dmp study guide

7/26/2019 DMP Study Guide

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IE 3304EXAM II SAMPLE QUESTIONSDr. S. Raman

NAME:________________ ____

Student ID #:____________ _______

IE 3304EXAM II

!"$ed %&' !"$ed Nte$(

Note: 1. Show all steps while solving numerical examples.

2 2. State all assumptions explicitly.

Question 1. (30 points)

Observe the specification of the part shown below. Do not scale drawing. All dimensions are ininches.

A. The raw material is AISI 1213 steel bar (diameter of 3.3 inches and length of !.3 inches" of

hardness 1#$ %&'%. The inventor of c)tting tools available to the compan are inde*able carbide ()ncoated"

single point tool inserts+ 12$ degree lip standard &SS drills+ coated carbide co)nterboring and

co)ntersin,ing tools and$ carbide+ inde*able end-milling tool inserts.


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a. ompare the feat)res on o)r specified part with the feat)re tables

provided. Identif feat)res on o)r part. /ist all o)r feat)res in the table shown below.(&I'T0 o) might be re)ired to flip the part over at some point. hec, raw material

specifications to determine the n)mber of passes".

eature eature !lassi"ication eature Name an# $ype

1 %xterna& rotational %n# "acing& le"t

2

*+rotational Threads+ right

3 *ternal Sho)lder+ right

4 *ternal nd facing+ right

# *ternal linder

! Internal+rotational lat sho)lter+right

5 Internal lat face hole+ right

b. Decompose ever feat)re into one or more operations. 6a,e entries into the table as shownbelow.

eature eature Name an# $ype 'peration 'peration Name1 %n# "acing& le"t '1 ace turning

2 $hrea#s & right '2 threa#ing

cylin#er '3 ough straight turning

'* inish straight turning

3

shoul#er& right ' ough shoul#er turning

'+ "inish shoul#er turning

* nd face+ right ', ace turning

+ %lind hole+ right '- #rilling

,

lat sho)lder ' counter/oring

c. 7repare a precedence table as shown below. 6a,e s)re o) write the r)le for each

precedence.


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'peration rece#ing operations an# reason "or prece#ence

'1

'2

--

'3 '2 (location)

'* O3 (intermediate s)rface "

' O2 (dimension" (location"

'+ O# (intermediate s)rface "

', O! (location"

'- O! (location"

' O+O! ( location"

(30 oints)

2 or the data specified in 7roblem II+ and the additional data below+ perform a machining time

analsis as specified below in s)b-)estions 1-!.

. The machine tool to be )sed is an A6 (1$&7" /athe. 8or, holder is a standard three-9aw

ch)c,.D. The ma*im)m allowable depth of c)t in t)rning and facing+ on the A6 lathe )sed+ is $.1#

inch while the minim)m depth of c)t is $.$4. (&int0 depth of c)t is a radial distance". All critical tolerances for part (si:e and geometr" are achievable witho)t )se of grinding+

honing+ lapping+ polishing or )ltraprecision operations.

. Standard shan, width of single-point tools is $.! inch with tool tip at the center of the shan,

width. Incl)ded angle at the tip of the single-point tool is ;$


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*. Determine the feedrate and c)tting speed for drilling the central hole in the part+ from the

accompaning table.

. alc)late the approach allowance for drilling the central hole.

+. alc)late the linear speed and machining time in drilling the central hole.

Question 3 (*0 points)

Answer the following in 2-3 sentences each.

a. 8hat is process planning=

Process planning is the coordinated selection and sequencing of machining operations to convert a rawmaterial to a finished product. It contained an orderly listed process details.

b. *plain (with s)itable e*amples" an three tpe of precedence emploed while preparingoperation se)ences.

i. Intermediate feat)re0 e*ample+ ro)gh t)rning has to be done prior to finishing. Similarl+

drilling is done before boring+ reaming+ co)nterboring+ or co)ntersin,ing. In other words+the hole has to be drilled before modifications.

ii. Dimensioning0 for e*ample+ facing perpendic)lar to the clinder. Then dat)m feat)re a+

has to be established first+ or facing has to be done prior to t)rning.

iii. 8or, piece locations0 some machinists do an end facing and partial clindrical t)rning of

one end of wor, material prior to other machining operations. Therefore+ the partiall t)rnedclinder becomes the locating s)rface for s)bse)ent machining operations.

c. 8hat are the fo)r components of time in the calc)lation of prod)ction time= *plain each ina sentence or two.

6achining Time0 Total time when feed is engaged

'on-machining Time0 All e*tra>repetitive activities d)ring machining of a part.Down Time0 Time spent fi*ing brea,downs and bottlenec,s.

Set)p Time0 Time to gather tools and get machine read.

d. 8hat is the difference between drilling+ reaming and boring operations=

Drilling0 It is a m)ltipoint hole-ma,ing operation done with a standard si:e.

%oring0 *pansion of an e*isting hole+ created after drilling. Single point+ non-standard holema,ing operation.

?eaming0 6)ltipoint+ precise+ more acc)rate hole ma,ing operation+ carried o)t after drilling.

e. 8hat is a tapping operation= 8hat is co)nter-boring=

Counter-boring: Creates seat or depression for bolt heads.


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Tapping: It is used for making smaller (depth) internal threads.

f. 8hat is face milling= &ow is it different than peripheral milling= 8hat is end milling=

Face: Uses a tool that is Perp to the work part. Face of tool is doing machining.Peripheral: The axis of the tool is parallel to the direction of cut. dge of cylindrical side is doing

machining.nd !illing: Is a type of peripheral milling" face and the peripheral are used for slotting" milling etc

g. 8hat are the advantages to )sing ' 6achines+ in terms of time and cost=

&igher prod)ction rate

Shorter lead times

6)ltiple milling+ t)rning+ and drilling operations &igh precision

?ed)ced waste

h. 8hat are three basic tpes of a)tomation in man)fact)ring=

Fixed automation - the processing or assembly steps and their sequence are fixed by the

equipment configuration ( automobile assembly line )

Programmable automation - equipment is designed with the capability to change the program

of instructions to allow production of different parts or products ( CNC machine ) Flexible automation - an extension of programmable automation in which there is virtually no

lost production time for setup changes or reprogramming

i. 8hat are open loop control sstems= 8hat are closed loop sstems=


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9. *plain the wor,ing of a ' 6achining sstem.

The ' machine comprises of the comp)ter in which the program is fed for c)tting of themetal of the 9ob as per the re)irements. All the c)tting processes that are to be carried o)t

and all the final dimensions are fed into the comp)ter via the program. The comp)ter th)s

,nows what e*actl is to be done and carries o)t all the c)tting processes. ' machinewor,s li,e the ?obot+ which has to be fed with the program and it follows all o)r

instr)ctions.

Some of the common machine tools that can r)n on the ' are0 /athe+ 6illing machines+Drilling 6achine etc. The main p)rpose of these machines is to remove some of the metal so

as to give it proper shape s)ch as ro)nd+ rectang)lar+ etc. In the traditional methods these

machines are operated b the operators who are e*perts in the operation of these machines.

6ost of the 9obs need to be machined acc)ratel+ and the operator sho)ld be e*pert eno)gh toma,e the precision 9obs. In the ' machines the role of the operators is minimi:ed. The

operator has to merel feed the program of instr)ctions in the comp)ter+ load the re)ired

tools in the machine+ and rest of the wor, is done b the comp)ter a)tomaticall. The

comp)ter directs the machine tool to perform vario)s machining operations as per theprogram of instr)ctions fed b the operator.

@o) dont have to worr abo)t the acc)rac of the 9obB all the ' machines are designed tomeet ver close acc)racies. In fact+ these das for most of the precision 9obs ' machine is

comp)lsor. 8hen o)r 9ob is finished+ o) dont even have to remove it+ the machine does

that for o) and it pic,s )p the ne*t 9ob on its own. This wa o)r machine can ,eep ondoing the fabrication wor,s all the 24 ho)rs of the da witho)t the need of m)ch monitoring+

of co)rse o) will have to feed it with the program initiall and s)ppl the re)ired raw

material.

6ost of the man)fact)ring companies are now e)ipped with the ' machines as the mar,etshave got ver competitiveB however+ getting the e*pert labors for operating these machines is

becoming )ite diffic)lt. ven the machine operators of these das prefer to operate the

machine b programming instead of operating it man)all. In most of the machine toolstraining instit)tes the new operators are ta)ght man)al machining as well as ' machining

and programming.


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*tra0

8hat are operation precedencies= And wh are the needed =#peration precedence is the ta$le to indicate how an operation must $e done prior to

other operations. They are needed to determine feasi$le operation sequence.

What is the difference between internal threading and tapping of holeson a lathe? When is each employed?Tapping with a tap is a multipoint operation whereas threading is performed using a

single point tool. Internal threading is used when deeper threads are required andtapping is employed when small threads are needed.

What are 4 main factors used to assess machinability? Explain in somedetail.

Tool life: The life of the tool usually determines num$er of tool changes. !ore toolchanges means less productivity and low quality%urface &oughness: The finish of the part is governed $y the material com$ination andcutting parameter selectionForces and power: 'utting forces are measured to calculate powerType of chip: 'ontinuous chips are common. (ong chips must $e $roken and shortchips fly out a lot. )uilt up edge is undesira$le

Give two examples of single-point operations and two examples of multi-point (fixed geometry operations

%ingle point operations: Turning" )oring!ulti*point +fixed geometry,: !illing and -rilling

What is spot facing? How is it dierent than Counter-Boring? What is CounterSinking?

Spot facing is performed to atten/smooth the surrounding surface around a hole to provide,for example, a good seating for nuts, bolts, and washers.Counterboring on the other hand, produces a depression on the surface to accommodate theheads of screws and bolts below the workpiece surface.Countersinking produces a conical cavity to allow a screw head to sit at on the workpiecesurface.

What instrument is used to measure cutting forces during machining?-ynamometer" %train*gauge

10 operations on a latheFacing, Straight urning, aper turning, Cutting o!,

"oring, aper turning, #ro$ling with a form tool, %rilling, &xternal 'rooving, (nternal

'rooving, Face 'rooving, hreading, )nurling, Sanding, *eaming, Form Cutting 10 operations on a Mill: Slab milling, climb milling, slotting, side milling, straddle

milling, form milling,conventional face milling, partial face milling, face milling, endmilling, high speed end milling, form milling, Slitting, pocket milling, contour milling.

rilling operations: %rilling, core drilling, step drilling, counter boring,

countersinking, reaming, center drilling, gun drilling, trepanning, tapping, orbitaldrilling, vibration drilling, spot facing.

+hen is tapping employed as an alternate to internal threading-ne reason for using apping as alternative to internal threading is when the internaldiameter is too small to $t a tool.


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dditionally, tapping presents the advantage of high speed production compared withthreading, nevertheless tapping doesnt allows for ad0usting thread $t, means once the holeis tapped, si1e and position of the thread is $nal.

hreading is used when higher pitch and depth of thread are desired.

!ist the "asic t#pes of tool $aterials e$plo#ed in $achining%

2. 3igh Speed Steel 43SS563ighly alloyed tool steel capable of maintaining hardness at elevated temperaturesbetter than high carbon and low alloy steels

&specially suited to applications involving complicated tool shapes6 drills, taps,

milling cutters, and broaches wo basic types of 3SS 4(S(5

2. ungsten7type, designated 7 grades8. 9olybdenum7type, designated 97grades

8.Cemented Carbides4+C5 using powder metallurgy techni:ues with cobalt 4Co5 as the binder

wo basic types6

2. ;on7steel cutting grades 7 only +C7Co8. Steel cutting grades 7 iC and aC added to +C7Co

. Coated Carbides

Cemented carbide insert coated with one or more layers of iC, i;, and/or l8-


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where v B cutting speed TB tool life and nand Care parameters that depend on feed,depth of cut, work material, tooling material, and the tool life criterion used

nis the slope of the plot

Cis the intercept on the speed axis at one minute tool life

F. What are the $ain factors used to ealuate $achina"ilit#?

1% Machina"ilit#

o *elative ease with which a material 4usually a metal5 can be machined

using appropriate tooling and cutting conditionso %epends not only on work material

o ype of machining operation, tooling, and cutting conditions are also

important factors


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o ool life D longer tool life for the given work material means better machinability

o Forces and power D lower forces and power mean better machinability

o Surface $nish D better $nish means better machinability

o &ase of chip disposal D easier chip disposal means better machinability

*n /ddition the following should "e noted%

o 3ardnesso 3igh hardness of work material means abrasive wear increases so tool life is

reducedo Strength

o 3igh strength of work material means higher cutting forces, speci$c energy,

and cutting temperatureo %uctility

o 3igh ductility of work material means tearing of metal to form chip, causing

chip disposal problems and poor $nish

9ore implicitly, other factors also come into play.1% &olerances and Surface 2inish

o olerances

o 9achining provides high accuracy relative to most other shape7makingprocesses

o Closer tolerances usually mean higher costs

o Surface roughness in machining is determined by6

o 'eometric factors of the operation

o +ork material factors

o Eibration and machine tool factors

3% Selection of Cutting Conditions

o Cutting conditions6 depth of cut, feed, speed, and cutting uid

o hese decisions must give due consideration to workpart

machinability, part geometry, surface $nish, and so forth

4% 5roduct esign Considerations in Machiningo %esign parts that need no machining

o se net shapeprocesses such as precision casting, closed die

forging, or plastic moldingo (f not possible, then minimi1e amount of machining re:uired

o se near net shapeprocesses such as impression die forgingo *easons why machining may be re:uired6

o Close tolerances

o 'ood surface $nish

o Special geometric features6

o hreadso ccurate holes

o ccurate cylindrical sections

o Flat and/or straight surfaces

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