Manufacturing Engineering II lecture one (3).pdf

This lecture will provide clear understanding on manufacturing engineering, machining process, traditional machining process and on their examples.

1. University of Gondar
Instituteoftechnology
Departments of MechanicalEngineering
Manufacturing Engineering II meng
By;-Belete A. ( Msc.)

2. Lecture one
Traditional machine process

3. Presentation outline
The over all contents of dissuasion will be;-
Overviews of manufacturing Engineering
What important do manufacturing Engineering have
What are the basic manufacturing machining processes
Why traditional manufacturing
Examples of different traditional machining process
Types of cutting tools for traditional machining processes.

4. Objectives of the presentation
The objectives of this presentation is to address the over all points listed in
the presentation outline
The students are expected to go through those listed presentation outline.

5. Whatismanufacturing?
Latin definition;-manufactusmeaning ‘made by hand’ or ‘hand-made
InmodernEnglishdictionarycontext;-themakingofproductsfromraw
materialsusingvariousprocesses,equipment,operationsandmanpoweraccording
toadetailedplan.
generallymanufacturingisthe;-
Introduction and Overview of Manufacturing
the conversion of stuff into things.
“actofmakingsomething(aproduct) fromrawmaterials”

6. Important of Manufacturing
1.Technologically;-since technologyis the application of scienceto provide society anditsmemberswith
thosethingsthatareneededor desired;-
Technologyprovidestheproductsthathelpthe society to livebetter .
These technological products will be manufactured;
ManufacturingistheessentialfactorthatmakestechnologyPossible.
2.Economically;-Manufacturing is one wayby which nations creatematerialwealth;
Examples in us economy;- Sector % of GNP(Gross net
product)
Manufacturing 20%
Agriculture, mineral etc. 5%
Construction and utilities 5%
Servicesector;-retail,transportation,bank,
communication,educationandGovernment
70%
3.Historically;-to establish the future relative to the existing technology

7. Types of manufacturing process
The processes to accomplish manufacturing involve a combination of machinery, tools,
power, and labor,
A manufacturing process is usually carried out as a unit operation (single step in the sequence
of steps required to transform the starting material into a final product).
Two ways to define manufacturing: (a) as a technical process, and (b) as an economic process.

8. Cont.
Manufacturingoperations;-
(1).Processingoperations;-transformsaworkmaterialfromonestateofcompletiontoa
moreadvancedstatethatisclosertothefinaldesiredproduct.
Operationsthatchangethegeometry,properties,orappearanceofthestartingmaterial.
(2).Assemblyoperations;-joinstwoor
morecomponentstocreateanewentity,
calledanassembly,subassembly,orsome
othertermthatreferstothejoiningprocess
(e.g.fasteners,weldment).
Classification of manufacturingprocesses.

9. What is Machining?
Machiningisagroupofprocessesthatconsistoftheremovalofmaterialand
modificationofthesurfacesofaworkpieceafterithasbeenproducedbyvarious
methods.Thus,machininginvolvessecondaryandfinishingoperations.
Itisashearingprocessinwhichexcessmaterialsisremovedbycuttingtools.Itis
generallyperformedafterothermanufacturingprocessessuchascastingorbulk
deformation(e.g.,forging,bardrawing).
Theotherprocessescreatethegeneralshapeofthestartingworkpart,andmachining
providesthefinalgeometry,dimensions,andsurfacefinish.
Machining process

10. Why Machining and is it Important?
it is applicable to most materials
it can produce a variety of geometries and shapes
Screw threads
Accurate round holes
it can achieve closer tolerances than most other processes
Good dimensional accuracy and surface finish

11. Disadvantages with Machining
Wasteful of material
Chips generated in machining are wasted material
Time consuming
A machining operation generally takes longer to shape a given part
than alternative shaping processes
The accuracy of the components produce is dependent on the efficiency
of the operation personnel (operator)

12. Machining process
Types of machining process
1.Conventional/traditional/machiningprocess;-Itisthebasicmethodofthemetal
removingprocessthatremovesamaterialanddecreasesmetalmass.Theprincipal
machiningprocessesareclassifiedasturning,drillingandmilling.Other
operationsmiscellaneouscategoriesincludeshaping,planning,boring,broaching
andsawing.
2.Unconventional/nontraditional/machiningprocess;-,isamachiningmethod
thatuseselectricalenergy,heatenergy,lightenergy,electrochemicalenergy,
chemicalenergy,soundenergy,andspecialmechanicalenergytoremove,deform,
changeproperties,orplatematerials.

13. Traditional machining process
Amaterialremovalprocessinwhichasharpcuttingtoolisused
tomechanicallyremovesworksurfacesothatthedesiredpart
geometryremains.
Mostcommonapplication:toshapemetalparts.
Machiningisthemostversatileandaccurateofall
manufacturingprocessesinitscapabilitytoproduceadiversity
ofpartgeometriesandgeometricfeatures.

14. TURNING
A single point cutting tool removes material from a rotating
workpiece to generate a cylindrical shape;
Performed on a machine tool called a lathe;
Various types of turning that are performed on a lathe:
Facing
Contour turning
Chamfering
Cutoff
Threading
Turning operation

15. Cont. …
Facing Tool is fed radially inward
Contour Turning
Insteadoffeedingthetoolparalleltotheaxis
ofrotation,toolfollowsacontourthatisother
thanstraight,thuscreatingacontouredform
orprofile.
Facing operation;-reduces the
length of the workpiece.

16. Cont.
Chamfering;-Cuttingedgecutsanangleonthecornerofthe
cylinder,forminga"chamfer"
Cutoff;-Toolisfedradiallyinto
rotatingworkatsomelocationtocut
offendofpart

17. Cont.
Drillingoperation;-canbeperformedin
lathemachine
Threading;-Pointedformtoolisfed
linearlyacrosssurfaceofrotatingwork
partparalleltoaxisofrotationatalarge
feedrate,thuscreatingthreads
Knurling;-Inthis,aknurling
toolhavingtherequisiteserration
isforcedontothework-piece
thusdeformingthetoplayer.

18. LATHE SPECIFICATION
There are a number of factors that should be specified to fully describes a
lathe machine.
Distance between centers;-specifies the maximum length of the
job that can be turned.
Swing over the bed;-specifies the maximum diameter of the job
that can be turned.
Swing over the cross-slide;-specifies the maximum diameter of
the job that can be turn with the job across the cross-slide.
Horse Power of motor.
Cutting speed range.
Feed range.
Screw cutting capacity.
Spindle nose diameter and hole size.

19. Types of cutting in lath machine
OrthogonalCutting;-Cuttingedgeis
straight,paralleltotheoriginalplane
surfaceattheworkpieceand
perpendiculartothedirectionofcutting.
thedirectionofcutting.
ObliqueCutting;-Cuttingedgeofthe
toolisinclinedtothelinenormaltothe
cuttingdirection.Inactualmachining,
Turning,Millingetc/cuttingoperations
areobliquecutting

20. Machining parameters

21. Drilling
Creates a round hole in a work part
Contrasts with boring which can only enlarge an existing hole
Cutting tool called a drill or drill bit
Customarily performed on a drill press/droll machine.
Through Holes vs. Blind Holes
Through-holes;-drill exits the opposite side of work
Blind-holes;-drill does not exit work on opposite side

22. Cont.
Reaming;-Usedtoslightlyenlargeahole,
providebettertoleranceondiameter,andimprove
surfacefinish
Tapping;-Usedtoprovideinternalscrewthreadson
anexistingholeToolcalledatap
CounterboringProvidesa
steppedhole,inwhichalarger
diameterfollowsasmaller
diameterpartiallyintothehole

23. Cont.
Upright Drill
Stands on the floor
Bench Drill ;-Similar
but smaller and mounted
on a table or bench
RadialDrill
Largedrillpressdesigned
forlargeparts
WorkHoldingforDrillPresses;-Workpartcanbeclampedin
avise,fixture,orjig
Vise;-generalpurposeworkholderwithtwojaws
Fixture;-workholdingdevicethatisusuallycustom-designed
fortheparticularworkpart
Drilljig;-similartofixturebutalsoprovidesameansof
guidingthetoolduringdrilling.

24. Milling
Itisoneoftheconventionalmachiningprocesswhere;
Machiningoperationinwhichworkisfedpastarotatingtool
withmultiplecuttingedges
Rotatingmultiple-cutting-edgetoolismovedacrossworktocuta
planeorstraightsurface
Twoforms:peripheralmillingandfacemilling

25. Cont.
Machining operation in which work is fed past a rotating tool with
multiple cutting edges.
Axis of tool rotation is perpendicular to feed direction.
Creates a planar surface; other geometries possible either by cutter
path or shape.
Other factors and terms:
Milling is an interrupted cutting operation
Cutting tool called a milling cutter, cutting edges called "teeth“
Machine tool called a milling machine
peripheral milling, face milling

26. Milling machine and its operations
Millingisaprocessofremovingmetalbyfeedingtheworkagainstarotating
multipointcutter.
Themachinetoolintendedforthispurposeisknownasmillingmachine.
Itisusedformachiningflatsurfaces,contouredsurfaces,surfacesof
revolution,externalandinternalthreads,andhelicalsurfacesofvarious
cross-sections
Types of milling machine
1.Column and knee type
a)Plain milling machine.
b)Universal milling machine .
c)Omniversalmilling machine.
d)Vertical milling machine.
2. Table type milling machine.
3. Planer type milling machine.
4. Special type milling machine

27. Cont..
•Nevertheless,millingmachinesaretypicallydividedintoverticaland
horizontalmillingmachinesbasedonhowthespindleaxisisarrangedin
relationtotheplaneoftheworkpiece.
1.Verticallyorientedmillingmachines;-A
spindleofaverticalmillingmachineis
positionedatrightanglestothetable.Thecutter
ismovedverticallyoratananglebyswiveling
theverticalheadofthemachine
2.Horizontalorientedmillingmachines;-
Aspindleofahorizontalmillingis
positionedparalleltothetable.Thecutter
ismovedhorizontally.
vertically oriented milling machines
Horizontally oriented milling machines

28. Sizes of a milling machine
Thesizeofamillingmachineisspecifiedas;-
1.Thesizeofthetable(lengthandwidth)
2.Themaximumlengthsoflongitudinal,crossandverticaltravelofthetable.
3.Numberofspindlespeeds,numberoffeeds
4.Spindlenosetaper
5.Powerrequired
6.Netweightofthemachine
7.Thefloorspacerequired
8.Typeofthemachine
vertically oriented milling machines Horizontally oriented milling machines

29. Standard milling cutters
Different types of milling cutters are used in a milling machine depending
up on the shape and size required .
1.Plain milling cutter
2.Side milling cutter
3.Metal slitting saw
4.Angle milling cutter
5. End milling cutter
6. ‘T’ –Slot milling cutter
7. Fly cutter
8.Formed cutter

30. Cont

31. Peripheral Milling vs. Face Milling
Peripheral milling
Cutter axis is parallel to surface being machined.
Cutting edges on outside periphery of cutter.
Face milling
Cutter axis is perpendicular to surface being milled
Cutting edges on both the end and outside periphery of the cutter
peripheral milling face milling
Milling operations

32. Slab Milling;-The basic form of peripheral milling in
which the cutter width extends beyond the workpiece on
both sides
Slotting;-Widthofcutterislessthanworkpiecewidth,
creatingaslotinthework
ConventionalFaceMillingCutteroverhangsworkon
bothsides
Other milling operations

33. Cont.
EndMilling;-Cutterdiameterislessthan
workwidth,soaslotiscutintopart
Profile Milling Form of end
milling in which the outside
periphery of a flat part is cut
PocketMilling;-Anotherformofend
millingusedtomillshallowpockets
intoflatparts.
SurfaceContouring;-Ball-nosecutterisfedbackand
forthacrosstheworkalongacurvilinearpathatclose
intervalstocreateathreedimensionalsurfaceform.

34. Milling operations
Millingoperationsareoftwotypesrelativetothefeedandcutter
rotationdirection.
Downmilling;-Thecutterdirectionissamedirectionasthemotionofthe
workpiecebeingfed.
Upmilling;-Workpieceismovingtowardsthecutter,opposingthecutter
directionofrotation.Surfacefinishisbetterincaseofdownmilling,butthe
stressloadontheteethisabruptthatmaydamagethecutter.

35. Difference between up and down milling
Upmilling Down milling
There is propensity to lift work piece,so extra
clamping forces are required to fix job on table.
Forces are enough on job to press down. Thus
clamping difficulty is not so much.
Cutter turns against direction in which the work
is being fed.
Cutter turns in similar direction as to in which
the work is being fed.
It use of cutting fluid is complicated.It use of cutting fluid is simple.
Cutting force vary as of zero to maximum.Cutting forces vary as of maximum to zero.
Job tool movement is in opposite way.Job tool movement is in the similar direction.
Chip thickness differs as of minimum to
maximum.
Chip thickness differs as of minimum to
maximum.
It surface finish is improved. It surface finish is improved, if it is free as of
backlash error.
It is feasible. It is unfeasible.

36. Shaping and Planning;
Interrupted cutting
Subjects tool to impact loading when
entering work
Low cutting speeds due to start-and-stop
motion.
Usual tooling: single point high speed steel
tools.
Similar operations and operations are performed in planning machine
Both use a single point cutting tool moved linearly relative to the work part
A straight, flat surface is created in both operations

37. Cont.
planer machine
Shaper machine

38. Machining Operations and Part Geometry
Each machining operation produces a characteristic part geometry due to
two factors:
Relative motions between the tool and the work part.
Generating ;-part geometry is determined by the feed trajectory of the
cutting tool.
Generating shape: (a) straight turning, (b) taper turning, (c) contour turning, (d) plain milling, (e) profile milling

39. Cont.
Shape of the cutting tool
Forming;-part geometry is created by the shape of the cutting tool
Forming to create shape: (a) form turning, (b) drilling, and (c) broaching

40. Combinations of forming and generation
Both forming and generating to create shape: (a) thread cutting on a lathe, and (b) slot milling