Engineering Applications

202 Pages·1998·35.019 MB·English

by  James Ritchie, Graham Simpson

Engineering Applications
A Project-based Approach
James Ritchie
Graham Simpson
Department ofMechanical and Chemical Engineering,
Heriot-Watt University, Edinburgh, UK
UTTERWORTH
EINEMANN
Butterworth-Heinemann
Linacre House, Jordan Hill, Oxford OX2 8DP
225 WildwoodAvenue, Woburn, MA 01801-2041
A division of Reed Educational and Professional Publishing Ltd
-@..
A member of the Reed Elsevierplc group
OXFORD BOSTON JOHANNESBURG
MELBOURNE NEW DELHI SINGAPORE
First published 1998
Transferredtodigitalprinting2004
© James Ritchie and Graham Simpson 1998
Allrights reserved. Nopart ofthispublication maybereproduced in
anymaterial form (including photocopying orstoring inanymedium by
electronic means andwhether ornottransiently orincidentally tosome
otheruseofthispublication) without thewritten permission ofthe
copyright holder except inaccordance withtheprovisions oftheCopyright,
Designs andPatentsAct 1988orunder theterms ofalicence issued bythe
Copyright Licensing Agency Ltd, 90Tottenham Court Road, London,
England WIP9HE.Applications forthe copyright holder's written
permission toreproduce anypart ofthispublication should beaddressed
tothepublishers
British Library Cataloguing in Publication Data
Ritchie, James
Engineering applications: a project based approach
1.Engineering
I. Title II.Simpson, Graham
620
ISBN 0 7506 2577 5
Compositionby Genesis Typesetting, Rochester, Kent
Preface
Engineers are atthecore ofcivilisation asweknow it.Without engineers the world would notbe theplace
itistoday,inboth thecontext ofthegood andthebadinsociety andalltheman-made things weseearound
us. The responsibility that engineers carry as they design and make products, develop systems and do
analyses isimmense. People'slives andlivelihoods depend onengineering decisions; no-one canescape the
influence of engineering in today's modern world. Therefore, to hold the position of a practising engineer
can be both daunting and exciting.
The 1980sand 1990shave seenthe advent ofaggressive world-wide industrial competitionascompanies
adapt to meet the challenge ofinternational competition for their markets, both athome and abroad.At the
centre of this revolution isthe way in which engineered products arecreated, designed, marketed, sold and
manufactured by engineering companies. Engineers must have an appreciation of how products can be
designed formanufacture, howtheyneedin-builtreliability andquality,howtheymustmeetcustomer needs
and how these requirements can be met. The amazing rise of Japan as an economic superpower in the last
thirty years has been mainly due to the way in which their engineers understand and practise all of these
disciplines and are involved at all levels of any manufacturing company. There is an increasing emphasis
on the design and manufacturing functions within modern industrial companies to help them compete and
achieve world-class status. In themodem world ofbusiness theengineermay notbe theking but isatleast
the king's right-hand man.
Engineering design, problem-solving and manufacturing are the areas which every engineer must
appreciate if he or sheis to contribute in an effective manner totheir discipline, regardless of what type of
engineering theypractise. Notonlythetechnologicalproblems mustbeaddressed butalsothoseinfluencing
cost, people, the environment and society. Other skills in the areas of business, commerce, computing,
systems analysis, personnel, etc., must also be developed.
This book is intended for use by students who are pursuing a course which involves engineering design
and manufacture. Its main emphasis is on design for manufacture through a series of projects which range
from a simple, single item to more complex assemblies. Each of these design briefs will take the student
through thebasic process ofengineering aproduct, i.e. design, plan for manufacture, manufacture andtest.
Theintention istodevelop anappreciation oftheimportance ofdesigning products for manufacture sothat
they can be made effectively using the resources available.
Each project includes most of the associated engineering activities such as drawing office work,
manufacturing technology, engineering materials selection and treatment and production planning,
culminating in the manufacture and test of the final product. It is hoped that the projects will give an
introductionto these processes aswell asproviding agood foundation for more challenging design project
work in the future.
Some of the projects are not design-related, e.g. the assembly strip-down exercise and the financial
analysis. However, these are deliberately included to provide experience of other skills and knowledge
required by the modem engineer - presentational and analytical skills, financial skills, etc.
vii
Preface
So, why have we chosen the title Engineering Applications?
In the UK, Engineering Applications should be central to the engineering content of any accredited
Chartered Engineering course. It is divided into two sections, namely:
(a) EA1:an introduction to the fabrication and use of materials
(b) EA2: applications of engineering principles to the solution of practical problems.
The projects in this book cover material in both areas and are suitable for incorporation in any fully
accredited engineering degree course.
The book contains five main chapters, and a Quick Reference Guide. Each of these will now be briefly
explained in turn.
Chapter 1 defines products in a general sense in the context of the modern manufacturing market and
the environment in which companies who make products now find themselves competing. It also outlines
thecycleof 'EngineeringaProduct',emphasizing theimportance ofdesignformanufacture (DFM) andthe
benefits it can give a manufacturing company if applied properly. Further, it explains the manufacturing
system and typical departments associated with product development and manufacture in any company
along with some of the activities carried out and the documentation produced.
Chapter 2 outlines the process of design and drafting and how it has been managed in a traditional
manufacturing environment. It then explains how modern methods, which are being increasingly adopted,
arehelping somecompanies thriveintheinternationalmarketplace.Ageneralmethodology forapproaching
the projects is outlined along with instructions on how the design information must be presented.
Chapter 3 briefly outlines different forms of manufacturing and the need for carefully prepared
manufacturing information before product production takes place. Advice is also given on useful
background information material which will help students to tackle the manufacturing parts of their
projects.
Chapter4 outlinesthefunctionofprocessplanning. Oneofthekeydocuments produced foranyproduct
istheprocess plan; thisoutlines thesequence ofoperations totransform theitemfrom itsrawmaterial state
to the finished component or assembly. It also formalizes a methodology for creating process plans and
presents a few examples to help in the development of skills in this area.
Chapter5 outlines the projects. These are given numbers from Type 1through to Type 10,the degree
of difficulty tending to get higher as they are completed. The outlines are designed to support the project
specifications provided intheTutorResource Pack, which shouldbegiventoyouashandouts asyoutackle
each project type.
The Quick Reference Guide (Part Two) contains not only material for use during engineering
applications projects but also useful data and information which may be required in the rest of the course
and during a career as a professional engineer.
Finally,wehopethatstudentswillenjoythisfirstexperience ofdesigning andmanufacturing intheworld
of engineering and we hope that it will confirm their wish to become a professional engineer. Weare sure
that what is learnt by carrying out these projects will be relevant and useful in the future - good luck!
viii
Acknowledgements
Extracts from British and International Standards are reproduced with the permisson of BSI. Complete
copies can be obtained by post from BSI Customer Services, 389 Chiswick High Road, London W4 4AL
(telephone [phone]) orthrough national standards bodies.
Figure 1.4(page7)isanadaptation ofFigure 4.3(page57)from Production andOperations Management
Textand Cases, Terry Hill. Reproduced with the kind permission of Prentice-Hall Europe, 6 Wood Lane
End, Hemel Hempstead, Hertfordshire HP2 4RG.
The expanded planning method used in pages 38-40 is an adaptation of that given in the book
Introduction to Jig and ToolDesign, M.H.A. Kempster. Reproduced with the kind permission of Edward
Arnold (Publishers) Ltd, 338 Euston Road, London NW1 3BH.
The authors also wish to acknowledge the advice and assistance obtainedfrom their many colleagues at
Heriot-Watt University who have been involved in developing mechanical engineering EA teaching
programmes. Inparticulartheywould liketothank IanBlack, Norman Loch, BrentWilson, George Hartnup
and Bruce Davies for their input, support and encouragement over the years.
1
a
Engineering product
The engineer in today's society must be aware of how products are marketed, researched, designed,
developed and manufactured. The engineering of products involves a wide range of activities, all of which
have to interact efficiently and effectively such that companies can produce products which competein the
modern marketplace. As a consequence of this, engineers must be aware of all stages of product
developmentandmanufactureaswell astherelevantbusiness aspects associated with these. They alsoneed
tohave abroad understanding ofhow amodern company operates and competes aswell ashaving detailed
knowledge of specialistareas. Without the former it will be impossible to apply the latter successfully and
to its full advantage.
1.1 Products
Engineers need to develop and manufacture products, but what are they?
Products are consumable goods, items which are bought and used by people depending on what they
desire and/or need; they may buy the goods for their own use or on behalfof an organization or company.
All manufactured goods have alimited life-span, some of afew seconds, others of many years. Ultimately,
one way or another, their useful life will come to an end.
Bysimply looking around your surroundingsyouwillseeexamples ofproducts - furniture, pens, clothes,
dishes, newspapers, to name but a few.All of these have been manufactured to be sold at a specific price
which hastoensure aprofit forthecompanywhich manufacturedthem andtheretailer who soldthem, after
they have paid back their investment costs.
Some products, such as cutlery and screws, are very simple in form, consisting of only one part. Others
can be either simple or complex assemblies ranging from electrical plugs, light switches and door handles
to motor cars, aeroplanes and television sets.
These may be obvious examples of end products but it should be appreciated that the more complex
products may themselves be combinations of simpler products. Just as bricks are a product bought to be
combined together into a building which will in turn be purchased as a finished product so, for example,
electronic components are the building blocks purchased by companies manufacturing electronic products
for sale in the marketplace.
A manufacturing company may not make all, or indeed any, of the detail parts which go into its final
assembled product. There is nearly always a need for them to buy parts or raw materials from another
company, usually called a supplier or a vendor.
All products require the input of professional engineers at many stages, not only in the design and
manufacture of the product itselfbut also in the development and manufacture of the machines and other
ancillary equipmentused tomake it.Examples aremachines forcutting and sewing cloth, machine toolsfor
3
EngineeringApplications
producing metal components for cars, and computers used for controlling manufacturing processes and
ordering parts.
As mentioned previously, allproducts are bought and sold in the marketplace. When you see an item of
clothing, acompact disc, acomputer game or avideo which you then decide to buy,you are, in your own
smallway,stimulating ademandforthatproduct. Ifmanyotherpeople alsodecidetobuyitanditbecomes
more popular than any other competing product then it becomes a market leader. This gives the
manufacturer orretailer anexcellent chance ofmaximizing itsprofits before theproduct's life cycle comes
to anend. Demand for aproduct may fall for anumber ofreasons, such asit going out offashion, anyone
who was going to buy it has bought it, or competing products enter the market at a better price and
quality.
A product life cycle is considered to be the time from when it is introduced to the market until it is
withdrawn. As shown inFigure 1.1the traditional product life cycle was usually very long. This enabled a
business to make profits over a substantial period of time.
The modern product life cycle is often quite different. Due to increasing and aggressive worldwide
competition many manufactured products now have a shorter life cycle, and therefore it is necessary for
I
Buildup Stable Market I Declining
DEMAND ,
of Market I Market
<;
I I
I I New Product
I I
, I
~~ I
-'
Payback TIME (usuallyyears)
TRADITIONAL PRODUCTLIFE CYCLE
DEMAND
(A) Buildupof market
Design/Develop
(B) Stable
market
(C) Declining
market
TIME (months/years)
Investment Payback
MODERN PRODUCTLIFECYCLE
Figure 1.1Idealizedproductlife cycles
4
Engineering aproduct
companies todesign, develop and manufacture their productquickly and with good quality sothat they can
beat the competition to the marketplace and, most importantly, satisfy the demands of the customer. Then
new products or variants of existing products must continuously be developed (quickly) and introduced so
that a market lead is maintained. The engineer has a key role to play in this process.
The vast majority of products engineered and developed in the modern world need a market. No longer
canengineers develop products justbecause there maybe anengineeringortechnical challenge; the market
must be investigatedfirst. If it is found that a demand for a new product exists, then, and only then, is the
product developed in detail. Engineers must recognize that it is important to obtain the advice of experts
from sales and marketing before the detailing stage.
Thus engineers must be capable of applying their skills and knowledge to the effective development of
neworexisting products sothatthecompany theyworkforcan survive inthemodern marketplaceandkeep
or achieve a market lead. New designs need to be manufactured at a cost-effective price and quality. It is
therefore important that new products are designed to suit the manufacturing processes available as far as
possible. The concept of design for manufacture (DFM) is a key awareness which it is hoped EA projects
will give tothe modern young engineer.This awareness should notbe viewed inisolation but inthecontext
of acompany trying to compete in the modern manufacturing market; the advantages DFM can give it are
then apparent.
Nomatter how good thedesign ofaproduct, ifitcannot bemanufacturedeasily,costeffectively andwith
good quality, then the competition will soon catch up and deliver abetter, more marketable productbefore
the required market share is obtained.
1.2 The process of engineering a product
Thetraditionalorsequentialapproach toengineeringproducts isshown inFigure 1.2.Althoughitisimplied
from this diagram that all stages of product development should be carried out in this sequence, many
modern companies actually carry out some of these functions in parallel. They do this by using the
philosophy of simultaneous or concurrentengineering[1,2].This applies the team approach to the creation
of new products, bringing together 'experts' from design, manufacture, quality, marketing, etc. to work
together, thus enabling rapid product development. However, for the purpose of developing a detailed
understanding of the activities which take place during the engineering of a product, this text will look at
each stageindividuallyandsequentially. OnceEAprojects aretackled inthiswayitishoped thatthestudent
will see the relationships between each part of the diagram and considertwo or more stages together, thus
becoming aware of the need for and advantages of DFM and concurrent engineering.
After Marketing and Sales have identified the demand for a product, the engineering departments then
carry out the engineering process such that a competitive, cost-effective solution is obtained. These loops
may be gone round several times, either wholly or partially, depending on the product's engineering
Customer
Order
Deliverl Deliveryto
Design Plan Manufacture Service Customer
(DesignDept.) (ManufacturingDept.) (ProductionDept.) (Production/
(Prod.PlanningOpt.) Despatch/Service)
Conceptuallse ProcessPlan Machine Progress
Specify MaterialsScheduling Cast Deliver
Design WorkScheduling Inspect Package
Analyse MaterialsOrdering Fabricate Service
Detail WorksOrdering Assemble ProductionControl
Drafting Purchasing ProductionControl
Figure 1.2 Theprocess of engineering aproduct
5
EngineeringApplications
Customer
Order
Deliverl Deliveryto
Design Plan Manufacture Service Customer
(DesignDept.) (ManufacturingDept.) (ProductionDept.) (Production/
(Prod.PlanningOpt.) Despatch/Service)
Conceptuallse ProcessPlan Machine Progress
Specify MaterialsScheduling Cast Deliver
Design WorkScheduling Inspect Package
Analyse MaterialsOrdering Fabricate Service
Detail WorksOrdering Assemble ProductionControl
Drafting Purchasing ProductionControl
DESIGNORENGINEERING
DEPARTMENT
~//'/_--"'
:Uf _t!_ViiE/-\\----- ,~.... .":.«..
~'~¥ ChangReetqouDe.rtawing
,/// ~.~';-~\-.-~-1~O'-i'l~I ~A '~""" ,-.-
~
Specify III III ::bad....- i ~
C/Otl
Actioned
Conceptualize C r-- """""
Design/Analysis ~
I 1
DesignDetail F D
Drafting D
ConsIderations
Customerneeds, Ideas, Designs, Drawings, I
Fitness forpurpose, Concepts, ChangetoDrawingInfo.
Aesthetics, Productspecifications, I C/Ot!- --..........-..
Cost, Quality, Bill-at-Materials,
Operation, Performance, Raw material requirements.
Manufacturing requirements.
Figure 1.3 The design function
requirements. The feedback loops in the diagram represent recommendations for product improvement or
modification due to some need unforeseen at an earlier stage during the engineering process, e.g. a
modification to the design requested at the 'plan' stage to make it easier to produce.
The first stage of the 'Engineering a Product' process is called Design (Figure 1.3).
At the marketing stage the Design Department may have produced preliminary drawings or sketches.
However, once the company has decided to proceed with a new product, this department will specify,
develop, analyse and create it with particular regard to its operational, aesthetic and manufacturing
requirements. Attheendofthis stage,final drawings andbills-of-materialareavailable which arethenused
by the downstream manufacturing functions for product planning and manufacture.
Itisimportanttonote thatasmuch as80percent ofaproduct'sfinal cost canbecommittedatthedesign
stage. This is crucial to the eventual competitiveness of aproductin the marketplace and will be discussed
in more detail in Chapter 2.
When thedesign ofaproduct iscompleted, themanufacturingprocess begins: thisinvolves bothplanning
manufactureandmanufacture itself.Themanufacturingprocesscanbeexaminedbyinvestigatingtheconcept
ofthemanufacturingsystem,which maybeconsideredasatransformationprocess (Figure 1.4).Thiscanbe
6
Engineering aproduct
MANAGEMENT
TRANSFORMATION PROCESS
Methods ofTransformation } Manufacturing
andDesignFeedback Department
Product Scheduling/Planningof Production
Design Production and } Planning
Manu~cwringFeedback Department
Information
ConuolofProducnonand } Production
Design/Manufacturing Department
Feedback
Figure 1.4 The manufacturing system
viewedasanyotherphysicalengineeringsystem.Onreceiptofthedesigninformationitinvolves theinputsof
people, energy,materials, money andinformationbeing transformedinto finished products. These may take
theformofindividualpartsorassemblies. Managementhastheall-embracingresponsibilityfororganizingthe
inputs andthetransformationprocess suchthatthedesired outputs areachieved.
There are usually three separate departments involved in the manufacturing system process, namely the
ProductionPlanning Department, the ManufacturingDepartmentandtheProductionDepartment. Incertain
companies thesetitlesandtheirrolesmaybeswapped orcombined; however,forthepurpose ofthisbookand
EAprojectsthesearethedefinitions whichshallbeused.Theplanningstageiscarriedoutintwoareasbytwo
different departments, namely the Manufacturing Department and the Production Planning Department
(Figure 1.5).TheManufacturingDepartment,whichmayalsobeknown astheProcessPlanningDepartment,
prepares and plans detailed manufacturing information for each detailed part or assembly. The personnel
involved in this department may be called ProductionEngineers, Process Planners, Part Programmers, etc.
However, theirfundamentaltaskisthesame,thatofconvertingdesigns intomanufacturingprocess plansfor
useonthefactory floorbyexperiencedoperators.
Oneofthekey tasks intheEA projects outlined inthisbook istoprepare process plans for selected parts
designedbythestudent.
On receiving a finished drawing and bill-of-material, from Design, the process planners in the
ManufacturingDepartmentwoulddetermine:
(a) iftheitemistobemadein-house orpurchasedfromasupplier
(b) whatmanufacturingfacilities andprocessesarerequired toproduce theitem
(c) the sequence of operations required along with the manufacturing resources and tooling needed ateach
stage- some'design' oftooling andfixturing maytakeplace atthisstage
(d) rawmaterial requirements,sequence manufacturingtimes andcostestimates
(e) anyrecommendeddesign changes tofacilitate manufactureandliaison withtheDesign Department.
Thechosen manufacturingmethod would depend on:
(a) thepeople, machines, processes, tooling andmanufacturingsystem available
(b) therawmaterials recommendedandusedbythecompany
(c) thedrawing geometry,tolerancingandfinish requirements
(d) theestimatedmanufacturingtime andcost
7