General considerations of MAchine Design

Types of Design, Engineering Materials

1. GENERAL CONSIDERATIONS OF MACHINE DESIGN

2. S K Chand (Assistant Professor)
Government Engineering College, Raipur
INTRODUCTION
➢Designisessentiallyadecisionmakingprocess.
➢Foreveryproblem,weneedtodesignasolution.
•Designistoformulateaplantosatisfyaparticular
needandtocreatesomethingwithaphysicalreality.

3. Definition:Itisdefinedasaniterativedecisionmaking
activitytoproduceadrawingoraplantoconvertresources
optimallyintoaproductordeviceorsystemtosatisfythe
humanneeds.
Theultimateaimofdesignistoselectappropriate
shape,material,sizeandmanufacturingprocessdetailsin
suchawaythattheresultingmachinecomponentshould
performitsgivenfunctionsatisfactorily(i.e.withoutany
failure).
S K Chand (Assistant Professor)
Government Engineering College, Raipur

4. Design of a chair
Factors need to be considered
•Thepurposeforwhichthechairistobedesigned.
•Whetherthechairistobedesignedforagrownuppersonora
child
•Materialforthechair:Strengthandcostneedtobedetermined
•Aestheticsofthedesignedchair
S K Chand (Assistant Professor)
Government Engineering College, Raipur

5. Definition of Machine
Machineisdefinedasacombinationofresisting
bodieswithsuccessfullyconstrainedrelative
motionswhichisusedtotransformotherformof
energyintomechanicalenergyortransmitand
modifyavailableenergytodosomeusefulwork.
Machinescanreceivemechanicalenergyand
modifyitsothataspecifictaskiscarriedout.
S K Chand (Assistant Professor)
Government Engineering College, Raipur

6. Modification/ Transformation of
energy
Machine Elements
Machinedesigninvolvesprimarilydesigningmachine
elementssothattheytransmittheforcesandperformtheir
tasksuccessfully.
S K Chand (Assistant Professor)
Government Engineering College, Raipur

7. TYPES OF
DESIGN
ADAPTIVE DESIGN
DEVELOPMENTAL
DESIGN
NEW DESIGN
S K Chand (Assistant Professor)
Government Engineering College, Raipur

8. AdaptiveDesign:Basedonexistingdesign,
standardproductsorsystemsareadoptedfornew
application.
e.g.-Conveyorbelt,controlsystemofmachinesetc.
DevelopmentalDesign:Startingwithanexisting
design,finallyamodifieddesignisobtained.
e.g.-Anewmodelofacar.
S K Chand (Assistant Professor)
Government Engineering College, Raipur

9. NewDesign
•Thistypeofdesignisanentirelynewonebut
basedonexistingscientificprinciples.
•Noscientificinventionisinvolvedbutrequires
thinkingtosolveaproblem.
•Someresearchactivitymaybenecessary.
e.g.-ATV
S K Chand (Assistant Professor)
Government Engineering College, Raipur

10. TYPES OF DESIGN
BASED ON METHODS
RATIONAL DESIGN EMPIRICAL DESIGN
INDUSTRIAL
DESIGN
S K Chand (Assistant Professor)
Government Engineering College, Raipur

11. RationalDesign:Basedonthedeterminingthe
stressesandstrainsofcomponentsandthereby
decidingtheirdimensions.
IndustrialDesign:Basedontheindustrial
considerationsandnormsviz.marketsurvey,
externallook,productionfacilities,lowcost,use
ofexistingstandardproducts.
S K Chand (Assistant Professor)
Government Engineering College, Raipur

12. EmpiricalDesign:Basedonempiricalformulae
whichinturnisbasedonexperienceand
experiments.
e.g.-Whenwetightenanutonabolttheforceexertedorthestresses
inducedcan’tbedeterminedexactlybutexperienceshowsthatthe
tighteningforcemaybegivenby‘P=284d’wheredisthebolt
diameterinmmandPistheappliedforceinkg.
Thereisnomathematicalbackingofthisequationbutis
basedonobservationsandexperience.
S K Chand (Assistant Professor)
Government Engineering College, Raipur

13. ENGINEERING MATERIALS
Choiceofmaterialsforamachineelement
dependson
➢Properties
➢Cost
➢Availability
S K Chand (Assistant Professor)
Government Engineering College, Raipur

14. Common
Engineering
Materials
Ferrous
Materials
Non-ferrous
Materials
Non Metals
S K Chand (Assistant Professor)
Government Engineering College, Raipur

15. Importantferrousmetal
➢Castiron
➢Wroughtiron
➢Steel
S K Chand (Assistant Professor)
Government Engineering College, Raipur

16. Cast iron
➢Alloy of iron, carbon and silicon
➢Hard and brittle
➢Carbon content within 1.7% to 3%
➢Carbonpresence:Freecarbon/ironcarbideFe
3C.
Typesofcastiron:
•Greycastiron
•Whitecastiron
•Malleablecastiron
•Spheroidalornodularcastiron
•Austeniticcastiron
•Abrasionresistantcastiron
S K Chand (Assistant Professor)
Government Engineering College, Raipur

17. Grey cast iron
➢Carbonhereismainlyintheformofgraphite.
➢Inexpensive.
➢HighCompressiveStrength.
➢Graphiteisanexcellentsolidlubricantwhich
makesiteasilymachinablebutbrittle.
DesignatedasFG20,FG35orFG35Si15
Thenumbersindicateultimatetensilestrengthin
MPaand15indicates0.15%silicon.
S K Chand (Assistant Professor)
Government Engineering College, Raipur

18. White cast iron
➢Carbonpresentintheformofironcarbide
Fe
3Cwhichishardandbrittle.
➢Thepresenceofironcarbideincreases
hardnessandmakesitdifficulttomachine.
➢Verygoodabrasionresistantproperty
S K Chand (Assistant Professor)
Government Engineering College, Raipur

19. Malleable cast iron
➢Thesearewhitecastironrenderedmalleablebyannealing.
➢ThesearetougherthanGCIandtheycanbetwistedorbentwithout
fracture
➢Excellentmachiningproperty
➢Inexpensive
➢Usedformakingpartswhereforgingisexpensive
e.g.Hubsforwagonwheels,brakesupports
Designatedbasedonthemethodofprocessing
BlackheartBM32,BM30
WhiteheartWM42,WM35
S K Chand (Assistant Professor)
Government Engineering College, Raipur

20. Spheroidal or Nodular graphite cast iron
➢Graphiteispresentintheformofspheresor
nodules
➢Hightensilestrength
➢Goodelongationproperty
Designatedas:SG50/7,SG80/2
FirstnumbergivesthetensilestrengthinMPa
Secondnumberindicatespercentageelongation.
S K Chand (Assistant Professor)
Government Engineering College, Raipur

21. Austenitic cast iron
Dependingontheformofgraphitepresentthese
castironisclassifiedbroadlyundertwoheadings
➢Austenitic flake graphite iron, AFGNi16Cu7Cr2
➢Spheroidal/nodulargraphiteiron,ASGNi20Cr2
Usedformakingautomobileparts:cylinders,
pistons,pistonrings,brakedrumsetc.
S K Chand (Assistant Professor)
Government Engineering College, Raipur

22. Abrasion resistant cast iron
Thesearealloycastironandthealloying
elementsprovideabrasionresistance.
Typicaldesignation:ABR33Ni4Cr2
IndicatesatensilestrengthinMPawith4%
nickeland2%chromium.
S K Chand (Assistant Professor)
Government Engineering College, Raipur

23. Wrought iron
•Thisisverypureironwheretheironcontentisofthe
orderof99.5%.
•Itisproducedbyre-meltingpigironandadditionof
verysmallamountofsilicon,sulphurandphosphorus.
•Itistough,malleableandductileandcaneasilybe
forgedorwelded.
•Itispoorinshock/impactloading.
•Chains,cranehooks,railwaycouplingsandsuchother
componentsmaybemadeofthisiron.
S K Chand (Assistant Professor)
Government Engineering College, Raipur

24. Steel
•Thisisbyfarthemostimportantengineeringmaterialandthereis
anenormousvarietyofsteeltomeetthewidevarietyofengineering
requirements.
•Steelisanalloyofironandcarboninwhichthecarboncontentcan
belessthan1.7%andcarbonispresentintheformofironcarbide
(????????????
3??????)toimparthardnessandstrength.
Twomaincategoriesofsteel
➢Plaincarbonsteel
➢Alloysteel
S K Chand (Assistant Professor)
Government Engineering College, Raipur

25. Plain carbon steel
•Thepropertiesofplaincarbonsteeldependmainlyonthecarbon
percentage.Otheralloyingelementsusuallynotpresentinmorethan
0.5%to1%.
•DesignatedasC01,C14,C45,C70,wherethenumbersindicatethe
carbonpercentage.
Categorizationofplaincarbonsteel
➢Deadmildsteel-upto0.15%C
➢Lowcarbonsteelormildsteel-0.15%to0.46%C
➢Mediumcarbonsteel-0.45%to0.8%C
➢Highcarbonsteel-0.8%to1.5%C
Ingeneralhighercarbonpercentageindicateshigherstrength.
S K Chand (Assistant Professor)
Government Engineering College, Raipur

26. S K Chand (Assistant Professor)
Government Engineering College, Raipur
Alloy steel
•Thesearesteelsinwhichelementsotherthancarbonareaddedinsufficient
quantitiestoimpartdesiredproperties,suchaswearstrength,corrosionresistance,
electricandmagneticproperties.
Chiefalloyingelements
Nickel:Strengthandtoughness
Chromium:Hardnessandstrength
Tungsten:Hardnessatelevatedtemperature
Vanadium:Tensilestrength
Manganese:Highstrengthathotrolled/heattreatedcondition
Silicon:Highelasticlimit
Cobalt:Hardness
Molybdenum:Extratensilestrength
e.g.35Ni1Cr60,30Ni4Cr1,stainlesssteel(18/8steel):18%Crand8%Ni

27. Non-Ferrous Metals
Metalscontainingelementsotherthanironastheirchief
constituentsareusuallyreferredtoasnon-ferrousmetals.
Aluminium
•Thisisawhitemetalproducedfromalumina.
•Initspurestateitisweak&softbutadditionofsmallamounts
ofcopper,manganese,siliconandmagnesiummakesithard
andstrong.
•Itisalsocorrosionresistant,lowweightandnon-toxic.
S K Chand (Assistant Professor)
Government Engineering College, Raipur

28. Duralium
Thisisanalloyof4%Cu,0.5%Mn,0.5%Mgandaluminium.It
iswidelyusedinautomobileandaircraftcomponents.
Y-alloy
Thisisanalloyof4%Cu,1.5%Mn,2%Ni,6%Si,Mg,Feand
restisAl.itgiveslargestrengthathightemperature.Itisusedfor
aircraftenginepartssuchascylinderheads,pistonetc.
S K Chand (Assistant Professor)
Government Engineering College, Raipur

29. S K Chand (Assistant Professor)
Government Engineering College, Raipur
Magnalium
Thisisanaluminiumalloywith2to10%magnesium.Italso
contains1.75%Cu.Duetoitslightweightandgoodstrengthitis
usedforaircraftandautomobilecomponents.
Copper-alloys
Copperisoneofthemostwidelyusednon-ferrousmetalin
industry.itissoft,malleableandductileandisagoodconductor
ofheatandelectricity.

30. S K Chand (Assistant Professor)
Government Engineering College, Raipur
Brass (Cu-Zn alloy)
•ItisfundamentallyabinaryalloywithZnupto50%.
•Upto~37%,asZnpercentageincreases,ductilityincreases.
Beyondthatductilityfalls.
•Smallamountofotherelementsviz.leadortinimpartsother
propertiestothebrass.Leadgivesgoodmachiningqualityand
tinimpartsstrength.
•Brassishighlycorrosionresistant,easilymachinableand
thereforeagoodbearingmaterial.

31. S K Chand (Assistant Professor)
Government Engineering College, Raipur
Bronze (Cu-Snalloy)
Thisismainlyacopper-tinalloywheretinpercentagemayvary
between5to25.Itprovideshardnessbuttincontentalsooxidizes
resultinginbrittleness.DeoxidizerssuchasZnmaybeadded.
Gun Metal
Itisanalloywhere2%Znisaddedasdeoxidizingelementand
typicalcompositionsare88%Cu,10%Snand2%Zn.Thisis
suitableforworkingincoldstate.Itwasoriginallymadefor
castinggunsbutnowusedforboilerfittings,bushesetc.

32. Non-metalsareusedinengineeringpracticemainlyduetotheir
lowcost,flexibilityandresistancetoheatandelectricity.
Timber
•Thisisarelativelylowcostmaterial.
•Badconductorofheatandelectricity.
•Goodelasticandfrictionalproperty.
•Widelyused:foundrypattern,waterlubricatedbearing.
S K Chand (Assistant Professor)
Government Engineering College, Raipur
Non-Metals

33. Leather
Thisiswidelyusedinengineeringforitsflexibilityandwear
resistance.
Uses:beltdrives,washersetc.
Rubber
Ithashighbulkmodulusandisusedfordriveelements,sealing,
vibrationisolationandsimilarapplications.
S K Chand (Assistant Professor)
Government Engineering College, Raipur

34. Plastics
Thesearesyntheticmaterialswhichcanbemouldedintodesired
shapesunderpressurewithorwithoutapplicationofheat.These
arenowextensivelyusedinvariousindustrialapplicationsfor
theircorrosionresistance,dimensionalstabilityandrelativelylow
cost.
Therearetwomaintypesofplastics-
➢Thermosettingplastic
➢Thermoplastics
S K Chand (Assistant Professor)
Government Engineering College, Raipur

35. Thermosetting Plastics
•Thermosettingplasticsareformedunderheatandpressure.
•Itinitiallysoftensandwithincreasingheatandpressure,
polymerisationtakesplace.Thisresultsinhardeningofthe
material.
•Theseplasticscannotbedeformedorremouldedagainunder
heatandpressure.
•Someexamplesofthermosettingplastics:Phenolformaldehyde
(Bakelite),Phenol-furfural(Durite),Epoxyresins,Phenolic
resins.
S K Chand (Assistant Professor)
Government Engineering College, Raipur

36. S K Chand (Assistant Professor)
Government Engineering College, Raipur
Thermoplastics
•Thermoplasticsdonotbecomehardwiththeapplicationofheat
andpressureandnochemicalchangetakesplace.
•Theyremainsoftatelevatedtemperaturesuntiltheyare
hardenedbycooling.
•Theycanbere-meltedandremouldedbyapplicationofheatand
pressure.
•Someexamplesofthermoplasticsare:Cellulosenitrate
(Celluloid),Polythene,Polyvinylacetate,PolyvinylChloride
(PVC).

37. S K Chand (Assistant Professor)
Government Engineering College, Raipur