Unive rsiti
Malaysia
PAHANG
Engineering • Tec hnology • Creat ivity
FACULTY OF MECHANICAL ENGINEERING
BMM3611
MANUFACTURING PROCESSES LABORATORY
WELDING
(ARC WELDING)
Laboratory Date
Submission Date
Lecturer
1)
JPIPJP 2)
3)
Learning objectives
By the end of semester, students should be able to:
1. Know safe practices in manufacturing processing area.
2. To perform welding equipment with standard operation procedure
3. To do inspection for detecting weld defect
Members ID Section Signature
I
I
77
Welding (Arc Welding)
1. Introduction
A welding process is a type of joining processes to facilitate assembly or fitting together. It is
a coalescence of metals producing permanent joining of two materials. It is a process that
happen because of appropriate control of pressure, temperature and metallurgical conditions.
There are two types of welding processes. The first type is fusion welding i.e. coalescence is achieved
by melting the two metals to be joined, some joint adding filler metal. Fusion welding processes
available includes resistance spot welding, arc welding, and oxy-fuel gas welding.
Solid state welding is other type of welding. In this process, heat and/or pressure are used to establish
joining without melting of the parent metal and usually no filler metal is used. Some examples of solid
·state processes include friction welding forge welding, and diffusion welding.
Weld quality is determined by presence of cracks, geometry accuracy, inclusion, residual stresses, and
oxide layers. The quality of welds can be distinguished between mechanical properties such as welded
strength and its appearance such as surface cracks.
Quality of the welding joint is established by conducting tests on its welded joint. Each different type
of welding processes has its own limitation, capabilities, and reliability as well as condition for special
facilities and operator ability.
Shielded metal arc welding (SMAW) as shown in Figure 1, is one of type of Arc Welding. It is also
known as Manual Metal Arc Welding (MMA W) using a consumable electrodes that has core wire inside
and covered with a flux. It has power source of drooping characteristic which is constant current at
variable voltage. When electrode is ignited arc will be produce between the tip of electrode and metal.
This arc melt the flux, electrode core wire and base metal. Electrode is deposited on molten metal as
weld.
Core
Wire
Power
Cup of coated
__. .r._,_,,,I. "
Source
fi ux _ "'..____~,
1 · Gas
~ Droplet
S~g I <
Weld Metal ;___ _ __.::,,._....
Figure 1: Schematic illustration of SMAW
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Manufacturing Processes Laboratory
Figure 2: Safety items
2. Objectives
1. To do buttering on the suite oflow carbon steel by SMAW
11. To weld low carbon steel using SMAW with T-filler joint configuration
111. To do weld inspection on welded low carbon steel by visual observation and NDT (dye
penetrant)
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Welding (Arc Welding)
3. Experimental Setup
3.1 Safety
All student are strictly follow the safety and regulation in welding lab. Student
must wear all necessary items prior to do any welding works as shown in Figure 2
3.1 Equipment/Apparatus
Sing!~ Metal Arc Welding (SMAW) with electrode E60 I 3, Dye penetrant spray include
cleanmg, penetrant and developer, and welding Gauge.
B
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M*NtC ,~•, ...
ff 11 2:.;;
f • •
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e
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t '.es
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Figure 3: SMAW welding machine Figure 4: Electrode for welding low
carbon steel
3.2 Material Preparation
Before starting make sure that you are using a helmet for SMAW welding as well as protective
clothing. Cut the low carbon steel plate with dimension of 100 mm x 50 mm x 9 mm. Prepare
8 pieces with same dimension.
3.3 Buttering
Take one piece of plate with above dimension. To strike the electric arc when starting a SMAW
operation, the electrode is brought into contact with the surface of the specimen, dragged like
lighting a match, and then pulled away slightly. If the arc lights and then goes out, that means
the electrode was pulled too far away from the base metal. If the electrode sticks to the metal,
give a twist and it should come free.Using SMAW do buttering on the surface of the plate as
shown in Fig. 5. Prior to buttering, do pretest in order to determine the exact parameter of
welding parameter. Surface of the specimen is heated by SMAW with one pass and straight
line.
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Manu fact uring Processes Laboratory
Figure 5: Buttering on metal surface
3.4 T-fillet weld
Set up two plates of low carbon steel as shown in Fig.6. Clean the workpiece and fix both
specimens with clamps. Insert the electrode into the insulated holder and then set amperage at
levels that are recommended by the electrode maker. Next, determine th~ ?Pti~ize ~re length.
!ack weld the two pieces of metal to fix them in place. This will reduces JOlllt d1stort10n, which
ts caused by the expansion and contraction of metal as it is heated and cooled. For a fillet weld,
hold the electrode at a 45 degree angle or less to the weld. Lean the electrode 10 degrees to 30
degrees in the direction of the weld. Move at a steady speed and it is advice to use a short arc.
For upright sections weld both sides. When necessary for strength add a second layer (remove
slag before adding another layer). Move the electrode using a circular motion. Use a chipping
hammer to remove any slag before doing a 2nd pass on the weld.
Figure 6: I-Fillet Configuration Welding 1 F
3.5 Welding Inspection
There are few steps involve for Liquid Penetrant I ·
. . nspection as stated such as follows:
1. Pre-cleamng:
The specimen surface is cleaned to remove an dirt . 01.
done through solvents, alkaline cleaning step y ' ~amt, !
or grease. Cleaning may be
s, vapor egreasmg, or media blasting.
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Welding (Arc Weldi.ng)
ii. Application of Penetrant:
The specimens' surface is then appl ied with liquid penetrant. Generally, 5 to 30 minutes
dwell time is required to allow the penetrant to soak into any fl aws or defects. However,
the dwell time is still dependi11g on type of penetrant used, material tested and dimension
of the flaw or defects sought.
Figure 7: After application of Penetrant
iii. Excess Penetrant Removal:
The excess penetrant is needed to be removed fro m the surface. If it is does not remove
prope'.ly, it may leave a background in the developer area that can mask the defects
especially once the developer is applied. Besides, this situation may also indicate a wrong
defects or flaws , which might lead to poor inspection results.
Figure 8: Excess penetrant removal
iv. Application of Developer:
The welding inspection steps is followed by applying a white developer to the specimen.
There are quite number of developers available in the market such as non-aqueous wet
developer, dry powder, water-suspendable, and water-soluble. Developer need to be
selected based on the compatibility of the penetrant as well as inspection conditions. For
example, the specimen must be dried before applying non-aqueous wet developer (NAWD)
or dry powder, whereas for soluble and suspendable developers are applied onto wet
specimen. In addition, developer should form a semi-transparent coating on the surface.
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Manufacturing Processes Laboratory
\Vhen developer is applied onto the surf;ace Of ti,e specimen
. '.it will form a visible
f d c indicati 0 n
• d
which commonl y known as blee -out. oc L ation , onentation or type o e,ects can be
detected through the area that have bleed-out.
Figure 9: After application of developer
v. Inspection :
After that, inspection can be carried out through ultraviolet radiation using adequate
intensity (ie: 1,000 micro-watts per centimeter squared), with low ambient light levels for
fluorescent penetrant examinations. Duration for the inspection should be conducted after
IO to 30-minutes development time.
vi. Post Cleaning:
Finally, the specimen is cleaned after the inspection and defects are recorded.
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~l/3,[fi
~ : ~enetrori 1 , ~andestructi~
esting Moterlf
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Figure 10: Dye penetrant spray
)
84
\\ 'elding (,\ re \\'elding)
4. Questions
Sketch and identify all the defects on welded part.
I I. Justify whether the defects is non-compliance or accepted based on visual and dye
penetrant inspection.
I 11 . Suggest solution on how to prevent the occurence of the defects.
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Welding (A rc Welding)
Process Sheet
WELDING
(Arc Welding)
-
Work piece
Material type/grade :_ _ _ _ _ _ __
SMAW machine description
Brand
Model
Size(L x W x T (mm):_ __ __ _ _ _
Capacity:
- - - - -- - - -- ---
-
Electrode
Type
~elding (output quality & im provement)
Type of Inspection Sketch of defects Countermeasure
defects (V isual/NOT Test)
Process setting (for good quality welding part at lF position)
Current
Angle of electrode positioning
Estimated welding speed
87
.........
We lding (A rc Welding)
APPENDIX
Lab report format
Lab repm1 should have the following details :
I. Use a cover page similar to the labsheet format.
2. Contents for the report are;
• Introduction
• Raw materials
• Process tools
• Machines and their applications
• Case study - Process setting / Design consideration/ Product defect &
countermeasure
• Conclusion/Lesson learned
• References
3. Discuss the strengths and weaknesses of this laboratory. Did the laboratory help you to
learn the material better? Explain why or why not.
4. The report should be done in MS Word and an equation editor should be used for all
equations.
5. Equations should be numbered and plots should be numbered and referenced with a
descriptive caption.
6. Each group must submit a hard copy of the report.
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