:x

Chapter 13 Sl l t

Designing the statisticalprocess control system

r 0bjectivesl ( ) L \ . , , , i r ! l l r ' l i f l iq l r ( .1tr , \ r r \ r . , l ,s t rL,r l f r (n.ss . { , I t i , l , rn( l t l r '

i t r , , l i l \ , , inIrgf , r . f l : \s l . r , i . . l r ( l I i ! l ) r ( \er lL .s l ( ! ( r r l , ,1 . ( ! r l f ( )

l ( ) ( r , l , , l l l r rL) l ( ( i l lL,rrrr , i L i . f , ( \ .ss(.r i l r ( i l , I r ( l rnfn^, . rn(rr ll , ) ( \ t ' l ( i i f l l j f ( l , l , r , ,1 l l r ( n( \ r f , , ( lLI i nr l , r ( \ . r rkI l ( \ r l (l , ) , r l rL\ lLr( . 1h . ( ! r i ) r l ( ) r . , \ : . i ! , , , . r t , f ( \ r 'cs, l r r r l i l \l , ) r \ , r r i I r ' l , r l t ! ,hL r f , th\1. l ( , , L()s l i r lLr( l i t r r , rn( l Ltr , r l i i \

t 13.1 SPC and lhe quali ty management systeml , , i s ! r r . \srLr ls l . r t ic l j ( . r l f f ( i . ( \s. , jn1f( ' (51'( ) l j t r . I r r tb.rn !nf , ,nrt ' , ( ) , , r \ , 'g (( , r"r j iL l lkrr l l ( ) ( tL, , r Lt \ . $ l r i {h nrrLr l s l r sLlh ih, . f rNlsrni() , . ' . i , , . ,Sr,r . f l , I r l l l ( i \ \ L l ( r ! i l l i , ( , r { l i l lx ( , rg. l r i / . r t r ) . I l i \r :s( . l i , r lL, { l ( l ( in r . r , l r r l r ru f , t r , r / i t ) i i f r l )1. I r . t . r t iL,n t l rn)Uth i , / , r r irL i t t t , l l r r l t t r i r r i t r i \ t r |1, I l / , r /s/ , i r . ( . r | ( ] r I l . (Dsr( l f f . r l i ( )n I rust t ,e ] t i \ .nt( i lh i \ : ! \ l rDr rs i l l ( i r r \ i | l . l r . r khon( oi lh. qunl i t \ sk. lehrr lh( t r ( ( l i \ ! o i th! s\s l ( t l l is l { , ( rLrs( iDrpR)\rnrr 'nt {n pnr lu( ts,rD(1 \c l\ i .es Lhr j l gh f t \ lu. i i t !1 ( i r \ . r f i , r1 i ( ! r in the P(n.ssr\ . Ih. l t \Lrs r) l th(h hol f workt( l f . . f r (nr t t )p 1t) b, , l tonr shoul t l b. ( ! r ihe ] r f (N ss$. ThLs,, t )Pn),r .h ni . rkr 's i t possibl . t ( ) ( (DlrrJ l \ . r r i t ion nnLl , ! r . fe infof t . rnt l \ ,topR\(nl non.orrornr ingFrtr lLr tsrnr l :er \ .es, \ \h i ls ist .dr l i l \ i rnpf{) \ -

g0es !n nq thc stal s1 ca pr0cess c0r1ro svrte$ 337 &

' l -h. . l rn l i lv f r , r . , rgcnrenl s\ 's l fnr should nfrplY lo. fd in iefn. t $ i i th.rL.r . t iv i i i .s o i th. orq.niTnt ion. This brgins wi lh lh. id.nl i f i . . r l lo] l of thc( usl(nnrf R\ l r in,m(rr ls.rnd ends i i i lh lhr i i s i l is l , r . l ion, . l cror l t r . r r r \n.l i ( )n in l ( , i rc, bolh in l r f f . l l \ ' . f t l . \ l r rn i l l \ r l -h. . r .1 i ! r l i ( s n\1i lu 'c l f rnv1.. ( hss i i ( \ l in sr ' \ f f , r ls i \ , : r i t f . r .n l l ! nsfrrn,ss f r t . .ofr f r rn i f . r t i r rL,rrr l.onlRi l l in.r , h(Lr norr rs. lLr l l \ .nd sf . r i i .n l l \ rs l

{ i ) r ' , r fk( , t in l t j( I ) in i fL. l R s.rn l r ;

( I r ) L l ( ,s i i f ' ,( r \ ) sp. . i i \ L i r l t l( \ ) ( l ( , \ ( l ( i l ] ,n( . f r :

( \ r ) | r ' r l rn nr. . r :( \ L) |1, , \ , .s: t , , . , , i , r1r ;. t . , .1 ' . . r ' . " ' ,

"

, . t . , , " . .( i \ ) l ,nn, .ss ( i f { r , r r i ( t r , r r | ( r , . l r i l .

' ) l . l r . , r \ r . i i t r ' : . , . '

'( \ ) l r ' ( r i l t i ' l t

( I r ( \ t r ik \ l r ;( \ r i ) \ l t , r , ' r t . ( i l f , r l r rnr l ) :

{ \ i i i ) \ , r l ( \ ;{ \ i \ ) L l rs l r i l , , , l i , , i , / l ( )s is l i (s;t \ \ I n\ l , r l l r l i (nr , / ( ) | ( . rn l , f , ;

( \ \ i ) r , rh, , iL i l ! .^ i t ! ;( \ \ i i ) i r rJ in l , .n i r t

I l r ( ln i l i ( | , ,1 i g,nr l , r i i , , r , r ! , nrrr l \ \s1. , , , , \ r ( l i . , \ , ) , ! $ l i iL l , , , i (1r l l r ,n\ l rL in lnrrG(i l l l \ ' i r r ( , , t r ,1 i (nr , r ls l , ,n( l . r ( l l5()( , , ( - ) iL, l ) l l ( l r ( r (" , . : l l r . r l ( ,1! , . , ( lo.r l r , f , l r ( i r . r t f , t r r \s \ f , i r l ) i i l \ l ( , , i r , . \ . L(nrt i r i ! . r : ( r r r \ ( l, i r l ng inr t j (^rntrr i l | ! ,1! t1, , , r , , ! r r l t ( ) { l L l ( \ ! , , , l r r i r \ l l ) r (u\ l rLRsl , t J l l r l l l r ls , , r . ,n (n ' ! , I i ,^1i(r i r . l \ ' , , ,1 i ( r ,s. n,r l l , ' n iL f . io I ! r j r . h i l lr \ i rn. lh \ . f i i t i ,ns i . lnnl , , ( , \ l l r \ lh.n, ,nr . r ( r rs ( l , l ( , ( . rL r i , \ \ i , l l (J i( nrpl t , \ ( \ l l ( ) f ( l ( , n1t lh i i r l t \ ( i , in i , , , rn\ l ,n i , i , \ s lhr ,1 , r L( \ r l nr . , i ru.rr .n l q\s l ( !n , r r ( l , rsk l , ) \ ,1 1h( ( , lnfx l , i r ' 'h l r fk l r , r ,k () i f l , i r l ( ) t ! r ' , r t i ( i r l. . ,1 i l l i r rg\ ( ) l , tJrrs,

. ( , i ( h \h i l l 1, . r5 . i ( l i l i0r i r l l ) l . r t Lr({ ,1, . . r ( l r h i l l l

s l ighl l \ ( l i i l i , .n l ic i l inrs, i .LI $.r \s( , r ( t r ( r f lngt lx l ) ,Lr .s i . l \ l . rn\( l i rl ( r r . t i , i o l l ( | wL), I or l ( r sJl( :pf( ' t 'L( , i ] r the l i ( l ( l l l ) ( i rn l t ' . l ( r ) l ( \ l l , ! t | l

'1 . , \ , , r , , . , . . , ' . 1,1, , ' l l , r , , , . , i1\ . 1\ . ' \( i l ( r ln, f , r l i .c iL lhcr ' . ,11. nn in l in i l ( \ . r f ( .1\ o i \ , r \s() i . , ) , r \ ing(\r t l | ts jnr I l (s l r ) l l , rsLs th( . rL i lh( i r r \ ' . , r l l \ {1 in! ! , , f i ( i r : . , , | | r \ r f . rn. i t ) , r ) l :I r , l ingILl i f l r ( r r lorr lh(r l : l i r ' (or ! !11inr/ \ l : i / f tnPrI n l , , r \5(hr l l , \ .11in , r : inrLr l . r l i ,D oi . r ln)dr(1(D l , rs l Ihr ingefr i l !orhrnr,r .brngsnefJslo br contf tJ l f ( l i i lhoso.,rLLso: of \ Jr i . r tnD nf t ' nol to . rLr l l r l l ! hrgother h,rcndef p()cessfs .onr ploh \ . i f .nplble ()1 .ons s l fn. \ 'of r1 'Pf . r t . r l r i l i i \

Th! ro l roI lhemnnngfnrcnls\s lonr thf f l :h)df i i .ennl lcont |1r l pr)r fsspr i ) rcr lLIcs.nd m(.Lhods CiDl inu, l l s \ , iL i nr nud l , ln. l re\ i . ' t r w i l l erNofc

XT 338 Stal s l ca Process Conlro

ih.tprocedures are eiihcr followed orcorrectecl, thuscliminatingassignablc r)r speci.l c,ruses of v.rriation in mnterjals, mcthods, equipment,nl form. tiolr, et(., to ensurc a'coul.1 \,e do this iob with mol.( consistency?'aPPro.ch (Fi i ture l3. l ) .

s

3a

ffireeaoar. I

Operarion and conlrol

Conslslently satistied

FlquB 13.1 I rc sysloral ! rpproac r ro qm '1! mirr!enc r1

' lh. t . rsk ,) f nrr .rsrrr int , inspcct ing or che.kirrg is t . rk( n b] ' nrany to bethe pnssiv( on( ' of sort i ' rg out th( g(rxl i rom thc b.rd, whcn i t should be.tn ict i \ ' ( Pari of thf feedb.ck sr-st( nr k) prc\ent ef rors, drf( cts or Ioncr f(rrn.rn(c. Cli'ady .lnv.ontn)l slst('ln trnse(l on detcctio ol poorctudl i tv by post product i(r1/r)pcrni ion inspect()n (n chccking is uruet i-nblc, costly, $,astcfrllncl uncconomical. lt must br rcplac('d c\.ntuLlllvbv the strntrgy of prc!cntion,.n(l ihe nrsp.'ctrcn nrust b(' Lrse.l to ch.'ckiho sv5l.,, of transfoflnatitrr, rnther thin thc product. lnputs, drtpuisind frocrssi's need kr be mcasurcd for cffecii!.' quality manigement.Thc nreasurunr('nts monjtor quility and may be uscd k) llcternine thecxtunt of improvemcnts an.l c1('t('rioration. Mensururncnt may taketh(' form of simple counthg k) producc attrlbuic dnt , or it miy involvemore sophisticated nrthods to generate \Llrirblc data. Processes oper,aied withoui measuroncni ard feedback arc processes abo(t rvhichver,vlittle can be k]lorlr. Conversely, iflnputs and outputsc.r be nleas-ur'd and expressed in nunrbcrs, then somethhg is known about theprccess and control is possiblc. The firsi stat h usirlg measurement, as

gDes 0n q l l re stal s l ca pr0cess cantro system 339 I

par i of the process controls)st( ,m, is kr l . lent i f | pfcciscl \ thr nct iv i t i . 's ,mater i . r ls , eqLl ipmcft , r ' tc . , i ! h i .h \ \ ' i l l be mensLrrcd. lh iscnablese\ ' . ' rvol1c conterned \Ilth thc Proccss to trc .ble to relnt.'kr th. tirgrl \..rluesnn. l ihe focus pro\ ' ic lcd \ r i l l cnc()ur i$( inrpfolemLrrts.

For nlc. lsur.nrcnis to be Lrsc. l for ! rn l i tv jnrpr() !cnrcnt, thr \ mLrst hr, r .cc 'ph c l Lr) thc f .of l r in\1r l ! i 'd $ l th ihc pr{ \ .ss t rc in i t nrorsuf. l Th.s mplc sf l i nrcasuft m.f t , rnd ploi t i rg, or thf 'ho[ . f r I doinr ' ( hnrt ,r ! i l l gnin fnr m(ir . i l fo l rnd in lh is fcs|cct thnn .r f l , l i ( lnH lyP. , ) f obscrv.r i ron . r rd rcp(n t ing svst{ nr i !h i .h is inrposfr l ( ,n th. pRr.ss.rnd thos.sho,)pInrt( , i t Sinr i l i r l , " , r l sLr l l \ shoLr l t l notLr. us.( l l ( ) l lLrs l . rh,h( i \ \ 'l r . r ( l onr (1{ r r nn of l t r )LrP is, | | f l rss thr i r pfr f ( r r r . r r ( is rnt i f f l ! urk l . fI r ' " r r , , r | r . l l l ,

' . r ' . , ' " ' . ' . . ' | ' , ' ! | , | , | | . .

' \ | , : , r . I r .

'

r r | . I, r h,r \ \ b. (D th(.rssis l , rnfc thnl { r r r t ) . g i \ . I l r ) (o ! .1 , r pr()hl .nr { ) ftcrr( , \ . (n)s i .k l .s Pr\ fnt ing th. I r (11ss t ronr nr( \ ' l in l t i ls ( \ tu i f t r f .n lsl i rs l l inr . . . \ . r \ t inr .

0ut of-contro proced ureslhr ru lcs 1()r i r r l ( , r ' t 'n l r l i { )n ( i l , r )n ln) l Lhfr ls sh)| l { l h, , rgr . . r l . r ' r t l(1( l i ix \ l ns pnrt ( ) l l | l SI ' ( svsl .nr ( l ( iu i , l l r ,s. L.r fg( lv . tnr . ( r i r the f r ( )r rd1|11s t( , t f i ( ) l l (M.{ l r !hur , r f , , r i l of . ( i r l , ( ) l ( ( J(( ) s i lU,r t i ( i . t l r \ .1() l )s.l l is inrp() f t . r r t t l I t . ,k h l ) f ( ! ] ss ' , , I r f . r l ( , r ' r . ( sf(rr ls i r r th. s inrr &ry r(), rn 1)()( i fdndi ior , rnr l i l is n, !es\n,r l ( ) { f t t l r f i f inpUl( , rnd l l ! )s. o ilhe sufer\ rsor\ , In.rr , r l r 'n]enl n l lhr ( lcsrgrr st . r t .

( k , r l \ , i l nr . r r n() t . r ls n\ l \ hc f ( )ssibl f l ( i { l , . l i f r r ! r i . l i | ( ) rn\ l i \ ( , r . l i , , fssh()ul( i b. l . r l ( f , l rLr l t ln i I t ' rnul i . r i ( ,s l . r l f . ( i i ! l rnt i i \ , i Ig ! !h.r t h,r lf . ru l sh()Lr l (1 r tnk,w .r s! \ t ( r r r r t i ! r f f ro.rJr . l i ( , .or l jn{ o l i I loDn.r i i (nr ,i r , lu( l in l t ,11\ s igni l i . . r i t i ! ( i r ls ' , t lx possi l r l . ( ( )Lr fs(s( , f ( )1,( , in,r lvsis1, f . , r r { s, . rnd , rn\ . r . l i ( , | l t . rkr I is I \ i t . r l p,r f l ( t , rnr 5 l ) l s\ st(Jn (1, s ign

In sorr f l r ( {ess.s, th( . r f l ions nr(r1(r l lo roI . \ . or i ) rc\1Jrt .nus.s () l( l ( )C nre{,uis id{ lh.r . rp ih i l i l \ ( ) r . ,Lr t l ( ) r i t \ ' ( ) i t | . f f (ns\ i , tcr . r t ! )* ' lnthfse (nses, l lu! mLrsl b. . r nx ch, ,n is,r l ( ) f progtssi fB thr p11 l rnt i \ .n. l ions n) l r r . r r ieLl ( { r r l r \ sLrpcr! isor} nr , I r , rgcr l r r ) t , . rn( l ihr i r in legr,r t lon inh) rout ine Pr( \ .dutrs.

Whfn imfrovrm('nt nct ions ha!. 'bcfn tnk.n (nr the t ) rocess, rno.rsufc-mcnis shoulcl be used to confifm thc d('sifcd improvements and chccksmaLlc to dent i iv . rn! sr( le cf f . 'c ts ot th( r . i ions, whcther thev bc Lrcnci ic ia l ( , dctr iment,r l . l t mar be nr.ess.rr) h) (c i lcLr l . te conbol chrr tl imi ts s h( n s l r f f ic i fn i d. ta afe avai l . rb lc, nnl( ,$ ing thc chnnges.

xT 340 Stat ts l cai Process Contro

Computer ized SPC

Tt 13.2 Teamworkand pr0cess c0nt10l/impr0vemenl

Tlrer, Jr n, ,s . r \ n i l . b le m. v \ f ( , . ,mf Jr , . r .^rrs.r fe n.r( t "s, . , \ h i .h: l . lb l , ,he r , 'n, lLt lnc . , , ,n l . . i_nnd nn., nrJr i , .nnr J. , t , J, , | lar i . . r -aph., | l l r

- r .n m.rr \ . t . r t r - t . , . I4Jn., f th,8,1.o^r, . rnrr . ,emi.r ter \ \ . t rp.rLl . t \or , \ i | ,enn!r l in l : ' r , ,m.r tnr i . t , , . l . . r8r , r jnt . ,J.L.r ,m.h. | r . rnJ! . r l . r . .Jte-rL\ | , s rJr tu. i . . I r \ i r . ,n. ,br . r \ i . r , , i .p_ t , re\ \vr . t r . ,h t r . . r , ,br . .m,r . rnr . 'nrr t r r t rUt. , , , \ . rn, t l l . l - . , , . . r l rd!r . ,m.. Lr( \ , r \ t ) fu, , t .1,n_lro/ . h. , r l h. , l r Jp. i . i ,n nrt .* . r r , ' r r , r . . t . In .n i , ,g r t ) , .e f , ,*

" r t . r i , iJ . i r i . ." i . , r + ,^. .1r t , . r l . r l . r r rh, l . r inL.Ft , -Jet , rn. t t tn. tu, t ln i . tup.J i t , t " \ , . .1i re t l i , , r i ,ughlv L rrsh, ,d

]c.r 'q)fk r i l l p l . rv i nr.r iof r(rc in .rnv org.rniz,r t i (nr,s cf forts k) nlnkcn(l f r en(|ng rnrpfo!( 'mcnts. Ih. nfcr l tor te.rmwork..n trc s.( , | in

nr.rnt hLrnnn ict iv i t i (s In mosr (rgnni7.r i i (n1s, problcnrs ancl opporrtrnrf i fs ror rrnp()v( 'nicnt qist Lrctwo(,n drpnrhncnts. Sctd{)nr docs,r s in, l tcdL'p.rrnn(ni r^{n.rll lho In.nns h, sot\ e i protrtcm

",

t,.tug.,t"",t tn,p,.,,i.,,

sLrt) ()pl intr t()rr ol i pn,.oss s(, tdom improvcs i t r( ,h)r .r t svst(rn p(,rn)nnrncf. Mr)st s]srf lns rr( , .onptex,.rrr . i input tronr r I t lx,r( , t t 'v.rnlt . r , \ , \ - - i . r ,1t . r r ,1r hh,. r . t r . , . , t ,* . , r , r , t . r , , \ ! .nr . .1. . r r , , r , , , ! . r r ,ht ,l , . ,n,h,v l r l rnut l , { r t th. . , . r t . r . , . . , r i , ,nr , . ) I , . , \ .ntr . r l f . r r r , r th, Inr l ,nrenLrl io ol Sf ' ( . l t is rx,cossnry i r t nn)st orgnni, i r r(nrs k) nr(^,c rro;r . rstnt. ol lndcp( 'nd(Ircf io one of jnhrdft)encle11.(, , thR,ugh thc fo ( , t r ,

L. i i t lc shnfnrg of idtrs .n(t nr )rmnrion[\l:h.tnge.'f basic infornrarion

E\chnngc of bdsic id(,nsExchangc of fect ings r fd di t ; r

Elimnration oi fcarTrusr

(rpen {r)mnlunicniion

TIME

]he .onl:ynr:allon g:cones more ofen wfth each prosressi\'c step nr.r-L.c*"r l

' , l . r l . , r -h ip. lhcp,, . r r t . rhhi ,hr t r r , re.r_. . u r , rn rr i . . r \ i_hl , r lnr . l -p. ldbl i .hc, l A . . r t l r . . l \ , int .hrb.rrrrrr - th.r t lu\ tsF\ i , t (J

are gone..rnd opcn conrmunjcarbn $,iU Procced. rhjs is critical forne\'cFendnrg rmp(ryemc'rt and probtem solvjng, for ir allows peopleto supply good d.rta nnd a thc f.1crs u,itho r iear.

,is311 IDei gnrn() the s latrst ical pr0cess contr0t syst0E

lcrnN (! k br i r lgs di \ . rse t . rk 'nts. . \p(.r icnc.. , k.or ktgc ind ski . , k jnrrr ptur.css srtr ' . t ron. fhjsnl lo\^, \ i !a rrr ! . of pfolr lcnrs thnr. rc trc i ,o|dthf (chrr i (nl cornpctcnco of i f \ on! jndi l idrat to $ tJck] id. Ie,ar is

, l , t , ' ! ' ' , l | , , I ntr . . t . " . , . , .1. , r r . r1, , . . r . , , , . r , r r \ . . r . , , t , i , , . , , .

. '1, , \ ' . , i t l ' i , . . , . . , , . r . t r r , , , r . r r . . . . r . , t . .1,-^ l r , . : i . a, , , t , I , n

An,rnr! \ ' l l l r | | r r , t i (nrcJl( \ r i \c lv( ! r / \ t i rhcR,!Ul t \ ( ) t r \nr \ , r i , jgsir . ( t l r lnrLIr i ( i tc{ l r i r ( l us(\ t : ( i r rcon(, \h(rr t r l he rr , :prrrs ihJc 1, , f t , r i inr j rn inUk \ ( ) r nx! r r r r \ l l r .sfru\ l | ( ) l t l .h) i f , r t , . r r r ( i \ i I r l l \ r , i t ( \ i r l ( , i is i ( ! r ., r r i l , ! l i ( r r . r rs i l r , I | ( ! rG thcrnr,r \ Lr f .of( \ l , jn l l , t t , l r \ . r \ l l ( ) lhcl . . rnrn 'nrLr.rs( ! r rhch, jy, \ r r ( j1rh.( i t r ) r : \J,) |1. i ( ) fnr , ] \ . ls() l nr i fut( \ t r r iAtr l

l \ ' ( l f is r i I f r i l , r ih{ , nr fcr i | ts , r r r l s . j r l ! , s t r ) r rst ! .s. i ( rn l r j isrr . r l ( , f \ .sL, f ( ,n is( ! .s or olh(. fs t r h{ i ix \ \ t t , , \ | t t r ! $. i r . r t h.r t f ,1rr \ t Jh. f r j f t ( )s, ., , i nr fL, l { c js 11, i | 1, ! nr 11\ , l , l f , t ( l { ! is i , j , rs r f , r , tc . r j r t t rst , r ! l , ( ! r \ r ( j t r { .r . ik f I Ni i ILr t r \ . i r , , r i r i r ) i f ( i r lnI t f , I l (J | t j .L( jnrnlrrrr . , r r r ( ! r ( t jn in*t i t l, i l r i f f f ' r ) | t (

' r l (Nrfs i rv,Jt \ c, l i r t lx , ! i h i , t ( , lnrr \ r

Pr0cess im pfovemenl and ,Kaisen, leams\ tn ' (cssinj t ' r .o\cr j ( . r ) t , . , I j j rs. ] !Rj |1, ( r f ( \ , t , . s i t t r Lh, . . r f f r ] j f , r t r( r ' ( ih l ! \ i l l sLi l ls , ) , r r l { . \ f f r i ( , f .cs. t r , , r ( , t ) f , ju! t r t t , ,Sel t r rs lu i i i ( , r l t \

r ) \ in i r r r i t lnf I t t r i t . r (1. t l , . | r ( t \ j l \ ( , , r i , . r r t t ( .Lr lnr f l j t , t , ,nr , usU,r l l \ tnr. r t in) tc l I l r , ' \ i \ : th \ nR,.r)s, t rn. t t , )n,r l . I r1 l ( jJr . I f ru l r i ( l isL i l i , r . r f \I h. t . rsk j , r . f ' l r , r \ l ( jnr t t ) (ur , r f , r (J j lh( ,1 | l lL r I t ) l r r r . I ) ! or{ , jnr / . r t ( , rs,rL rhc r{ ! h, l , t , , l i l . . r t , rnt t I r , r f , r r . f i , r i t r r r , ts, L,ur prrrrss i , , i i , , , , , , , , , , , . , , rr ( , , rnrsN(, , ' \ i l l ) lLI l l r r r lhfv r , \1. | r ( l lhf r | , I ( I i I i ( j I I , I I r tc i i r ) i l i r ! r i )J .pr( ! r ,s: .l tJ , r r l r , l . t l r , ( ! r t i r ( , fnr t ! ( .1,( ,n tJf , jp.r , ) i i , rH tvsh,I j r ! in( tu(1, .st \ ' f , , \ \ (JfL, ( ( rnnr l n i . . r t i , r r r i t l j ( , t i rJ. LI r i ts . ( ) tn,r . t i , r t fnreLI l r . , , r f ( lt | l , ,J) , r \ , \5.r l r r rprncl l i lsc[ . t ] \ t . r t jn{ r t r i \ l r r ( ) , j ( lc , v( \ ! . r t , ( \ .*f r (nr l . r i r ! . . , r l r , , iL[ l f ( \s( . ! l

lh( . r r . r r r , r tdnrI() f f tu(cscrnr l r ( \ ( ! | . I l j , . . I Iq:(rLts j , l . l t ! , \ ( ( ) f ( . i , tlh is l \ ! , l . I r ( l i \ ! l f , r l r r i th in / r r r / ( ) j , r / l / . / , | j , , r r f \ , , r r r l i ( ( ) , rk l . r l .2(r l t ) t ris in i t !n1.rnr, t r t r ! . \ . r [ ,strrss t r t ,R, r t , t i rh. r t r i r h s] , ( . t . . l j I i ( l r l rs r t rcnr. l ' , . . ' , ' t . r . , \ | t t r t . , . . . . . , | | . , r t . . r t . | , . , , , , . J, . . , . . , . , r , t , t t .

r " , )n i rg,n(rr t in r f . ( (Drt) , I r \ , hhx.h t r ns. \ lo i r r r r r i r r l7 p.r ( .nt .nr fr . re n s rn\ ( j t r r 'gfn.r . ' l ,ng tn) .css, ( l ( . . i ( teLl lo h ! l r j dr . r t r n f l ( \ \ , .h. j f l ofr l , , , r , , , , . . | , , , | , . I I . \ | , . L . . . , , , . . t r t , . r , , r r t 1. . . . , | . . t . t . . . , ll . f ( ) ( ' ( \s \111, rh.rr i jd wi t l r rhr t . rsk I hev soo r{)Lrf l l t t r . r { i t h,rs i r fossibl( n i .o i r rp l ( t f the l lo, , \ chrfr . bf .au\ t ' the\ , . l t ( l r r ( ) r tu v t |nr t . fst . I r i lhftrlrrcs\ I'rotfossi\ el\ fi\ e olhr,r tcopk,, $,h(, $rrr in\ (n\ rd n lhc, nrvoi. ing, hrd n) bc bf tught t ( , thr hblc j r of t l . f {h i t th. nr . rP.oukl b. l i r l ishcdn) gi \ c. .onrpkle dcscr iptn ' r of rh( ,pr1)e.ss th is. isnbt ld gR) p $.( , rc

kept n)gethrr.s thc proccss impro|rmcnt tcam, since thcy werc th.,onlr pcople i |ho col lcctn cl ! could mak imp()remcnts. Sinrpte d.t . r1.ol lect ion mrthods, br,r insn)rmhg, causc and . f fect. fd l t rr lo anj lvsjs{ ' , r1 l r i r . ,J t .

_. t l r . . ^ i l . ,Jrr t , , f r . . , \ . . , .n.rcf i . t r , . .hr , i r r , - t , .tsrr , t l rc. . r r r l | 1, . ,* . r l , r r t , , r , , j r , \ r t r , . JU. ln rr , i r tn. .

Tho f l .x ib l l i t \ of thc f .us. afd c i f ( .ct (Ct&L/ dr.rgrnrn nrnkcs r t n st .nd. , r . i r , " ,1 L r t . r . , r . , f , . . t r r . , ! , . . t , . . , . t \ r . . , r t ln, , , . n. , r ! . , .1 i l , , t , ,n J,r-'L ' l .hr i r i r . . r rh, . r . l . l i . . . l i r _- \ r , , . , . , \ l r l . . r . r t r \ f. r r ' r . . , t . ' , , ,

' f . r ' \ . .Lt r , , \ . 1,r . , .1 t . , . r , \ . t , . . r , . t \ , r , f . r \ t . . rn.f t rn \ rnr f r t h i \ ur \ Lr fnr l , \ \ i t ! . r t iL,r i :

r \gnin lhr kr j ( t r ! l f l l j l . e.r t ru l | l1)nr th. ( &t l dr . rg l l rn orkjr c,)rn.s rronrt tu t thnl . i t nt s l t t t t id r nol iusr th( , .onrPk,k\ l d i l , . r l l r . , \ ! , ! r \ . f Ie. tr !c ( . ry l ( ) r l ( , \ .1( , l ) r l r r ( &| ( t i . I fnnr ic h,r t t r thc us. of . r r r , . rn] , f . t ) rcs(nt . rh\ ' . ( t t l l \ . r r lo ls rr . . rs oi . \ l ) ( , r r isc ()n rh( f i t i ,cr n|( t l ) r (uss(slr( Lng shrr l i f ( I . lh( ( &l l d i . l t r . )nr lh( ,n n. ts ns n .otk\ . l ion p{) i f l f t ) r thc."r(1 ' t knr) ! \ le( lgf o i Possibtr , .nuscs, f r ( ,nr sc!( , f . r t . rk, . rs oi . \ tcr i ( r f (rJr . r rst(r 'nr i I r in n t f . rn j is thc nrost . l le.r i \ r , nxrhxl ( ) i b l r i l l inq ihc( d. l j { l i , rgr . | ) r lh is.r l i \ i t \ . ( r r l f ihLrt( ,s l l |1, . r t l \ t , ) lh, InLl{ , rst . In l ing, bynl l th)s, i I \ (n! .d,( j l

. r t jn,ht f r ) r s i l I r l i { ) . t t r r r l . rgr , r r l t ,u.nr*.r i f t . r tJ)oinl r r r f t l r f .nr in, t r ' . rnr in( l $, i t r ( , lP i , rv l ( , i I r (1. \ , ( t ( I ) . r .1,ufs. ror

I i \ . . , , , t r . i , , , , i , t , , r , . , r .L. , rht r t r . r . , \ r . , t . , . , . , . , rh. . r , / .l i ( , r . 's /u)r i , r r ! t i1,rr , gr( jUps. th is is rhf i i rs l st . r8r in i t r ( , . f t ,n11( olt t . t . . . t . t . . . t , . , , , . . t r , t , ,1,r , , r . , . i , , . r . , . i . , , . , . r - r , . . , 1, . . , . , i1$, . ' , r . , r , . , r1 i . t \ , . r . . { f t . , r . r i , , , r L i \ , . I r1, , , , l r r i \ , , , . . " \ , . t . . . . , . , r1.inr \ t ) | pr f t o i i n l r l t sk i t t r !1, 1 l ( . \ i t )k, hr , rkt , ) | re,

. rn( t ] rk t rd. , jnspr\ rinr l RT.r i r ' hsls ls pn| l ( r lhf ( \ r r r pr( t rss I t r .soLa ect ,Kr i ic ,n.l .nr" ( )p( r . r t ( ,s i f th i \ \ . rv to r l inr in. ln, f foblem\ . r t rhr s()ur1.( , t ) r wor k' , ' - 1. ' ! , - l , . I |

' r , r r t r . , r . , . r . 1n. , . . . t \ t r i , , .n. . , r .1.r . , t r . , t , . , . ,. ( , . rn, l$s.r f t l les\ ( ipp(!rL r i rv tor t r ) t r t . rn\ . I ) ( t | ldu.c lnr i . rLr i t ih, .K. ' i , t , , , , . , , , . L l r t r i r . t . , t r . i , . , t11r. t l s r , r r i " r , . r . , .1ni t f i .Ls h. lP 1r() ln honr.rn, te.hni . . r l ind mi lef i . r l r fsourcrs rr(nn our-s id( iho gn)up I h. ! , r f t , f (^ .k l fd spf( . j f icr \ , l0r thr purtose ol ( , t inr_Ln.r t ing pr( , t r lcms nnd . i r l ing pro115q s, , ,1r .1

aI 312 Stat st cat Process l ]ont .o

I 13.3 lmprovements in the process1'o impntr f,1pn)ccss, ii is ilnportant first to recotniTc r{ hcther thc proccss, ,{ . l .^ i i - l rTr. , i l - ! t t r " ,p, , r . r t , . r . r .e, , . , . , . . , r ! , r , lh.t r r del . r r r ' . ' . . r* , '

- . i t - i . , f , , t . . . r - , . r . r . in, . ro\ . . Ier , t . r , .1. r . l,1so!/..s .rrc requi.r{t, and irtr/.i I sir/jsrl.rrt r,ro/s wjit he uscfut Iigure 13.2,

Des qn nO lhe stat s l cal process contro system 343aI

,'r rl0urc 13.2 The syshmali. approa.h to mprovenent

ItI 344 Slal s1 ca Process Coniro

r{hi(h js a.lcvclopment of rhe straieg],for pfocess nnprovencni pfesentcd in Chaptcr 11, ma\ bc Lrseiul hcre. Thc ()nrpaLjson of.rctLrdt prodrct qualitv char.ctcristics \r'irh ih., rqutremdlts linsp.ctn,r) is not a basistor n.hon on thc process, since unr.cephbl(,products or seni(jcs c

*Des 0i rg rhe stat s1 cr Dr0cess .0nrr0 srsrem 315 I

. iusfs/ ( fc. i . r l ( i Ises f r , l , r r rd to ih. s\ sr( , r f , or spf t i . t . r1|scs rotr t ( \ l loth. p() | l r Lrrr( l , r h ls or ] l r sIp.r \ is i ( ! r / \gr tnth!us.oi th.sysr i \n. i i .r t )pr1)r .h nf( l ihr , .ppn)t)r j ih ' krhniqr[s I . i11 h. ] t Lhf \ !p.n isor to

N1.rrr . '9. nf I t n l rst r l rm()nsir . rh, ( t r no) ihn.nl n, t l r is . r I t r ( ) , r { h l r \ , f fo\ i ( l i rg l r , r ( lonrt rn i l t l r ( . I r , .ss. f \ f fs{ , I f . ( ,5. Iht ,sr rcrrrrrccs r i t li . l ' 1, . ' ,

- . . r , r ' i i . , t , r . i . , . , r , | | , . , . , . t r , , . . t . , . t . r .

r t rc1rt h\ hnr( tLr fc , rn( l . r L,rnrnrr tDr.nt r0 inql l I t I rh i f l t , \ r , , i , r r r ( , i I1 lrnpr( i \ ( ,nrcn1 Ih(si l l f r ( i \ r , th( ,o i l | f t l I l , ( i , r , , ( )0r f i \ | rB.r f r r { r r \ , .r f i r i r . 'g.n ' ( f tn\ t .nrnrhr\ i rgr f r . (Jt l |1\ .n l j i ) j r Ih\ , r t j . ! l r j r f r : r tnr( .i fL l . t [ ) r l ] r \ . \ r ' r \ or . , c! ,n r l r r

Pr0cess c0ntr0l charts and mpr0vmentslherIrph,rssrhi ,hrrrrrqLh,. t t , r r . ( lo,Uj f ! ( . , , r ,d r i t r ) f r ( \ ( , f rc j r r r , )sinrp,) , in l i l j l ) l i . , r l j ( r rsJt , f lh. t , rVintr l r i .h| , ( \ { ,sc. , ! r r r t , l ( .hnrrs, lcn , l i { \ l J l j ( , \ \h( j ( |1,1 |o l l \ .U,( \ l t ' , r , l r i ( j f r . ( ! r rn,r ,hr j r is , rn,r , t in ih.fc( i r ( l r r r ( ) l \ , r i . r l , l i tv h\ t l r (N(, . r r t l r ( , f ( ) r l t ( ,1 (J|( , r r t t ( )n t r . r t , rht( , ( ,1(r ,c( , f \ i IS , in{ l f , I j rN nc : l ( . i , r t ( . , r { ( ,s (n \ . r i , r r i tn u ! . r I l t Lrn\ l' l l . ' r ' ' l . r r ' , r . r l r I r r r r t , . . r . , , r r . . , , r , L L.

ln lh i \ $.rv lhr t , r ( \ ( s: ( ) r L ( j | t i r l r ( r rs i r f fk\ f l l . f I r r r . r \ t t , . t j l ( \1. . r r r ( li i r l l r rs l r i r ( ,n lsnr i [ l f l tJ ih( . ( ( ! ] tRj l f r . I i ! f rs. l ( ) r ( , t

. . t i ! , inr I r (^1.nrcI lqlhsrssl l \ ! , , r j l i r ]L|( . t t t \ i txr1, f f ( j1t , !s\ i ! ( ,n\ tLkr i ( jn\ i , r l t r , \ i r i r l r i tr lv i ) r . rs l r . r r rn, I l i . . r ${11l l i l l . r t r , r ( . ( l l ( ) ( l . r . r1!rs i | ) t s. | I lk , , , j r r f . \lJ lh, , . I l r r l | , i r i ls ( f t l r ! , r i r (N r , , , t t f , r f l t , r t r , I l ! , r r .11\ , j t ( l r , r l ( \ t 1. , i ! | .. r l l r , r . r l l ( f , r \1f f ( j r , l j fL, , l l r ( . j r l \ j , i t i { j r r , n i l l i . ( l i r . r i ( , lh{ , nr t r ( \ fr i r { rs $ hi{ h l r . r \ ( , b.(1r nr, r{ l ( . 1, \ . r . r f r . f r ( \ l ot l r rx. , . r r i , ' r l : , /1. th,r l l l r ( ,r r ( t r k\1 (J l l ) , ( \eqs r . r i r . r l r i l i t \ i : I r , r i f tJ ru l l ,L r l r ( , f inr t , r {^.nr. I ls

:w

fiq0rc 13 3 Coirfrn6 profr,,! rroroldfdt rrt .1oi f iQr dj ,i

TI 346 Stal s l ca process Conlro

can then tak place (Figure 13.4). Simitarl, artribute or cusum charismay be u_scd/ to show a decreasing tevcl .r ""-t". .r

".,".",

., f.,,_portion ofdefects and to indjcatc i;provemcnis in capabitir)r.

6 Continuous process

To minim ze

identily common causes

a FIC!ru 13.4 pro@$ m0roy6ment slaods

llli:i.,'l-ll.*"" .:"1..r situnti(ms. action srsnars nre srver when the,ilr,11t,:'il;"t:ll::,:Jli:;il illl; ::. lt,l":.: ;11::,1il,":i:11i.lilt.il-:;:j :t:':;,:lij,'Jlll, ;*.1:lit:iiH;;' lil;i;:l*;linNSt also b(,sousht out and managcd so that tl"y l"__" p".i.iir.iprccess opcration. Significant lari;ti()1 betwecn batches ni _ot".tnl:,i:'jl'::i:*'j:ji[::i"1;:

.xt*l::l':::.'r.".'.".."" ;.;.;;;d!m.,nds,h.,, ir,"., ",i',,', ;; ; 1;'t,f :ilTfrJ".:,:li:',iJl i::ll:

:;"::$t f;t'H*i;.lili, lt,ililiilill.,ll:i::"t'fl i,: i?j.,n : tlunderstandinS an improvement, rather rhan gt*,_ -a

i,""i,."a"".r,'

The never-ending jmprovement cyc le:;:'i"x'1":.i' ji'*:":,I",t":i;:f i#l'J;:jff :"j:"Tn"l;::ilj

r|, lx. r rL(r i i s l r rL rr r ( l l , t ln, l , r , L. \ r . ( , r j j ! i i { r I r i ( j \ r . r j j ( . j rL

. l i r t . . i j, l lL\ l I ) ( . | ) , r , i 1 i , \ L I t 1 | i I r ( l l , ) I l j , ! , \ l t , , f \ , , i . t ! . . i , r t ( , r \ r j I t r iL t r, , \ l \ l t r i l . .n l l ! r i , ' l rn.rLr l , rn, l , i ( . r i l \ t r . r t , . l , r ( , i r , r , \ ( r ) i ( . I l

l \ t i \ l , t { ( \ . l r , r . L, j , r \ , l , t ! , lLrr , r j ( , . i ( j , i I jJJ,Lj lL. , j j ( . , ,1. . IL, t ,L\ , , i , ( , \! l r , ' r L l l \ . ,1 , . ,1(( l t t , ( , , .1r , , l l r r l . l \ .1 t , , t ! r i , r \ r . . , i r r r t r \ t . i , f t , , , ,L()r i l l ! . ( ' l l , \1, \ , . \ \ r l r ( r r I I i | , , I , i t ( I r \ , \ , ) I l l r ( , r i f r , \ t . , , ( ,L i l ( , | ( , L,r r

l r r r 13 5

' , | l, , l r : l l , l , i :L ( , l r ( r \ .LLIr l , l , I l r l , - l r t rL. . t t j , ( l , , r , , L l ! .

r r r r l , t ' \ t . iL. f l ( . r l t , \ l l ' ( ) ( 15r l , , l r ( . r : |1, r l . l , r \ ! i - . : . ( ) r l l , | t .( l \Lt ' , r i , . i i r l i ( . l , i l ( , \ \ , ,q1(, t ' i . . . .1, , 'Lr t l ! , ,1, , , - . i t t t , \ l , , . t , r r l

\ \ r , r l , ! ( . r ! ,1L L|r t r , . , , t ! , i | ( t )L t ,L, t l , ( , r i i l l r .1. , , \L. : . ,\ \ r , i . r ( . I iL LI . I t ' I I I | , , , i l rL Lir I ,Lr l ' lL i i l i | i tL,r r r , r r , l t . \ t , , l r , lL L . l ( , r ! , . . . . , ( ,u lL l l ! | lL, , ( \ l\ \ l r , ' l , i , . r1, , . i ( \ lLr r . , i t ! ,Lt , t I rL j , r t ,L L, t ( , t t r ( tJ, , \ , . . . . '\ \ l r ( ' , i , .11,( , : . ( t , t . 1. , . , , L l r ( i r 1, , Lr '\ \ ) . j r . r , . | ! , t , ( \ t i \ ( . t j r t l rL. i r r r t , , t ) \ , , j r t , I t i . l t , , I t j ( \ . , r r r i j , tL 1L., i , ( , ' , . , l l , , r L l I r r , l l , i r I i l i

i l , t ) \ t Lr . . i ( r I rL r . . r i . . t , r l L I ' i( | r , r , . fL( , r r r l t l r t ! t r ( ' .( ] r l ] ] l ] ] ' . l r l ]L l ( . \ ! . ] ] \ \ \ t l | | \( . l r i r i , i l , , l , r L| , , (1. . . ,L l r f n.r l , r , , | ( L, I j1 i I r r r t L j rL l I r L

II 348 Stal ls l lca/ Process Contfol

established, ou iput iden ti fied and rhe cusfomers noted, then the team isready for the implem.'ntation stage.

Jmplement (Do)The implement.tion elfort lr'ill have the purpose of:

,i dcfining the processes that 'villbe improvcd,

* idcntifyinS and selecting opportunities for improrement.

The improfement team shoulcl accomplish the followin8 steps during

r Define the scope of the SIPOC systenr to be improved.rnd map orflowchart the processcs within this system.

i Idcntify the kev sub proc!'sses that will contribuie to thi'objcctivesidentified in the plannjng stage.

* ldentify the customcr-s ppiier relationships throuShour th(. key

These steps can bc completed bv thc imp()vement ttam through theirpresent knowlcdge of the SIPOC system. Thjs knowlt'dgc ivill bcadvanced throuShout thc improvemcnt cffort and, $,ith each cycle, rhemaps/fk)t't charis nnd C&E diagrams should be updatd. Tho f(nl(,wingstages will help thc tcam makc impft^/ements on thc selccicd process:

r Identify and select the process in the system that will offef the gratestopportunities for improvement. The team may find that a completcdprocess flowchaft will faciliiate and communicatc undefstanding ofthe selctd process to all team members

! Document the steps and actions that afenecessarv kr make improvc-ments.It is often usetulto considerwhatthe flo\,! chart would look likeifeveryjob was done right the first time, often called'imagineerinB'.

, Define the C&E relationships in the process using a C&E diagram.r ldentify the importani sources of data concerning the plocess. The

team should develop a data collection plan., ldentify the measuremenis $'hich will be used for ihe vadous parts

i Identify the largest contributors to variation in the process. The teamshould use their collecijve experience and brainstorm the possiblecauses ofvar iai ion,

During the next phase of the imprcvement effort, the team *'ili applythe kno\'ledge and undrstanding gained from these efforts and gainadditional knowldge about the piocess.

Ih(]T

; tED

cl

,U]t ic

rDaidtim

'DeaEn

sP,

in

{De

obj

de

AnallThe l

jmpr

Geni

Plan,impr

videc

Ir1

&De5 gnrn! l r re s la l ,s l ra pforess c0nrr0r sy-.1e n 319 !

Data (Check)l ] l dnt . r .o l l rct i (n fhnsc hrs thc h, ( t r \ rng obicctr \ csl

I i , l : l t l ( { t {1. tn f r ( !n rh. pfocos\.r \ ( ]ct fnnjnrd in thc f r tnnning.rr( lrmf l f nr f n l . r t l ( , r f h,r \ f 5I l f i f I i f ( , thc st . rbr l t ) o l thr fnr fss usini t rhf lpf fopr j i r ( , . ( ! r rn) l.h i ( In.rho( l (s)I l lhr f r r r , .ss is st . rb t , . ( lcrr , f r r i r ) . i t r ( , . , r f . r t r i l l \ , ) t tht , f r (ussl ' r ( i \ c ( ) r ( l is fn i \ . rn\ t l r . r ) r ics c\ t . r l r tshcd in the ur i . r ptr . r { rl l lhf t , ! r f r , rLr !J\( \ l , r r r \ unp n| | f ( t . \errrs ( l r r i r ]g, l , r l . r , ( ) t . f t r ( r r .( l . l t ,nni I f thr i r rp ict thc! . rv i t t i r . r \ . of t t r nrpr( \ rJnerrr ( , I i , f rt fc l . rn, lh! rn.r f \ / i l ( jn, h,r f ts, I rJ ( &t , ( t i . I r , ]nrs, so 1hr, t , r l , r . , , c.l ion rr ] t ls 11, ( L f .nt br( t r \ ' t ( .dge.

Analyse (Act)I l r f f r fp( \c ol ih is ph,r ! f rs n) , rn,r t \ ! , lh( , t ,nJ nl ts oi rh. f , i ( j f th,r \ . \, I rJ h. l t t l , r f lor l l r ' . ( . \ t . i l , f t , , f i r Ipr . r r . I rcrrr l ror i |11 rhispt i . rseoti r r f r ) ! , nr( , f 1, th. i r ) l l ( i ! r i r rg shL'L:1Ll t ' r , , rL.corIpt ishct l

I ) ( , icnJr i r r . lh. . r ( t j ( r r 1, . l l r . t r ( \ fss $.h( l r \ i i t )c Rr l r r i rct . th s i i i lr ( i ' ! r lL lv 1h. , r f rLts, , ,

.1)r fh i f . r i i ( ! rs ol int I i : i t j . r t r i r r . . , l l . t . , ,Lnrt( \u l lh.s. nr) l l ( l b. n( i r , \ l o| , rn ufr l . r l ( . ( l hr f f o1 l t j f fn\ fs\I ) t \ ' .1( I r ) l r1\r l , r L l r ( l , ,sr . | r ( l ing1) i rh. . , r r is( \ , rnLt cf i , \ i . .l r \ f . l l r , r l lh, , r l 'R(( l eh,rng.s l r , r r I l tn, , r t i ( j f rh\ t L) , f . r ( t ( j r j L l r ( ,qfr . r i r . ( l tn) l ( t i \ .sl , l r | ] i i i \ i l i . r l . f , |1fr(rr ts.nl l ( ) rq. | j iTr t roIs str i , t r \ i I t t i . \ ( ) l \ ( \ lin. I r , | l \srs, I I l l ( lnoj l , ' t r ( in. , ' r i rn, ' r . rgr , r f t ! r l ( ) r l t r ( . ( \ . I rnror( t .L ll ) ( t f r " i f , t l t { , l r i ( !1 i ! .s lorr l ! , r ] ( . \ t , , \ [ r l (J j inr l ] ro! .n(rrr I , i ) l , l fnrs.rrLl ( , l ) }1! lLr i i t i fs d, : ,oveR,Lt r I rh is rr , r t ( ,sho!t( l h. fo,r \ i ( j { . r rJ i \(nr t ( \ l i \ ( , ! i r - l ! t r f . ( ,1r()r ls. l ' . r f , , r r ) .h.rr \ s l r r rk l L\ , , ( jnsLrt t ( \ l Inrn i l j f{xfr o \ \ ' ( ) f r i nn!1 f r , \ is f r l l ( ) , rs\ isr in th r \ t j r l r ( ,ss I i rs inc\s t ( [ .s\ e,Ll( : igrr { l l l ' l { ) r ) r . ry be f( \ l rL i lu l l , j n.hir . ! | s l { t ) ( h,r , rg.s in pcrh,rnr.r j ( . .

l '1. 'n. 11o,,hcf l , i . t f l , t ) ( r \ ) , ns t t r , ( \ ( t ( s ( j l r . r r ( \1. wi l l t ( . , r ( t loInrfr( ) !crn(I l \ i l i l is i , r lLrr nJ. j rnr \ l \ b\ lhr t r , . I f ( i , r fs( , rnr) . (Urhr\ \{ \ . r . i r i I 'kNrfg l r ( i I r

' f ( .ph. 'n, l t r nr(rUr,r ' I r ( ,ss t } ! \ t t . t r iL i , r l ( r r i \ l r ( r\ . id, \ l l l l l { . rnr .&l . f f . r \s.r \ i r . r |1) t { , t r .11. ( J]r , tn h s. / t r , r | | f rot is i5l ( ) { r rsLLr, l l t l ' l ) ( A ( l t ) ( \ n 'n b. . ( )nrr , ' f l ( , , r { , r l ( ! r ' t .h.rrrg. , rn\ t t r in! t

sr 13.4 Taguchi methods( i fn(11i l .guchi h,rs delLn.d n rrumhrr of m(, ih, s n, s i t l rLr t t . in( ,oust !

. , r , . , . , . | . f . . , r t r I t ,

-

, t . , , , , I

',!x 350 Star sr cr Pro.e!s Cfntro

i i t t | r ! : l fs t inr i r r \ t ( j th, r rcr i rs (r th is $1j f l ( I h. t i { ! ( h i nr( . th({ i \ | l jn\t r . r ( r ' \ { l . rcr l r ,k l . r t { ) r r r ,n,r i I h( , , r i t i f r ts

1t ) l i I l ( i : \ l ! I . l i ( i | ,(1. \ L| tJ l l ) r ( ! l I r t { . l r r tJ.r .s\ . \ , I r ( t t f ( \ l1rr l r ( j f ,r t ! ru{ | I ' r i I i \ , I r , r l r ( r r ,\ l r l rsL ( r i l \ f l . r r f ( r l ( , \ | . f tnr l r r rc

Total loss funot ion

(

/ ! 9a

r,r ,K-AV f t ' : r l f ro l , :prnurr .r tv :R 7 j s

!f rk. y lo 1!.rk 1!ln t.nn y!4r.r lrinn |rnt .t 6 !l

t r l

F iqure 13 6 rr . r . r r i r rLr t iorr ,0r{ ! r | r r r r , r

prod!.1 ; l | re. . . r rcof th{r rpec h.alr!r rs

k.y lo work bdler t raf

*Dcsi0n ng the stal s l ca pr0cess c0ntro system 351 I

th:r t , i f set correcth, i s fc i f icat ion should b. .cDtrect a i thc posi l jon$ hir 'h the customer would l ike to receive al l th. prodLrct . t h is inrpt iesth.rt thc centfe of thc sP( cifi.ation is 1\hrrc thf cusknner's pr(rccss r!()fksbcst. I todLrct lust rbo\ ( , t lnd just belol^ onf of th. l imi is is to al l inrcntsJ| l r i pu.poses thr. sa f , i t , loes noi Pcrfonn sisni f ic .n i lv di f t0rcnr V inlhr tLrs l r )mLy's proccss.nd thr lossts rr . Lrnl lkclv to hn\c thc pf t ) f i loshos,n in ( . r ) . I lx co\ t ( t n inr |onfornrnn.c is nrorf l i l ( 'LV to i I ] t rc.se cont i f ! (nrs l r ' . rs the.rr tur l \ i r i .b le produccJ nro\ .s i \ ! , r ! f ronr th( .cnir !

Des gn of pr0ducts, process and pr0duct i0nl i ) f r f \ ' pr( , r lu, I or s, , f ! i .c r \1, nrn! ' i r l . | t i lv thfcc s l . rHcs ot J.s ign thft f { r lL ic i ( ( ) f s. f ! i t . ) ( l r \ ign, th( t r ( [ \s( , , r nt lhol l )dcsign.n{] lhr f |1), lu. l ! ,n {of ( } \ ' rnt j r r r ) , l rs ign U.r , l r (n th.s. (J! i !Lnppirrg sr . rg, s h.rsnrrnr s lcfs, t ln,()ui l \ r ts tJ l whi .h . rn,() ikrr rh. inPLrt5 | ) o l lx , r sk, fs. I r r f. r l l lhe s lcts, t l r . rukhi fg,) l lhr ( )ut fu is l ( ) lh. | r \ l rL i |1! Iur ts {) l thcinPLrl5 ( , f thc fe\ i s l { } r ( l , . , r r lv . r I l r . ts i | l ,qLr,r l i ly , r .d .o\ t (n t l l n s( | l lin( l rnnl pr( \ l r ( l ( i f s .N.r In i ju, l r i 's . l ( , . ( l , rssi l i \ ' . r t i ( r r ( )Jth(s. lh( \ ,s l . rg.s rrr \ . 1, , , Lr{( l lo J ,c( t I r . | r , rA.nr, . l ' \ r l1( , r l r r ) t ( i r r l \ 1(J (h( i l | . .s t . r { rs L)ut i ls , , lhc \ , ) ) . r rn l ( ! tL l )s rrr l lhr i r \ , r r ( )us i r jh r l . r . .s 1i( , l l ( )s i Iglh is rrr(r le l , r r . rn,r l l nrc. l i \ nr() \ . ( l t ( ) ! .1( .1 t ( , . stu(1\ ' ' | . r f r^f , \1 J( \ ! n '\obt( \ ls , k, . r 'h i ( \ ( , ' l , lcLrsrd ' r ! l iv i l \ , , 1( i in.( isc lh( .Jel , th {n Lrn{kJ:r . t r lLru, . r t r l 1, , l tn,r l l \ Lnrp()vc th. l f ($,rbi l i l ! , , i \u(ress 1, , ! \1rr ls higl r rLt l r l i lV l ( \ f ls

I ) .s igrr nrrs{ i f . l1 | ( lc { , ) ls i ( l .ht ion ol l lx f . t r ,nt i r l Pfutr cnrs \ ! l r i rh$i l1. I is . . rs.r . ( ,nsel lurrr , o l lh. ot(J i r l ing.r I ( l . r r ! j f ,nrnrcrr t . r l ( ( ! r l iI ( !N Lr)( l , r \ !h i .h t l r r p| . ( ! lu( I or s. f \ , . r $ i l l L,c Lr i lh f r r r lLr .c( l n,r l us.r l .I i , tur l l ) ' , th,(o\ ls in.Ur|1\ l ( lur i r rS t t r r l t | . t i ( ,n $i l l L\ ' , l . t r fnr in.( l t ) \ 'l l r , ' I r | | | , r | | | | | . , ' | | r | , ) - I , | . L i ( , , r r . , l . In L, , l i r : -11 t , . , r , t r , .wi l l r l ' r1r !s.o5l . r (JIe! l ,u l t | , nnroUnl r ' \ tcnJcd (rrr b( rcdLr. f ( l t r \( r r . t ! r l ( (DsLder.r l io | ( ) t . , ,ntr{ ,1 r l l f rng the in i t i . r lJesi&r ol lh( ,pr(r Iss.ln ih.s( , . )n( l nrnrrr ( ) tk,r wivs, lhrr ' ls l hrg. inn,rPl , r \ bfhf fu ih(thr . ( s lnSrs of J. \ f lopm(r i

ln th is.onlc\ i , I iguchi r l is tn l i t l r ishfs b( ' t rer ,n i )n ln1. ' ind i ) t f l inf 'qui l -i iy n l rn igcnr lnt . On lLnr Inetho( ls nf t l . 'chnic.r i . t ids us( Ll for lhe.onbolol r pfocrss or the contr() l ot qLral i ty d rrr ing th. proLlLr( t ion of f rodu.r \nnd scr! i rcs b, f tJ idh th. subj(ct of th is book. of f - i inc nrethocls usrt( chnical ,1ids in thc dcsign oi pro.lucts and pn,.rss('s. T(x) often ihr oliljnc nrcthods.rre b.rscd on tho e\nlLration ofproducis nnd proccsscs r.rherihan their impfo!cmcni. I l f i (Jr i is . t i r . 'c tc ' .1 nn!ards.ssessur i l fe l l rh i l i tyr . thcr than to re! ics i r16 thc design of both prodLrct .nd pf t rc. 'ss \ i thn vi(\! to fcmo\'lng potcnti.l jnlpcriections bv dcsign. Clff line mcthocl:;

xa 352 Stat ist ical Process Control

r( he-r J ire. rcd tow,I J\ ,npr^\ inf , | t - ( ( dp.rbr. l l ) ot Je- icn A \ . , r iet)^r re. tu-rq,ue. r , u po\\ ib le ,n lni . , iudl i tv f .dn in_ .r( t ivr t \ J lo ,nL tuJ;- l J. tu,r ,dtedm$orl rheu.pot r , , rmdtqudt i t \ m.rn. ,cem.. . r r \ ) rem..lh( Judi l .n{^ l .untr , , l proc, .durc- rhe.Lr rerr , , , .

" r r r" tpr" .eJu' , . ,an, tfailure mode and effecr anatysis (FMEA) appliect on a'company._n ittebasis

Reduct ion in var iat ionRedrcing thc varntion oflei, processes, rnd hence pro.luci pafamctersabout tlreir t.rgei \,?lucs, is thc primarv objecii\ r, oi a qual;ty impror,em' rr f for j . ,n m.. Th, s rLi ,*Frr dJ t , r . ,ct i c, . r . r r , ,n; ,p, . , i , , r i .n- ,nIrrn- nr \ rmtt . uFp,r . r rL l t , h l . r i rnr t . . , ,n\ , . ) _ lh, . id. . r r \ . r r th, . . U..tomer is cqual ly sat isf icd with. l l rhe val l res lv i thin Lhi,st ieci f icnr ionl imits and is suddcnty not s. t isf i ( l h,hcn .r v.r lLrc st ips oursjJc the spccif i r l i ' r ,h,nl . Ih, f r , . t r . , . . , t . t , ) r rnA.rn, t , , r . ,n, .h.nin. , \ t , !J, , .m.. ,urr . r , r ' r . . ' nr" t . , , cn.dr. , . , ' rJ rJ, . . t , rch fn, . i r r t - s t , ,* , . p.rr . rm,.h.r_. , r \ ' .u-r in. iJ, th, . -Jn\r t ,c.rr i , .n h. , - ,J. In.rn\ , , f ,y.r th,r ; . hh,r , r , , rm,. .h,n, . r1. , \ ' . t i . , . ' .h, j .1 i . r r . , , . , \ - . . t , , \ , , , . t r , r ,* , .1t J.r t r , r - rnn.rnrInjr . i \ r t , . { r . t . . r , r i , ,n r . t , r l - ,n, r r . . h. . , r r . r t r r r . . , i t \ . , , , . r . r r \l i ics ind h.nco a mutt ipt ic i ty of sourc(,s () f !nr i i r ion s,hich di l combircto l l i \ , ( the n)t . l \ r r i . r t ionIor vi i r iablcs, ihc mid spcci f i . . t ion or sonr(, othcr tnrgot vntLro shoutdbo si .r t ( 'd nk'rg wirh .r sPccif i (d !rr id lr i t i r t , . rbout this i , i tuf . for t t rosep'r f tonnnncf ch.rr .ctcr isr ics rhnr.nnnot b( ' m.dsLrrcd on.r cont inuo|sscnk ii is better t.r cmpioy a scntr' su(h,rs; r,\coltent, very goo.l, good, fair,r|nsnnst.rctory, rcrv poor; rathor thun . sjmple pass or fai1, go;d or b,r(l.T,qufhr i r t ' . ,Ju,c,r th 'L\ *rcJ. . rnfr . , . rh t . , .F. icr inE n. , r r ,n. , t \ . .1u,^

next three sub-secii()ns

Design sysiemThe,application of scienrific, engine.ynrg and rechnical knowlcdg k)prodLrce a

_basic tunctionnl prorotvpe desi8n requires a fLrndanrentatunderstanding ofboth thenced ofcusbmers and thc production possi_bilities. Trade-offs are not being sought at ttris srage, bur thc;e .rrcr(]qurcments tora clear definjti.,r of rhe cusk)mer,s reat needs, possibll,classified a-s critical, important and dosirabte, and an equaly ciear dciIn l r "n. , . r . , l - , .ufpl ier ' . , r .h | ( . rn, ,br t i , r ro." .pon.Jlul t c.e rF, ,o_no. ' bl ! di- l i . rc.r i . \ inq b,. t rve,.r thp u-c ot ( , r . r i r ; re, h rutoB) . , rJ th.development of new rechniques.

Des qnrnq the stat ist ca proress c0nlrot sysrern 353 g

Parameter designl l r is tntx i ls . r *udl ( ) i ih.( .hoi .pr1).csss\s l ( , r r1 desiHf

. i rn.d nt . . t r ic !Ing Lne 'nost

rot ] | rst ( rpcf i t ionr i sct t ings tho\. $,hirh s i rcr .h k, .stro \ l r f tnrrons ( i t rnputs.l?( \_( 'ss d. \ r lo l )Dr.r ts t .nd n) nro\ . rh,( t r rgtr

.y( t fs . t .hc nrosi n\ otLil ro ' ry d.vfk)Pmenls h,rr l t , , s i rd l t ra is c i rh. f h)r i t r !n. \p. . t r t l f ( ,sLrt tq(1( | lu] l , r t ( ly oLr{ l \ !LJ , rnr l Lr f ( tcfsr , ! \ j ) i , f s , , ( (css r f n, h r( , ! rnr c\ t { .h\ l11\ ! l ls , hLrt , , r t (Lrr t ) , i fk , f , rnrs i , tc, . l ) t . , rn,1 rrnrct inrcs rrrrstr . . r r ing,( l r , r t - | )c\ ( , l iJ l )D{!rr nr , \ $ , ) f lhfu|{h iL,r r t t r ( \ r .k,s {) t , r { ,nr t l inr l jr . , . , . , | r I r , . t ' r . r l r , ' \ i r r , , t . r . i . i . . . . r , . t . , r t . . r . , , , , , , , ; , , . . .

, | , t . ' . . , . i . , , . r i . , , . t . t . . , . , \ , r . t . , r . . . , , , .r , ' r . 11, . , . , r r i , { , , , , , r . i . r r t . \ r , r . r , . r t 1r , , . . r , . , t , r . . . . r ,, ) ' i , t i \ \ t i t r , r . . r r t , . r t j r . l . . r , . , t ! L j r . . , , r t . . , r .lh l ynrr . ' t i (nrs i r ) r t r ( , ( i r i t t I rs S( j f jc f r \ f rs. \ . I r l l t r ( . ( r jv nr l l r . r j ts i j r\ . | . | ' | r | . \ , | , , , . |

' l , r , ' , r . . . , , r , . t . , . , , l , l . , r r t r . . r . , , r r ,

, I r ' | \ | r , , , ' , , . . . | | r , . .1.1, . . , . . t , . r r . , , t , . , . , ! i . . . i . | | , . , . | . i | , | , .( n,ss h, f , \ l \ ,11)n.h L,rn l , ) f f r ic r i ( le \ . r f i , r t r (Ds , , r . r j I r . r l ( , , r r , I r ( j l r1t , s() i t .lc(rr iu, { .1(

,

\1.r r i r rs l i . rvr , I 'cr I Lte,r l lnct l t , , , r l l , t r ! t r ) r , r wi , l . f , r r r le , ,1:" , , , ' i ' | . .1 | , | . , , , , , i . , , . . r , . . . r . r . i r i . . . , . , i i r . .l r . l ' r ' . r l 1. . l r . , j r ,

. , , , t r , . , ' . i .a , . . . r . i , i , l , , r . r t . .

t r r ( r ' \ , j rL, r ( ) |s r th. f . r$ nr,r l . r , r t . $ i rh l l r ( , t , . . rst i , r rk. , j ( ( , , , r lh.l . rs l ( (n lh( . r I . r l t iRl l , i ( l thet( , \ l i l ( , i f ( l rs i f \ ( ( ! r \Ln[ t \ t r . rn( ] t { ,q, , ) r ( ! r .c, ' (1, l l j f wi(1, \nr i , r t i ( ! rs wtr .h ( , \ rst

. ,n) t r , ! | , r1L , j r , j rk l I r . r r r . r ,k l rl r l ) r* . ' r '1 l , . r l lh.() th. f

. I (1, g.rr)r0 j l (1, \ Srs $ i r i .h.r l t t r \ . , r t inr i t r \ t I r I l t ( .1rr sr / .s l " l ' ( , , ' . ( (Trt , ) l r lL, t ( ) r l t h jgt j t r . \ . r f i , rbtr , 131)r)r , l r v (JJ l t r . hr i l , r fl ( !nr . s lu ly i fL th.(rrr ! l t i r ! rs L r , tcr t rh,( I sr j ( / r f ( )L,usl , r ( ,ss L. ) t r ( ,. r ( h f \ ( \ l ,s I h, . (nr i ( \ I ( ,1 f . i r , r f ( , r . f ( t .s i r i r

Jolerance desliJn\

1, , , , ] ,1 r , r r , . , , . r . . , , . . , . . . . r . . . . . t . ,h. . . r i . r , , . . , r . , . , r . : . . .1.r' r , ' t i t , t . I ' | , , I | , . . i , . , . r t . ,1, . , . r . . , r , t , . r . , . , . , r . , .foslr ( ) l lJrr lU.t io l ( ) , o l l , r r t i ( ! r . ! r ( t Ltr , t t )5s.s r({{ ' | ( r t , t ( . lo lh( . LrLs' t !n( l r rs j , r t t | r ) r" |er torn. r ( r . \ r f t i t ( ) | l l is . r t l l ) is sr . rg. lhnl thf t ( ) lcr . rn(c { l , .s igrr ot L.r f \ ( ' . . tot t r ,s f .ns(s lo.r i ld i lor , r l ,1, , . " t ,u, , , , r r t , .hunr. I r n) fnr , in( ] th, i i

. i rhf f t r ] . r i r ( t r r .ss r)r , r r l i f ! i , r l l t . r \ oufs i . rv L, f ! t into (J( inr i r r , r I lh( l rsh. o i pfo. .ssc(] t ( ! ) (1.lh.s( lhru str ' } rs pnls t11)nr t lx , ( , r ig in.r t

.of .epl o l lhc p( j t ( , I t i . l lor . rPnr.ss of t11tr iu. i , t l r |1) t8h t l r t , ( lc \ ct i t ) r rxIr ( , t thr I rosi rotrusr conrt ir0 ' rs.ot oprrr t i r )n, h) rht fonlpronl isf rn\ otver l t r ,hen s! f t i r rg . (onrnxJc r lo l (J i rn.es nfr l io(us on rhc n(,ecj h) r1JI)s id. , r . . r t l r ] { ) f fot | l r t i i l\ . , r . , r . . L, r . . , ! , . \ \ t tsr , . , . . . i r r . . - r r ! , . , r i . | ,1,- \ . r t , r , r r , , r - t i r !t ' r . . , . - r l , . ,1. , f \ h,r , . |L. , t , . . i r r . , r t \ , .

. , r r . | , . r . , . I | | i l_ | | | , . , , .lr.()n thc thr.{ potrts of \ icr,.

tlI 354 Stal s l cal Process Contfo

Stat ist ica l ly p lanned exper imentsErperjmentation is nccessary under various circumstances aJld in par-ticularin order tocstablish theoptimunr conditionswhich give rhe mostrobust process

- to assess the parameter dsign. 'Accuracy' and 'preci-

sion', as deftred in Chapter 5, may now be regarded.s'normal seftings,(targot or optimum values of the variolrs parameters of both processes andproducts) and'noise'(both the random variat ion and the'room'foradjustmcnt around tire nominal setting). Ifthere is aproblem it will notnormally be an unachievabte nomnlal settir8 bui unacceptablc nois.Noise js recognized as the combination of the random variatbns arrdthe ability io deieci and .tdjust for drifts of the nominal sciting. Expei-mentation should, thcrcforc, be directed towards mnintaining the nom-inalscttingand assL'ssing thc issociated nois under various cxperimentalconditions. Somc of thc steps in such research will ahcadv bo familiark) ihc read.r. Thcsc includc grouping data togethea in order to reduccthc cffcct on thc obscrvntions of the random conponent of thc noiseand eiposing more r.adily the effectiveness of the control mechanism,the identification of special causes, the search for their origins and theevaluat ion of indn' idual components ofsomc of thc sourcs of random

Noise is dividcd into thrce classes, outer, inner ancl bctwocn. Outer noiseincludcs thosc varhi ions whosc sources l ie outside thc management '$.ontrols, such as variations in the cnvjronmeni which influence theproccss (for cxamplc, ambicnt temperature fluctuations). lnner noisearises from sources which arc within mdnagemsnt's control bui not thesubject of the normal routinc f{rr proccss control, such ns the conditionor agc ofa machine. Betwc('n noisc is that k)lcrdied as.l part of the con-trol technques in usc this is ihc'room'nccded b detect change andcorred for it. Tradc{)ff bciwcen these differeni types of noise is somo-times necessary. Taguchiquotcs the case of a tile manufacturef who hadinvcstod in a large and expnsi!c kiln for baking tiles, and in which thchat trans frr thiollSh the over a nd iho rcsu ltant temPerature cycle v arLation gave ris b an Lrnacceptable degree olProduct variation Whilst are-design ofihe oren was not impossiblc-both cost and time made thissolutbn unavailablc - the kiln gave rise to'oui.'r'noise Effort had,therefore, to be dirccted io('ards finding oiher sources of variatbn,ci ther 'inne r' or 'between', and, by reducing the nolse they contribllted/bringing the total noise to an accePtable level. It is only ai some muchlaier date, when specifyinS the requiremcnts of a ne*'kiln, that theproblem of the outer noise becomes availablc and canbe addressed

In many processs, the number ofl'ariables which.an be the subject ofexperimentation is vast, and each variable willb the subjcct ot a num-ber of sources of noise rvithin each of thc three classes So th Possible

I

Ii

I

al l

ixrlthr\h

Histhc

'ng

II

lmt

actiI-rthrrimf

imI

xTDes On ng the stal s l ca pr0cess contro syslem 355

ronrbinatrns for experimcniain)n is semin8l-v endless. Thc 'sLrtistic-i1lv planned experiment' is a s)'stcm directed io$ ards nrnlimizhg thc.lnount of experimentation kr lleld the m,rximum of rcsults and indoing this to take accountofboth accuracyand precision -rlominal sctiingr and noise. Tatuchi recoFlizrd that in any oniloirlg indushLrl Pruccssth list of thc major sources of variation and ihe critical Paramctcrsivhich ar( af fccted by'noise'are alrcidt known. So the conrbinnt ion oiu sefu I expedmcnis ma_v be reduced h) a manageable numbcr bv mnknlguse of this inhc'rcnt knowleLlia(. [xPerimcnLrtiof can b( uscd h) idcntify:

the design prrnmctcrs r.hich hiv( :r latgc imp.rct on the Produ(t'sp.rrametcrs and /or pcrformancf;th. ' ( t 's ign pnrnmctcrs $,hich h.ve fo inf lut 'ncf on thf ProdLrrt ofprocss perfornrancc c hr r .rct.ristics;thc sctt t rg of desi$n p.rramctcrs at l 'vels t 'h lch nr lnimiTe the nois(r ! i th in the f crfonnan.c.hnrnct( ' f is i icstthr. sctt inB of Llcsign pnrnmctcrs $'hi .h wi l l fcduce !nr i . r t ion \di iholr t. rdvr.rsely. t fcct i f t j cost.

As with nenrly rll thc tcchnrlrn s rnd faci'ts ol SI'C, thc 'd( siiin of exP(linrents ' is not new; ' f ipPet used t l rcse tcchniqu(s in Ih( hr t ik i t r ! lLrstrvmorc ih in 50 te.rrs ngo Al , [8 $, i th ihc ( ' thor qtrnl i ly i ] ( r rus, l rg l r .h i hnscnLrrgedthcrvor ld 'sviet !of th( IPPl ic.r t ionsoI(s l . r t r l ishcdh. l rn iqLres.l l isnlr i ( ' r .ontr ibut(nrsnt inenrt)h.rs i r ingth( cost{ , f qur l i tyby seoflhc n)tr l loss fLrrct ion nnd thc sub div is iof of complt x ' ; r robl i t t r solvinB' ink) mxnngf.bl t ' comporlcnt prr ts. l hr ' . ru l lx) f hop.s thnt th is b(x)kwi l l m.kr r s i rn i lnt mod( 's i , contr ibut ion to lvnrds thc unLl i fs i rnding.rnd .dopt ion of under ut i l izcd pfo.r 'ss nr i rnngorn( 'n l Fr inciPl(s.

IT 13.5 SummarizingimprovemenlLmprcving proclu.ts or service.tual i ty is nchie\ ' . 'd through inrPro!1-mnts in the proccssci thnt producc thc Proctuct of the servi.c ll.r(.h.rctivit,v trnd each job is part of a proccss s'hich c.n be imP(\'cdlmprovement is dcriled fLcrnl peopl(' lcaming and the iPp()achcs PrC-sented abovc prolide a 'roa.l nrap' itr Progress io b('mad(' Thc mrlllthflrsi of thc approach ls a team with common obiectivcs - ush8 theimprovement cyclc, definint current knot{4edte, building on thai kno\{'ledte, and making changes in the proccss. lntegrated into ihc cycle areIn, r \o. l - dn. i r , 'u l , lhrr s r l l c{ ' . 'n.

" thu l ( ."ni , rE l roce..

Whcn this strategy is cmployd, th qLrality of Products ancl servic('s jsimproved, job satisfaction is enhanced, commmicatiorls are sircngihenc.l,

xI 356 Stat ist icat procoss Control

productivity is increased, costs are to$rercd, market sharc rises, ner,l:!:,i1" f.l'L,o"o "lo "dditbnai pronts rbw r. .,r,". *..a-", pi.."."rnrprovement as a business srraregy provides rewjrds to evervoneIn\ol \ (cr cL! t .m!1- rccer\ i . \ . rJJL for their monu1. ernplnlee.s.r in i . ,b.1. ur . r ! . . rnd , ,h nu \ or , l rdnt otLiL.r . d1. rph., r . iccr . i th.r h i , . r t th\ 'urcJn_i / r l i r .n, d l ' rb lp ot F.r \ In{ f t , . , t dr \ ,oend, fhr , , t r , ) l . g} s l h. . thc ( , r ; ; "nrnre.rd In,r , r !^nrn.rnR.r rvhih

. (main (L,rnFet,r i \ p,n q or td m.)r t pr . inthe twenty,f irst cenrury.

aT Chapter hightights I

II: '

.

l : ::::nl] l" r r.ur,, rru_r be m.rn.rc(.m(.nr L.,n_m,rnrcnr r.r (r,,.,1r . ' . l r . r , . l . t \ F. , t i . \ , )nJ . , , to, Umprt , \ I In, I r . r ! :cm,.r t _) . tenr.

l l l . T: l : : :11." : l l . , , r ,h(

. \ _r , nr i . i , . , ,u{ i .nry, , \ ( .n1,1rr . , r_n,urrr

\ . ,n, . ' i , , r , . I pIr r .n. . I hc.r_r, , rn \h, .utLr . rppt) t . , . rnJinteract with al1 .rct iv i t ics of thc orsanizaIon.I | ) ( r^, , , , |h, n.rr , r i i .nrunr n

- t , .m i . t . , J, . f in, . . I rJ. . , . , t r , , r f r , \ ,* \ \lY ' \ f . r ' r . . . r 'd lhrm(rrr . , r . . tJr . , \_{(rn.r . r . t r r . r rLtr , \ i , r \ . i LrFUr.fr t pr ' , . ra1r ' r t \ r rr l t , , , \ r .J , , r (hJrrrcr l) l I l l - lT ' ' i ' ' i ' ' \ { r r i r ' p"* . ' r i . . ,n 'q,rr ,nr ' ' , ' . i \ r ' (

- } - , ,m.r r r , . r \ t r | ix . r , r , . r i . r t . , , l . r i tnr , .at . , r , t , , \ n , r . , . r , \ i InrFt l r , iJ , - rrn. .r f rrr r i i \ t ht . nr, . . r \urr .n,1r l \ nru\r t \ . , r rLrfr |d hy ( t- , . L '1\ ,rr jL, \ , . , \ , , t . , , . ,1. , . , rh( r - , ,_ rh, , .mf l r . i . T, , . r h, . .1" f

" , ; t , ; r ,u: ;* ; . ; -, rnrf lo \ ' ) l \ u prUbt, .n\ .lhr'ru](s for iDh,rprc,i.rtion of contf(n ch.rrts rn.t procedures kJ b(,f r , l l , 'u. . i , rh,n . \ r l , '1r ,ntr \ , t , r ) , . ! , . : ,u.rr i , ! , \ ' . r , .v,r . ,n ,h. ,ut , inr , r i i r . , J, . rn, l r t , r nL. \ i . , - t - . , r t , r th, . \ t \ .v. t . .m Jcr i tn.rr . ,m\v, i r r nt . r r r , r \ i t r t r . , t , . .n. , , . r t i . rL. ,Lr . i r r t r . , , . tm.nl t I n. , , .1or; . , ' rT,r t r i rF rr nn. . r

'n, \ i , r l : l , r r i r J.1\1ntr | , , . 1, , I ,h,r . t ( f r r \1..1, . c InnLrt . l r , ,n, , l l r , . lu\ . r r t t |1r , \ \p! . ^ r r l I in1i r , , -n, , t , . h,ng,*to c('mprc\ systt'ms. Ltood cornmunication mtjct nni.n,, o."

"r."niiortor succcssful SpC tcamwork and neetnrgs must be nranaged_I nr "

c l l rTfr : , ) , i r . rr redr. r \ , r rr .ut . Lrr , ,u;hr r , , ;erher b1 n-ar_,r+mc'r l tu t . , . I t . . , fn1. . , . r r pr . ,b\-n. I ,n".* . mrl . f l , , \v . , r , ) r , .. r ' ,unt l t r re | . ro\ ' r ! . h, , th i I m. .utJ. t I r i . r ! . r rd * .n i . r : or6rrr iz.r-ttons. l)roblenlsolving sroLrps *il ercntuaiiy gr'"

".y t., pi..,r,i"Irlprcvention te.tms.Al l pro' , \ -e. oerer i , rr . r ' ( . h i th nr( t r( \e:llll:,i-.r'IJ nB"r h ho ""-t"*''. "'.';:::lll::T:l];l,:"1 :::\vhr. ,h \ l ( 1, , . ,1\ \ r r I b( U-.o. l h i - F. tu r . . , . r . r ' , ,n b\ n-an j t . .mFrl( ,

' , , t r . r l , hdf i . .h, \ r lJ nur , r r t1 be u{o r , , , , ^ntrot . but . r \ n1 . r iLr lurc(ru, .nI \ ,

' r . rb i t ih. The D , , f ru,_i \1.rJ^nUri iJtron rnd , t .mirrr i , r rnr \ i 'J . r , r ot \ r r iJ , i , , r , m.rr b, . , t , , r r led rnd r t e t im,t . , ,dJu-reo r . cord-ulBri rrr reilcct rhc impR,\emellr\.

TTMii

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If i t l

R,,)

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II

l II

2\

t3I

t4\

Des qn nq rhe statrs l t0at process contr0 s!stem 357 X

' \e!r ord ing inr f ro\arnrcnt t . rkes pt . r .e l l r thc I ) f lntng.\ .ct | . o i p l , rn,"npleln. . r

(do), . .cor. t L l , rhr (check), r f i lvs. ( .d) l t .DCA)

' I hc l . rprnosc rnglni , . , f I igLr.hi h.rs dcf infd d nUnrtrcr o i nrerhod\ k)f t r lLrc i ' rosrsandlnrpro!( ,q| l . r I t \ r I l isni . , rhod\.r fpr i run(tort t ,uf tx\r( l'ngs: t lx t r ) t . l losq i !n.r io| ; . lcs i i ln oi f rodu. ls p r . .sscs iJrd f r )r l r . t ion; reduft ion i r r vrr jnt i ( j . j , rnd ( t . r l is t i . . r l tv pt . rnfo( l c\ f f r im(;rrsi , r*Lr.hi

. ! m.r in () | l r i lLrr ion is l r ) f r r t . r f i l , pf( jpk. , , n"u, , , i t t , " . ,ppI. r l r ' ins r)r \ ( rnrc.srnLr i is l l \ l lcr t rnrLl Ics.Jr ' rpr( i \ . r r rnts, l , rml .n r( ,nrr \ \ , ) rk , r f ( l t l r . l . ( hfr l ! . ( , , i Sl)( , h i t ll ( I r l r , , ( lu,r l i t \ f r ( ! lL i ( rs r f i l s . fv j .cs. l ( { , . , . (ars. L,c| l ( , f rofrnrUl i. r l roIs n"( l l , i l r sr t sJ.r( r l { r r , i , r , f , , , rs, \ l f r ( ! t r j . f t \ i t \ , or . r fkel str . rn. . I r ( t

, r r1. t . r r r , r

l:tr References and further readinoNlt ! l l , , \ 11, ! r . l l 'Sr \ 5r ! i r i r l l ( r . - . ( - \ , r l t \ ' . r i r , r r r / r ! r | r . \ , , j t [ j , No ]

f t 11, l !( ) r l in( I , l5 r l l l l ) : r ) / , r i r l ( , | r r / r / / t l r / / , i " , , r j r , , | , r , , r r r r r i (l iL l l r r r , )n l j l l . r r r r , r r r j , ( ) \ l ( j r r1, L K

l ' l l , I I ( L)( , r ) \ / , ( n I l l r ^ l , . r

i t l / : . ,1 l ) , r \ , ,1 l ;1 i t , t t l r tnr r : . t n r l, \L l ! l r ! , f W( \ l ( \ t L K

l \ / ,1,L, | (Lrq)) l \ t l t t i . \ , j t \n r , ! / ) ( , l , i i , . \ j l t i t tn\ t , r j r t r l \ \ r i l r l \ , . ,\ \ ( - ) ( (_\r . r iL\ l ! , , r ! . \ l i t r r , ,1. . , Wt, t 5 \

l l r \ . l i 1 l le i r ) . l l ' j r \nt n j j th l r \ t , l t , ! j , r l r r / UIr N,Lt ,J r( t t i , i l t r , tLt , Nt\ \5 l . r l ! ! rhoj \ , I l l t r l r i t Nl . r r . l in! Srrrr t i ( . i l , r ! r \ \ ( r j r r j \ . r r j ( \ r ) t \ |n

I t r l t r r r , l ! , , l r r t , r i \ rNrr l L r . t \ t i ( L, \ r \ . , \ !n- l t i1, ! ! , Nt s rL \ ( , N t , t S \l rArr l )1,(

.1 t )sr i ) r r r r r l r r rn\ t ! , t ) t r i i t r l r r , t r r , r i , t t , t r i rn t ,L\ t r r L\ t \ / \ r \ ! \ i. r l inr . l i t \ , i . J . i f , r

r r , ( i r i ' f ! i r . l l t rnLl ] . iLrrr . t r j . I ( q!r l, r r / !

' , , i r r i r r , ( /L !11.r t I l , N. t l r , i . r r f :t l t t i l 1 r j t r t t \ \ r r t t l

&lI Discussion questionsI I \ f l , r n h(^ i I d( \ r in!rn,r l nr , r i , . ts.nrurt svst , , | r r . rn tx,Lt t ( j , ( r l l \ .

f11\1ss\ , 1. ' t r 'D( i 'yer1, . rs(rr \ ! \ l r \ lh( .s\str ,nrJrr lSp(r( \J l r iqLr( . \:h(r lL l b( ' in l r { t r1!ccLI i ( jgcth. f l , ) , I r . r \ nrrr b.nef i . i , r l

. I r \ r2 Whit is lhf r ( ) l .of tcamnork in protcss rrrp,n\rnrclr? ( \ \

. . r , r t t r ,s nrpl( tcfhniqLr(s () i probl fnr L lent i i i ( i torr . rn( l s() t \ inc lx, t t l f . r l rsto inrpro! . ' pro.ess.s l

I I ) isruss in d. t . r i l th. ' f f \1, f .nding inrpru\crncnt. \ . t ! , , rnJ nk r t r jsr" I r ' ,n l r \ . | , - , , i I r r . | ,1. . r l r t , t r l

1 \ \ rhdt . r rc t lx m.r jor hc.rdhgs oi l . r j tuchi s . fpro.r .h rn rcdlc ingcosts ind ImpR)\ in i j qual i t \ nr nr . rUf i ( t l r f ing? Ln.ter . . .h of rhesr,

xI 358 Stat istrcal Process Conrrol

headings, giyc a brief sumnary of Taguchi,s thinkjng. Exptain hoi,r ts i . . 'pfru. , ,hf , .u lo b, . , f t , t i , .o ind\ . r \q R.J r . In; l i re \ , ' i . l r^n . , t \ , , r t rn, , * ,e- .h, , ,J b, . : m.11pr , ,1. . . 1; , ., i r rnr Inf r . \ ' n- , n l d l : t i \ in. ( )ut l . r r , . I t t rn j - , t ( p dpnroaL h,r , .F_i ! r_ing nomi'ral trrgei lnlues nnd tolcrances for variabtes (produca orprocrss par.rmeiers) and c\ptain holv this wilt hclp b achielc this