1.0 TITLE
Shield metal arc welding (SMAW).
2.0 OBJECTIVE
1. To
demonstrate some mostly used SMAW.
2. To
build a pad techniques at on mild steel plate.
3. To
specify the suitable welding process and techniques required on SMAW
4. To
observe and discuss the influence of SMAW parameters.
5. To
observe and discuss the influence of SMAW and filler wire.
6. To
determine differences between the welding process, the weld ability of
materials and be aware of potential problem associated with each of them.
3.0 INTRODUCTION
Shielded
metal arc welding (SMAW), also known as manual metal arc welding (MMA or MMAW), flux shielded arc welding or informally as stick welding, is a manual arc welding process that uses a consumable electrode coated in fluxto
lay the weld. An electric current, in the form of either alternating current or direct
current from a welding power supply, is used to form an electric arc between the electrode and the metals to be joined.
As the weld is laid, the flux coating of the electrode disintegrates, giving
off vapors that serve as a shielding gas and providing a layer of slag,
both of which protect the weld area from atmospheric contamination.
Because of the versatility of the
process and the simplicity of its equipment and operation, shielded metal arc
welding is one of the world's most popular welding processes. It dominates
other welding processes in the maintenance and repair industry, and though flux-cored arc welding is growing in popularity, SMAW
continues to be used extensively in the construction of steel structures and in
industrial fabrication. The process is used primarily to weld iron and steels (including stainless
steel) but aluminium, nickel and copper alloys can also be welded with this method.
Type
of plate : Mild Steel
Distance between
specimen and electrode : 2 mm
Electrode
diameter: 2.6 mm
Traveler
speed: 2 x 2.6 mm (electrode diameter)
= 5.2 s
Length of specimen: 100 mm
Thickness specimen: 5 mm
Width specimen: 50 mm
4.0 APPARATUS
APPARATUS
|
NAME
|
 |
Face Shield
|
 |
Brush
|
 |
Wire Brush
|
 |
Hand Glove Leather
|
 |
Workpiece
|
 |
Player
|
 |
Leather Apron
|
 |
Chipping Hammer
|
 |
Electrode
|
 |
Welding Torch
|
4.1 INDUSTRIAL
APPARATUS
INDUSTRIAL
APPARATUS
|
DESCRIPTION
|
 |
STICKWELD
140STL
|
 |
Kemppi
Master MLS 2500 (3-Ph 415V) IGBT
|
5.0 EXPERIMENTAL PROCEDURE
1. The
workpiece is cleaned before welding.
- The power cable connection is checked before start the experiment.
The connection torch cable to proper welding terminal on welding machine
and work cable end is connected to proper terminal on welding machine.
3. Work Clamp is placed as close to the weld as
possible.
4. Then, an electrode is inserted in the
electrode holder. A 2.6 mm diameter electrode was required to weld the specimen
of 100mm x 50 mm x 5 mm.
5.
The
welding machine was start by pressing on button.
- Start the welding with the end of electrode was touched to proper
place on weld joint with distance 2 mm to the specimen, usually just ahead
of weld bead, with current shut off; lower helmet and the torch was
holding with two hand.
7. The
electrode holder position is in between 60° to 80° angle.
8. Lastly,
use a chipping hammer and wire brush to remove slag. Remove slag and check weld
bead before making another weld pass.
6.0
RESULT AND DATA ANALYSIS
The specimen that have been
welding by process (SMAW).
Specimen have been cut by
using grinding machine(hilmi betulkan nama mesin ni)
Tensile strength test
7.0 DISCUSSION OF RESULT
From
this experiment, we have study and demonstrate the process of Shielded Metal
Arc Welding (SMAW). We also have exposed on how to build a pad techniques on at
mild steel plates. Then the assistance lecturer teach us with specify the
suitable welding process and techniques required on SMAW. Before we start the
process welding, we must wear the proper attire such as safety boot, jacket,
leather apron, leather glove, and also face shield in state of safety
precaution. After we have finished welding the specimen, we were continued to
perform the tensile strength specimen by using Universal Testing Machine. As in
all manufacturing process, the quality of a welded joint is established by
testing. We used transverse tensile test to perform the specimens remove actual
welded joints and from the weld- metal area. The stress strain curves are
obtained by this test. From the graph above, we have recorded all the reading
measurement required. The maximum force needed to break the specimen is 28.7797
kN. The energy produced is 57.5643 J and the maximum tensile strength to break
the specimen is 196.295 MPa. In this process, we can see that our welding
quality is so poor as the time taken to make the specimen break is too
short.
Based on the result obtained, there
are several factors that affected the welding beads size and shape. For this
experiment, the main three factors that contribute to the results of the
welding beads are the angle, the travel speed and the arc length. For the
angle, the tip of the welding gun is supposedly to be 60° to 80° to the
specimen and the drag technique is used for this practice. If the drag
technique used is correct, it will result to deeper penetration and a narrow
bead. Besides that, the travel speed also plays an important role to gain good
welding beads. When the travel speeds too slows, the bead will become wider and
build up higher. While if it having too fast welding speed, the welding bead
will become thin with elongated semicircles and the penetration quality is also
poor. The third factor is the arc length. If the arc length is too long, the
welding will become uneven and some splatter will show. Besides that, the arc
and sound will be inconsistently when the welding process been conducted.
Other than that, the penetration
into the base metal is also poor. Next, if the arc length is too short, the
weld also shows poor penetration into the base metal. The welding bead may rise
above the base metal. During the welding process, the electrode may attach to
the base metal.
There are some defect
occur on our specimen that have been welded. One of them is porosity. There is
small cavity or holes resulting from gas pockets in weld metal. The possible
cause of the porosity is the workpiece is dirty before welding process is
carried out. We must remove all grease,
oil, moisture, rust, paint, coatings, slag, and dirt from work surface before
welding. Other than that, we can see the incomplete fusion at the end of our
joining specimen. The failure of welded metal to fuse completely with base
metal. The possible cause occur is because improper
welding techniques . we must to place
the stringer bead in proper locations at joint during welding. Other than
that,we must adjust work angle or widen groove to access bottom during welding.
The momentarily hold arc on groove side walls when using weaving technique. We
also must keep arc on leading edge of weld puddle.
8.0 CONCLUSION
From this experiment, we have
demonstrated mostly on how to use SMAW. We also have been performing with build
a pad technique at on the mild steel. The defect and the quality of the welding
bead is due to several factors which are the change of voltage, current,
welding speed and welding angle. The skill of each student for getting a good
welding result can be enhancing through everyday practice. So, the objective of
this experiment is occur as we have achieved this purpose of doing Shielded
Metal Arc Welding (SMAW).
9.0 RECOMMENDATION
·
Proper cleaning and the
prevention of contaminants from entering the weld zone
·
Improved the welding
technique such as preheated the weld area.
·
The angle from the tip of
the welding gun to the welding base should be around 60° to 80°.
·
Get the rights welding
speed to obtain good welding bead.
·
Set the current to the proper amount.
·
Adjust the position of
hand, get the right grip of the welding torch and sit down if necessary.
·
Adjust the arc length
while conducting the welding.
10.0 REFERENCES
1. Kalpakjian.Schmid(2010)
“Electrodes of Arc Welding”, 6th Edition,
Prentice Hall.
2. G.M.Evans.,
N.Bailey(1997) “Metallurgy of Basic Weld Metal”, Woodhead Publishing.
3. Weld
Integrity and Performance (1997), ASM International
5. J.E.Linnert(1994)
“Welding Metallurgy”, 4th Edition., vol 1, American Welding Society.
6. Tool
and Manufacturing Engineering Handbook, (1986)Vol 4:Quality Control and
Assembly, Society of Manufacturing Enginees.
7. W.A.Bowditch.,K.E.Bowditch(1997),
“Welding Technology Fundamental”, Goodheart-Willcox.
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