, the basic facts of the MIG welding process and techniques.

LIST OF CONTENTS Page NoHistory of MIG 2MIG Overview 3Power Sources 5Feeder 7MIG Handpieces 12Regulators 14Shielding Gas 15Stick Out 16Travel 17Wire Electrodes 18Process Types 19 i) Short Circuit / Dip ii) Globular iii) Spray iv) Pulse SprayAmperages 22MIG Welding Hazards 25Personal Protection 26Troubleshooting 27

Branches and Outlets throughout New ZealandCheck your Yellow pages

or www.weldwell.co.nz

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HISTORY OF MIG / MAG (GMAW)GMAW was developed during the early 1940’s and technology was taken from the TIG welding process that was already around at the time. MIG (MAG) welding has the advantage of a particular gas shield that TIG has, and then adds the advantage of a continuous consumable wire electrode.

At the time the MIG process was able to increase the production of war manufacturing. It has since become one of the main stages of manufacturing from that time until the present day. Through the years MIG/MAG has undergone changes in the types of wires, gases, and power sources, but the principles remain the same. With the onset of the manufacturing in the 1960’s and 1970’s the types of wire electrodes have been upgraded to give wire electrodes with higher deposition rates, better finishes and wires more suitable for more modern steel types.

The welding gases have also evolved in the same way to make MIG welding faster, more efficient and with a better finish.

One of the major changes has also been with power sources and feeders. MIG welding power sources have, over the years, gone from basic transformer types to the highly electronic power sources of the world today.

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MIG OVERVIEWA MIG welder uses a DC voltage controlled electric power source (different from that of an arc welder), connected to a wire feeder which holds a spool of the type of wire needed to do the job. The feeder will push the wire down what is known as a MIG handpiece. This is done by feeding the wire through a set of rollers. A suitable gas mixture is also fed down the MIG handpiece. Different gases are used for different types of wire.

Basically, the MIG process uses a gas or gas mixture to displace the air around the arc that is being formed between the wire being used and the base metal. This is done by using an electric MIG power source. The electrode is still being melted with an electric arc, but in the case of MIG it is a special wire which is mechanically fed into the arc.

The feed rate is adjusted depending on the thickness of the material being welded. The voltage of the electric power source is also adjusted depending on the material thickness being welded.

Advantages of MIG Welding 1) Welds most metals. 2) Simple technique and very easy to learn and use.

3) Higher deposition, greater speed and a lot more efficient than most other forms of welding.

4) Minimised weld defects. 5) Produces little or no slag. 6) With the correct wire and settings, can be welded out of position.

A MIG welder at work

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Application

1) Fabrication and Manufacturing i) Due to increases in speed and efficiency, MIG welding is

well suited for Fabrication and Manufacturing. ii) Clean up time is greatly reduced due to little or no slag.

2) Repair and Maintenance i) Lightweight MIGs can be portable. ii) Easy for the D-I-Yer to learn. iii) Welds various types of material. iv) Great for the farming industry with the use of gasless wire

which makes it possible to weld outdoors. v) Single phase domestic power supply MIGs are available.

3) Professionals i) Panelbeaters, bodyshops, etc ii) Truck repairers.

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POWER SOURCESMIG welding power sources have come a long way from the basic transformer type power source to the highly electronic and sophisticated types we see around today.

Even though the technology of MIG welding has changed, the principles of the MIG power source have, in most cases, not. The MIG power sources use mains power and converts that mains power into CV (constant voltage), DC (direct current) power suitable for the MIG welding process.

MIG welding power sources control voltage – this is done by either voltage stepped switches, wind handles, or electronically. The amperage that the power source produces is controlled by the cross sectional area of the wire electrode and the wire speed, ie the higher the wire speed for each wire size, the higher the amperage the power source will produce.

Because the output of the MIG power source is DC (direct current) the terminals on the front will have + pos and – neg on the output side. The principles of electric circuits states that 70% of the heat is always on the positive side. This means that the lead that is connected to the positive side of the welder, will carry 70% of the total energy (heat) output. The connections (polarity) can be different for different electrode wires, so the operator must check this when connecting up the leads for the MIG process.

Other things to check about the MIG power source :-

1) Amperage needed to do the job. Will it be sufficient?

2) Does it have a suitable voltage range (eg do the volts go low enough for light material, or does the voltage go high enough for spray welding if it is needed?)

3) Power supply three phase or single phase? Is there enough mains power to allow the MIG welder to perform at its best?

4) Is weight a problem? If so, is the inverter type welder more useful?

5) Will a mobile MIG power source be better to do the job (as some engine drive welders have a CV [constant voltage] range)?

6) Would a multi process type power source be a better choice, as most multi process MIG welders have a CC (constant current) range, which would allow the power source to be used for more than MIG alone?

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WIRE FEEDERThe wire feeder is the part of the MIG welding set up that — i) Controls the speed of the wire electrode and pushes this wire from the

feeder through the welding handpiece to the workpiece. ii) Provides the path for welding current to be passed from the welding

power source through the interconnecting lead to the feeder and then to the welding handpiece.

iii) Provides gas flow control through a solenoid valve. The gas is fed down from the gas regulator to the weld area via the feeder and then the MIG welding handpiece.

Wire feeders come in many different shapes and sizes, but they all do the same basic job roles. Feeders can be separate from the power source or built into the power source itself. Feeders are made up of different parts, each having a different job role. (See Fig. 1, page 8.)

Wire spool holder. This is designed to hold the spool of the correct wire size in place on the feeder to ensure the wire electrode is on the correct input angle for the drive roller to be able to do its job properly.

The spool holder also has the job of being the spool brake, so that when the rollers stop turning the wire spool will stop without over-running, this can also be a cause for the wire electrode to tangle up on the spool or run down the side of the spool – this would cause the wire electrode to jam. The brake pressure must be set correctly, so as not to put too much pressure on the spool and stop it turning freely when the rollers are turning; but it must have enough tension to stop the wire spool from over-running.

To set up the brake please read the feeder manual as each feeder has a different way of setting the spool holder brake.

Open Feeder

Built-in Feeder(compact machine)

Fig. 1

Closed in Feeder

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Drive Motor MIG welding relies on smooth and constant wire feed. Lower quality machines usually have poor feed systems. The wire drive motor has the job of turning the drive rollers (this can be one or more sets of rollers). Undersize drive motors can result in poor feeding of the wire electrode down the MIG welding handpiece. This will have the effect of making the overall performance of the MIG machine sub-standard as compared to a machine with a quality drive system.

Drive Rollers The drive rollers grasp the wire electrode and continuously feed the wire down the MIG handpiece into the welding arc. The rollers need to be selected by – i) the wire size ii) the type of wire to be fed. Each type of wire may need a different style

of roller groove – eg V rollers for steel and other hard wires V-Knurled for Fluxcored wire U-Grooved for aluminium and other soft wires U-Cogged for soft shelled fluxcored wires

The idea of using the correct roller is to have a good wire drive without crushing the wire. The pressure roller is also used to set the wire tension. This must be set with enough pressure to feed the wire electrode, but not too much tension as to crush the wire.

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All the wire guides on the input and output side of the rollers must be i) lined up to feed the wire straight into the rollers ii) lined up in a way as to make sure the wire is lined up with the grooves

in the drive rollers iii) all guides must be as close as possible to the drive roller to prevent

the possibility of the wire bunching up.

Wire Feed ControlsThe wire feeder will have its own built-in control system. The number of controls that will be built into the feeder will depend on the type of feeder (some feeders come with more bells and whistles) but the most common are

i) Wire speed – this control is the adjustment for how fast the drive rollers will turn and as stated earlier, the faster the wire speed for each wire size the more amperage the power source will produce. The wire speed controls can be labelled as wire speed, eg ipm or mpm, or as a percentage from the slowest speed being zero to the highest speed being 100%.

The amperage being set by the wire speed setting will also have an effect on the speed of travel and the deposition rate of the wire (how fast the weld metal is being put onto the weldpiece); with the advantage of, the higher the amperage the thicker the material that can be welded.

ii) Purge switch. Some feeders have a purge switch. This is to allow the gas flow setting to be set on the gas regulator without turning of the wire feed roller or without any welding power being turned on.

iii) Burnback. Burnback is the setting of the degree that the wire electrode will melt back towards the contact tip at the completion of the weld. If there is too much burnback the wire electrode will melt back onto the contact tip, possibly damaging it. If there is not enough burnback set, the wire electrode will not melt away from the weldpool and can be left stuck to the weld metal.

iii) Spot timers or stitch modes are to be found on some feeders. These controls normally control the time the drive roller will turn for after the trigger contactor has been activated.

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The Handpiece ConnectionThe handpiece connection is the system in which the MIG handpiece is connected to the wire feeder. There are various types of MIG handpiece connections. Different manufacturers can use any one of many systems to connect their handpieces to the wire feeder.

When ordering a new handpiece tell the supplier a) the type of handpiece you need, including amperage rating b) the type of connection on the feeder so the handpiece can be supplied

to match the connection

The handpiece connection is also the area where the wire electrode, welding current and welding gases are passed onto the welding handpiece. This means these components should be checked for damage or leaky seals etc, so the connection will do its job correctly.

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1) Aircooled or watercooled2) Current rating. The operator must select the correct size handpiece.

Using a handpiece that is not sufficiently rated for the machine may result in the handpiece overheating. This may result in a poor weld and damage to the handpiece. A handpiece with an excessive rating will be larger and heavier than the smaller handpiece, which could result in discomfort for the operator.

3) They all have parts that will wear out (consumables eg liners, tips, diffuser, nozzle, etc.)

Let’s take a look at each part

Liner The liner causes the most problems I have faced out in the workshop. First, they have a life span that is approximately one to four rolls of MIG wire depending on the quality of the liner and wire. The life of the liner will also be increased if the operator removes and cleans it by soaking in non-corrosive and a non-toxic solvent. Each wire size needs to have the correct wire size liner. Be aware some liners may fit more than one size of wire.

There are also different materials for different types of wire electrode, eg steel or stainless liners for solid wires and Teflon liner for aluminium.

The liner length is most important. In the field it is very common to find even newly fitted liners that have been cut too short. This results in the wire being able to move around behind the welding tip and leading to bad wire feeding. The liner has to be fitted correctly and different MIG handpieces will often have a different way of ending up with a liner that is the correct length.

Please don’t just take out the old liner and cut the new one to the same length. It could end up with an incorrect result. Please refer to your MIG handpiece manual.

All MIG handpieces should be laid out straight ont he floor before trimming the liner, to prevent the new liner being cut too short. Do not cut the liner if the handpiece lead is coiled up.

MIG HandpiecesThe MIG handpiece is connected to the wire feeder, and its job is to deliver the wire electrode, shielding gas and the electrical welding current to the welding site. There are a lot of different shapes and styles of MIG handpieces out in the marketplace (Fig. 3) but they all have things in common- (Fig. 2).

Contact Tube

Shielding Gas

Weld PoolWeld Metal

Electrode

Fig. 2

Arc

Base Metal

Gas Nozzle

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Gas Diffusers The gas diffuser’s job is to make sure that the shielding gas is delivered to the shielding nozzle correctly. It is designed to make the gas come out as straight as possible and equally supplied around inside the gas shield nozzle. Diffusers can be made of different materials, eg copper, brass or fibre. Some diffusers will also be the tip holder.

Tip Holder This is the item which holds the welding tip in place. Again, tip holders can be very different in design and are very often unique to that brand of MIG handpiece.

MIG Tips The MIG tip is the key to good welding. First of all, it is the way that welding amperage is delivered to the welding wire electrode, often with a very high amperage.

Most tips are made of copper alloy, and as a rule you only get what you pay for. The better the alloy the better the tip will pass current to the wire electrode and the less wear the MIG tip will have; also the less the tip will oxidize. The size is important. The right size tip must be selected. If the selected tip size is too large the wire electrode will not make a good contact, leading to poor welding performance.

If a tip selected is too small, the wire electrode will feed poorly and may even jam in the contact tip.

Fig. 3

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REGULATORSThe job of the gas regulator is to reduce the bottle pressure gas down to a lower pressure and deliver it at a constant flow. The constant flow of gas is fed to the feeder then through the interconnection to the handpiece, down the handpiece to the weld area.

Different gases don’t always use different fittings, so check with your supplier what type you will need.

As well as different types of regulators for different gases there are also different styles of regulator as well. The two main ones are regulators with (Fig 4) and without (Fig. 5) flow tubes. Both regulators do the same job, but have a different way of setting the gas flow. The amount of gas flow needed to do the job will depend on the welding gas and the job being done, but a common setting to start with is 10 L/min.

Fig. 4 Fig. 5

SHIELDING GASThe shielding gases are necessary for MIG/MAG welding processes to protect the welding site from gases that are in the surrounding air, eg nitrogen and oxygen. If the weld pool is contaminated by these gases fusion defects can be caused, also porosity and the embrittlement of the weld metal.

The choice of the shielding gas depends on the type of material being welded and the type of electrode wire being used. CO2 (Fig. 9) was commonly used but now argon-mixtures (Figs. 7 and 8) are becoming more common. Argon mixtures are more user friendly and result in higher deposition rates.

Non-IonizedShielding

Gas

Nozzle

Fig. 6 Shielding Gas Area at the Arc

Fig. 7 - 75% Ar - 25% CO2

Fig. 8 - 50% Ar - 50% CO2

Fig. 9 - CO2

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With the advent of different welding gas suppliers, each with their own belief on what gas mixture they make, it is difficult to list which gases are needed for which job. Please see your local gas supplier or Weldwell agent.

The flux core open arc range of wires produce the gas shield as the material in the core burns off, protecting the welding site.

The desirable rate of gas flow will depend on the type of electrode wire, speed and current being used and the metal transfer mode.

As a rule small weld pools 10 L/min medium weld pools 15 L/min and large spray weld pools 20-25 L/min

Too much gas flow can be just as bad as not having enough. The reason being that if the gas flow is too high it will come out of the MIG handpiece This will cause

1) air to be sucked into the spinning gas

2) cause turbulence of the weld pool

Both resulting in a poor weld.

STICK OUT

Nozzle Shroud

Contact Tube

Contact TipContact Tube-to-work distanceStick out

Nozzle-to-work distance

ArcLength

Workpiece

Stick out is the distance of the contact tip to the workpiece. Changing the stick out will change the resistance that is present between the contact tip and the workpiece. (Fig. 10.)

Increasing the stickout will increase the resistance and both the voltage and amperage will be lessened. This will lessen penetration and the weld will achieve less heat. (Fig. 13.)

Once the stick out becomes too long a poor weld can result caused by a shallow penetration and possible lack of fusion between the weld metal and the base metal.

A short stick out can help give a good start but can make the weld profile becoming concave, thus making a lower strength weld. (Fig. 11.)

Too short

Normal

Too long

16

Fig. 10

Fig. 11

Fig. 12

Fig. 13

Travel Direction

a

b

Fig. 16 - Work Angle - Flat Position (front view)

DIRECTION OF TRAVEL AND ANGLEWhen MIG/MAG welding the direction of travel is now coming down to operator preference. Travel using the push method will result in a weld that is wider, flatter and has less penetration and better appearance than the drag method. (Fig. 14.)

The dragging method will result in a narrower, higher crown and a deeper penetrating weld. (Fig. 14.)

The angle to the direction of travel should be 10 - 15 degrees (Fig. 14.)

If a fillet joint is being welded the handpiece should be a 45 degree to each plate. (Fig. 15.)

In the downhand position (flat) the handpiece should be 90 degrees to the flat joint. (Fig. 16.)

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Fig. 15

Fig. 14

WIRE ELECTRODESThe selection of the wire electrode to be used in the MIG/MAG process is a decision that will depend on 1) the process being used (eg, solid wire or fluxcore wire) 2) the composition of the metal being welded 3) welding indoors or outdoors 4) joint design 5) cost 6) mechanical properties of the weld material and those that are a match

for the base material.

All wire electrodes contain deoxidising agents which can be silicon, manganese or aluminium. The job of the deoxidising agent is to help prevent porosity caused by oxygen and other contaminants.

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15 kg spool of MIG/MAG Wire

PROCESS TYPESShort Circuiting Transfer ( Dip) - Fig. 17

Globular Transfer - Fig. 18

Short circuiting transfer is a method of metal transfer in which metal is deposited only when the wire actually touches the workpiece. Metal is not transferred across an open arc. The short circuiting transfer has a lower current than other methods of metal transfer (spray and globular). This means lower heat input and therefore more suitable for welding thinner materials. It is also suitable for welding out-of-position.

The globular method of metal transfer is formed when the voltage is increased over the short circuitry method. As the voltage is increased an arc length is formed (a gap between the end of the wire electrode and the workpiece). The voltage fits into the area between short circuitry transfer and spray transfer.

The globular method of metal transfer is very rarely used as the metal droplets travelling across the arc are unstable and can be described as wobbly. The resulting weld has a lot of spatter and the welding is not pretty, as the weld pool is unstable because of the bad metal transfer across the welding arc. Globular transfer has poor weld appearance and cannot be used out of position.

separatepinch separate

moltenpool

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The principle of dip transfer can be further explained as follows. On touching the workpiece a short circuit is formed back through to the power source (a). Welding current will flow, thus heating up the wire

electrode, thiswill cause the wire electrode to pinch (b), the wire will separate (c) and a little of the electrode wire is left in the weld puddle (d). The heat of the arc then flattens out the molten pool (e), the wire feed will overcome the heat of the welding arc and come down, touch the workpiece (f) and the cycle starts all over again. The sound that is produced from short circuit transfer should be smooth and consistent and have a sound very much like frying bacon.

a b c d e f

Fig. 17

Fig. 18

Spray Transfer - Fig. 19

The spray method of metal transfer occurs when the voltage is increased over both the short circuiting method and the globular method. As the voltage is increased a good arc length should form and the metal droplets should become uniform in shape as they cross the arc in a consistent manner. Once the correct setting for the spray transfer mode is found the arc sound will become smooth.

To obtain a good spray mode of welding shielding gases containing a blend of argon is used. (Please see your gas supplier for their correct mixture.) The spray method of metal transfer can be used with most of the common welding wire electrodes (eg mild steel, aluminium, stainless steel).

The advantages of metal spray transfer are i) high deposition rates ii) good travel speeds iii) good looking weld appearance iv) little weld spatter v) good weld fusion vi) very good on heavy sections

The disadvantages of the spray mode are i) higher capacity power source needed ii) weld position is limited to flat and horizontal fillet iii) the cost of using a more expensive mixed gas iv) higher radiated heat is produced so extra protection is needed

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Fig. 19

Metal droplets

Pulsed Spray Transfer

Pulsed spray transfer has a steady stream of metal droplets crossing the welding arc. The pulsed power source supplies the welding arc with two types of welding current.

1) Peak current - this current allows the formation of metal droplets which then cross the welding arc.

2) Background current - the background current will keep the arc alive, but doesn’t allow for any weld metal transfer.

Pulsed spray transfer allows time for the weld puddle to freeze a little on the background current cycle, which allows for i) more control of the weld puddle ii) more time for impurities to float to the top of the weld pool resulting in

cleaner and stronger welds

Advantages i) able to spray thinner metals ii) less heat input iii) stronger welds iv) more weld control v) out-of-position welding

Disadvantages i) higher set up costs ii) needs operator training iii) lower deposition rate

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MIG

Vol

ts /

Am

ps

Stee

l

Thick

ness

mm

Volts

CO2

Volts

Ar

75/

CO22

5

Amps

Shor

tCi

rcui

t

Amps

Spra

y

Shor

t Ci

rcui

t0.8

mm

Spra

y0.8

mm

Shor

tCi

rcui

t0.9

mm

Spra

y0.9

mm

Shor

tCi

rcui

t1.2

mm

Spra

y1.2

mm

0.816

-17

15-1

640

-55

50-6

02.3

-2.5

3.1-3

.4—

2.7-2

.9—

—0.9

17-1

815

-16

50-6

070

-80

3.1-3

.43.8

-4.5

2.7-2

.93.6

-4.1

—1.8

1.218

-19

16-1

770

-80

90-11

03.8

-4.5

5.6-6

.43.6

-4.1

4.5-5

.61.8

2.3-2

.81.5

19-2

017

-18

90-11

012

0-13

05.6

-6.4

6.3-8

.64.6

-5.6

6.1-6

.62.3

-2.8

3.0-3

.32.0

20-2

117

-18

120-

130

140-

150

6.3-8

.6—

6.1-6

.67.1

-7.6

3.0-3

.33.6

-3.8

3.221

-22

18-1

914

0-15

016

0-17

0—

—7.1

-7.6

8.1-8

.63.6

-3.8

4.1-4

.55.0

21-2

218

-19

160-

170

180-

190

——

8.1-8

.69.1

-9.7

4.1-4

.54.7

-5.0

6.323

-24

21-2

218

0-19

020

0-21

0—

—9.1

-9.7

10.2-

10.7

4.7-5

.05.3

-5.6

8.023

-24

21-2

220

0-21

022

0-25

0—

—10

.2-10

.710

.7-13

.25.3

-5.6

5.6-6

.99.5

24-2

523

-24

220-

250

300

——

10.7-

13.2

5.6-6

.99.5

Wire

Fee

d Sp

eed

(mm

/min

)

23

Stainless

Thicknessmm

VoltsCO2 S/S

AmpsShortCircuit

AmpsSpray

VoltsAR + 2%O2 S/S

ShortCircuit0.9 mm

Spray0.9 mm

1.2 19-20 50-60 70-80 — 3.1-3.8 4.6-5.21.5 19-20 70-80 90-110 _ 4.6-5.2 5.8-7.02.0 20-21 90-110 120-130 _ 5.8-7.0 7.6-8.32.5 20-21 120-130 140-150 _ 7.6-8.3 8.9-9.54.8 21-22 140-150 160-170 23-24 8.9-9.5 10.2-10.86.3 21-22 160-170 180-190 24-25 10.2-10.8 11.4-12.08.0 21-22 180-190 200-210 24-25 11.4-12.0 Use 1.2 9.5 200-210 220-250 25-26 Use 1.2 Use 1.611.0 220-250 300 26-27 Use 1.6 Use 1.6

Thicknessmm

ArgonVolts

AmpsSpray

Spray0.9 mm

Spray1.2 mm

Spray1.6 mm

3.2 21-22 110-130 8.9-10.2 6.1-6.9 —5.0 23-24 140-150 10.8-11.4 7.6-8.3 —6.3 24-25 180-210 —— 8.9-9.5 4.3-4.78.0 26-27 200-230 — 10.2-10.8 5.1-5.310.0 26-28 220-250 — 11.4-12.2 5.6-5.811.0 28-29 280 — — 6.1-6.9

Aluminium

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MIG WELDING HAZARDSFumesFumes from the MIG welding process are produced by the burning of contaminants on the surface of the material being heated.

The MIG welding of galvanised metal is extremely dangerous to the operator because of zinc poisoning unless suitable protection is used.

HeatWelding in any form produces heat which can cause burns and the possibility of fire.

Ultra Violet LightDuring MIG welding Ultra Violet Light production is at the higher end of the scale and suitable eye protection must be used. All the operator’s skin should be covered to avoid burning, which could lead to skin cancer.

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PERSONAL PROTECTION

26

Jacket

Fire retardant pants/overallsboots

Skull CapHelmet

Mask

WeldingHelmetlens

Gloves

WeldingHelmetlens

Gloves

27

TROUBLESHOOTING (Reproduced with permission from Miller Electric, USA)

When troubleshooting gas metal-arc welding processes and equipment problems it is well to isolate and classify them as soon as possible into one of the following categories: 1) Electrical 2) Mechanical 3) Process

This eliminates much needless lost time and effort. The data collected here for your benefit discusses some of the common problems of gas metal-arc welding processes. A little thought will probably enable you to solve your particular problem through the information provided.

Problem 1: Electrode wire stops feeding while welding

Probable Causes Suggested Remedy

1. Welding machine’s contactor open Check for open circuit volts2. Fuse blown in welding machine’s primary Replace fuse3. Welding machine’s control circuit fuse blown Replace fuse4. Primary power line fuse blown Replace fuse5. Wire feeder’s control relay defective Replace control relay6. Wire feeder’s protective fuse blown Replace fuse. Find overload cause7. Wire feeder’s drive rolls misaligned Realign drive rolls8. Drive roll pressure too great or too little Loosen and readjust drive rolls9. Wire feeder’s spindle friction too great Loosen and readjust nut pressure10. Excess loading of drive motor Clear resistance in drive assembly11. Drive rolls worn; slipping Replace drive rolls12. Feeder drive motor burned out Test motor; replace if necessary13. Handpiece liner dirty, restricted

Remove liner, blow out with compressed air

14. Broken or damaged handpiece casing or liner Replace faulty part15. Handpiece trigger switch defective Replace switch; check connection16. Contact tube opening restricted; burnback of electrode

Replace contact tube

17. Friction in handpiece liner Check wire liner – clean, replace parts as required

18. Sharp or excessive bend in handpiece cables or liners

Straighten handpiece cables and/or replace liners

19. Liner too short Refit new liner that is the correct length

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Problem 2: Porosity in weldProbable Causes Suggested Remedy

1. Dirty base metal; heavy oxides, mill scale

Clean metal before welding

2. Gas cylinder valve off Turn cylinder valve on3. Gas regulator’s diaphragm defective Replace diaphragm or regulator4. Flowmeter cracked or broken Replace and repair5. Gas hose connections loose Tighten fittings6. Gas hose leaks Repair or replace7. Not enough gas flow Increase flow rate8. Moisture in shielding gas Replace gas cylinder or supply9. Freezing of CO2 regulator/flowmeter Thaw unit; install gas line heater or high

volume CO2 regulator10. Wrong gas for type of wire or type of transfer

Install proper gas

11. Wire feeder’s gas solenoid defective Replace solenoid12. Too much wire feed speed (amperage) Reduce wire feed speed13. Handpiece and/or cables leaking gas Test; repair or replace faulty parts14. Contact tube extended too far out from nozzle for short circuit transfer

Move distance from nozzle end to max of 3.25mm

15. Nozzle-to-work distance too great Should be recommended by wire manufacturer

16. Improper handpiece angle Use correct handpiece angle17. Welding travel speed too fast Adjust conditions for slower speed18. Electrode not centred in nozzle Adjust contact tube, nozzle and wire19. Voltage (arc length) too high Lower voltage20. Short circuit current too high. (Not enough slope)

Adjust slope setting if adjustable

Problem 3: Electrode Wire stubs into workpieceProbable Causes Suggested Remedy

1. Too much slope. (Too much droop) Reduce slope settings as required. (Find flatter Volt-Amp curve)

2. Arc voltage too low Increase voltage3. Too much wire feed speed Reduce wire feed speed4. Poor work connection Connect properly

Problem 4: Electrode wire feeds but is not energised. Little or no welding arc

Probable Causes Suggested Remedy1. Primary power line fuse blown Replace line fuse2. Machine’s contactor plug not tight in receptacle

Tighten plug in receptacle

3. Machine’s contactor control leads broken

Repair or replace

4. Machine’s Remote-Standard switch defective or in wrong position

Repair or replace; position correctly

5. Machine’s primary contactor coil defective

Replace

6. Machine’s contactor points defective Replace points or contactor7. Welding cables loose on machine terminals

Tighten connections

8. Work connection loose (or incomplete circuit due to rust or paint, etc.)

Connect properly to work; clean andtighten connections

9. Wire feeder contactor plug not properly connected

Tighten plug

10. Contactor relay defective Repair or replace

Problem 5: Excessive spatter while welding

Probable Causes Suggested Remedy1. Too much voltage Reduce voltage2. Not enought slope or inductance. (Too flat of a slope)

Increase slope or inductance as needed. (Add more droop)

3. Too high of a gas flow Reduce flow rate as required4. Contact tube recessed too far inside nozzle

Use longer contact tube

5. Wrong electrode wire Use correct electrode wire6. Wrong welding technique Use proper technique

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Problem 6: Weld bead appearance shows a need for more amperage and/or larger bead

Probable Causes Suggested Remedy

1. Volt-amp (wire feed speed) condition too low

Increase voltage and wire feed speed slowly

2. Too much slope Decrease slope (Find a flatter Volt/Amp curve)

3. Wire feed speed too slow Increase wire feed speed

1. Volt-amp (wire feed speed) condition too high

Reduce voltage and wire feed speed slowly

2. Not enought slope Increase slope. (Find a slope with more droop)

Problem 7: Weld bead appearance shows a need for less amperage and/or smaller bead

Probable Causes Suggested Remedy