Basics of Welding (ARC, TIG, MIG)- Techshore Institute

This presentation offers a comprehensive introduction to the fundamentals of welding, focusing on three widely used techniques: ARC, TIG, and MIG welding. It covers the essential principles, equipment, and safety practices associated with each method, providing a clear understanding of their applications and advantages. Whether you're a beginner or looking to refresh your knowledge, this material is designed to equip you with the foundational skills needed to work with these welding processes. Ideal for students, hobbyists, and professionals in the field, this presentation serves as a valuable resource for anyone interested in mastering the basics of welding.

1. Basics Of Welding
Techshore Institute
(Top Welding Institute in Kerala)

2. Welding
•Welding is a process of
joining metals
* With the application of heat,
*With or without the
application of pressure,
* With or without the
application of filler metal to
form a metallurgical joint.

3. Types of WeldingTypes of Welding
FusionFusion
•SMAW
•Gas / Brazing
•TIG
•GMAW(MIG/MAG)
•FCAW
•SAW
Non-FusionNon-Fusion
•Forge Welding
•Resistance Welding
•Thermal Spraying
•Electron beam welding.
•Laser beam welding.
•Soldering

4. Types of Joints
•There are 5 types of
joints …

5. Fillet and Groove Welds
•Groove and fillet welds can be
made on many types of joints

6. What are Welding Positions?
•There are various positions that a weld can be made in:

7. Why is Welding Important?
•Many things around us
are welded …
•Pipelines that bring
fresh water
•Towers that carry
electricity to houses
•Cars and buses that
take people where they
need to go

8. Can All Metals Be Welded?
•Most metals can be welded, but not all
•The three most common weldable metals include:
•Mild Steel - inexpensive and strong
•Stainless Steel – does not rust
•Aluminum – does not rust and is light weight
Mild steel Stainless Steel Aluminum

9. Arc Welding

10. What is Arc Welding?
•Arc welding is most commonly used to join two
pieces of metal
•The welder creates an electric arc that melts the
base metals and filler metal (consumable) together
so that they all fuse into one solid piece of metal
Steel Pipe – Tack
Welded
Root Pass or
“Stringer Bead”
Final weld after
several beads are
made

11. Basic Steps of Arc Welding
•Prepare the base materials: remove paint
and rust
•Choose the right welding process
•Choose the right filler material
•Assess and comply with safety
requirements
•Use proper welding techniques and be
sure to protect the molten puddle from
contaminants in the air
•Inspect the weld

12. The Arc Welding Circuit
•The electricity flows
from the power source,
through the electrode
and across the arc,
through the base material
to the work lead and
back to the power source

13. Basic Electricity
•Voltage – The electrical
potential or pressure that causes
current to flow
•Measured in Volts
•Current – The movement of
charged particles in a specific
direction
•Measured in Amps
•Polarity
•DC- (Direct Current
Electrode Negative)
•DC+ (Direct Current
Electrode Positive)
•AC (Alternating Current)
DC+
DC -
AC

14. SMAW welding

15. SMAW Principles
•The American Welding
Society defines SMAW as
Shielded Metal Arc Welding
•SMAW:
•Is commonly known as ‘Stick’
welding or manual arc welding
•Is the most widely used arc
welding process in the world
•Can be used to weld most
common metals and alloys

16. SMAW Welding Circuit
•Current flows through the electrode cable, to the electrode
holder, through the electrode, and across the arc.
•On the work side of the arc, the current flows through the
base material to the work clamp and back to the welding
machine.

17. SMAW Process
Let’s take a little closer look at the SMAW process…
1
Travel direction
Electrode
Arc2
Weld Puddle3
Shielding Gas
4
Solidified Weld Metal5
Slag
6

18. 1- The Electrode
•Is a consumable - it gets melted
during the welding process
•Is composed of two parts
•Core Rod (Metal Filler)
Carries welding current
Becomes part of the weld
•Flux Coating
Produces a shielding gas
Can provide additional filler
Forms a slag

19. 2- The Arc
•An arc occurs when the
electrode comes in contact
with the work-piece and
completes the circuit …
like turning on a light!
•The electric arc is
established in the space
between the end of the
electrode and the work
•The arc reaches
temperatures of 10,000°F
which melts the electrode
and base material
Can you identify the weld joint
and position being used?

20. 3- Weld Puddle
•As the core rod, flux
coating, and work pieces
heat up and melt, they
form a pool of molten
material called a weld
puddle
•The weld puddle is what a
welder watches and
manipulates while welding
1/8” E6013 at
125 Amps AC

21. 4- Shielding Gas
•A shielding gas is
formed when the
flux coating melts.
•This protects the
weld puddle from
the atmosphere
preventing
contamination
during the molten
state
The shielding gas protects the molten
puddle from the atmosphere while
stabilizing the arc
2
3
Shielding Gas
4

22. 5- Solidified Weld Metal
•As the molten weld puddle
solidifies, it forms a joint
or connection between two
pieces of base material
•When done properly on
steel, it results in a weld
stronger than the
surrounding base metal

23. 6- Slag
•Slag is a combination of the
flux coating and impurities
from the base metal that float
to the surface of the weld.
•Slag quickly solidifies to form
a solid coating
•The slag also slows the
cooling rate of the weld
•The slag can be chipped away
and cleaned with a wire brush
when hard
This welder chips the slag off of a
weld during the repair of railroad
tracks

24. Application Activity
The electrode
The arc
Weld puddle
Shielding gas
Solidified weld
metal
Slag
1
2
3
4
5
6
Let’s review the SMW process …
•1 =
•2 =
•3 =
•4 =
•5 =
•6 =

25. SMAW Equipment Set Up
1.Turn power supply on
2.Connect work clamp
3.Select electrode
a. Type
b. Diameter
4. Adjust output
a. Polarity
b. Amperage
6. Insert electrode into electrode
holder

26. SMAW Process Variables
•Settings on the machine
•Polarity : AC, DC+, DC-
•Amperage Output
•Operator Controlled
Variables
•Work Angle
•Travel Angle
•Arc Length
•Travel Speed
A straight AC machine will not
have a polarity switch like this
AC/DC machine

27. Striking an Arc
•To begin the SMAW Process, you must first strike an arc.
This can be done using one of the following techniques:
•Scratch start – scratch the electrode on the base metal like a
match
•Tap Start – tap the rod against the base metal

28. Work Angle
•The work angle is the
angle between the
electrode and the work
as depicted on the left
•Work angles can vary
depending on the
position the weld is
being made in
90°

29. Travel Angle
•Also commonly called
Lead Angle
•The travel (lead) angle is
the angle between the
electrode and the plane
perpendicular to the weld
axis
20-30°

30. Arc Length
•After striking the arc, maintain a 1/8” distance between
the electrode and the workpiece
•If the arc length becomes too short, the electrode will get
stuck to the workpiece or ‘short out’
•If the arc length becomes too long; spatter, undercut, and
porosity can occur
Arc Length = 1/8”

31. Travel Speed
•The travel speed is the
speed at which the
electrode moves along the
base material while welding
•Too fast of a travel speed
results in a ropey or convex
weld
•Too slow of a travel speed
results in a wide weld with
an excessive metal deposit
The travel speed impacts the
shape of the bead.
End of Weld

32. Restarting a Bead
•Here is the proper technique for restarting a weld:
1. Strike Arc Here
2. Move Electrode to
Crown of Crater
3. Resume Forward
Travel

33. Advantages of SMAW
•Low initial cost
•Portable
•Easy to use outdoors
•All position capabilities
•Easy to change between
many base materials
What safety precautions should be
taken by these welders?

34. Limitations of SMAW
•Lower consumable
efficiency
•Difficult to weld very
thin materials
•Frequent restarts
•Lower operating factor
•Higher operator skill
required for SMAW
than some other
processes
Building a barge in a large shipyard

36. WEAR
“LOSS OF MATERIAL” CAUSED IN AN
ENGINEERING SYSYEM.

37. TYPES OF WEAR
PRIMARY
•FRICTION
•ABRASION
•IMPACT
SECONDARY
•CAVITAION
•CORROSION
•HEAT
•EROSION

38. FRICTION
•FRICTIONAL WEAR IS CAUSED BY
MOVEMENT OF ONE METALLIC SURFACE
OVER THE OTHER CAUSING LOCALISED
MATERIAL LOSS.
•NO ABRASIVE MATERILA IS INVOLVED.
•EXAMPLES : SHAFT JOURNALS, BEARINGS

39. ABRASION
•LOSS OF MATERIAL FROM A
PART CAUSED BY THE ACTION
OF HARD FOREIGN MATERIAL
IN MOTION OR UNDER LOAD.
Ex :Raw Mill roller, Chutes etc

40. TYPES OF ABRASION
•GOUGING : Large coarse abrasives strike the surface and
remove large amount of material.
Ex: Chutes.
•HIGH STRESS : Wear caused by crushing of abrasive
material between metal parts. High stress abrasion.
Ex: Grinding rollers..
•LOW STRESS: Small abrasive parfticles move rapidly over
the part. Low stress abrasion.
Ex : I D Fans.

41. IMPACT
•WEAR DUE TO IMPACT IS THE RESULT OF
SUCCESSIVE SHOCK LOADS CAUSED BY AN
OBJECT STRIKING AGAINST AN OTHER
AND CAUSING LOCALISED COMPRESSION,
DEFORMATION, CRACKING, FLAKING OR
FATIGUE.
•Ex: Impactor arms, hammer crusher.

42. EROSION
•WEAR CAUSED BY FINE ABRASIVES
CARRIED IN A HIGH VELOCITY FLUID
STREAM
•Ex: Pumps, ID Fans

43. HEAT
DEGRADATION MODES
•WARPAGE/DISTORTION
•MATERIAL SOFTENING
•MATERIAL EMBRITTLEMENT
•OXIDATION/SCALING
•THERMAL CRACKING
•THERMAL SHOCK
•THERMAL FATIGUE
Ex: Cooler plates in Cement Kiln.

44. CORROSION
•RESULT OF CHEMICAL OR
ELECTROCHEMICAL ACTION OF
ENVIRONMENT ON THE BASE METAL.
Ex: Pumps, Valves, Screw Conveyors

45. ELECTRODE
-
WORK PIECE
+
+
-
PENETRATION
CONCENTRATION OF
HEAT MORE AT
ELECTRODE
SHALLOW PENETRATION
LESS DISTORTION
MORE HEAT GENERATED
AT WORK PIECE
DEEPER PENETRATION
CLEANSING ACTION ON
WORK PIECE
Selection of Polarity

47. IDENTIFICATION FOR CI
•SHAPE
•CHIP TEST
•SPARK TEST
•SOUND TEST
•TAB TEST – TESTING WELDABILITY OF JOB

48. BRASS Vs BRONZE
BRASS BRONZE
ALLOY ZINC &
COPPER
ALLOY TIN & COPPER
MALLEABLE HARD & BRITTLE
USED UNDER
STRESS
CORROSION
RESISTANT
GOLDEN COPPER

49. GMAW
(MIG/MAG Welding)

50. GMAW Components
•Let’s look a little closer at the GMAW process
Travel direction
Electrode
1
Arc
2
Weld Puddle
3
Shielding Gas4
5
Solidified Weld Metal
Generally, drag on thin sheet metal
and push on thicker materials

51. Thank You
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