UNIT 1: DESIGN PHILOSOPHYINTRODUCTION:MachineDesignis definedas theuseof scientific principles, technical informationandimaginationinthedescriptionof amachineoramechanical systemtoperformspecificfunctions with maimum economy and efficiency!"#$IC %ROC&DUR& O' M#C(IN& D&$I)N:The *asic procedure of machine design consists of a step+*y+step approach +++++ from gi,enspecifications a*out the functional re-uirements of a product, to the complete description inthe form of drawings of the final product!f configMarket SurveyDefneSpecifcations of ProductStudy Alternative Mechanisms for Product & select proper mechanismPrepare general layout of confguration& select joining methods Design individual componentsPrepare Assembly & detail drawings & modify drawings after testing prototype "#$IC R&.UIR&M&NT$ O' M#C(IN& &/&M&NT$:The*roado*0ecti,eof designingamachineelement istoensurethat it preser,esit1soperatingcapacityduringthestipulatedser,icelifewithminimummanufacturingandoperatingcosts! Inordertoachie,ethiso*0ecti,e, themachineelementshouldsatisfyfollowing *asic re-uirements: $trength Rigidity 2ear resistance Minimum dimensions and weight Manufactura*ility $afety Conformance to standards Relia*ility Maintaina*ility Minimum life cycle costD&$I)N O' M#C(IN& &/&M&NT$:The design of machine elements is the most important step in the complete procedure ofmachine design! In order to ensure the *asic re-uirements of machine elements,calculations are carried out to find out the dimensions of the machine elements! Thesecalculations form an integral part of the designing of machine elements!Specify functions of elementDetermine forces acting on elementSelect suitable material for elementDetermine failure mode of element'ig!:+ "asic procedure of design of machine element '$I"I/T3 $TUD3:Once the pro*lems need has *een esta*lished and the specifications ha,e *een prepared,accepted and su*mitted, the feasi*ility study is done! The purpose of this study is to chec4the possi*ility of success or failure of theproposedpro0ect *othfromtechnical andeconomic standpoint! In this study, ,arious -uestions are to *e answered:+5! Is any natural law *eing defied67! #re some of the specifications *eyond what is technically a,aila*le at present68! Is there any dependence on scarce materials69! 2ill the cost of the end product *e too high6The person doing the feasi*ility study will *e the engineers with strong design *ac4ground,4nowledgeof engineeringsciences, agood4nowledgeof material usage, 4nowledgeofproduction methods and re-uirements of the sales department! In fact, it is li4ely that themen responsi*le for the feasi*ility study will *e same engineers who will ultimately ha,ethe design responsi*ility for the o,erall pro0ect!.uite often, as a result of feasi*ility study, some changes are to *e made in thespecifications and re-uirements in order to pro,ide a greater li4elihood of pro0ect success!D&$I)N $3NT(&$I$:Determine geometric dimensions of elementModify dimensions for assembly & manufacture Prepare working modeldrawing of elementThedesignsynthesisisdefinedastheprocessof creatingorselectingconfigurations,materials, shapes and dimensions for a product! It is a decision ma4ing process with themain o*0ecti,e of optimi:ation! Indesignanalysis, thedesigner assumes aparticular mechanism, aparticularmaterial etc and with the help of this information, he determines the dimension ofthe product! In design synthesis, the designer has to fi the o*0ecti,e! The o*0ecti,e can *e cost,minimum weight or ,olume, maimum relia*ility or maimum life! The second stepis mathematical formulation of these o*0ecti,es and re-uirements! The final step ismathematical analysis for optimi:ation and interpretation of the results!U$& O' $T#ND#RD$ IN D&$I)N:$tandardi:ationis definedas o*ligatory norms, towhich,arious characteristics of aproduct should conform! The characteristics include materials, dimensions and shape ofthecomponent, methodoftestingandmethodofmar4ing, pac4ingandstoringof theproduct! # standard is defined as a set of specifications for parts, materials or processes! Theo*0ecti,e of a standard is to reduce the ,ariety and limit the num*er of items to areasona*le le,el! #codeisdefinedasasetofspecificationsfortheanalysis, design,manufacture,testing and erection of the product! The purpose of code is to achie,e a specifiedle,el of safety!There are three types of standards+++++++++++++++++5! Company standards ; used in a particular company or a group of sister concerns!7! National standards ; eg!+ "!I!$, D!I!N < )ermany=8! International standards ; eg! ; I!$!O$tandardi:ation offers following ad,antages:+5! The reduction in types and dimensions of identical components, ma4es it possi*leto manufacture the standard component on mass scale in a centrali:ed process!7! #,aila*ility of standard components ha,e considera*ly reduced the manufacturingfacilities re-uired *y an indi,idual organisation!8! $tandard parts are easy to replace when worn out due to interchangea*ility!9! The application of standard machine element reduces the time and effort needed todesign a new machine!>! The standards of specifications and testing procedures of machine elementsimpro,e their -uality and relia*ility!$&/&CTION O' %R&'&RR&D $I?&$:The @si:eA of the product is a general term, which includes differentparameters li4e power transmitting capacity, load carrying capacity, speed anddimensions of the component such as height, length and width of the product!%referred num*ers are used to specify the @si:esA of the product!There are two terms namely:+5! "asic series < R>, R5B, R7B, R9B, RCB=!" Deri,ed series #&$T(&TIC CON$ID&R#TION$ IN D&$I)N:&ach product has a definite purpose! It has to perform specific functions to the satisfactionof customer! Thecontact *etweentheproduct andthepeoplearisesduetothesheernecessity of the functional re-uirement!The eternal appearance is an important feature, which not gi,es grace and lustre to theproduct *ut alsodominatesthesaleinmar4et! Thisisparticularlytrueforconsumerdura*les li4e automo*iles, household appliances and audio ,isual e-uipment!The growing reali:ation of the need of aesthetic considerations in product design has gi,enrise to a separate discipline, 4nown as @industrial designA! The 0o* of an industrial designeris to create new forms and shapes, which are aesthetically pleasing!Theoutwardappearanceof theproduct hasundergonemanychangeso,ertheyears!There are fi,e *asic forms:+5! $tep form ; eg! ; multi+storeyed *uildings7! $treamDstreamline ; eg! ; automo*ile8! Taper ; eg! ; tapered *loc4s9! $hear ; eg! ; free standing engineering products>! $culpture ; eg! ; ellipsoids, para*oloids$election of proper colour is an important consideration in product aesthetics! The choiceof colour should *e compati*le with the con,entional ideas of the operator!

Colour MeaningRed Danger ; (a:ard ; (otOrange %ossi*le dangerYellow CautionGreen $afetyBlue Caution ; ColdGrey DullThe eternal appearance of the product is a cumulati,e effect of a num*er of factors suchas rigidity and resilience, tolerances and surface finish, motion of indi,idual components,materials, manufacturing methods and noise!&R)ONOMIC CON$ID&R#TION$ IN D&$I)N:&rgonomics is defined as the relationship *etween man and machine and the applicationof anatomical, physiological andpsychological principlestosol,ethepro*lemsarisingfrom man ; machine relationship!&rgonomicsergon E nomoswor4 natural lawsInformation reception Information displayM#N M#C(IN&Correcti,e actionMachine controls'ig!:+ Man ; machine closed loop system'rom design considerations, the topics of ergonomic studies are as follows: #natomical factors in design of dri,er1s seat /ayout of instrument dials and display panels for accurate perception *y theoperators Design of hand le,ers and hand wheels &nergy ependiture in hand and foot operationsF and /ighting, noise and climatic conditions in machine en,ironment!