mec 2202 introductory book

MEC2202

Manufacturing processesFaculty of Engineering and Surveying

In t roduc to ry bookSemester 1 2013

Published by

University of Southern QueenslandToowoomba Queensland 4350Australia

http://www.usq.edu.au

© University of Southern Queensland, 2013.1.

Copyrighted materials reproduced herein are used under the provisions of the Copyright Act 1968 as amended, or as a result of application to the copyright owner.

No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means electronic, mechanical, photocopying, recording or otherwise without prior permission.

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Table of contents

PAGE

Essential information 1

Introduction 2Personnel 2Course outline 2Course structure 3

Study schedule 6

Assessment 7

Assignment 1 9

Assignment 2 11

Formula sheet for MEC2202 13

Past examination 17

Solutions to selected questions in the past examination paper 27Forming Processes: Part A 27

MEC2202 – Manufacturing processes 1

Essential information

The topics in the following list provide important information that will assist you with your study. You can access a handout containing the information on your StudyDesk through the ‘Essential information (study materials)’ link <http://usqstudydesk.usq.edu.au/file.php/1/sitefiles/DeC/essential_info/essentialhandout.pdf>. You will need your UConnect username and password to access the file. Please make sure you read this information carefully before commencing your study.

• Getting started <http://usqstudydesk.usq.edu.au/file.php/1/sitefiles/DeC/essential_info/getting_started.pdf>

• Course specification <http://usqstudydesk.usq.edu.au/file.php/1/sitefiles/DeC/essential_info/course_specification.pdf>

• Support <http://usqstudydesk.usq.edu.au/file.php/1/sitefiles/DeC/essential_info/support.pdf>

• UConnect<http://usqstudydesk.usq.edu.au/file.php/1/sitefiles/DeC/essential_info/u_connect.pdf>

• Assignment submission<http://usqstudydesk.usq.edu.au/file.php/1/sitefiles/DeC/essential_info/assignment_submission.pdf>

• Grading levels<http://usqstudydesk.usq.edu.au/file.php/1/sitefiles/DeC/essential_info/grading_levels.pdf>

• Course evaluation <http://usqstudydesk.usq.edu.au/file.php/1/sitefiles/DeC/essential_info/course_evaluation.pdf>

• Residential schools<http://usqstudydesk.usq.edu.au/file.php/1/sitefiles/DeC/essential_info/residential_school.pdf>

• Library<http://usqstudydesk.usq.edu.au/file.php/1/sitefiles/DeC/essential_info/library.pdf>

• Referencing APA<http://usqstudydesk.usq.edu.au/file.php/1/sitefiles/DeC/essential_info/apa_referencing_guide.pdf>

• Referencing Harvard AGPS<http://usqstudydesk.usq.edu.au/file.php/1/sitefiles/DeC/essential_info/harvard_referencing_guide.pdf>

• Optional purchase of study materials<http://usqstudydesk.usq.edu.au/file.php/1/sitefiles/DeC/essential_info/optional_purchase.pdf>

• USQ policies and procedures<http://usqstudydesk.usq.edu.au/file.php/1/sitefiles/DeC/essential_info/policies_procedures.pdf>

2 MEC2202 – Manufacturing processes

Introduction

This book is a guide to the course MEC2202 Manufacturing Processes. It contains details of the presentation and assessment of the course, a study programme, assignments to be submitted by the student and other information. You should refer to this book regularly throughout your study of the course.

Personnel

The examiner of the course is Dr Hao Wang.

Dr Wang completed has Bachelor of Engineering in Materials at Nanjing University of Science and Technology, and Master of Science in Materials at the Institute of Metal Research, Chinese Academy of Sciences. He then joined the Shanghai Institute of Ceramics, another institute under the Chinese Academy of Sciences, as a research engineer. He moved to Australia in 1994. After working at Monash University and Comalco Alumunium Ltd for a while, he came to the University of Queensland to conduct his PhD in Materials Engineering. He was an ARC Australian Research Fellow before he came to USQ. His research interests lie on solidification and metal forming, amorphous and nano-structured materials, and bio-materials.

Course outline

A knowledge of manufacturing processes is essential for any student involved in production or design engineering and is highly desirable for students concerned with most other branches of engineering. This is because the method by which a component is produced will always determine, to some degree, its:

• cost

• design and hence its ability to fulfil the function for which it was originally devised

• behaviour in service, since each process has its own inherent defects and characteristic influence on the properties of the metal and/or the manufactured assembly.

Patently, anyone engaged in the field of engineering who utilises components without some regard to their design limitations and potential behaviour in service, is guilty of neglect.

This introductory study cannot attempt to impart the depth of knowledge of manufacturing processes required by those engaged in production or design engineering. For these students, the information presented in this course will be extended in studies of materials and manufacturing conducted in other courses.

The course is presented in two discrete parts as indicated in the course structure. Part A is concerned with forming processes and Part B with metal cutting processes.

A study programme and timetable for the course is given in the study schedule. The two parts of the course should be studied concurrently as indicated.

NB: Formula sheets are provided in this introductory book and at the end of study book 2.


Course structure

Course DVD/video

MEC2202 Manufacturing Processes we have introduced two DVDs titled ‘Casting’ and ‘Plastics’. You may obtain a copy of the DVD/video from the Off-Campus Library Service.

To obtain a copy on loan of this DVD/video log on to DocEx on the Library website. Access can be gained from the USQ website>The Library> Off-Campus Students (under Information For…).

Students in the Toowoomba area could also phone 46312589 to arrange to collect a copy.

Remember: Fines and penalties will be incurred for late return or late renewal of the item on loan. This DVD/Video must be returned to the USQ Library by the end of semester.

Manufacturing processes

PART B

Cutting operations

Thread

manufacturing

processesPrinciples of metal

cutting

Cutting tools for

machining

Abrasive

machining

processes

Milling and

broaching

processes

PART A

Forming

Manufacturing

costs

Casting

processes

Powder

metallurgy

Forming

processes Forming of

plastics,

ceramics &

compositesWelding

processes

Turning, boring

& related

processes

Non traditional

machining

processes

Rapid

prototyping

operations


Program structure

The relationship of this course to others in the Bachelor of Technology and Bachelor of Engineering programmes is illustrated schematically below.

Structure of

Materials

Mechanical

Behaviour of

Materials

Fine

Measurement

Manufacturing

& Production

Systems

Industrial

Engineering

Quality

Assurance

Industrial

Relations

Joining

Processes

Forming

Operations

Cutting

Operations

MEC1201

Engineering Materials

MEC2202

Manufacturing Processes

MEC3203

Materials TechnologyMEC3204

Production EngineeringENG3003

Engineering Management

and

ENG4004

Engineering Management

Science


Direct lecturer contact

You can also contact the lecturers direct with simple technical queries (e.g. difficulty studying topic or doing assignment, not clear on set activity, need more explanation). When you telephone please be specific about the problem you wish to discuss (e.g. diagram on page 39 of Study Book 1: Assignment No. 1, Question 3) and ensure that you have study materials at hand when you make the call. Such a detailed approach could save you time (and money).

H Wang

Tel: (07) 4631 2549

email: [email protected]

Faculty of Engineering and Surveying Fax: (07) 4631 2526


Study schedule

Week Module/TopicPart A

Module/TopicPart B Assessment

1 Introduction

Module 1: Manufacturing costs

2 Manufacturing simulation(Internal students only, details available on StudyDesk for external students)

3 Module 2: Casting process

4 Module 3: Forming process

Reminder: End of week 4 is the last date to drop courses without academic or financial penalty.

5 Module 4: Powder metallurgy

6 BREAK

7 BREAK

8 Module 5: Forming of plastics, ceramics and composites

Assignment 1Due: 15 April 2013

Reminder: End of week 8 is the last date to drop courses without academic penalty.

9 Module 8: Principles of metal cutting

Module 9: Cutting tools

10 Module 10: Turning, boring, drillilng and related processes

11 Module 11: Milling, broaching and sawing processes

Module 12: Abrasive machining processes

12 Module 13: Form generation process

Module 14: Non-traditional machining processes

13 Module 6: Welding processes Assignment 2Due: 20 May 2013

14 Module 7: Rapid prototyping

15REVISION

16–17 EXAMINATION PERIOD


Assessment

The summative assessment of your performance in the course comprises:

Two (2) assignments, each with a value of 150 marks (total 300 marks).

One 2-hour examination with a value of 700 marks. The paper will be divided into two sections. Section A is forming and Section B is cutting. Students need to attempt all questions.

Assessment scheme

Assignments must be posted by the due date or they will not be marked. Because answers to the assignments will be issued immediately after the due date, no requests for extensions of time to complete assignment work will be entertained.

If you are unable to complete an assignment by the due date for reasons beyond your control, e.g. late receipt of study materials, illness, etc. you should advise the examiner in writing. Documentary evidence in the form of a doctor's certificate or a note from your employer should be provided.

Final examination

There is one 2-hour examination in this course. Section A will assess your knowledge of manufacturing costs, forming processes and welding processes whilst Section B will be concerned with cutting operations and numerical control. The paper is a restricted examination; students will be permitted to use a calculator but may not have access to any other materials.

In order to successfully complete the course it will be necessary for students to achieve 50% of the total possible marks for the course and at least 50% of the total marks for the final examination.

A copy of the previous final examination paper with solutions is provided at the end of this introductory book.

Assessment number Objective total

Module objective 1 2 3

1

5

4

2

Assessment total 150 150 700 1000


Notification of results

Your result certificate will be mailed at the end of semester. If you have any queries, send only written enquiries to DeC (no telephone enquiries).

• If you do not satisfactorily complete all of the specified assessment requirements for the course you will receive a FAIL grade.

• In some cases, an INCOMPLETE grade may be awarded. If this is the case, a Statement of Requirement for Further Work will be issued or you may be required to sit for a supplementary or deferred examination.


Assignment 1

Question 1

(75 marks)

A company has a requirement for 25 liquid filters per month, the principal component of which is its cast iron body, see the figure below. Suggest how this casting could be most economically produced, assuming that each month's demand is produced in a single batch.

What are the pros and cons if the part is vertically cast? What will happen if the part is horizontally cast? Draw the side views of the completed mould assemblies for the two options.

Based on your observations, which option (vertically cast or horizontally cast) is better. Explain your choice of option.

Due date: 15 April 2013

Weighting: 15% or 150 marks

Examiner: A/Prof H Wang

Note: Penalty for late submission will be the loss of all marks


Question 2(75 marks)

The following information is known for a broaching machine and a milling machine, each of which could be tooled up to produce a certain component. Assuming straight line depreciation over 10 years,. A 40-hour week is worked over 50 weeks per year. The life of the tools of the two machines is assumed to be over 400 hours.

(a) If 1000 components are produced, what would be the cost per piece using each machine? And which machine should be used?

(b) What is the breakeven point for the manufacture of the component on the two machines? Illustrate the breakeven analysis in graph.

Milling machine Broaching machine

Initial cost $ 8,000 $ 16,000

Tooling cost $ 60 $ 900

Material cost/piece $0.15 $0.15

Labour cost/hour $1.60 $1.00

Cycle time/piece 4 min 1 min

Setter' rate/hour $3.20 $3.20

Setting-up time 3 hours 2 hours

General overhead/hour $7.50 $12.10


Assignment 2


Turning is performed on a work material with shear strength of 800 MPa. An orthogonal cutting operation is performed using a rake angle of 10o, depth of cut to=2.0 mm, and the width of cut w=5 mm. The chip thickness ratio is measured after the cut to be 0.5. The coefficient of friction is 1.2.

(a) Determine: (i) chip thickness; and (ii) shear angle.

(b) Determine (i) shear force; (ii) friction angle; and (iii) cutting force. Draw a force diagram to indicate the relationships between these forces.

(c) If the cutting speed is 200m/min, then determine:

(i) power required for cut in kW;(ii) metal removal rate in cm3/min; and(iii) specific power of the material cut.

Question 2

(60 marks)

(a) What is the difference between turning and milling? What is the difference between peripheral milling (slab milling) and face milling?

(20 marks)

(b) What are the five principle parameters of a grinding wheel? Using a commercial wheel as an example to explain how a grinding wheel is specified.

(20 marks)

(c) In grinding process, which are the methods can be used to increase materials removal rates? And which are the methods can be used to improve surface finishing?

(20 marks)

Due date: 20 May 2013

Weighting: 15% or 150 marks

Examiner: A/Prof H Wang

Note: Penalty for late submission will be the loss of all marks


Formula sheet for MEC2202


General Energy

Orthogonal machining Tool life

Turning

V πDN=

MRR Vft=

PuP

MRR-------------=

PPu MRR CF

E-------------------------------=

U Us Uf+=

UFc

ft-----=

UFsVs

ftV-----------

Fs αcos

ft φ α–( )cos--------------------------------= =

Uf

FVc

ftV---------

Frft------= =

φtanr αcos

1 r αsin–-----------------------=

rttc---=

μ βtanFc αtan Ft+

Fc Ft αtan–-----------------------------= =

R Fc2

Ft2

+=

Fc

tb Ss

φsin------------

β α–( )cosφ β α–+( )cos

------------------------------------=

Ft

tb Ss

φsin------------

β α–( )sinφ β α–+( )cos

------------------------------------=

Fs Fc φcos Ft φsin–=

Fn Fc φsin Ft φcos+=

Ss

Fs

As-----=

Astb

φsin-----------=

Ss

Fc φsin φ Ft φsin2–cos

tb--------------------------------------------------------=

Sn

Fn

As------=

Sn

Fc φsin2 Ft φsin φcos+

tb----------------------------------------------------------=

P FcV=

VTn C=

VT C n R 1 n–( )⁄n

=

R J H⁄=

TT R1n--- 1–=

CT L LA+( ) fN⁄=

MRRVtf2

------- for facing=

OfD d–( )2Lt

------------------Lw=

Roughnessf 2

8CR-----------=

CTL LA+( )

fN--------------------=


Drilling Milling

Electrochemical machining Grinding

Broaching Rapid prototyping

Shaping

MRRDVf

4----------=

Power MRR Pu×=

fm ftNn=

CTL LA L0+ +

fm----------------------------=

LA t D t–( )=

MRR wtfm=

tc 2fttD----=

P Pμ MRR×=

frCIA------

CEgr--------

VAt-----= = =

TmLfr---=

MRR frA=

IEAgr-------=

RgrA-----=

t2vNV--------

D d+Dd

------------- f

for internal cylindrical grinding

•=

t2vNV--------

d D–Dd

------------- f

for internal cylindrical grinding

•=

t2vNV--------

fD----=

KPw----

Pf b v××-------------------= =

(

(

)

)

Pitch, P 1.75 Lw=

LB nr ns nf+ +( ) P Lrp Ls+ +=

MRR trnwV=

T i

Ai

vD------- T d+=

T c Ti

i l=

nl

=

V πDNs=

V2 Ns

Rs------------=

MRR wtNs f=

CTw

Ns f---------=


Past examination

A copy of the 2006 examination for this course follows. A perusal of this examination paper should enable you to:

• Note the style of the questions set by the examiners for the course.

• Preview the standard required by the end of the course.

• Test your knowledge, as part of your preparation for the exam.

• Please note that no other past examination papers will be supplied.


UNIVERSITY OF SOUTHERN QUEENSLAND

FACULTY OF ENGINEERING AND SURVEYING

Course No: MEC2202 Course Name: MANUFACTURING PROCESSES

Assessment No: Internal [ X ]

External [ X ]

This examination carries 70 % of the total assessment for this course.

Examiner: DR. H WANG Moderator: DR. H. KU

Examination Date: JUNE/JULY, 2006

Time Allowed: Perusal - Ten (10) minutes Working - Three (3) hours

Special Instructions:

This is a RESTRICTED examination.

Students are permitted to write on the examination paper during perusal time.

Non-programmable calculators are permitted. Students must note the make and model of the calculator used in the examination on the front of the answer book (or examination paper where applicable). This may be subject to checking by the supervisor.

All examination question papers must be submitted to supervisors at the end of every examination and returned to USQ.

One (1) sheet of graph paper is attached.

This examination contains Two parts. Students must attempt all questions.

The value of each question is different and is indicated in the exam paper.

Commence each answer to the questions on a new page of the examination booklet.

Any non-USQ copyright material used herein is reproduced under the provisions of Section 200(1)(b) of the Copyright Amendment Act 1980.


MEC2202 MANUFACTURING PROCESSES JUNE/JULY 2006 Page 1 __________________________________________________________________________________________

Page 1 of 5

Part A: Forming Processes

QUESTION 1 (100 marks)

The following information is known for a component that can be produced with equal facility upon either of the two machines cited.

Capstan Single spindle Lathe automatic

Tooling cost $600 $3,600

Setting up time 1 hour 8 hours

Tool setter’s rate per hour $8.00 $8.00

General overheads per hour (including depreciation costs) $30.0 $40.0

Material cost per component $1.00 $1.00

Time to produce one component 5 min. 1 min.

Direct labour cost per hour $10.00 $5.00

(a) If the component can be sold for $5 each, what is the breakeven point for each machine? illustrate the break even analysis in graph. (50 marks)

(b) If 1000 components are required, which machine should be used and what would be the cost per component? How about if 2000 components are required? (50 marks)


(a) Compare to the multiple-use mould casting processes, what are some major advantages and disadvantages of sand casting? Describe the process steps in sand casting? (30 marks)

(b) Describe the process steps in investment casting? (20 marks)

(c) What are some of the more attractive features of die casting process compared to sand casting? (20 marks)

(d) Describe the process of low pressure die casting and high pressure die casting. Comparing these two processes, what are the most attractive features for each process? (30 marks)



Page 2 of 5


(a) What are the three main hot working processes? Describe each process. (40marks)

(b) What are four main cold working processes? When designing parts to be shaped by bending, what are the two main factors need to be considered? (30 marks)

(c) What is the main difference between hot working and cold working? List at least two advantages and two disadvantages of cold working. (30 marks)


(a) How does the fabrication of a thermoplastic polymer differ from the processing of a thermosetting polymer? (20 marks)

(b) In what ways is injection moulding of plastic similar to die casting of metals? (20 marks)

(c) What are the basic two classes of ceramic materials, and how does their processing differ? (20 marks)

(d) What are the advantages and disadvantages of powder metallurgy? Compare briefly the relative merits of powder metallurgy and low pressure die casting as means of producing small engineering components. (20 marks)

(e) Define “heat affected zone” in welding? Why preheating is sometime performed? (20 marks)



Page 3 of 5

Part B: Cutting Processes


(a) In the orthogonal cutting operation the following data applies:

Feed rate = 0.20 mm/rev Depth of cut = 2.0 mm Cutting speed = 200 m/min Cutting force =1800 N Normal force = 900 N Tool rake angle = 5o

Chip thickness ratio = 0.4

Sketch the orthogonal machining process and force diagram (40 marks) and find:

i) chip thickness; (10 marks) ii) shear plane angle; (10 marks) iii) resultant force; (10 marks) iv) power required for the cut in kW; (10 marks) v) metal removal rate in cm3/min (10 marks) vi) specific power of the material cut in KW/cm3/min. (10 marks)

(b) What variables or factors need to be considered in machining operation? (40 marks)


(a) What is the tool-workpiece movement relationship in turning? What is the difference between turning and boring? (20 marks)

(b) What is the basic difference between facing and parting (cut-off) in turning operation? (20 marks)

(c) What functions are performed by flutes on a drill? What can happen when an improperly ground drill is used to drill a hole? (20 marks)

(d) What are the parameters that need to be considered for abrasives? Describe the different possible interaction between grit and workpiece during abrasive machining.

(20 marks)



Page 4 of 5


(a) What are the three broad categories of milling? What are the two common ways of classifying milling cutters? (20 marks)

(b) Explain what steps are required to produce a T-slot (such as that found in milling machine table) by milling. (20 marks)

(c) What are the basic features of saw blades? (20 marks)

(d) What are the main parameters we use to describe the profile of a thread? How to cut threads on a lathe? (20 marks)



Page 5 of 5

END OF EXAMINATION


Solutions to selected questions in the past examination paper

Forming Processes: Part A


(a) Advantages (any 2 of the 3):

• Low cost for the initial set-up, eg dies or moulds, suitable for small production volume• No restriction on component size, therefore can be used for large component• No restriction on metal melting point, component size, therefore can be used for higher

melting point ferrous metals.

Disadvantages (any 2 of the 4):

• Need a separate mould for each casting. Can be costly if the production volume is high, it can also cause dimensional and property variation from casting to casting.

• Surface finishing is low• Low cooling rate usually lead to coarse microstructure • Low productivity.

Process steps (at least 1, 3, 4, 5 and 6):

1. Patten making2. sand preparation3. mould and core making4. melting raw materials5. pouring melt to mould6. After solidification and cooling, removal of sand mould7. cleaning and inspection.

(b) Process steps (at least 1, 3, 5, 7 and 8):

1. make wax pattern2. several patterns are attached to a sprue to form a pattern tree3. coat the pattern tree with a thin layer of refractory materials 4. The full mould is formed by covering the coated tree with sufficient refractory

materials to make it rigid5. hold the mould in an inverted position, heat it to melt the wax and let it drip out of the

cavity6. preheat the mould to eliminate all contaminants. 7. pour the molten metal and let it solidify. 8. break away the mould and separate the castings from the sprue.

(c) (any 3 of the 5)

1. reusable mould2. good surface finish3. good dimensional accuracy4. fast cooling rate to produce a strong structure 5. high productivity.


(d) In low pressure die casting, the liquid metal is forced into the cavity under low pressure---approximately 0.1MPa ---from beneath so that the flow is upwards. The advantage of this approach over traditional pouring is that clean molten metal from the centre of the ladle is introduced into the mould, rather than metal has been exposed to air. Gas porosity and oxidation defects are thereby minimized and mechanical properties are improved.

In high pressure die casting, the molten metal is injected into mould cavity under high pressure. Typical pressures are 7 to 350 MPa. The pressure is maintained during solidification, after which the mould is opened and the part is removed. The use of high pressure is the most notable feature. There are two main types of high pressure die casting: hot-chamber and cold chamber. The advantages of high pressure die casting are high production rate, thin section are possible.

Question 3

(100 marks)(a) Rolling, forging and extrusion.

Rolling is a deformation process in which heated metal is passed between two or (more) rolls which rotate in opposite direction. The thickness of the work is reduced by compressive forces exerted by two opposing rolls. The rolling equipment is called rolling mills. The high investment cost requires the mills to be used for production in large quantities of standard items.

Forging is a deformation process in which the work is compressed between two dies, using either impact or gradual pressure to form part. The process is further sub-divided into open-die forging, impression-die forging and press forging.

Extrusion is a compression forming process in which a pre-heated billet is placed into a container and isforced through a die of the required section to produce long lengths of uniform cross-sectional shape. Almost any cross-sectional shape can be extruded. The process is used primarily for non-ferrous metals. The dimensional tolerances of extrusion are very good.

(b) Squeezing, shearing, drawing and bending.

Minimum bend radius. It depends on the ductility of the metal.

The length of a flat blank that will produce a bent part of the desired dimensions.

(c) Hot working is performed above the crystallization temperature of the metal. The recrystallization temperature varies greatly for different metals, being below room temperature for lead and above 550oC for plain carbon steel. While cold working is performed under the recrystalization temperature.

Advantage (any 2 of the 3):

1. close dimensional tolerances are possible2. good surface finish is maintained3. improved strength maybe achieved by work hardening.

Disadvantages (any 2 of the 3):

1. large forces are required, and tooling and equipment are therefore expensive. 2. there is a limit to the amount of deformation that is possible before intermediate

annealing treatment is required.3. it often leaves residual stress in the metal.

mec 2202 introductory book

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