2. Butt Welding
• Butt welding is another type of electric resistant welding. The two weld metals
are placed in a machine in face to face matching and both are clamped
• These clamps are act as a electrode. These clamps are carrying the current.
• The weld metals are matched correctly same axes and same line touching each
• Both weld metals are holding under pressure. The source current is given
through the electrode to the weld metal and supply is continuing until its
reaching melting temperature.
• Previously load is applied to the metal and sufficient melting temperature,
both are play master role for completed the butt weld.
• During this welding process heavy current is required.
• Sheets 1.5 mm. thick and 250 mm. in diameter may be welded by butt weld.
Pipes, tubing, bars, rods, light and medium weight structural shapes may be
welded by butt weld.
3. Application Of Butt Welding:-
• Little thickness of ferrous and non-ferrous can be weld.
• It has large application in wire drawing industries.
4. Spot Welding
• Spot welding joint is one type of electric resistance welding. Generally joining
the sheet to sheet, sheet to rolled sections, wire to wire etc. by this spot weld
• The spot welding is very effectively, which can replace the rivet joints and is
very speedy process, this spot welding machine does not need skilled operator,
it can be operated by semi-skilled labour.
• The principle of spot welding is shown in the bellow diagram. In this machine
basically having a transformer core (T) which is having a primary winding (PW).
• This primary winding tapped at a number of points. The secondary winding
(SW) has the two ends of a circuit (C) which is connected two arms made of
copper or bronze.
5. • Each side has a copper electrode, this electrode of spot welding produce the
sufficient heat to fuse the joining metal. The lower arm is generally stationary
and upper arm is movable (upward and downward). The technical terms are
rocker arms or electrode arms. The electrodes of spot welding is cooled by
water, the water is passing through the inter looped water line.
6. The Essential Factor Of Spot Welding:-
• The welding current.
• The time of current application.
• The pressure of electrodes.
• The shape or area of electrodes.
• The surface condition of welded material.
Advantages Of Spot Welding:-
• In this welding process is free from fumes and spatter.
• Generally it has nothing maintenance or no skilled persons are required for
• No skilled persons are needed to operate the spot welding.
• Welding cost is minimum.
7. Carbon-Arc Welding
• The carbon-arc welding is the type of arc welding. Where carbon or graphite
are used as a electrode. There are two methods used for produced an arcs,
the single-carbon process and another is the twin-carbon process.
• The main difference is, the twin-carbon arc welding carried electrically
independent torch. The carbon-arc welding is invariably carried out with direct
• The heat is produced between carbon electrode and work piece, base metal
melts with this heat and additional filler metal can be added where extra
• The essential point of this carbon-arc welding is that the filler rod quite
difference from the ordinary filler rod. Because it cannot be connected with
8. • The carbon arc welding is suitable for particularly for non-ferrous metals
because of the availability of reducing atmosphere around the arc which
does not allow the oxidation of the metal to take place.
• Work piece distortion is less.
• Process is suitable for any kind of joint.
• Weld heat can be controlled very easily through changing of arc length.
• Welders are made skilled in short time.
• It is simple welding process.
• Big range of metals and their alloys can be welded.
10. Metal arc welding
• In electric arc welding is only a electrical spark, otherwise it is nothing.
• It is fusion welding process. It is work in a closed electrical circuit in which
• If a small gap formed in the circuit then there an electrical spark is
occurred, which is called electrical arc.
• In this spark or arc are contain a huge amount of temperature like 34000C-
40000C. Due to this huge temperature, the weld metal can be fuse in
arc welding process.
11. • In the arc welding the heat is produced through an electrode or arc welding rods.
The electric arc is produced between consumable electrode and the work piece.
• The current is continuously supplied through the consumable electrode and fillet
deposited on work piece. Thus the electric arc welding process is carried out. The
electrode which is passing the current is made with flux coated, these types of
electrode is called bar electrode.
• The coating flux are melt at the time of welding and deposited upper level of filler
metal as a slag, which is removed by chipping or grinding process after normal
cooling. The filler metal is called electrode in arc welding practice.