Coursework 1- CAD CAM

ME 4332

ME 4332

Computer Ai

Computer Aided Design and

ded Design and Manufacture

Manufacture

Precision Manufacturing Machines, Tools and

Precision Manufacturing Machines, Tools and

Work-holding Devices

Work-holding Devices

Name:

Name: RC RC WisidagamaWisidagama

Index No:

Index No: 120735C 120735C

Date of Sumission:

P!"T #

$a%out

!igure 1 " Wor#shop $a%out &'ot to sca$e()

&eneral Information

*he die and mo$d center consists of 5 C'C machines+ as sho,n in figure 1+ name$%+

Ari- .1000 C'C .ertica$ Machining Center &.MC( ,ith !anuc contro$$er  /artford  1000 C'C .ertica$ Machining Center ,ith Mitsuishi contro$$er  ing par# E6' C'C in# EDM

ing par# W W* C'C Wire EDM Ari- *'C 430 C'C *urning Center &athe(

n addition+ the Coordinate Measurement Machine &CMM( room contains a De Meet6chut 443 CMM unit+ ,hich can e used to chec# fine to$erances and for re8erse engineering purposes)

Discussion - Selection of N'('N' machines for different a))lications

Due to the a8ai$ai$it% of a $arge numer of 'C6C'C de8ices+ this discussion ,i$$ e $imited to the machines a8ai$a$e in the Die and Mou$d Center)

•  'C6C'C mi$$ing operation

A mi$$ing machine can e simp$% defined as a de8ice that can perform machining operations

simu$taneous$% at $east a$ong t,o a-es+ using an end mi$$ as a primar% cutting too$) Depending on the orientation of the spind$e+ the% can e c$assified main$% as 8ertica$ or hori9onta$ mi$$ing machines) n  'C6C'C mi$$ing+ the main t%pes are+

o  'C6C'C .ertica$ Machining Center &.MC( o  'C6C'C /ori9onta$ Machining Center &/MC( o  'C6C'C :oring Mi$$

.MCs are used in app$ications ,here most of machining is carried out on one face of the ,or#piece during one setup+ such as f$at p$ate t%pe ;os) n addition to the asic three a-es+ a fourth a-is can e created % insta$$ing a rotar% head on the ta$e+ either hori9onta$$% or 8ertica$$%+ ,hich ma% then e used for inde-ing or contro$$ed rotar% motion) .MC is the most common t%pe of machining center a8ai$a$e in ,or#shops) /MCs are used for instances ,here machining must e carried out in mu$tip$e surfaces of a part in a sing$e setup) *he% usua$$% inc$ude an inde-ing ta$e and pa$$et changer) /ence+ the% are usua$$% priced higher than .MCs) 'o /MCs are a8ai$a$e in the Die and Mou$d center)

:oring mi$$s usua$$% contains a hori9onta$ spind$e a-is and are simi$ar to /MCs+ e-ception eing that the primar% purpose is oring) arge $engths can e ored at a gi8en time due to the a8ai$ai$it% of a specia$$% designed <ui$$ to accommodate the too$)

•  'C6C'C turning operation

*urning operations are carried out % the use of a $athe+ using an e-terna$ too$ to remo8e materia$ ,hi$st the chuc#ed a-is=s%mmetric ,or#piece is eing rotated around the spind$e a-is) A 'C6C'C $athe is usua$$% #no,n as a turning center) n addition to the traditiona$ $athe operations such as turning and oring+ processes such as dri$$ing+ groo8ing+ threading+ #nur$ing and urnishing ma% e carried out ,ith ease) *he t,o asic t%pes are hori9onta$ and 8ertica$+ c$assified according to the spind$e a-is) n addition+ these de8ices ma% come in t,o+ three+ four or si- a-is forms+ thus  pro8iding features for machining of e-treme$% comp$e- geometries)

•  'C6C'C E$ectro=Discharge Machining &EDM( operations

*he t,o most common t%pes are the die sin#ing machining centers and ,ire EDM) *he% use the  princip$e of spar# erosion of meta$s during an e$ectrica$ discharge+ ,here the ,or#piece is

surrounded % a die$ectric f$uid) Wire EDM is used in app$ications of generating contours e8en in e-treme$% thic# ,or#pieces)

*servations

Machine S)ecifications +asic Information

• .ertica$ Machining Centers

Machine  'umer 

>o,er upp$%

*ra8e$ &mm( *rans8erse &m6min( Ma- !eed &m6min( Ma-pind$e peed &R>M( *a$e Contro$$er   *%pe ? @  ? @  ? @  Dimensions &mm( * $ot &mm( oad capacit% &#g( .CC01 3 ph AC 102 0 20 10 24 24 1 10 10 10 000 120-50 1-5-100 00 !anuc .CC02 3 ph AC 100 0 510 30 30 30 24 na na na 000 1150-510 na 700 Mitsuishi

• E$ectro Discharge Machining &EDM( o in# EDM o Wire EDM Machine  'umer  >o,er upp$%

*ra8e$ &mm( Ma-imum Meta$ Remo8a$ Rate &mm36min ( >$aten Distance &mm( Dimensions Ma-E$ectrod e Mass &#g( Ma-Wor#piece Mass &#g( :est roughnes s finish

? @  Wor# *an# &mm( Wor# ta$e &mm( EMC03 3 ph AC+ 4)5 #.A+ 0 A &ma-( 00 00 500 0 40 = B50 1B50-1050 -530 1200-700 300 00 0)2 m6RA Machine  'umer  >o,er upp$%

*ra8e$ &mm( er8o *ra8e$ &mm( Wor# /ead *ra8e$ &mm( E$ectrode uide *ra8e$ &mm( Dimensions E$ectrode Diameter &mm( Ma-Wor#piece Mass &#g( ? @ Die$ectric !$uid Reser8oir Capacit% &( Wor# ta$e &mm( EMC04 3phAC 1200-700

• *urning Centers o *each=n C'C athe Machine  'umer  >o,er upp$% Distance  et,een centers &mm(

Ma-imum s,ing o8er cross s$ide &mm(

Ma-imum s,ing o8er  ed &mm(

P!"T  *servations

'utting Tool Information

*%pe Materia$ 'o) of f$utes Diamete r  8era$$ ength &mm( !$ute ength &mm( han# Diameter &mm( /e$i-Ang$e &deg(

Endmi$$ Caride 2 1)5 40 4 4 45

2)0 40 4 4 45 3)0 4)0 4 3)0 4)0 5)0 )0 )0 10)0 12)0 14)0 1)0

20)0 Rough caride 10)0 12)0 1)0 :a$$ End Mi$$ o$id caride 1)0

1)5 2)0 2)5 3)0 4)0 5)0 )0 )0 10)0 12)0 1)0 Chamfer Cutters !ace Mi$$

'utting fluid Information

o Ca$te- Che8ron 310 genera$ purpose cutting f$uid o *ransformer oi$

Discussion  Selection of tools and cutting fluids for 'N' machining

uccess in meta$ cutting depends on the se$ection of the proper cutting too$ &materia$ and geometr%( for a gi8en ,or# materia$) A ,ide range of cutting=too$ materia$s are a8ai$a$e ,ith a 8ariet% of   properties+ performance capai$ities+ and costs) *hese inc$ude high caron stee$s and $o, 6medium a$$o% stee$s+ high=speed stee$s+ cast coa$t a$$o%s+ cemented carides+ cast carides+ coated carides+ coated high=speed stee$s+ ceramics+ cermets+ ,his#er=reinforced ceramics+ sia$ons+ sintered  po$%cr%sta$$ine cuic oron nitride &C:'(+ sintered po$%cr%sta$$ine diamond+ and sing$e=cr%sta$

natura$ diamond) *he e$ements ,hich inf$uence the decision are

o Wor# materia$ characteristics+ hardness+ chemica$ and meta$$urgica$ state+

o >art characteristics &geometr%+ accurac%+ finish+ and surface=integrit% re<uirements(

o Machine too$ characteristics+ inc$uding the ,or# ho$ders &ade<uate rigidit% ,ith high

horsepo,er+ and ,ide speed and feed ranges(

o upport s%stems &operatorFs ai$it%+ sensors+ contro$s+ method of $urication+ and

chip remo8a$(

n addition+ the t%pe of too$ materia$ a$so depends on+

o /igh hardness o /igh hot hardness

o Resistance to arasion and ,ear due to se8ere s$iding friction o Chipping of the cutting edges

o /igh toughness &impact strength( o trength to resist u$# deformation

o ood chemica$ stai$it% &inertness or neg$igi$e affinit% ,ith the ,or# materia$(

*he reduction in temperature great$% aids in retaining the hardness of the too$+ there% e-tending the too$ $ife or permitting increased cutting speed ,ith e<ua$ too$ $ife) n addition+ the remo8a$ of heat from the cutting 9one reduces therma$ distortion of the ,or# and permits etter dimensiona$ contro$) Coo$ant effecti8eness is c$ose$% re$ated to the therma$ capacit% and conducti8it% of the f$uid used) Water is 8er% effecti8e in this respect ut presents a rust ha9ard to oth the ,or# and too$s and a$so is ineffecti8e as a $uricant) i$s offer $ess effecti8e coo$ant capacit% ut do not cause rust and ha8e some $uricant 8a$ue) n practice+ straight cutting oi$s or emu$sion cominations of oi$ and ,ater or  ,a- and ,ater are fre<uent$% used) .arious chemica$s can a$so e added to ser8e as ,etting agents or detergents+ rust inhiitors+ or po$ari9ing agents to promote formation of a protecti8e oi$ fi$m on the ,or#) *he e-tent to ,hich the f$o, of a cutting f$uid ,ashes the 8er% hot chips a,a% from the cutting area is an important factor in heat remo8a$) *hus the app$ication of a coo$ant shou$d e copious

and of some 8e$ocit%) *he possii$it% of a cutting f$uid pro8iding $urication et,een the chip and the too$ face is an attracti8e one) An effecti8e $uricant can modif% the process+ perhaps producing a coo$er chip+ discouraging the formation of a ui$t=up edge on the too$+ and promoting impro8ed surface finish) /o,e8er+ the e-treme pressure at the too$"chip interface and the rapid mo8ement of 

the chip a,a% from the cutting edge ma#e it 8irtua$$% impossi$e to maintain a con8entiona$ h%drod%namic $uricating fi$m at the too$"chip interface) Conse<uent$%+ an% $urication action is associated primari$% ,ith the formation of so$id chemica$ compounds of $o, shear strength on the fresh$% cut chip face+ there% reducing chip"too$ shear forces or friction) !or e-amp$e+ caron tetrach$oride is 8er% effecti8e in reducing friction in machining se8era$ different meta$s and %et ,ou$d hard$% e c$assified as a good $uricant in the usua$ sense) Chemica$$% acti8e compounds+ such

as ch$orinated or su$furi9ed oi$s+ can e added to cutting f$uids to achie8e such a $urication effect) E-treme=pressure $uricants are especia$$% 8a$ua$e in se8ere operations+ such as interna$ threading &tapping(+ ,here the e-tensi8e too$",or# contact resu$ts in high friction ,ith $imited access for a f$uid) n addition to functiona$ effecti8eness as coo$ant and $uricant+ cutting f$uids shou$d e sta$e in use and storage+ noncorrosi8e to ,or# and machines+ and nonto-ic to operating personne$) *he cutting f$uid shou$d a$so e restora$e % using a c$osed rec%c$ing s%stem that ,i$$ purif% the used

coo$ant and

cutting oi$s)

P!"T .

Work holding devices and methods

*servations

*he t%pica$ ,or# ho$ding techni<ues used in the Die and Mou$d Center+ as oser8ed+ are+

o .ise ,ith remo8a$e ;a, p$ates to ad;ust for 8arious geometries &Mechanica$6/%drau$ic( o 3 ;a, and 4 ;a, chuc# 

o C$amp sets o . $oc#s o * s$ots

o  'uts and o$ts

o pecia$$% designed ;igs

Discussion  Selection of /ork holding devices for different a))lications

n the design of the ,or# ho$ding de8ices+ t,o primar% functions must e considered

locating

and clamping

)

Locating

refers to orienting and positioning the part in the machine too$ ,ith respect to the cutting too$s to achie8e the re<uired specifications)

Clamping

refers to ho$ding or  maintaining the part in that $ocation during the cutting operations &resisting the cutting forces()

 Jigs

and

fxtures

are specia$$% designed and ui$t ,or# ho$ding de8ices that ho$d the ,or# during machining or assem$% operations) n addition+ a ;ig determines a $ocation dimension that is  produced % machining or fastening)

A jig is a special work holding device that, through

built-in eatures, determines location dimensions that are produced b

machining or astening operations

) *he #e% re<uirement of a ;ig is that it determines a

$ocation dimension) *hus+ ;igs accomp$ish $a%out % means of their design) A

fxture

is

a special

work holding device that holds work during machining or assembl operations

and establishes si!e dimensions

) *he #e% characteristic is that it is a

special

,or#ho$ding de8ice+ designed and constructed for a particu$ar part or shape) A genera$=purpose de8ice+ such as a chuc# in a $athe or a c$amp on a mi$$ing machine ta$e+ is usua$$% not considered to e a fi-ture) *hus a fi-ture has as its specific o;ecti8e the faci$itating of

setup

+ or ma#ing the part ho$ding easier) :ecause man% ;igs ho$d the ,or# ,hi$e determining critica$ $ocation dimensions+ the% usua$$% meet a$$ the re<uirements of a fi-ture)

o

"ositive location

 = A fi-ture must+ ao8e a$$ e$se+ ho$d the ,or#piece precise$% in space to

 pre8ent each of 12 #inds of degrees of freedomG$inear mo8ement in either direction a$ong the

#

=+

 $

=+ and

%

=a-es and rotationa$ mo8ement in either direction aout each a-is)

o

&epeatabilit -

dentica$ ,or#pieces shou$d e $ocated % the ,or# ho$der in precise$% the

same space on repeated $oading and un$oading c%c$es) t shou$d e impossi$e to $oad the ,or#piece incorrect$%) *his is ca$$ed Hfoo$ proofingI the ;ig or fi-ture)

o

Ade'uate clamping orces -

*he ,or# ho$der must ho$d the ,or#piece immoi$e

against the forces of gra8it%+ centrifuga$ forces+ inertia$ forces+ and cutting forces ut not distort the part) Mi$$ing and roaching operations+ in particu$ar+ tend to pu$$ the ,or#piece out of the fi-ture+ and the designer must ca$cu$ate these machining forces against the fi-tureFs ho$ding capacit%) *he de8ice must e rigid)

o

&eliabilit -

*he c$amping forces must e maintained during machine operation e8er% time

the de8ice is used) *he mechanism must e eas% to maintain and $uricate)

o

&uggedness

- Wor# ho$ders usua$$% recei8e more punishment during the $oading and

un$oading c%c$e than during the machining operation) *he de8ice must endure impact and arasion for at $east the $ife of the ;o) E$ements of a de8ice that are su;ect to damage and ,ear shou$d e easi$% rep$acea$e)

o

(esign and construction ease -

Wor# ho$ders shou$d use standard e$ements as much

as possi$e to a$$o, the engineer to concentrate on function rather than on construction detai$s) Modu$ar fi-tures epitomi9e this design ru$e as the entire ,or# ho$der is made from standard e$ements+ permitting a o$t=together approach for sustantia$ time and cost sa8ings o8er custom ,or# ho$ders)

o

Low profle

= Wor# ho$der e$ements must e c$ear of the cutting=too$ path) Designing $ugs

on the part for c$amping can simp$if% the fi-ture and a$$o, proper too$ c$earance)

o

)orkpiece accommodation -

urface contours of castings or forgings 8ar% from one

 part to the ne-t) *he de8ice shou$d to$erate these 8ariations ,ithout sacrificing positi8e $ocation or other design o;ecti8es)

o

*rgonomics and saet

= C$amps shou$d e se$ected and positioned to e$iminate pinch

 points and faci$itate ease of operation) *he ,or# ho$der e$ements shou$d not ostruct the $oading or un$oading of ,or#pieces) n manua$ operations+ the operator shou$d not ha8e to reach past the too$ to $oad or un$oad parts)

o

+reedom rom part distortion -

>arts eing machined can e distorted % gra8it%+ the

machining forces+ or the c$amping forces) nce c$amped into the de8ice+ the part must e unstressed or+ at $east+ undistorted) ther,ise+ the ne,$% machined surfaces ta#e on an% distortions caused % the c$amping forces)

o

+lexibilit

 - *he ,or# ho$ding de8ice can $ocate and restrain more than one t%pe &design(

of part) Man% different schemes are eing proposed to pro8ide ,or# ho$der f$e-ii$it%) Modu$ar 8ise fi-turing+ programma$e c$amps using air=acti8ated p$ungers+ part encapsu$ation ,ith a $o,=me$ting=point a$$o%+ and 'C=contro$$ed c$amping machines are some of the more recent$% de8e$oped s%stems) Despite their f$e-ii$ities+ these c$amping s%stems ha8e some significant dra,ac#s) *he% are e-pensi8e+ and the indi8idua$ s%stems ma% not integrate ,e$$ into indi8idua$ machine too$s)

C$amping of the ,or# is c$ose$% re$ated to support of the ,or#) An% c$amping+ of course+ induces some stresses into the part that can cause some distortion of the ,or#piece+ usua$$% e$astic) f this distortion is measura$e+ it ,i$$ cause some inaccurac% in fina$ dimensions) *he o8ious so$ution is to spread the c$amping forces o8er a sufficient area to reduce the stresses to a $e8e$ that ,i$$ not  produce apprecia$e distortion) *he c$amping forces shou$d direct the ,or# against the points of 

$ocation and ,or# support) C$amped surfaces often ha8e some irregu$arities that ma% produce force components in an undesired direction) Conse<uent$%+ c$amping forces shou$d e app$ied in directions that ,i$$ assure that the ,or# ,i$$ remain in the desired position) Whene8er possi$e+ ;igs and fi-tures shou$d e designed such that the forces induced % the cutting process act to ho$d the ,or#piece in position against the supports) *hese forces are predicta$e+ and proper uti$i9ation of  them can materia$$% aid in reducing the magnitude of the c$amping stresses re<uired) n addition to

$ocating the ,or# proper$%+

the stops or ,or#=supporting areas must e arranged so as to pro8ide ade<uate support against the cutting forces) As man% operations as are possi$e and practica$ shou$d e performed ,ith each c$amping of the ,or#piece) *his princip$e has oth ph%sica$ and economic aspects) :ecause some stresses resu$t from each c$amping+ ,ith the possii$it% of accompan%ing distortion+ greater accurac% is achie8ed if mu$tip$e operations are performed ,ith each c$amping) !rom the economic 8ie,point+ if the numer of ;igs or fi-tures is reduced+ $ess capita$ ,i$$ e re<uired and $ess time ,i$$ e spent hand$ing the ,or#piece $oading and un$oading)

When ;igs or fi-tures are used in connection ,ith chip=ma#ing operations+ ade<uate  pro8ision must e made for the eas% remo8a$ of the chips) *his is essentia$ for se8era$ reasons) !irst+ if chips ecome pac#ed around the too$+ heat ,i$$ not e carried a,a% and too$ $ife can e decreased) E8en though chips and dirt a$,a%s ha8e to e c$eaned from the $ocating and supporting surfaces % a ,or#er or % automatic means+ such as an air $ast+ the design detai$s shou$d e such that chips and other deris ,i$$ not readi$% adhere to+ or e caught in or on+ the $ocating surfaces+ corners+ or o8erhanging e$ements and there% pre8ent the ,or# from seating

 proper$%) uch a condition resu$ts in distortion+ high c$amping stresses+ and incorrect ,or#piece dimensions)

*he cost of the ,or# ho$ders must e ;ustified % the <uantities of production in8o$8ed+ and their primar% purpose is to increase producti8it% and <ua$it%) Whi$e ,or# is eing  put into or eing ta#en out of ;igs and fi-tures+ the machines ,ith ,hich the% are used are not ma#ing chips) *he $oading and un$oading time p$us the machining time &a$so ca$$ed the run time( p$us an% de$a% times e<ua$s the c%c$e time for a part) *he $oading and un$oading time is great$% inf$uenced % the choice of c$amps)

*he ,or# ho$der is as critica$ as the machine too$ and the cutting too$ to the fina$ <ua$it% of the part) *he use of the ,or# ho$der e$iminates manua$ $a%out of the desired features of the part on the ra, materia$) Manua$ $a%out re<uires a high$% s#i$$ed ,or#er  and is 8er% time consuming) *he ,or# ho$der permits a $ess s#i$$ed person to achie8e <ua$it% and repeata$e production ,ith far greater efficienc%

P!"T 0

.D model

!igure 2 " 3D mode$ of the gi8en part

*he part is to e made from a cuic stoc# of mi$d Caron stee$ &e-act a$$o% sti$$ un#no,n( of dimensions 4 mm - 5 mm - 40 mm)

o !acing to f$atten surfaces and enhance para$$e$ism " >$aning machine

o Dri$$ing through ho$e at center of diameter 25 mm " + 4;a, chuc#+ athe+ 5 mm dri$$ it+ 10

mm dri$$ it+ 20 mm dri$$ it+ 25 mm dri$$ it+

o Dri$$ing 35 mm ho$e on one side to a $ength of 20)1 mm " 4 ;a, chuc#+ athe o >rofi$e mi$$ 2B mm ho$e " .MC+ end mi$$

o Jse a s$otting machine to generate the interna$ sp$ine " 4 ;a, chuc#+ sp$ine cutting too$+

rotar% inde-er 

o >rofi$e mi$$ the e-terna$ contour " .MC+ end mi$$

2ustifications

o *he p$aning machine is used to otain f$at para$$e$ surfaces on the cuica$ ,or#piece to

minimise the uti$isation of .MC so that other urgent ;os can e carried out)

o Dri$$ing is carried out on manua$ $athe to reduce cost and unnecessar% C'C machine time) o $otting machine is used to generate the interna$ sp$ine due to a8ai$ai$it% of re<uired sp$ine

cutting too$ and eas% rotar% inde-ing)