ESAB India Your partner for welding

•Employs around 750 persons •ESAB is represented in almost every part of the country•Sales and support is established every industrial location•5 manufacturing plants•Sales regions:

– North– South– East– West– Central

Taratala (Kolkata)Taratala (Kolkata)

Sriperumbudur (Chennai)Sriperumbudur (Chennai)

ESAB IndiaEquipment production centers

ESAB IndiaEquipment sales offices

New Delhi

Mumbai

Kolkata

Chennai

Nagpur

MMAW / SMAW PROCESS

i) This is a group of processes in which the heat required for fusion is generated by the electric arc formed between a metallic electrode and the base metal. The electrode is consumed in the arc and provides the filler metal for the joint.ii) Electric arc was discovered by Sir Humphrey Davy in 1801.iii) Oscar Kjellberg of Sweden is credited with being the pioneer of modern coated arc welding electrodes. In 1907, he was granted a patent on covered electrodes. By 1907 first welding generator was introduced in the U.S. market.iv) The electric arc is an ideal source of welding heat. v) Among the arc processes MMAW is the most common, versatile and inexpensive one and accounts for over 60% of the total welding in advanced countries and over 90% of the total welding in India.

THE WELDING ARC

A welding arc is the passage of electricity across a gap between an electrode and the parent metal or work.

Arc length is related to arc voltage.

Common Welding Power Sources

Transformer – AC In AC Out Conventional Rectifier- AC In DC

Out Inverter Based Rectifier – AC In DC

Out

Equipment for every arc welding process

Common Welding Processes

Manual Metal Arc Welding (MMAW)

Metal Inert Gas/Metal Active Gas (MIG/MAG) Welding

Tungsten Inert Gas (TIG) Welding

Submerged Arc Welding (SAW)

Advantages Of MIG Welding

The MIG /MAG welding process provides many advantages in manual and automatic metal joining for both low and high production applications. Its combined advantages when compared to MMAW ,TIG & SAW :

• Welding can be done in all positions.• No slag removal required. High weld metal deposition rate.• Overall times for weld completion about 1/2 that of covered

electrode.• High welding speeds. Less distortion of the workpiece.• High weld quality.• Large gaps filled or bridged easily, making certain kinds of

repair welding more efficient.• No stub loss as with covered electrode.

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Process Variables – GMAWVARIABLES DESCRIPTION

Welding Current Has a non-linear relationship with electrode feed speed or melting rate

Polarity(Straight / Reverse)

DCEN – Direct Current Electrode Negative or Straight Polarity

DCEP – Direct Current Electrode Positive or Reverse Polarity

Arc Voltage An approximate means of starting the physical arc length

Travel Speed The linear arc rate at which the arc is moved along the weld joint

Stick Out The distance between the end of the electrode and the contact tube

Burn Back A time delay between wire feed unit starts to brake the wire until the power unit shuts off the welding current

Electrode Diameter

Higher electrode diameter requires higher current than comparatively smaller diameter electrodes and produce

higher weld deposition

Shielding Gas Shields the molten metal from atmospheric contact

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Shielding Gases used in GMAW

Shielding Gases provide a shielding to the weld metal from

the atmospheric contact and have a pronounced effect on

• Arc characteristics• Mode of metal transfer

• Penetration and weld bead profile• Speed of welding

• Undercutting tendency• Cleaning action

• Weld metal mechanical properties

Types of shielding gases used in GMAW are

• Carbon Dioxide (CO2)• Argon

• Helium• Oxygen

• Mixtures of above Gases

PARAMETERS DESCRIPTION

Arc Voltage It is the electrical potential between the electrode and the work-piece

Slope Measured at two stable arc conditions of the CV characteristics

Inductance The inductance in the circuit controls the rate of current rise and in turn the pinch effect.

WELDING PREPRATION- GMAW

The GMAW Power Source should have a Drooping Characteristics.

When welding is in progress the relation between the Welding Voltage (V) and the Welding Current (I) is expressed by the following mathematical formula

V = 14 + 0.05 I

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ESAB GMAW Product Range

Diode based GMAW

• MIGMATIC 250• MIGMATIC 400

• POWER COMPACT 255

Thyristorised GMAW

• AUTO K 400• AUTO K 600

Inverter based GMAW

• ESABMIG 300i / C300i• ARISTOMIG 300 / C300• ARISTOMIG 400 / U400• ARISTOMIG 500 / U500

Principle of Material Transfer

MIG/MAG welding is performed in two waysdepending on the transfer of the metal;

SPRAY TRANSFER WELDING

OR

DIP TRANSFER WELDING

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Wire feed speed = welding current

Increased current (= wire feed speed) gives deeper penetration

Date/Month/Year. 28

Voltage, Mig/Mag

Increasing the voltage• increases the arc length

• produces a hotter, wider weld pool• reduces the short-circuiting frequency when

using short-arc welding (=larger droplets)• produces more spatter.

Too low a voltage produces a tendency to spatter.

When welding thin sheet materials, short-arc welding facilitates high production speeds without burning through the material. For such applications, use a low arc voltage

setting, with stable arc (use a high short-circuiting frequency)

High Voltage Medium Voltage Low VoltageLong arc length Medium arc length Short arc length

weld profile butt weld

weld profile fillet weld

With constant wire feed speed

Date/Month/Year. 30

InductanceInductance affects MIG/MAG welding when

short arc welding.When welding with spray arc inductance influences only

the start.

Low inductance:• a distinct and concentrated arc

• somewhat more spatter• for welding thin wires and low currents

High inductance:• softer arc

• hotter process• pool spreads somewhat better

• used for thicker wires

too high inductance results in fewer short circuits, unstable arc and sputtering tendencies at low arc

voltages

Low Medium High

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Welding torch – front end parts

•Learn to identify parts & correct assembly

• Check front end parts• Clean periodically

• Learn nozzle cleaning and liner replacement procedure

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Choose the right contact tip

Size ofelectrode

Recommended nozzle opening

Short arcCO2

Spray arcAr/CO2 or pure Ar

Nozzle Diff. Nozzle Diff.0,6 0,8 0,2 0,9 0,30,8 1,0 0,2 1,1 0,31,0 1,2 0,2 1,5 0,51,2 1,5 0,3 1,7 0,51,6 1,9 0,3 2,1 (1,9) 0,5

Date/Month/Year. 34

Wire feed unit - rollers

Feed roller types:• Feed rollers must suit the wire diameter in use. • Rollers are grooved for two or more different wire diameters.

Turn roller 180 degrees for other groove. • V type rollers for harder mild steel, stainless and cored wires• VK type rollers are for cored wires (V groove, knurled)• U type rollers for softer Aluminium wires

Date/Month/Year. 35

•Electricity

•Electromagnetic fields

•UV,IR and visible light radiation

•Air pollution

•Fire and Spatter

•Noise

•Ergonomics

The welder’s working environment

Welders are members of an occupational group which is exposed to a number of difrrent enviromental problems

Effective protection can reduce the health risk

Date/Month/Year. 36

Electricity

Risk of electric shocks• The level and duration of

the current• The current path through

the body• The frequencey of the

current

Human beings are extremely sensitive to current that passes through thier bodiesSeriuos injury can be caused by curremt of just 20 to 30 mA

Date/Month/Year. 37

Welding equipment

EN 60974-1

Open circuit voltage

DC Max 113V

AC Max 80 V rms

Date/Month/Year. 38

UV,IR and visible light radiation

• Eye damage• Skin damage• Thermal radiation

The diffrent welding methods give diffrent levelof radiation

Mig/MagMMA

Tig

Date/Month/Year. 39

Air pollution- FumeWelding fumes are a result of the vaporisation and oxidation of different substances

In the arc which is caused by high temperature

Material safety data sheet are availble for each product specifying the level and

conatent of the fume

Date/Month/Year. 40

Fire and spatter

Date/Month/Year. 41

Noise

Date/Month/Year. 42

ErgonomicsWhen welding heavy material manually and during assembly welding

the loads are very static. Positioning welding also give high load.