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Sohar University
Faculty of Engineering
Mechanical & Mechatronic Engineering Program
Laboratory/Workshop Manual
MANUFACTURING PROCESSES
MECH2118
Level 2
Course Coordinator: Dr. Ghassan Al-Kindi
E-mail: [email protected]
Tel: 26720101 Ext. 125
Teaching Assistant: Mrs. Sarraa Naser
E-mail: [email protected]
Tel: 26720101 EXT 186
Year: 2011-2012
Laboratory
Manual
MECH2118
FACULTY OF ENGINEERING - SOHAR UNIVERSITY
Manufacturing Processes – MECH2118 Page 2
Sl
No Contents
Page
Number
1 General instructions 3
2 Safety precautions 4
3 Instructions for lab experiments 6
4 Guidelines for writing lab report 7
5 Experiment# 1 Workshop activities 12
6 Experiment# 2 Heat Treatment of Steel 15
Laboratory
Manual
MECH2118
FACULTY OF ENGINEERING - SOHAR UNIVERSITY
Manufacturing Processes – MECH2118 Page 3
GENERAL INSTRUCTIONS
The exercises in this manual are designed to give the students an introduction to
laboratory and workshop procedures for performing experiments in manufacturing
processes. The purpose is to provide students with a deeper understanding of theoretical
principles by observing phenomena, by measuring physical characteristics and by
comparing measured versus calculated results. This “hands-on” experience is essential to
an engineering technology student.
In addition to following the procedures given for a lab, each group of students will be
required to submit a lab report documenting the experiment and the results. Documenting
laboratory and workshop results in a clear and concise manner is just as important as
conducting an experiment properly. The laboratory discipline and the reporting principles
presented herein will extend directly to any engineering test lab in industry.
A goal of the Faculty of Engineering is training students to work well in teams in the
pursuit of a common objective such as a lab experiment. Thus students have to learn to
organize themselves into team groups, and to allocate responsibilities among themselves.
Laboratory
Manual
MECH2118
FACULTY OF ENGINEERING - SOHAR UNIVERSITY
Manufacturing Processes – MECH2118 Page 4
SAFETY PRECAUTIONS
It is important that each student should read the safety precautions and procedure
followed before coming to the lab.
I. All equipment and instrumentation shall be handled carefully to avoid damage
during experimental operations. At no time shall any equipment be relocated from
its position in the Lab. Any anomalies encountered with equipment during an
experiment shall be brought to the instructor‟s attention immediately.
II. No repairs or attempted repairs shall be performed on any lab equipment;
including instrumentation, fixtures, and especially pressurized systems or
components Only the equipment specified in the Equipment List for each
procedure shall be used. When given in test procedures, the sequence of steps
specified in each procedure is mandatory. No steps shall be performed out of
sequence.
III. Operational areas shall be maintained clean and orderly, free of trash or
combustible materials.
IV. Food and beverage are not permitted in the Lab.
V. Smoking is prohibited.
VI. Equipment taken from storage racks or cabinets shall be returned to designated
storage locations. The area where the lab was conducted shall be cleaned, and
returned to the condition found when entering the lab to begin the procedure.
VII. Should an unsafe condition develop during the experiment, report to the
instructor to prevent injury to team members or damage to lab equipment.
VIII. Upon observing a hazardous or potentially hazardous condition that could occur if
uninterrupted operation is allowed, ANYONE participating in or observing the
experiment can issue a “STOP” command.
IX. Keep fingers and loose items of clothing away from all moving parts
X. Liquids like tea, coffee etc are need to be kept well clear of the equipment
XI. No joking, playing or horsing around in the laboratory
Laboratory
Manual
MECH2118
FACULTY OF ENGINEERING - SOHAR UNIVERSITY
Manufacturing Processes – MECH2118 Page 5
XII. For any queries contact the concerned staff member.
XIII. If any emergency arises call on the following numbers
EMERGENCY TELEPHONE NUMBERS:
Emergency
Help:
Fire
Department:
Campus
Security:
STUDENT NAME: ____________________________
STUDENT ID NUMBER: _______________________
SEMESTER AND YEAR: ____________________
Laboratory
Manual
MECH2118
FACULTY OF ENGINEERING - SOHAR UNIVERSITY
Manufacturing Processes – MECH2118 Page 6
INSTRUCTION FOR LAB AND WORKSHOP EXPERIMENTS
1- A team consisting of 4 to 6 students will perform each experiment.
2- Lab reports are due at stated and advertised dates, normally within two weeks from
the activity date.
3- All students are expected to read the experiment thoroughly before starting the
lab/workshop work. Questions about procedures or precautions should be resolved
by asking your laboratory instructor before the experiment. Each group must
prepare their own report.
4- Lab groups will consist of groups. Grades will be based on participation, accuracy
of data recording and reduction, completion of tasks for lab procedures and the
report itself.
5- The marks allotted for Lab work is out of 10 and Laboratory reports are graded on
a scale of 0 to 10. Please refer to your course profile to know the final mark weight
allocated to the Lab/workshop activities.
6- When students have finished the experiment, they must clean their
apparatus/equipment and leave their bench clean and tidy.
7- Your reports are due for submission by the stated date. If not submitted by
the required date they will be rejected.
Laboratory
Manual
MECH2118
FACULTY OF ENGINEERING - SOHAR UNIVERSITY
Manufacturing Processes – MECH2118 Page 7
GUIDELINES FOR WRITING LABORATORY REPORT
A lab/workshop report is the perfect place to start practicing technical writing. Each
student will be responsible for preparing a report after completing each laboratory
exercise. The required content and format of the report are given in the following
sections.
Cover page
Introduction
Objectives
Theory
Equipments used
Procedure
Observation and calculations
Sample calculation
Results ,analyses and discussion
Conclusions
References
Cover Page
The report shall have a cover page with the following information provided:
Experiment Number.
Title of experiment.
Laboratory Manual
Course title
Date of submission
Student‟s name
Student ID
A standard cover page is shown in the following page:
Laboratory
Manual
MECH2118
FACULTY OF ENGINEERING - SOHAR UNIVERSITY
Manufacturing Processes – MECH2118 Page 8
Sohar University
Faculty of Engineering
Mechanical & Mechatronic Engineering Program
Laboratory/Workshop Report
MANUFACTURING PROCESSES
MECH2118
Lab/Workshop Experiment # 1,2,3 etc
Title of the experiment
Student’s Name 1:…………………………………………..…….. SID…………………..
Student’s Name 2:…………………………………………..…….. SID…………………..
Student’s Name 3:…………………………………………..…….. SID…………………..
Student’s Name 4:…………………………………………..…….. SID…………………..
Student’s Name 5:…………………………………………..…….. SID…………………..
Student’s Name 6:…………………………………………..…….. SID…………………..
Group:…………………………………………..……..
Date:…………………………………………..………..
Laboratory
Manual
MECH2118
FACULTY OF ENGINEERING - SOHAR UNIVERSITY
Manufacturing Processes – MECH2118 Page 9
Objectives
Objective is the aim of the experiment to be done in the laboratory/workshop. The
objective or objectives of the experiment should be stated at the beginning of the report.
One or two sentences are usually sufficient to summarize the purpose of the experiment.
Theory
For an engineering lab class this will probably involve one or two explanations, and a
statement of key mathematical expressions. Unless you have been asked to do so, there is
no point in writing out standard derivation from textbooks.
Equipments Used
This section should include a brief description of the test/work apparatus and
instrumentation that was used. Where appropriate, a schematic diagram should be
included that identifies the major components of the test system.
Procedure
A description of the procedure that was used to obtain the test results shall be provided.
Summarize the detailed steps that were used; do not repeat the detailed steps in this
section. There is a well established tradition of using the passive voice when describing
experimental procedure
Results and analysis
Experimental results should be presented in a clear and concise manner. The way you
describe the outcome of your experimental results and theoretical relationship is
important. Test results obtained from the experiment shall be
• Tabular
• Graphs/Engineering drawing
• Digital photographs
• A combination of the above.
Laboratory
Manual
MECH2118
FACULTY OF ENGINEERING - SOHAR UNIVERSITY
Manufacturing Processes – MECH2118 Page 10
Conclusions
This section summarizes your conclusion regarding the results. If the results differ from
those expected, provide an explanation based on an analysis of the data. Examine any
assumptions that were used that could be adversely affecting the results. Consider
experimental error as a cause of the differences. The conclusions should be based on (1)
the experimental results, and (2) supporting technical rationale and analysis.
References
Give references used like books, web site and other documents etc.
a. Books
Author, A. A., Author, B. B., and Author, C. C. (year). Title of book: Subtitle. (Edition [if not
first]). Place of publication: Publisher.
Example
Holtz, R. D. and Kovacs, W. D. (1981). An Introduction to Geotechnical Engineering, 1st
Edition, Prentice Hall.
b. Thesis
Author, I.N. (YEAR). Title of Thesis. Unpublished PhD Thesis. University.
Example
Jones, H. C., Cross, W & Smith, K. M. (1999). Get your dissertation done. Baltimore: University
of Baltimore Press.
c. Journal or Conference Papers
Author(s) Year, „Article Title‟, Journal Name, vol. Volume, no. Issue, pp. Pages.
Example:
Seaman, C.B., Mendonca, M.G. & Kim, Y.M. 2003, „User evaluation and evolution of a
prototype management tool‟, IEEE Transactions on Software Engineering, vol. 29, no. 9, pp.
838-51.
Laboratory
Manual
MECH2118
FACULTY OF ENGINEERING - SOHAR UNIVERSITY
Manufacturing Processes – MECH2118 Page 11
d. Websites
Author. (Date published if available; n.d.-no date- if not). Title of article. Title of web site .
Retrieved date. from <URL>.
Example
United Nations Environment Programme (2001). Environmental Aspects of Phosphate and
Potash Mining. Retrieved January 2008. From
www.mineralresourcesforum.org/docs/pdfs/phosphate_potash_mining.pdf
Laboratory
Manual
MECH2118
FACULTY OF ENGINEERING - SOHAR UNIVERSITY
Manufacturing Processes – MECH2118 Page 12
Experiment # 1
Workshop Activity – Manufacturing of Door Sliding Lock Assembly
INTRODUCTION:-
Mechanical workshops are currently considered as the heart of all industries. The most
important tasks of mechanical workshop are the development and construction of
equipment and machinery, tools, jigs and fixtures, and all mechanical assemblies.
Different manufacturing operations can be conducted in each mechanical workshop;
however, the types and size of available machinery, tools, raw materials, handling
equipment, and the experience of the technical operators all dictate the capability of that
workshop to manufacture/assemble a certain part or equipment.
Mechanical workshops usually contain general-purpose conventional machines to allow
manufacturing flexibility in producing variety of parts and assemblies. However the
successful operation of such conventional machines heavily depends on the skill and
experience of these machine operators.
In this activity students will learn how to use workshop machinery and practice several
manufacturing tasks to improve their understanding on how things are made as well as to
broaden their knowledge on workshop technology.
OBJECTIVES:-
To practically apply metal cutting including turning and drilling, metal forming,
welding, and fitter works towards the manufacturing of a door sliding-lock
assembly.
To experience the practical workshop atmosphere, understand the safety
procedure in workshops, be familiar with workshop safety gears, and use the
different workshop tools properly.
Laboratory
Manual
MECH2118
FACULTY OF ENGINEERING - SOHAR UNIVERSITY
Manufacturing Processes – MECH2118 Page 13
APPARATUS:-
Different machines and tools will be used during this session. The main of these are:
1. Reciprocating sawing machine.
2. Conventional turning machine (Lathe machine).
3. Vertical drilling machine.
4. Arc welding equipment.
5. Hydraulic press equipped with metal forming die.
6. Different hand-held files.
7. Calipers, Scales, and Vernier.
Set of proper tools suitable for each operation will also be provided.
PROCEDURE:-
A number of steps are required to be followed. The student will be given a certain
manufactured assembly of the door lock, hence their task is to do a reverse engineering
by attempting to manufacture similar assembly.
After a quick tour inside the workshop, the student will be briefed on how to handle their
task. The achievement of the student tasks will include a number of practical steps. These
steps may include the following stages:
Stage 1 Dimensional measurement of the model and identifying the types and shapes
of the required raw materials.
Stage 2 Sawing of the base plate (6mm thickness)
Stage 3 Fitter works (sharp edge chamfering)
Stage 4 Cutting of the cylindrical shaft by sawing
Stage 5 Turning operation of the shaft on a conventional lathe machine (Metal
Cutting)
Stage 6 Metal-forming on a hydraulic press
Stage 7 Drilling operations on a vertical drill
Stage 8 Assembly of the parts
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Manual
MECH2118
FACULTY OF ENGINEERING - SOHAR UNIVERSITY
Manufacturing Processes – MECH2118 Page 14
Stage 9 Welding (Arc welding)
Stage 10 Finishing operations (Chamfering, Cleaning, and Inspection)
OBSERVATION AND CALCULATIONS:-
It is expected that students observe and identify the types of tools used in each operation
as well as recognize the different parameters (e.g cutting speed, depth of cut, federate,
etc.) used in each manufacturing operation. Students are expected to apply engineering
calculations that they learned during this course and present these calculations in their
report. Calculations may include but not limited to force, pressure, and power utilized in
metal forming, machining time, cutting forces, and power requirement during machining.
RESULTS AND ANALYSIS:-
Students are required to comprehensively measure all manufactured parts and assembly
dimensions. They will use these to produce proper engineering drawing of each part as
well as the final assembly. The students are also required to discuss all process stages that
they followed to manufacture the required assembly and provide detail information about
each process stage.
Laboratory
Manual
MECH2118
FACULTY OF ENGINEERING - SOHAR UNIVERSITY
Manufacturing Processes – MECH2118 Page 15
Experiment # 2
Heat Treatment of Steel
INTRODUCTION: -
Heat treatment operations are performed on metal work parts at various times during their
manufacturing sequence in order to achieve one of the following aims:
To soften a metal for forming prior to shaping.
To relieve strain hardening that occurs during forming.
To strengthen and harden the metal near the end of the manufacturing
sequence.
The principle heat treatment types of steel include the following:
Annealing.
Hardening (Martensite formation).
Tempering of Martensite.
Surface hardening.
OBJECTIVES: -
The purposes of this experiment are to:
Investigate the processes of heat treating of steel
Study hardness testing and its limits
Examine microstructures of steel in relation to hardness
Laboratory
Manual
MECH2118
FACULTY OF ENGINEERING - SOHAR UNIVERSITY
Manufacturing Processes – MECH2118 Page 16
APPARATUS:-
Electric furnace (up to 1300oC).
Rockwell/Brinell Hardness measurement machine.
THEORY:-
To understand heat treatment of steels requires an ability to understand the Fe-C phase
diagram shown in the provided Figure. Steel with a 0.77 wt% C is said to be a eutectoid
steel. Steel with carbon content less than 0.77 wt% C is hypo-eutectoid and greater than
0.77 wt% C is hyper-eutectoid. The region marked γ (austenite) is face-centered-cubic
(FCC) and α (ferrite) is body-centered-cubic (BCC).
There are also regions that have two phases. If one cools a hypo-eutectoid steel from a
point in the austenite region, reaching the upper transformation line, ferrite will form
from the austenite. This ferrite is called pro-eutectoid ferrite. When the lower
transformation line is reached, a mixture of ferrite and iron carbide (cementite) forms
from the remaining austenite. The microstructure of hypo-eutectoid steel upon cooling
would contain pro-eutectoid ferrite plus pearlite (α+ Fe3C).
The size, type and distribution of phases present can be altered by not waiting for
thermodynamic equilibrium. Steels are often cooled so rapidly that meta-stable phases
appear. One such phase is martensite, which is a body-centered tetragonal (BCT) phase
and forms only by very rapid cooling.
Much of the information on non-equilibrium distribution, size and type of phases has
come from experiments. The results are presented in a time-temperature-transformation
(TTT) diagram shown in the provided Figure. As a sample is cooled, the temperature will
decrease as shown in the Figure. At point Ps, pearlite (a mixture of ferrite and cementite)
will start to form from austenite. At the time and temperature associated with point Pf, the
austenite will have completely transformed to pearlite. There are many possible paths
through the pearlite regions. Slower cooling will cause coarse pearlite to form, while fast
cooling will cause fine pearlite (Bainite) to form.
Laboratory
Manual
MECH2118
FACULTY OF ENGINEERING - SOHAR UNIVERSITY
Manufacturing Processes – MECH2118 Page 17
Cooling can produce other phases. If a specimen were cooled at a high rate of cooling,
martensite, instead of pearlite, would begin to form at Ms temperature, and the austanite
would be completely transformed to martensite at temperature Ms by avoiding the
enterance in the nose of the pearlite zone boundary. Martensite causes increased hardness
in steels. Unfortunately, hardness in steels also produces brittleness. The brittleness is
usually associated with low impact energy and low toughness. To restore some of the
toughness and impact properties it is frequently necessary to "temper" the steels. This is
accomplished by heating the steel to a temperature between 500ºF (260ºC) and 1000ºF
(540ºC).
Tempering removes some of the internal stresses and introduces recovery processes in the
steel without a large decrease in hardness or strength.
To obtain the desired mechanical properties it is necessary to cool steel from the proper
temperature at the proper rates and temper them at the proper temperature and time.
Heat Treatment of Steels
Common steels, which are really solid solutions of carbon in iron, are body-centered-
cubic. However, the carbon has a low solubility in bcc iron and precipitates as iron
carbide when steel is cooled from 1600oF (870
oC). The processes of precipitation can be
altered by adjusting the cooling rate. This changes the distribution and size of the carbide
which forms a laminar structure called pearlite during slow cooling processes.
If steel is quenched into water or oil from 1600oF (870
oC) a metastable phase called
martensite forms, which is body-centered-tetragonal. This phase sets up large internal
stresses and prevents carbide from forming. The internal stresses produce a high hardness
and unfortunately, low toughness. After cooling, to restore toughness, steels are tempered
by reheating them to a lower temperature around 800oF (426
oC) and cooling. The
tempering relieves the internal stresses and also allows some iron carbide to form. It also
restores ductility.
Laboratory
Manual
MECH2118
FACULTY OF ENGINEERING - SOHAR UNIVERSITY
Manufacturing Processes – MECH2118 Page 18
Laboratory
Manual
MECH2118
FACULTY OF ENGINEERING - SOHAR UNIVERSITY
Manufacturing Processes – MECH2118 Page 19
PROCEDURE:-
You will be provided with 6 specimens of SAE1045 steel (Medium carbon plain steel)
for your study. Measure the hardness of all specimens using the HRA scale.
1. Heat the six specimens in one furnace at 1600oF (870
oC) for 1/2 hour.
2. Remove one specimen from the furnace and cool it in air on a brick.
3. Remove two specimens and quickly drop them into water; the transfer should take
less than one second. A little rehearsal could help. Be careful not to touch the
specimens before they are cooled in water.
4. Remove another two specimens and quickly drop them into oil; the transfer
should take less than one second. A little rehearsal could help. Be careful not to
touch the specimens before they are cooled in oil.
Laboratory
Manual
MECH2118
FACULTY OF ENGINEERING - SOHAR UNIVERSITY
Manufacturing Processes – MECH2118 Page 20
5. Turn off the furnace with the one left specimen inside. Allow the sample to
remain in the furnace for one hour. The air-cooled and furnace-cooled specimens
can be cooled in water after one hour. (Why? Answer this in your report).
6. Measure Rockwell hardness of the quenched specimens before the next step.
7. Temper 1 each of the quenched specimens (one specimen quenched in water and
one specimen quenched in oil) 30 minutes at 800oF (430
oC). After tempering, the
specimens can be cooled in water.
8. Measure hardness of all 6 samples using the Brinell and Rockwell A or C scales.
OBSERVATIONS AND CALCULATIONS:-
1. While hardness measurement, if more than one impression is made per sample,
average the Brinell diameters for each specimen.
2. Compute the Brinell hardness numbers and compare with the numbers read from
a conversion chart for Rockwell A or C to Brinell.
3. Graph BHN (x-axis) versus Rockwell Hardness numbers (y-axis).
4. Graph Rockwell A or C hardness vs. tempering temperature (oC).
5. Compute the ultimate tensile strength (psi) of all specimens from the average
BHN for each specimen using:
σult= 500 x B.H.N.
RESULTS AND ANALYSIS:-
Within your report you should discuss the data referenced in the "OBSERVATIONS
AND CALCULATIONS” as well as the following:
What is the purpose of quenching and tempering steel?
Discuss the sources of error for the various hardness testers, the relative ease with
which they may be used, and the comparative consistency of test results.
What factors probably contributed to the scatter in the hardness data?
Which hardness test appears to be most accurate?
Laboratory
Manual
MECH2118
FACULTY OF ENGINEERING - SOHAR UNIVERSITY
Manufacturing Processes – MECH2118 Page 21
Using the inverse lever law, estimate the amount of carbide (Fe3C) present at
1338oF (just below the eutectoid temperature) for SAE 1045.
What are (or should be) the differences in the microstructure for each heat
treatment process and how do these differences correlate with hardness?
Discuss errors in this experiment and their sources.