BOC_MIG_320R_420R_Manual

BOC MIG 320R/420R

O P E R AT I N G M A N U A L

P R O D U C T S T H A T P E R F O R M

BOC Limited ABN 95 000 029 729

Riverside Corporate Park10 Julius AvenueNorth Ryde, NSW 2113AUSTRALIA

Details given in this document are believed to be correct at the time of printing.Whilstproper care has been taken in the preparation, no liability for injury or damage resultingfrom its improper use can be accepted. IP 20883 AZZAUS 1003 2K

BOC is a trading name of BOC Limited, which is an operating company within The BOC Group, the parent company of which is The BOCGroup plc.The stripe symbol and the word BOC are a registered trademark of The BOC Group plc and used under licence by BOCLimited. BOC Industrial is a trademark of BOC Limited. © BOC Limited 2003. Reproduction without permission is strictly prohibited.

BOC Limited 970 – 992 Great South RoadPenrose,AucklandNEW ZEALAND

For more information on any BOC IndustrialTM product orservice call the BOC Customer Service Centre on:P

AUSTRALIA

131 262Email: [email protected]: www.boc.com.au

NEW ZEALAND

0800 111 333Email: [email protected]: www.boc.co.nz

2 3

Contents

1. Safety Precautions

1.0 Health Hazard Information 4

1.1 Personal Protection 4

1.2 Electric Shock 5

1.3 Use of Gas Cylinders 5

1.4 User Responsibility 5

2. The MIG Welding Process

2.0 MIG Welding 6

2.1 How the Process Works 6

2.2 MIG Welding Equipment 7

2.3 The Modes of Metal Transfer 7

2.4 Power Source 9

2.5 Voltage Selection 9

2.6 Wire Feed Roll Tension 9

2.7 Duty Cycle 9

3. Shielding Gases

3.0 Overview 10

3.1 General Instructions for Pressure Regulators 10

3.2 GMAW Shielding Gas Selection Chart 11

4. Plant Specifications 12

5. Plant Contents 13

6. Operating Controls

6.0 Diagram A – BOC MIG 320R & MIG 420R 14

6.1 Wire Speed Control 15

6.2 Thermal Overload Indicator 15

6.3 Power On/Off Switch 15

6.4 2T & 4T Trigger Function 15

6.5 Polarity Selection – Positive Cable Socket &

Negative Cable Socket 15

6.6 Control Fuse 15

6.7 Inductance Setting 16

6.8 Operation of Cooling Fan 16

6.9 Burn Back Control / Inch Control 16

6.10 Voltage Switch Selection 16

7. BOC Wire Feeder

7.0 Diagram B – WF2 & WF4 Wire Feeder Controls 18

7.1 Diagram C – WF2 & WF4 Internal Diagram 19

7.2 Diagram D – WF2 Wire Feeder Spare Parts 20

7.3 Diagram E – WF4 Wire Feeder Spare Parts 21

8. BOC MG42i Gun

8.0 Features 22

8.1 Specifications 22

8.2 Diagram F – MG42i 22

8.3 BOC MG42i Gun Spare Parts 23

8.4 BOC MIG Machine Optional Extras 23

9. Installation of Power Source9.0 Transport & Lifting of the BOC

320/420R MIG Machines 24

9.1 Machine Work Site 24

9.2 Welding & Return Cables 24

9.3 Connection to Mains Power 24

9.4 Mounting & Locking of Wire Spool 24

9.5 Automatic Wire Feed to MIG Gun 25

9.6 Fitting the Spool 25

9.7 Adjustment of Feed Roll Tension 26

9.8 Adjusting Wire Hub Brake 26

9.9 Regulator 26

9.10 Shielding Gas 26

9.11 Gas Cylinder 26

10. Periodic Maintenance10.0 Wire Feed 27

10.1 Cables 27

10.2 Power Source 27

10.3 Consumable Parts 27

11.Trouble ShootingHow to Rectify GMAW & Machine Faults 28-29

12.Terms of Warranty 30

14. Glossary 31

Welcome to a better way of welding

Congratulations on purchasing a BOC 320R/420R MIG Machine

The BOC MIG range are products that perform with reliability and the

backing of a leading welding supplier.

This manual provides the basic knowledge required for MIG welding, as

well as highlighting important areas of how to operate the machine. By

following these steps, your BOC MIG machine will provide trouble-free

service.

Access to a wealth of experience and technical information accumulated

over the years makes the BOC range of equipment a world leader.

BOC equipment and technical support is available through our national

BOC Customer Service Centre or contact your local Gas & Gear outlet.

BOC Customer Service Centre

AUSTRALIA

131 262Email: [email protected]: www.boc.com.au

NEW ZEALAND

0800 111 333Email: [email protected]: www.boc.co.nz

5

1.2 Electrical Shock• Never touch “live” electrical parts.• Always repair or replace worn or damaged

parts.• Disconnect power source before performing

any maintenance or service.• Earth all work materials.• Never work in moist or damp areas.

1.3 Use of Gas Cylinders• Always use the recommended shielding gas

for the application.• Read labels and Materials Safety Data Sheet

(MSDS) before use.• Store upright and use in well ventilated,

secure areas away from pedestrian or vehicle thoroughfare.

• Guard cylinders against being knockedviolently or allowed to fall.

• Wear safety shoes and gloves when handling cylinders.

• Always move cylinders securely with anappropriate trolley.

• Keep in a cool well ventilated area away from heat sources, sources of ignition and combustible materials, especiallyflammable gases.

• Keep full and empty cylinders separate.• Keep oil and grease away from cylinders

and valves.• Never use force when opening or

closing valves.• Don’t repaint or disguise markings and damage,

if damaged return to BOC immediately.• Keep head and face away from the cylinder

valve when opening.• Read and follow instructions on compressed

gas cylinders and associated equipmentAS2030 Parts1&2.

Further details regarding these steps and otheractions you can take for safer storage andhandling refer to BOC Limited.

1.4 User Responsibility• Read the Operating Manual prior to

installation of this machine.• Unauthorised repairs to this equipment may

endanger the technician and operator andwill void your warranty. Only qualifiedpersonnel approved by BOC should perform repairs.

• Always disconnect mains power beforeinvestigating equipment malfunctions.

• Parts that are broken, damaged, missing orworn should be replaced immediately.

• Equipment should be cleaned periodically.When necessary, vacuum inside of wirefeeder compartment.

PLEASE NOTE that under no circumstancesshould any equipment or parts be altered orchanged in any way from the Standardspecification without written permission givenby BOC.To do so, will void the EquipmentWarranty.

Further information can be obtainedfrom the Welding Technology Institute ofAustralia (WTIA).

• “Health and Safety in Welding” TN7.Published by WTIA,PO Box 6165 Silverwater NSW 2128Phone (02) 9748 4443.

• “Fume Minimisation Guidelines”www.wtia.com.au

1.0 Health Hazard InformationThe actual process of GMAW (MIG) is the onethat can cause a variety of hazards.

All appropriate safety equipment should beworn at all times, i.e. headwear, hand and bodyprotection. Electrical equipment should be usedin accordance with the manufacturer’srecommendations as “electric shock can kill”.

Eyes

The MIG process produces rays that can injureand cause permanent damage. Fumes can causeirritation.

Skin

Arc rays are dangerous to uncovered skin.

Inhalation

Welding fumes and gases are dangerous to thehealth of the operator and to those in closeproximity.The aggravation of pre-existingrespiratory or allergic conditions may occur insome workers. Excessive exposure may causeconditions such as nausea, dizziness, drynessand irritation of eyes, nose and throat.

Shielding Gases (Carbon Dioxide or inertgases) in high concentrations when working inconfined spaces may lead to dangerous lowlevels of oxygen, resulting in asphyxiation.

Ventilation and fume extraction should be used to minimise exposure levels in accordancewith Australian Standards.The operator shouldbe trained to work in a manner that minimisesthe exposure.

1.1 Personal Protection

Respiratory

Confined space welding should be carried outwith the aid of a fume respirator or air suppliedrespirator as per AS/NZS 1715 and AS/NZS1716 Standards.

Eye Protection

A welding helmet with the appropriate weldingfilter for the operation must be worn.Weldingarc and the reflective arc flash will hurtunprotected eyes. Protective welding screen andgoggles should be provided for others workingin the same area.

Recommended filter shades for arc welding

Less than 150 amps Shade 10*

150 to 250 amps Shade 11*

250 to 300 amps Shade 12

300 to 350 amps Shade 13

Over 350 amps Shade 14

*Use one shade darker for aluminium

Clothing

Suitable clothing must be worn to preventexcessive exposure to UV radiation and sparks.Protective gloves, spats, apron and weldingshield are recommended.

1. Safety Precautions

4

SSTTOOPP

6 7

2.2 MIG Welding EquipmentThe equipment used for MIG welding consists of:• power source (transformer/rectifier

or inverter)• wire feed unit (designed to allow

the wire to feed freely and evenly)• wire rolls• regulator (adjusts and maintains

constant gas pressure)• flow meter (adjusts and maintains

constant gas flow rate)• gas cylinder• gas shielding (protects weld from

atmospheric contamination)• contact tip

2.3 The Modes of Metal TransferThe mode or type of metal transfer dependsupon the current, arc voltage, electrodediameter and type of shielding gas used. Ingeneral, there are four modes of metal transfer.These are:

i. Dip transfer Also known as short-circuiting arc or short-arc,this is an all-positional process, utilising low heat input.

The use of relatively low current and arc voltagesettings causes the electrode to intermittentlyshort-circuit with the weld pool at a controlledfrequency. Metal is transferred by the wire tipactually “dipping” into the weld pool, and theshort-circuit current is sufficient to allow thearc to be re-established.This short-circuitingmode of metal transfer effectively extends therange of MIG welding to lower currents so thinsheet material can readily be welded.

The low heat input makes this technique wellsuited to the positional welding of root runs onthick plate, butt welds for bridging over largegaps and for certain difficult materials whereheat input is critical. Each short-circuit causesthe current to rise and the metal “fuses” off the

end of the electrode. A high short-circuitingfrequency gives low heat input. Dip transferoccurs between ±70-220A, 14 – 23 arc volts. Itis achieved using CO2 and argon based gases.

ii. Spray transfer

In spray transfer, metal is projected by anelectromagnetic force from the wire tip in theform of a continuous stream of discretedroplets about the same size as the wirediameter. High deposition rates are possible andweld appearance and reliability are good.

Most metals can be welded, but the technique islimited generally to plate thickness greater than6mm. Spray transfer, due to the tendency of thelarge weld pool to “spill over” cannot normallycarry out Positional welding.The mainexception is aluminium and its alloys where,primarily because of its low density and highthermal conductivity, spray transfer in positioncan be carried out.

The current flows continuously because of thehigh voltage maintaining a long arc and short-circuiting cannot take place. It occurs best withargon based gases.

iii. Globular transfer

Metal transfer is controlled by slow ejectionresulting in large, irregularly shaped “globs”falling into the weld pool under the action ofgravity. CO2 gas drops are flung abouthaphazardly, while with argon based gases thedrops are not quite as large and are transferredin a more axial direction.There is a lot ofspatter, especially in CO2, resulting in greaterwire consumption, poor penetration and poorappearance. Globular transfer occurs betweenthe dip and spray ranges.This mode of transferis undesirable for normal welding applicationsand may be corrected when encountered byeither decreasing the arc voltage or increasingthe amperage. Globular transfer can take placewith any electrode diameter.

2.The MIG Welding Process

2.0 MIG WeldingMIG (Metal Inert Gas) welding means that theshielding gas used is inert, it does not chemicallycombine with the welding materials.The purposeof shielding gas is to protect the arc processagainst the defective effects of air as well as tocool down the welding gun. In steel welding, thechoice of shielding gas influences the spatteramount, productivity, penetration, welding speedas well as the seam profile.

The MIG welding process is very popular in thefabrication and construction industries becauseof its advantages over other types of welding.

2.1 How the Process WorksMIG welding embraces a group of arc weldingprocesses in which a continuous electrode (thewire) is fed by powered feed rolls (wire feeder)into the weld pool. An electric arc is createdbetween the tip of the wire and the weld pool.The wire is progressively melted at the samespeed at which it is being fed and forms part ofthe weld pool. Both the arc and the weld poolare protected from atmospheric contaminationby a shield of inert non-reactive gas, which isdelivered through a nozzle that is concentricwith the welding wire guide tube.

MIG welding is usually carried out with a hand-held gun as a semi-automatic process.The MIGprocess can be suited to a variety of jobrequirements by choosing the correct shieldinggas, electrode (wire) size, and welding parameters.Welding parameters include the voltage, travelspeed, arc (stick out) length and wire feed rate.The arc voltage and wire feed rate willdetermine the filler metal transfer method.

This application combines the advantages ofcontinuity, speed, comparative freedom fromdistortion and the reliability of automaticwelding with the versatility and controllability ofmanual welding.The process is also suitable formechanised set-ups, and its use in this respect isincreasing.

MIG welding can be done using solid wire, fluxcored, or a copper coated solid wire electrode.

The shielding gas or gas mixture may consistthe following:• argon • carbon dioxide • argon and carbon dioxide mixtures• argon mixtures with oxygen or helium

mixtures

Each gas or gas mixture has specific advantagesand limitations.

Other forms of MIG welding include using aflux-cored continuous electrode method usingCO2 shielding gas, or using a self-shielding flux-cored wire requiring no shielding gas as the fluxcreates it’s own shielding gas.

wirespool

powersource

drive rolls

gas nozzle

shielding gas

contact tube

workpiece

+

–

Figure 1: Schematic interpretation of MIG Welding

8 9

iv. Pulsed transfer

Pulsed arc welding is a controlled method ofspray transfer, using currents lower than thosepossible with the spray transfer technique,thereby extending the applications of MIGwelding into the range of material thicknesswhere dip transfer is not entirely suitable.

The pulsed arc equipment effectively combinestwo power sources into one integrated unit.One “side” of the power source supplies abackground current which keeps the tip of thewire molten, the other “side” producing pulsesof a higher current which detach and acceleratethe droplets of metal into the weld pool.Thefrequency of transfer of these droplets isregulated primarily by the relationship betweenthe two currents.

Pulsed arc welding occurs between ±50-220A, 23 – 35 arc volts. It occurs only withargon and argon based gases and enableswelding to be done in all positions.

2.4 Power SourceMIG welding heat is generated by the flow ofcurrent though the gap between the end of thewire electrode and the workpiece.A voltage forms across this gap which varieswith the length of the arc.To produce a uniformweld, the welding voltage and arc length mustbe maintained at a constant value by:• feeding the wire into the weld zone at the

same rate at which it melts or;• melting the wire at the same rate it is fed

into the weld zone

The constant voltage power supply wasdeveloped for MIG welding because of the needfor better arc control.The constant voltage(CV) welding power supply has a relatively flatvolt/ampere characteristic.This means that apre-set voltage level can be held across its range.

2.5 Voltage SelectionWelding voltage is selected by a switch orswitches on the front panel.The higher thenumber or combination of numbers on eachswitch will give a higher welding voltage (seevoltage switch selection table).Voltage isselected according to the material, thickness,wire diameter and type of weld required i.e.short or spray arc.

Warning: Never switch voltage selector when welding as this will damage the switch(s).

2.6 Wire Feed Roll TensionMost wire feed systems consist of two or fourfeed rolls.They are a combination of a drivenroll with a groove machined into itscircumference, and pressure rolls that putphysical pressure on the wire.When the driveroll rotates, the wire is fed through the rolls tothe gun.

With the wire feed running, adjust the feedroller pressure so that the wire reel can bestopped by slight pressure. If the roller pressureis too light the wire will feed erratically.Too higha pressure will cause twisting of the consumablewire and flaking of the protective coppercoating which will clog the wire liner.

2.7 Duty Cycle

Most welding equipment is tested and rated at a certain duty cycle.This duty cycledetermines a machines’ output limitations incurrent and time to avoid internal componentsfrom overheating and is based on a 5 or 10minute cycle.The BOC MIG 320R has a dutycycle of 320 amps at 50%.The BOC MIG 420Rhas a duty cycle of 420 amps at 50%.

Summary of MIG transfer modes

TRANSFER WELDING OPERATING RANGE WIRE USES

METHOD POSITIONS VOLTS AMPS DIAMETER

Short arc All 13 to 23 60 to 200 0.6 to 1.2mm Light gauge(dip) material

Globular arc Flat or horizontal 20 to 26 200 to 280 All Between dip (fillets) and spray

Spray arc Flat or horizontal 24 to 40 210 to 410 0.8 to 1.6mm Material (fillets) over 5mm

Figure 2: Dip Transfer – A short-circuiting arc in progress

Figure 3: Spray Transfer

Figure 4: Globular Transfer

Figure 5: Pulsed Transfer

TENSIONER

COURSE STEPS FINE STEPS

11

3.2 GMAW Shielding Gas Selection Chart

Light Steel

APPLICATION ARGOSHIELD MODE BENEFITS

Sheet steel Argoshield 40 Spray/DIP Clean and fast low bead profile

Light gauge steel Argoshield Light Spray/DIP Economical and fast for

general light work

High quality Argoshield 54 DIP Excellent finish on sheet

steel, minimal clean up –

electroplating quality

Heavy Steel


Welding to AS1554 Argoshield Universal DIP/Spray Excellent penetration and

Standard speed.Weld to x-ray quality.

Positional welding Argoshield 52 DIP Stiff arc with low spatter,

excellent penetration

Stainless and Low Alloy Steel


Economy Stainshield DIP Stiff arc with low spatter,

excellent penetration

High speed Argoshield 61 DIP/Spray Excellent penetration and

finish. Also suitable for

positional welding

Non – Ferrous Welding


Sheet aluminium BOC Welding Argon Spray Economical

(up to 6mm)

Braze welding bronze

to other metals Specshield Copper Spray Increased performance

Light gauge Alushield Light Spray High speed – clean finish

Heavy gauge Alushield Heavy Spray Deep, wide fusion.

(over 10mm) High deposition rates

3.0 OverviewShielding gases for MIG welding are important forkeeping the arc stable and protecting the moltenweld metal from contamination during welding.

The major function of a shielding gas is tosurround the weld zone with a protectiveshroud of non-reactive shielding medium.This removes harmful elements from theatmosphere (oxygen, nitrogen gas) which would give a poor quality weld deposit if they contacted the molten metal.

Different shielding gases or gas mixtures areused when welding various metals; for example,pure argon is commonly used for the welding ofaluminium and copper. Stainless steel requiresan argon or argon oxygen (O2) and heliummixture with a maximum of 3.6% carbondioxide (CO2) content and carbon and lowalloy steels can be welded with carbon dioxideor argon-oxygen-CO2 mixtures.

There are, however, certain points, which mustbe explained to show the effects of mixing ofgases on the type of bead and penetration.

Argon gives a smooth wide spread whilst CO2

adds to penetration.The addition of smallpercentages of oxygen provides better “wettingaction” – reducing the surface tension of the weld.

Careful consideration of various mixtures has led to a range of gases to suit manyapplications, and the choice of shielding gasrequires due care.

Typical shielding gases used for this processinclude:• argon/oxygen/carbon dioxide• carbon dioxide • argon/carbon dioxide mixtures• argon helium mixtures

The recommended flow rate for argon andargon mixtures is 14 L/min (14 litres perminute) and 18 L/min (18 litres per minute) forCO2 when used with a heated regulator.

Post flow of the shielding gas is needed toprotect the solidifying weld metal fromcontamination from oxygen, nitrogen and watervapour in the atmosphere.

3.1 General instructions forpressure regulators

PLEASE NOTE It is important that you readand understand the operating instructionssupplied with the regulator before using it.

Regulator connection1. Fit the regulator “bull-nose” into the cylinder

valve and tighten the nut (do not over tighten).2. Turn the regulator knob in an anti clockwise

rotation, so that there is no pressure on theregulator diaphragm.This is the fully off,no-flow position.

3. Attach hose nut/nipple to the regulator outlet.

Setting the regulator1. Open the valve of bottle slowly.2. The high pressure gauge will show the

pressure in the bottle.3. Adjust the regulator knob until the desired

pressure is achieved on the low pressuregauge (12 to 20 L/min usually).

4. Pull the torch trigger to simulate a weldingcondition, and readjust the regulator knob tothe desired pressure that will be requiredwhile welding (it is normal for the gasdelivery gauge to drop back while in use dueto pressure drop when in the static position).

Close the valve of the cylinder after welding has stopped. If the machine will be out of usefor a long period of time, you should close theregulator knob to act as a secondary valve.

3. Shielding Gases

10

12 13

4. Plant Specifications 5. Plant Contents

The packages include:

BOC MIG 320R (Part No. B621532001)

• MIG gun MG42i Euro fit – 4 metre standard gun (Part No. BMG4202/4)• Power source 320R• WF2 Wire Feeder (Part No. B621720001)• WF4 – optional (Part No. B621740001)• BOC 6000 Argon regulator – 45 L/m (Part No. 105206)• Digital volt/amp meter• Gas hose• Under carriage• Work lead 35mm2

• Primary cable – 5 metre• Wheel kit

BOC MIG 420R (Part No. B621542001)

• BOC MIG gun MG42i Euro fit – 4 metre standard gun (Part No. BMG4202/4)• Power source 420R• WF4 Wire Feeder (Part No. B621740001)• BOC 6000 Argon regulator (Part No. 105206)• Digital volt/amp meter• Gas hose• Under carriage• Work lead 50mm2

• Primary cable – 5 metre• Wheel kit

DESCRIPTION MIG 320R MIG 420R

Part number WF2: B621532001 B621542001

WF4: B621532002

Supply Voltage (V) 380-415 380-415

Frequency (Hz) 50/60 50/60

Phase 3 3

Rated primary current (A) 14 23

Supply Fuse (recommended A) 20 25

Primary cable length (m) 5 5

Welding Current (Amps) 40-320 40-420

Duty Cycle 50% @ 320A 50% @ 420A

Output Voltage OCV (V) 15.7-41.1 16.5-48.9

Voltage Steps 40 56

Inductance Settings 2 2

Remote interconnection cable length (m) 8 8

BOC gun/length (m) MG42i/4 MG42i/4

Wire Feed Speed (m/min) 0-18 0-18 or 25

Wire Diameter (mm) Solid 0.6-1.2 0.6-1.6

Soft 0.8-1.2 0.8-1.6

Flux cored 0.8-1.6 0.8-1.6

Weight Power Source (Kg) 97 108

Dimensions HxWxL (cm) 77x42x98 77x42x98

15

6.1 Wire Speed Control Wire speed control isobtained by adjustmentof the knob mounted onthe front panel.Themaximum wire speed is18 m/min.The WF4 canbe increased to 25 m/min by replacing the drivegear. Use material number B4265250 (seeDiagram E, page 21).

6.2 Thermal Overload IndicatorA yellow light on the front panel indicates thatthe machine is overloaded and will shutdownautomatically.The cooling fan will continue torun and the “overload” will reset automaticallyafter cooling down. Always check air circulationhas not been obstructed.When the light goesoff you may continue.

6.3 Power On/Off SwitchIn the “O” position all controls of the machineare without power.

Illuminated when “ON”.

6.4 2T and 4T Trigger FunctionShielding gas flow and wirefeed are regulated from thegun switch.The suitableprocedure is selected with thewelding procedure selectionswitch, which has threedifferent positions:

2-sequence (2T)

Gas flow and wire feed starts, when the gunswitch is pressed and stops when the switch isreleased.The duration of wire feed can bepreset with the Timer control.

4-sequence (4T)

Gas flow starts, when the gun switch is pressed.When the switch is released, wire feed startsand welding begins.When the gun switch ispressed again, wire feed stops and when theswitch is released, gas flow stops.The durationof wire feed can be preset with the Timer control.

Spot welding

Gas flow and wire feed starts, when the gunswitch is pressed and stops automaticallyaccording to Timer setting or when the gunswitch is released.Note: The procedure does not start if Timerselection is set on 0-area.

Timer potentiometer

The duration of welding can be adjusted withTimer potentiometer.Wire feed and gas flowwill stop automatically after a preset time, ifthey are not stopped before that manually fromgun switch.

6.5 Polarity Selection – Positive Cable Socket andNegative Cable SocketFor welding with Steel, Stainless Steel (SS), orAluminium (Al) solid wires (gun positive), placethe dinse plug in the positive (+) socket andlock by twisting clockwise.The work lead isthen connected to the negative (-) and locked.

For gasless flux cored wires, reverse polarity(Gun negative) connect the dinse plug to the negative plug & lock.The work lead is thenconnected and locked to the positive (+) plug(see page 14).

6.6 Control FuseTo prevent possible overload or system shortcircuit a control fuse (8A) has been installedand is located on rear of machine. Fuses arelabelled T8A.

14

6. Operating Controls

6.0 Diagram A – BOC MIG 320R and MIG 420R (MIG 420R shown)

ITEM DESCRIPTION

1 Weld mode – 2T/4T/spot time

2 Spot/stitch timer

3 Wire speed control

4 Main power on/off switch

5 Thermal overload indicator

6 Voltage switch – course

7 Voltage switch – fine

8 Negative cable socket-

inductance setting

9 Positive cable socket

10 Euro Gun connection

11 Gun holder

12 Control cable socket

13 Control fuse

12

45

67

3

8

10

11

9

12

13

BOC MIG 420R OPEN CIRCUIT VOLTAGE STEPS (56 STEPS)FINE SWITCH COURSE SWITCH

1 2 3 4

LOW 15-28V

1 16.5 18.6 21.0 24.3

2 16.9 18.9 21.5 24.9

3 17.1 19.2 22.0 25.5

4 17.3 19.6 22.3 26.0

5 17.6 20.0 22.8 26.9

6 18.0 20.3 23.3 27.6

7 18.2 20.7 23.7 28.2

HIGH 28-48V

1 29.5 32.8 37.1 42.7

2 29.8 33.4 37.9 43.7

3 30.3 33.9 38.7 44.7

4 30.7 34.5 39.3 45.7

5 31.2 35.1 40.2 46.7

6 31.7 35.8 40.9 47.8

7 32.2 36.4 41.7 48.9

WARNING – Do not adjust the voltage setting while welding.

1716

6.10 Voltage Switch SelectionThe table below indicates the open circuit voltages for each setting.

BOC MIG 320R OPEN CIRCUIT VOLTAGE STEPS (40 STEPS)FINE SWITCH COURSE SWITCH

1 2 3 4

1 15.7 18.9 23.6 31.5

2 16.0 19.2 24.1 32.4

3 16.2 19.5 24.6 33.3

4 16.5 19.9 25.1 34.2

5 16.7 20.2 25.7 35.0

6 16.9 20.6 26.2 36.1

7 17.2 21.0 26.8 37.2

8 17.5 21.4 27.8 38.4

9 17.8 21.8 28.4 39.7

10 18.0 22.2 29.2 41.1

WARNING – Do not adjust the voltage setting while welding.

6.7 Inductance SettingThe BOC MIG 320R/420R has two negativeconnectors on the front panel marked “I” and“II” and are used for connecting the work cableor gun polarity cable depending on the polarityrequired (see (6.5) polarity selection).Connecting to either connection will affect theamount of inductance in the welding circuitwhich will change the arc characteristics whenwelding in the short arc range.“I” will have lessinductance and will allow a “cooler’ arc withslightly more spatter and is generally used forthinner materials or when using CO2 shieldinggas.“II” has more inductance that creates asmoother arc with more heat input and issuited to thicker material, aluminium andstainless applications. It is recommended thatboth settings are used to determine to bestconnection for each weld application.

6.8 Operation of Cooling FanThe cooling fan will automatically turn on after30 seconds of operation and will continue for aperiod of five (5) minutes after welding hasceased or when the thermal overload releases.Air intake is via the rear panel.

WARNINGDo not switch off main power to machine untilfan has stopped.

6.9 Burn Back Control/InchControlThe burn back and inch controls are locatedinside the wire compartment of the machine.

18 19

7. BOC Wire Feeder

ITEM DESCRIPTION

1 Wire Speed Control

2 Weld Mode – 2T/4T/Spot time

3 Spot/stitch timer

4 Euro Gun Connection

5 Pull/Push Control Optional

6 Gun holder

7.0 Diagram B – WF2 and WF4 Wire Feeder Controls (WF4 shown)(WF2 Part No. B621720001,WF4 Part No. B621740001)

ITEM DESCRIPTION

1 Wire Inch

2 Burnback Control

3 Feed Roll Tensioner

4 Wire Inlet Guide

5 Feed Roll Securing Knob

6 Spool hub

1

6

45

34

21

5

3

2

7.1 Diagram C – WF2 and WF4 Internal Diagram

ITEM DESCRIPTION

1 Wire Inch

2 Burnback Control

3 Feed Roll Tensioner

4 Wire Inlet Guide

5 Feed Roll Securing Knob

6 Spool hub

WF2

WF4

3

4

21

5

6

2120

WIRE DIAMETER PART NO.

FE MC 0.6 – 0.8mm B3134140 white

FC 0.9 – 1.6mm B3133700 orange

SS AL 0.8 – 1.6mm B3134290 silver

7.2 Diagram D – WF2 Wire Feeder Spare Parts 7.3 Diagram E – WF4 Wire Feeder Spare Parts

B4265240 0-18 m/min

B3134290 orange

B3134300 silver

B4267220 plastic

B4265250 0-25 m/min

WIRE FEED ROLL TYPE 0.6mm/0.8mm 0.9 – 1.0mm/1.2mm 1.4mm/1.6mm

FE SS AL Plain B3133810 white B3133210 red B3133820 yellow

FE FC Knurled – B3133940 red B3133990 yellow

AL U-groove – B3133960 red –

WIRE DIAMETER PART NO.

0.6 – 0.8mm B3134140 whiteFE MC FC

0.9 – 1.6mm B3133700 orange

SS AL 0.8 – 1.6mm B3134290 silver

WIRE FEED ROLL TYPE 0.6mm/0.8mm 0.9 – 1.0mm/1.2mm 1.4mm/1.6mm

FE SS Plain B3133810 white B3133210 red B3133820 yellow

FE FC Knurled – B3133940 red B3133990 yellow

AL U-groove – B3133960 red –

B4285900 brass

B4102283 plastic

B4265240

Guide Tube Guide Tube

Feed Roll

Feed Roll

23

8.3 BOC MG42i Gun Spare Parts (refer to Diagram F, page 22)

DIAGRAM NO. DESCRIPTION PART NO.

1 Gas nozzle – standard B4255530

Gas nozzle – long B4255530E

Gas nozzle – conical B4273510

2 Insulating bush B4248710

3 Contact tip 0.8mm/M8 B9580122

Contact tip 0.9mm/M8 B9580121





4 Contact tip adapter M8 B426964001

5 Insulating ring B4270290

6 Gooseneck 45 degree standard B4270750

Gooseneck 60 degree long B4270780

Gooseneck 45 degree short B4286450

7 Liner – steel 0.6 – 0.8mm/4m (white) B4188577

Liner – steel 0.9 – 1.2mm/4m (red) B4188587

Liner – steel 1.4 – 1.6mm/4m (yellow) B4188590

Liner – DL Teflon 0.8 – 1.6mm/4m AL (silver) B4300850

Liner – DL Teflon 0.8 – 1.0mm/4m SS (silver) B4302690

Liner – DL Teflon 1.2 – 1.6mm/4m SS (silver) B4302710

8 Trigger switch B4290120

9 Handle B4305240

10 Retaining ring B4302780

11 Cable support B3133490

12 Euro connection block B9580159

8.4 BOC MIG Machine Optional ExtrasDESCRIPTION MIG 320R MIG 420R

Push/Pull Gun KMW Sync. Unit B6219100 B6219100

Remote Wire Feeder Hanging Bracket B3135870 B3135870

22

8.2 Diagram F – MG42i (Part No. BMG4202/4)

8.0 FeaturesThe BOC welding gun range has been selectedto match the capabilities of the BOC MIGrange.The gun selections for each machine will optimise the machine’s performancecharacteristics to ensure reliability and trouble-free operation. Colour coding of the gunconsumables and wire feed rolls are to ensureparts match and for quick identification whentrouble-shooting wire feed problems.

Other features of the welding gun rangeinclude:• Ergonomic design for improved operator

comfort• Swivel head for flexibility• Lightweight European design• Cables of varying length (optional)• Euro quick connection• Trigger protection• Colour coded sizing to ensure correct drive

rollers/liner match

8. BOC MG42i Gun

8.1 Specifications

PART NO. WELDING WIRE SIZES (mm) DUTY CYCLE

GUN/CABLE (m) AR, AR + CO2 CO2

BMG4202/4 MG42i/4 0.8 – 1.6 350A/60% 420A/60%

11 10 9 5 4 23 168

12 7

24 25

9. Installation of Power Source

9.0 Transport and Lifting of theBOC 320R or 420R MIG MachinesNOTE

• Never transport the BOC MIG on its side.• Never use the BOC MIG on its side.• The BOC MIG weighs between 100 – 126kg.

9.1 Machine Work SiteThe BOC MIG machines must be located on ahorizontal and dry base.The area must havegood ventilation and be free of dust and otherair blown hazards. Always allow free space atthe front of machine as well as at the rear toallow adequate air circulation through themachine. Protect the machine from rain andtemperatures over 30°C in direct sunlight.Always ensure that the BOC MIG machinecooling air ducts are clean and unrestricted.

9.2 Welding and Return CablesThe table shown below is typical loadingcapacities of rubber insulated copper cables atambient temperature 25°C and a conductorsurface temperature 90°C.

CABLE CROSS DUTY CYCLE

SECTIONAL AREA 100% 60% 30%

16mm2 146 A 187 A 263 A

25mm2 193 A 245 A 351 A

35mm2 239 A 310 A 438 A

50mm2 304 A 392 A 555 A

NOTE• Never load welding cables beyond their

design capabilities.• All electrical contact points should be clean

and free of oil, grease and rust.

9.3 Connection to Mains PowerThe BOC 320R and 420R come complete with primary power cable. A qualified electrician must be used to fit the primary plugof suitable size.

9.4 Mounting and Locking of Wire SpoolRelease the locking tabs on the hub by turningthe locking knob to the OPEN position. Mountthe spool in place. Note the rotation from thedirection of spool.Turnknob to CLOSED/LOCKED position.

NOTECheck filler wire spool forno protruding parts whichcould rub against chassis ordoor of wire feeder unit.Dragging parts couldexpose chassis of wirefeeder unit to a shortcircuit of welding voltage.

9.5 Automatic Wire Feed to MIG GunWARNING! Keep fingers away frommoving drive rolls when feeding the wire.

Prior to loading, ensure that the diameter of thewire matches the feed rollers. Repositioning thewasher from either side of the drive roller canchange the feed roller wire diameter groove.Release wire from spool and at the same time,maintain pressure to avoid wire spill from reel.Inspect the wire end for sharp edges, and ifnecessary, cut the end off with pliers to preventdamage to liner. Ensure wire is clean to easewire feeding. Straighten approximately 20cm ofwire and feed through to the back of the inletguide towards the feed rolls. Do not releasefeed roll pressure. Press wire inch switch. Feedthe wire through to the feed roll ensuring thatwire is in the feed roll grooves. Continue tofeed wire through the gun to the contact tip.

9.6 Fitting the SpoolNOTEThe BOC 320/420R is designed for use with 300mm diameter spools with a 50mmdiameter hub.

1. Select the correct feed roll groove and size from the table on pages 20-21 to suitthe wire in use. BOC’s 320/420R comes with the 0.9mm/1.2mm Plain V – Groovefeed roll as standard. Reposition washer if necessary.

2. Fit the spool so that the wire feeds off the top of the spool towards the wire feed mechanism.

3. Ensure that the spool locking pin locks thespool in place.

4. Turn the locking knob 90° to lock in place.

WARNING!Hold the wire to prevent it from coming off thespool. Make sure the wire is free of burrs &sharp edges before feeding.

5. Carefully release the wire end to free it from the spool.

6. Cut wire back to remove any twists or bends.

7. Straighten about 10cm of the free end.

8. With the Feed Roll tensioner released,gently feed the wire through the inlet guideand the feed roll.

9. Hand feed 30cm of wire into the MIG gun cable.

10. Ensure the wire is located in the Feed Roll groove and then close the Feed Rolltension mechanism.

11. Adjust Feed Roll tension.

12. Remove the gun nozzle and contact tip whenfeeding the wire to avoid jamming.

SECURINGKNOB

SELECTINGWASHER

FEEDROLL

FEEDROLL

PLACEMENT OF GROOVE

26 27

The working environment or amount of use the machine receives should be taken intoconsideration when planning maintenancefrequency of your BOC MIG welder.Preventative maintenance will ensure trouble-free welding and increase the life of the machineand its consumables.

10.0 Wire Feed• Worn wire feed rolls and guide tubes should

be replaced.• The wire guide tube should be set as near as

possible to the feed rolls but without touchingthem. Check spool brake adjustment.

• Check electrical connections.• Loose connections must be tightened.• Clean dirt and dust from unit. If using

compressed air wear eye protection.

10.1 Cables• Check condition of cables and connections

daily. Do not use faulty cables!• Check mains cable condition to ensure they

are safe.• Any repairs on the mains cable must be

carried out by authorised personnel only.

10.2 Power Source• Check electrical connections of the unit at

least twice a year.• Clean oxidised connections and tighten.• Inner parts of the machine should be cleaned

with a vacuum cleaner and soft brush.

• Do not use any pressure-washing devices.• Do not use compressed air as pressure may

pack dirt even more tightly into components.• Only authorised electricians should carry out

these repairs.

10.3 Consumable PartsRegular replacement of consumable parts isrecommended for trouble-free welding.These parts include:• conduits• contact tips• gas nozzles

For the full range of replaceable spare parts,see page 23.

10. Periodic Maintenance9.7 Adjustment of Feed Roll TensionAdjust the tension of the feed rolls via thetensioner to promote smooth, even wire feed.

NOTEExcessive pressure will damage the wire coating and increase feed roll wear.

9.8 Adjusting Wire Hub BrakeHub brake adjustment is obtained by adjustingthe tensioning nut located in the centre of thehub.This is behind the spool locking knob, thatcan be removed by pulling the locking knob out.Wire tension should be enough to stop the reelfrom unwinding when the motor stops, but lowenough not to overload the wire feeder motorand gearbox.

9.9 RegulatorRefer to Operating Instructions supplied withthe BOC Regulator and connect the hose tothe Regulator hose nipple.The regulatorsupplied with the 320/420R machines is theBOC 6000 Argon Regulator (Part No. 105206).

9.10 Shielding GasCheck with a BOC Gas & Gear oragent/distributor for the correct BOC shielding gas. Suggested gas flow is 15 – 20 litresper minute.

9.11 Gas Cylinder• Always chain cylinder to trolley or

upright fixture.• Never transport cylinder mounted to

machine. Always remove before lifting.• Open cylinder valve slowly. Never place your

face over valve when cracking cylinder.

Part No. 105206

TENSIONER

2928

FAULT POSSIBLE CAUSE REMEDY

Lack of fusion Voltage too low Increase voltage

Excessive spatter Incorrect voltage setting Readjust voltage setting

Incorrect shielding gas Check selection

Insufficient inductance Increase inductance if possible

Blocked gas nozzle Clean nozzle regularly and

spray with an anti-spatter

Irregular weld shape Current too high for selected voltage Reduce wire feed speed

Excessive stick out Contact tip closer to work

Wire wander Replace contact tip

Incorrect shielding gas Check selection

Travel speed too slow Increase speed

Excessive gas flow Set to 15-20 L/min

Weld cracking Dirty work piece, i.e. grease, Clean and degreasepaint scale, rust prior to welding

Weld beads too small Slow wire speed down

Weld too deep Reduce voltage and wire feed speed

Highly restrained weld Revise setting procedure

Excessive voltage Decrease voltage

Fan not working Fan controlled by control card Fans starts 30 sec after start of

weld and continues for 5 min

after end of weld

Porosity Insufficient shielding gas Set to 15-20 L/min (Argoshield)– more if windy position

Dirty work piece Clean work thoroughly

Arc voltage too high Reduce voltage

Air entering into gas Check gas connectionsshielding system

Excessive gas flow rates Set to 15-20 L/min

Spatter on gas nozzle Clean nozzle and regularlyspray with an anti-spatter

Wrong wire analysis Check selection

11.Trouble Shooting

How to Rectify GMAW and Machine Faults

FAULT POSSIBLE CAUSE REMEDY

Mains power on but no Control fuse blown Replace fuse welding power – contact BOC for service

Fault in control circuit of Gun Check Gun control plugged in,repair switch in Gun handle

No mains power on machine Power supply switch open Close switch

Primary fuse blown Replace fuse

Open circuit breaker Reset breaker

Disconnection in primary circuit Repair connection

Mains power on, no wire feed Control fuse blown Replace fusebut contractor operates when – contact BOC for servicetrigger is actuated (clacking

Wire stuck in liner guide or Clean or replace if necessarysound in power source)contact tip

Wire feeds but arc won’t strike Poor or no contact between Inspect clamp and work area work piece and earth clamp ensure good contact

“Erratic” stop start wire Worn or dirty contact tip Replace contact tipfeeding causing uneven

Worn wire guides Replace and alignwelding conditions

Wire spool runs stiffly Reduce tension on spool

Worn, dirty, kinked conduit Clean or replace

Cold weld puddle Incorrect machine settings Increase heat input

Incorrect shielding gas Replace gas

Bad connection Check and tighten connection

Faulty diode Contact BOC for service

Undercutting Speed too slow for current Increase speed

Gun angle too low Raise Gun angle

Voltage too high Reduce voltage

Lack of penetration Current too low Increase wire feed speed

Inconsistent current pick up Renew contact tip

Stick-out too great Shorten stick-out

Joint preparation too narrow Widen preparation

30 31

13. Glossary12.Terms of Warranty

ASEAAustralian Standard Equal Angle

Burn backFusing the wire electrode to the contact tip

CO2

Carbon dioxide

Contact tipA short tube fitted to a MIG gun to passelectrical current onto the wire

Current densityThe current for a given filler wire diameter

Deposition rateThe weight of metal deposited in a unit of time,expressed as kg/hr

Duty cyclePercentage of time, for a test period duringwhich power supply can be operated at itsrated output without overloading

Dwell timeThe period of time the nozzle remains on thejob after welding to protect the cooling weld

Flow meterA gas flow measuring device connected to theregulator to adjust operating flow rates

Globular transferMetal transfer which takes places as globules ofa diameter larger than that of the electrode

GMAWGas metal arc welding

Inert gasShielding gas consisting of argon or helium or amixture of the two

LinerSupply conduit that the wire electrode feedsthrough

RectifierA power source developed to supply directcurrent (DC) for welding from an alternating(AC) mains power supply

Short arc transferMetal transfer in which fused particles of wireelectrode are detached in rapid successionduring the repeated short circuiting contactsthe weld pool

SpatterThe metal particles which are expelled duringwelding on to the surface of the parent metal ora weld and which do not form a part of the weld

Spray transferMetal transfer which takes place as a rapidlyprojected stream of droplets of a diameter nolarger than that of the wire electrode

StickoutThe length the wire electrode projecting pastthe contact tip during the welding

VariablesOperating conditions such as volts, wire speed,travel speed and gas flow rate that areadjustable before and during welding

Weld timeTotal time involved between the start and finishof welding current during the make of one weld

BOC will provide a warranty to the initial enduser of BOC welding equipment as covered bythe terms and conditions below. BOC willrepair or replace at its option any parts orcomponents that fail due to defects in materialor manufacture within the warranty period.All warranty work must be carried out by anauthorised BOC service provider, using genuineparts and approved procedures.The warranty is affected on the date of sale to the initial end user. Verbal promises that do not complywith terms of the warranty are not binding onthe warrantor.

Limitations on Warranty

The following conditions are not covered underthis warranty: problems due to natural wear andtear; non-compliance with operating andmaintenance instructions; connection toincorrect or faulty voltage supply (includingvoltage surges outside equipmentspecifications); incorrect gas supply or pressure;transport or storage damage; damage due tofire and other natural causes i.e. lightning orflood.This warranty does not cover freight,travel and insurance costs – these costs are theresponsibility of the end user.

This does not restrict or modify any warrantiesthat are imposed by any statute including theTrade Practices Act and which by Statutecannot be excluded, restricted or modified.

Note: Under the terms of warranty, wear partssuch as drive rollers and guide tubes are notcovered. Direct or indirect damage due to adefective product is not covered under thiswarranty.The warranty is void if changes aremade to the product without approval from

BOC, or if repairs are carried out using non-approved spare parts.The warranty is void if anon-authorised person carries out repairs.

Warranty Period

The warranty is valid for the period shownbelow from the date of purchase to the initialend user and provided the equipment is usedwithin the published specification limits.

5 years Main transformer, Inductorand Rectifier.

2 years All other parts includingcontrol circuit board.

3 months Mig guns.

No Warranty Wear parts andconsumables e.g. feedrollers, guide tubes.

Undertaking Warranty Repairs

BOC or their authorised service provider mustbe informed of warranty defects within thewarranty period. Before any warranty work isundertaken, the initial end user must provideproof of purchase and serial number of theequipment in order to validate the warranty.Any parts replaced under the terms of thewarranty remain the property of BOC.

Documents

BOC_MIG_320R_420R_Manual