GROUP 5
IMAM KASDUGI ( 183310005 )
DANIEL K. NAINGGOLAN ( 183310150 )
AGUSNUR FUADI ( 183310036 )
WIRAWAN NURKHOLIS ( 183310173 )
RIKI SUTRIYANTO ( 183310101 )
Welding is a common process for
joining metals using a large variety of applications. Welding occurs in several
locations, from outdoors settings on rural farms and construction sites to
inside locations, such as factories and job shops. Welding processes are fairly
simple to understand, and basic techniques can be learned quickly.Welding is
the joining of metals at a molecular level. A weld is a homogeneous bond
between two or more pieces of metal, where the strength of the welded
joint exceeds the strength of the base pieces of metal.
At the simplest level, welding involves the use of four components: the metals, a heat source, filler metal, and some kind of shield from the air. The metals are heated to their melting point while being shielded from the air, and then a filler metal is added to the heated area to produce a single piece of metal. It can be performed with or without filler metal and with or without pressure.
There are several types of welding that are used today. Gas Metal Arc Welding (GMAW) or MIG, Gas Tungsten Arc Welding (GTAW) or TIG, Flux Core Arc Welding, and Stick Welding are the most common found types in industrial environments.
At the simplest level, welding involves the use of four components: the metals, a heat source, filler metal, and some kind of shield from the air. The metals are heated to their melting point while being shielded from the air, and then a filler metal is added to the heated area to produce a single piece of metal. It can be performed with or without filler metal and with or without pressure.
There are several types of welding that are used today. Gas Metal Arc Welding (GMAW) or MIG, Gas Tungsten Arc Welding (GTAW) or TIG, Flux Core Arc Welding, and Stick Welding are the most common found types in industrial environments.
Common
Terms
There is a
large vocabulary of specific welding terms. Knowing these terms is essential to
learning about welding as well as understanding how to weld.
1. Arc Burn
Arc burn is a metallurgical notch
caused by ground clamps or striking an arc on the base metal at any point other
than the weld groove or immediate area that will be covered with the weld cap.
2. Base Metal
The base metal is the metal that is
to be welded or cut. It is commonly referred to as the workpiece.
3. Butt Weld
A butt weld is a joint between two
workpieces that are aligned on the same plane.
4. Cover Pass
The cover pass finishes the welded
joint. It is higher than the adjacent surface and overlaps the groove.
5. Filler Pass
The filler pass follows the hot pass
and fills the weld groove flush, or almost flush, with the surface of the
workpieces.
6. Fillet Weld
A fillet weld is the joining of two
workpieces with triangular cross-sections at approximately 90 degrees.
7. Heat-Affected Zone
The heat-affected zone is the area of
metal near the weld metal that was not melted during welding, but did
experience changes in its mechanical properties and/or microstructure due to
the heat applied.
8. Hot Pass
The hot pass is the pass immediately
following the stringer pass.
9. Joint
The hot pass is the pass immediately
following the stringer pass.
10. Plug Weld
Plug welding is filling a hole or gap
in one piece with weld or filling a hole and attaching the piece with the hole
to the surface of another base piece.
11. Polarity
Polarity is the manner in which the
electrode holder and workpiece connect to the electrical supply. This can be
either direct current electrode negative, or DCEN, meaning straight polarity or
direct current electrode positive, or DCEP, meaning reverse polarity.
12. Spot Weld
Spot welding is the process in which
the weld pieces are pressed together with pressure, then a current is passed
through them in a small spot and the two pieces are melted together at that
location. Spot welding can be performed on metals from 0.5 to 3 mm.
13. Stringer or Root Bead
The stringer pass, or root bead, is
the first pass in the weld. It is typically made without any weaving motion.
14. Weld Groove
Weld groove refers to a V- or U-shaped
groove created by the beveling of the workpiece edges that will be joined.
15. Weld Metal
The weld metal is the portion of the
base metal that is melted during the welding process.
16. Weld Pass
A weld pass is a single progression
of welding along the joint. After a complete pass, it is referred to as a weld
bead.
17. Welding Electrode
In arc welding, the electrode is used
to pass current through the workpiece to fuse the two pieces together.
Types of
Weld Joints
There are
five common types of weld joints used in all types of welding: corner joints,
edge joints, lap joints, tee joints, and butt joints.
Corner Joint – When two pieces are
perpendicular to each other and one piece’s edge meets the end of the other
piece’s surface, it is referred to as a corner joint. Common corner joints are
edge to edge, flush corner, and half overlap, each with their own benefits.
Edge Joint – An edge joint is when
two edges of weld pieces are adjacent and in parallel planes with each other.
The weld does not penetrate completely through the joint thickness so it should
not be used in high stress or pressure situations.
Lap Joint – A lap joint in welding
occurs when a bead is made on the surface of one workpiece and the edge of the
other piece. It should be performed with no gap between the two pieces.
Tee Joint – The edge of one workpiece
meeting the surface of the other workpiece with material on both sides of the
edge is called a tee joint.
Butt Joints – When two workpieces are
aligned on the same plane and joined by a weld along their edges, it is called
a butt joint. They are used where high strength is required because they are
reliable and can withstand stress better than any other type of weld.
Welding Symbols
Welding can be performed in thousands
of combinations regarding position, welding type, welding dimensions, and many
other varying components of welding.
Due to its diverse nature and the
precise needs of the industrial world, a complex collection of symbols has been
created to dictate exact weld details. This allows designers to precisely
indicate the type, style, and other details of a weld using a symbol on a print
for the piece being manufactured or otherwise altered.
The joint is the basis of reference
for welding symbols. It has an arrow pointing to it and connects to the
reference line. Including the arrow, there are eight elements of a welding
symbol, explained below:
Reference Line – The reference line
is used to designate the type of weld, weld location, size of the weld, extent
of the weld, contour of the weld, and many other pieces of vital information.
Arrow and Other Side – All welded
joint symbols have an arrow and other side, which is opposite the arrow side
and used to indicate the location of the weld with respect to the joint.
Weld Symbols – Weld symbols, as
opposed to welding symbols, indicate the desired type of weld.
Dimensions and Other Data – This
information provides the details regarding the size of the weld and any other
data needed to find the proper weld size.
Supplementary Symbols – Supplementary
symbols give information on whether the weld is a “weld all around” or a “field
weld.” It also indicates the desired contour of the weld.
Finish Symbols – The finish symbol
dictates how the weld should be shaped or ground after the completion of the
weld.
Tail – The tail of the symbol is used
to designate the process by which the metals will be welded. It is also used to
indicate the welding specifications, process, and other supplementary information
regarding the weld.
REFERENCE
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