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Solutions for Fundamentals of Modern Manufacturing , 5/e (published by Wiley)  MPGroover 2012

25 NONTRADITIONAL MACHINING AND THERMAL CUTTING PROCESSES Review Questions 25.1 25.1

Why re the nontr nontrdit dition ionl l !ter !teril il re!ovl re!ovl pro"es pro"esses ses i!port i!portnt# nt# Answer. $esons for i!portn"e of nontrditionl !teril re!ovl pro"esses re (1) the need to shpe ne% !etl lloys nd non&!etls tht re diffi"ult to !"hine by "onventionl pro"esses' (2) the reuire!ent of unusul nd "o!ple %or* prt +eo!etries' nd () the need to void surf"e d!+e %hi"h is often sso"ited %ith "onventionl !"hinin+.

25.2

-here re four four "te+or "te+ories ies of nontrd nontrdition itionl l !"hinin !"hinin+ + pro"esses pro"esses,, bsed bsed on prin"ipl prin"ipl ener+y ener+y for!. for!. !e the the four "te+ories. "te+ories. Answer. -he four "te+ories re (1) !e"hni"l, but not in"ludin+ "onventionl !"hinin+' (2) ele"tri"l' () ther!l' nd () "he!i"l.

25. 25.

o% o% does does the the ult ultr rso soni ni"" !"h !"hin inin in+ + pro" pro"ess ess %or* %or*## Answer. n ultrsoni" !"hinin+, brsives "ontined in  slurry re driven t hi+h velo"ity +inst the %or* by  tool vibrtin+ t lo% !plitude nd hi+h freuen"y. -he tool os"illtes in  dire"tion perpendi"ulr perpendi"ulr to the the %or* surf"e, surf"e, nd is fed slo%ly slo%ly into into the %or*, so so tht tht the shpe shpe of of the tool tool is for!ed in the prt. -he brsives, i!pin+in+ +inst the %or* surf"e, perfor! the "hip re!ovl.

25. 25.

es" es"ri ribe be the the %t %ter er 3et 3et "utt "uttin in+ + pro" pro"es ess. s. Answer. Wter 3et "uttin+ uses  hi+h&pressure, hi+h&velo"ity stre! of %ter dire"ted t the %or* surf"e to "ut the %or*.

25.5

Wht is the the differen"e differen"e bet%een bet%een %ter %ter 3et "uttin+, "uttin+, brsive brsive %ter 3et "uttin+ "uttin+,, nd brsive brsive 3et "uttin+# "uttin+# Answer. W4 "uts %ith  nrro%, hi+h velo"ity %ter stre!' 6W4 dds brsive +rits to the %ter stre!' nd 64M "uts %ith brsive prti"les tht hve been dded to  hi+h velo"ity ir stre!.

25.7 25.7

!e !e the the three three !in !in type typess of ele"t ele"tro ro"h "he! e!i" i"ll !"hi !"hini nin+ n+.. Answer. -he three types re ele"tro"he!i"l !"hinin+, deburrin+, nd +rindin+.

25.8 25.8

dentify dentify the the t%o t%o si+nif si+nifi" i"nt nt disd disdvn vnt+e t+ess of ele"tro ele"tro"he "he!i" !i"ll !"hini !"hinin+. n+. Answer. isdvnt+es of 9M in"lude (1) "ost of ele"tri"l po%er to operte the pro"ess, nd (2) "ost of disposl of ele"trolyte slud+e.

25.:

o% does in"resin+ in"resin+ dis"hr+e dis"hr+e "urrent "urrent ffe"t ffe"t !etl re!ovl rte nd nd surf"e surf"e finish in ele"tri ele"tri"" dis"hr+e !"hinin+# Answer. 6s dis"hr+e "urrent in"reses, !etl re!ovl rte in"reses nd surf"e finish is de+rded.

25.; 25.;

Wht Wht is !ent !ent by by the the ter! ter! over" over"ut ut in in ele"t ele"tri" ri" dis"h dis"hr+e r+e !"hin !"hinin+ in+## Answer.
25.10 25.10

dentify dentify t%o t%o !3or !3or disdv disdvnt nt+es +es of of pls! pls! r" "utti "uttin+. n+.

9"erpts fro! this %or* !y be reprodu"ed by instru"tors for distribution on  not&for&profit bsis for testin+ or instru"tionl purposes only to students enrolled in "ourses for %hi"h the tetboo* hs been dopted. Any other reproduction reproduction or translation of this work work beyond that permitted by Sections 107 or 108 of the 1976 United States Copyriht Act without the permission of the copyriht owner is unlawful!

25&1

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Answer. -%o disdvnt+es of P6 re (1) rou+h surf"e on "ut ed+e nd (2) !etllur+i"l d!+e to "ut surf"e.

25.1 25.11

Wht Wht re so!e so!e of of the fuels fuels used used in oyf oyfuel uel "utt "uttin+ in+## Answer. Prin"ipl fuels re "etylene, M6PP (!ethyl"etylene&propdiene), propylene, propne, nd nturl +s.

25.12 25.12

!e the the four four prin"i prin"ipl pl step stepss in "he!i" "he!i"l l !"hin !"hinin+ in+.. Answer. -he four steps re (1) "lenin+, (2) !s*in+, () et"hin+, nd () de!s*in+.

25.1

Wht re re the three three !ethods !ethods of perfor!in+ perfor!in+ the !s*in+ !s*in+ step step in "he!i"l "he!i"l !"hinin+# !"hinin+# Answer. -he three !s*in+ !ethods re (1) "ut nd peel, (2) s"reen resist, nd () photo+rphi" resist.

25.1 25.1

Wht Wht is  photor photoresi esist st in "he!i" "he!i"ll !"hin !"hinin+ in+## Answer. 6 photoresist is  !s*in+ !teril tht is sensitive to li+ht. When eposed, it "he!i"lly trnsfor!s nd "n be re!oved fro! the surf"e of the %or*, levin+ the desired surf"e unprote"ted by the !s*nt.

Probe!s 6ns%ers to proble!s lbeled "A# re listed in n 6ppendi 6ppendi t the b"* of the boo*. A$$i%&tion Probe!s

25.1

=or the the follo%i follo%in+ n+ ppli" ppli"tion, tion, identify identify one or or !ore nontrditio nontrditionl nl !"hini !"hinin+ n+ pro"ess pro"esses es tht tht !i+ht !i+ht be used, used, nd present present r+u!ents r+u!ents to to support support your your sele"tion sele"tion.. 6ssu!e 6ssu!e tht tht either either the the prt +eo!etry +eo!etry or the %or* !teril (or both) pre"lude the use of "onventionl !"hinin+. -he ppli"tion is  !tri of 0.1 !! (0.00 in) di!eter holes in  plte of .2 !! (0.125 in) thi"* hrdened tool steel. -he !tri is re"tn+ulr, 85 by 125 !! (.0 by 5.0 in) %ith the seprtion bet%een holes in e"h dire"tion > 1.7 !! ( 0.0725 in). Soution? Possible pro"esses? E'M nd L'M "n !*e holes of this si@e %ith depth&to&di!eter rtios s lr+e s 0.125/0.00 > 1.25.

25.2

=or the the follo%i follo%in+ n+ ppli" ppli"tion, tion, identify identify one or or !ore nontrditio nontrditionl nl !"hini !"hinin+ n+ pro"ess pro"esses es tht tht !i+ht !i+ht be used, used, nd present present r+u!ents r+u!ents to to support support your your sele"tion sele"tion.. 6ssu!e 6ssu!e tht tht either either the the prt +eo!etry +eo!etry or the %or* !teril (or both) pre"lude the use of "onventionl !"hinin+. -he ppli"tion is n en+rved lu!inu! printin+ plte to be used in n offset printin+ press to !*e 285 by 50 !! (11 by 1 in) posters posters of of Ain"olnBs Ain"olnBs Gettysbur+ Gettysbur+ ddress. ddress. Soution? Possible pro"ess? photo"he!i"l en+rvin+' !*in+  ne+tive of the spee"h nd trnsferrin+ this to either  sil* s"reen or dire"tly to the photoresist %ould see! to be the !ost stri+htfor%rd !ethods.

25.

=or the the follo%i follo%in+ n+ ppli" ppli"tion, tion, identify identify one or or !ore nontrditio nontrditionl nl !"hini !"hinin+ n+ pro"ess pro"esses es tht tht !i+ht !i+ht be used, used, nd present present r+u!ents r+u!ents to to support support your your sele"tion sele"tion.. 6ssu!e 6ssu!e tht tht either either the the prt +eo!etry +eo!etry or the %or* !teril (or both) pre"lude the use of "onventionl !"hinin+. -he ppli"tion is  throu+h&hole in the shpe of the letter A in  12.5 !! (0.5 in) thi"* plte of +lss. -he si@e of the CAC is 25 by 15 !! (1.0 by 0.7 in) nd the %idth of the hole is  !! (1/: in).






the %or* !teril (or both) pre"lude the use of "onventionl !"hinin+. -he ppli"tion is  blind&hole blind&hole in the shpe shpe of the letter letter G in  50 !! (2.0 in) in) "ube of steel. steel. -he -he overll overll si@e si@e of the the CGC is 25 by 1; !! (1.0 by 0.85 in), the depth of the hole is .: !! (0.15 in), nd its %idth is  !! (1/: in). Soution? Possible pro"esses? ECM nd EDM %ould be useful for po"*etin+ opertions su"h s this.

25.5 25.5

Mu"h of of the %or* %or* t the the ut&6ny ut&6nythi thin+ n+ o!pn o!pny y involv involves es "utti "uttin+ n+ nd nd for!in+ for!in+ of of flt shee sheets ts of fiber&+lss for the plesure bot industry. Mnul !ethods bsed on portble s%s re "urrently used to perfor! the "uttin+ opertion, but produ"tion is slo% nd s"rp rtes re hi+h. -he fore!n sys the "o!pny should invest in  pls! r" "uttin+ !"hine, but the plnt !n+er thin*s it %ould be too epensive. Wht do you thin*# 4ustify your ns%er by indi"tin+ the "hr"teristi"s of the pro"ess tht !*e P6 ttr"tive or unttr"tive in this ppli"tion. Soution? n pls! r" "uttin+, the %or* prt !ust be n ele"tri"lly "ondu"tive !teril. =iber +lss is not ele"tri"lly "ondu"tive. P6 is therefore not n pproprite pro"ess for this ppli"tion.

25.7

6 furniture furniture "o!pny "o!pny tht !*es upholstered upholstered "hirs nd sofs sofs !ust !ust "ut "ut lr+e lr+e untities untities of fbri"s. fbri"s. Mny of these fbri"s re stron+ nd %er&resistnt, %hi"h properties !*e the! diffi"ult to "ut. Wht nontrditionl pro"ess(es) %ould you re"o!!end to the "o!pny for this ppli"tion# 4ustify your ns%er by indi"tin+ the "hr"teristi"s of the pro"ess tht !*e it ttr"tive. Soution? Wter 3et "uttin+ %ould be n idel pro"ess for this ppli"tion. W4 "uts throu+h fbri"s ui"*ly nd "lenly, nd the pro"ess "ould be redily uto!ted.

Ee%tro%(e!i%& M&%(inin)

25.8

"A# (S units) n n 9M opertion the frontl %or*in+ re of the ele"trode is 1555 !! 2. 6pplied "urrent > 1200 !ps nd volt+e > 12 volts. -he !teril bein+ "ut is ni"*el (vlen"e > 2). onsult -ble 25.1 for the spe"ifi" re!ovl rte of ni"*el. () f the pro"ess is ;0E effi"ient, deter!ine the rte of !etl re!ovl in !! /!in. (b) f the resistivity of the ele"trolyte > 150 oh!&!!, deter!ine the %or*in+ +p.

> .2  10 &2 !!/6&s Soution? () =ro! -ble 25.1, the spe"ifi" re!ovl rte C > =ro! 9. (25.7) " (25.7) " #" > f > f A > A (C$ / A) A) A > A > C$ > > (.2  10 &2 !!/6&s)(1200 6) r r > (C$ > 1.0 !! /s > 272 !! /!in 6t ;0E effi"ien"y " effi"ien"y " #" > 0.;(272 !! /!in) > 22*+ !!,-!in (b) Given resistivity r > > 150 oh!&!!, $ oh!&!!, $ > %A > %A// r r in in 9. (25.2). $errn+in+,  $errn+in+,  > %A > %A// $r $r 2  > > (12 F)(1555 !! )/(1200 6)(150 oh!&!!) > ./*.0 !! 25.: 25.:

(DSS (DSS units units)) -he -he fron frontl tl %or*in %or*in+ + re re of of the the ele"t ele"trod rodee is .8 in 2 in n 9M opertion on pure lu!inu!. 6pplied "urrent > 1500 !ps nd volt+e > 12 volts. onsult -ble 25.1 for the spe"ifi" re!ovl rte of lu!inu!. () f the 9M pro"ess is :5 per"ent effi"ient, deter!ine the rte of !etl re!ovl in in /hr. (b) f the resistivity of the ele"trolyte > 7.: oh!&in, deter!ine the %or*in+ +p. Soution? () =ro! -ble 25.1, the spe"ifi" re!ovl rte C > > 0.000127 in /6&!in " #" > f > f A > A (C$ / A)( A)( A) A) > C$ r r > (C$ " #" > C$ > > 0.000127(1500) > 0.1:; in /!in t 100E effi"ien"y. effi"ien"y. 

,






but the the ele"trode ele"trode used used to "ut the the hole hole is sli+htly sli+htly less thn thn 5 !! on its its sides sides to llo% llo% for for over"ut, over"ut, nd its shpe in"ludes  hole in its "enter to per!it the flo% of ele"trolyte nd to redu"e the re of the "ut. -his tool desi+n results in  frontl re of 25 !! 2. -he pplied "urrent > 1200 !ps. () Dsin+ n effi"ien"y of ;5E, ho% lon+ %ill it t*e to "ut the hole# (b) f the tool %ere desi+ned %ith  frontl re eul to the hole si@e, ho% lon+ %ill it t*e to "ut the hole# Soution? () Given tht C > > .8  10 &2 !!/6&s =ro! 9. (25.7) f (25.7) f r r > > C$ / A > A > (.8  10 &2 !!/6&s)(1200 6)/(25 !! 2) > 0.1:12 !!/s 6t ;5E effi"ien"y, effi"ien"y, f r r > > 0.;5(0.1:12 !!/s) > 0.182 !!/s -i!e to !"hine > (12 !!)/(0.182 !!/s) > +1/ s 3 */*+ !in

(b) -he re of the sure hole > 5 2 > 1225 !!2 f r r > > C$ / A > A > (.8  10 &2 !!/6&s)(1200 6)/(1225 !! 2) > 0.072 !!/s 6t ;5E effi"ien"y, effi"ien"y, f r r > > 0.;5(0.072 !!/s) > 0.0 !!/s -i!e to !"hine > (12 !!)/(0.0 !!/s) > ,04/5 s 3 5/4* !in Co!!ent? -he ele"trode desi+n %ith the hole in the "enter redu"es the ti!e to !"hine by  f"tor of 5 be"use of the redu"ed frontl re.

25.10

(DSS units) units) 6 .5 in di!eter di!eter throu+ throu+h h hole is to be "ut "ut in  blo"* blo"* of titniu! titniu! (vlen" (vlen"ee > ) by ele"tro"he!i"l !"hinin+. -he blo"* is 2.0 in thi"*. -o speed the "uttin+ pro"ess, the ele"trode tool %ill hve  "enter hole of .0 in, %hi"h %ill produ"e  "enter "ore tht "n be re!oved fter the tool bre*s throu+h. f the effi"ien"y of the 9M opertion is ;0E, %ht "urrent %ill be reuired to "o!plete the "uttin+ opertion in 5 !inutes# Soution? 9le"trode frontl +p re A re A > > 0.25(.52 & .02) > 2.55 in 2 =ro! -ble 25.1, the spe"ifi" re!ovl rte C > > 0.00010 in /6&!in f r r > > C$ / A > A > 0.00010 $ 0.00010 $ /2.55 /2.55 > 0.0000;2 $ 0.0000;2 $ in/!in in/!in t 100E effi"ien"y. 6t ;0E effi"ien"y f effi"ien"y f r r > > 0.;(0.0000;2 $ 0.;(0.0000;2 $ ) > 0.00005 $ 0.00005 $ in/!in in/!in -o "ut throu+h  2.0 in"h thi"*ness in 5 !inutes reuires  feed rte f r r > > 2.0/5 > 0.0 in/!in f r r > > 0.0 > 0.00005 $ 0.00005 $ $ > > 0.0/0.00005 > *251 A/

Ee%tri% Dis%(&r)e M&%(inin)

25.11

"A# (S units) 6n ele"tri" dis"hr+e !"hinin+ opertion is perfor!ed on tun+sten. eter!ine the !ount of !etl re!oved in the opertion fter one hour t  dis"hr+e "urrent of 20 !ps for this !etl. Dse !etri" units nd epress the ns%ers in !! /hr. $efer to -ble .1 for the !eltin+ te!perture of tun+sten. Soution? =or tun+sten, the !eltin+ te!perture +iven in -ble .1 > 10 . Dsin+ 9. (25.8), " (25.8), " #" > &$ > &$ /' m1.2 > 77(20)/(10 1.2) > 0.5;;8 !! /s > 2*51 !!,-(r

25.12

(DSS units) units) 6n ele"tri" ele"tri" dis"hr+ dis"hr+ee !"hinin+ !"hinin+ opertion opertion is is perfor!ed perfor!ed on @in". @in". eter!ine eter!ine the !ount of !etl re!oved in the opertion fter one hour t  dis"hr+e !per+e > 1: !ps for this !etl. Dse D.S. usto!ry units nd epress the ns%er in in /hr. $efer to -ble .1 for the !eltin+ te!perture of @in". Soution? =or @in", the !eltin+ te!perture +iven in -ble .1 > 8:8 =. Dsin+ 9. (25.8), " (25.8), " #" > &$ > &$ /' m1.2 > 5.0:(1:)/(8:8 1.2) > 0.0251 in /s > */5.0 in,-(r






f r r > " > " #"/ A > A > 0.0050/2.55 > 0.002085 in/!in -i!e to !"hine the 2.0 in"h thi"*ness ' m > 2.0/0.002085 > 1+,/1 !in 3 *+/.+0 (r 25.1 25.1

(DSS (DSS units units)) 6 !etl !etl re!ov re!ovl l rte rte of of 0.00: 0.00: in/!in is "hieved in  "ertin 9M opertion on n iron %or* prt. Wht !etl re!ovl rte %ould be "hieved on lu!inu! in this 9M opertion, if the s!e dis"hr+e "urrent %ere used# onsult -ble .1 for the !eltin+ te!pertures of iron nd lu!inu!. Soution? =ro! -ble .1, the !eltin+ te!pertures of iron nd lu!inu! re 2:02 = nd 1220 =, respe"tively. =or iron, " iron, " #" > 5.0: $ 5.0: $ /2:02 /2:021.2 > 5.0: $ 5.0: $ /18,; /18,; > 0.0002;2 $ 0.0002;2 $ in in/!in Given tht " tht " #" > 0.00: in /!in 0.0002;2 $ 0.0002;2 $ > > 0.00: $ > > 0.00:/0.0002;2 > 28. 6. =or > lu!inu!, " lu!inu!, " #" > 5.0:(28.)/1220 1.2 > 1;.1:/7255 > ./.2225 in,-!in Co!!ent? e"use the !eltin+ te!perture of lu!inu! is si+nifi"ntly lo%er thn tht of iron, the !etl re!ovl rte is bout 2.: ti!es fster.

25.15

(S units) units) n  %ire %ire 9M opertio opertion n perfor!ed perfor!ed on 12&!!&thi 12&!!&thi"* "* 10:0 10:0 steel usin+ usin+  tun+ste tun+sten n %ire ele"trode %hose di!eter > 0.125 !!, pst eperien"e su++ests tht the over"ut %ill be 0.02 !!, so tht the *erf %idth %ill be 0.175 !!. Dsin+  dis"hr+e "urrent > 15 !ps, %ht is the feed rte tht "n be used in the opertion# 9sti!te the !eltin+ te!perture of 0.:0E "rbon steel fro! the phse di+r! di+r! of =i+ure =i+ure 7.. Soution? =ro! =i+ure 7., ' m > 1500 for 10:0 steel Dsin+ 9. (25.8), " (25.8), " #" > 77(15)/(1500 1.2) > ;;70/:075 > 1.22 !! /s > 8.;2 !! /!in =rontl re of *erf A *erf A > > 0.175(12.0) > 1.;: !! 2 f r r > > 8.;2/1.;: > ,/,, !!-!in

25.17

"A# (DSS units) 6 %ire 9M opertion is perfor!ed on  slb of 1/2&in&thi"* lu!inu! plte usin+  brss %ire ele"trode %hose di!eter > 0.005 in. t is nti"ipted tht the over"ut %ill be 0.001 in, so tht the *erf %idth %ill be 0.008 in. -he len+th of the "ut > 12 in. Dsin+  dis"hr+e "urrent > 10 !ps, %ht is the epe"ted ti!e to "ut throu+h the plte# onsult -ble .1 for the !eltin+ te!perture of lu!inu!. Soution? =ro! -ble .1, the !eltin+ te!perture of lu!inu! is 1220 =. Dsin+ 9. (25.8), " (25.8), " #" > 5.0:(10)/1220 1.2 > 50.:/7255 > 0.00:12 in /!in =rontl re of *erf A *erf A > > 0.50(0.008) > 0.005 in 2 f r r > > 0.00:12/0.005 > 2.2 in/!in -i!e to !"hine ' m > 12.0/2.2 > 5/* !in

25.18

(S units) units) 6 %ire 9M 9M opertion opertion is used to "ut "ut out pun"h&nd pun"h&nd&die &die "o!ponent "o!ponentss fro! 25&!!&thi"* 25&!!&thi"* tool steel pltes. o%ever, in preli!inry "uts, the surf"e finish on the "ut ed+e is poor. Wht "hn+es in dis"hr+e "urrent nd freuen"y of dis"hr+es should be !de to i!prove the finish# Soution? 6s indi"ted in =i+ure 25.:(), surf"e finish in 9M "ould be i!proved by redu"in+ dis"hr+e "urrent nd in"resin+ freuen"y of dis"hr+es.

C(e!i%& M&%(inin)






spe"ified depth, nd (") reuired di!ensions of the openin+ in the "ut nd peel !s*nt to "hieve the desired po"*et si@e on the prt. Soution? =ro! -ble 25.2, the penetrtion rte for this "o!bintion > 0.025 !!/!in nd the et"h f"tor ( f"tor ( e > 1.85.

() e+le"tin+ the f"t tht the initil re %ould be less thn the +iven di!ensions of 200 !! by 00 !!, nd tht the !teril re!ovl rte ( " ( " #") %ould therefore in"rese durin+ the "ut s the re in"resed, re A re A > > 200  00 H (0  0 & (15)2) > :0,000 H 1; > 8;,:08 !! 2 " #" > (0.025 !!/!in)(8;,:08 !! 2) > *115/2 !!,-!in (b) -i!e to !"hine (et"h) ' m > 15/0.025 > +.. !in 3 *./. (r (") Given ( Given ( e > 1.85, under"ut u > d / ( ( e > 15/1.85 > :.58 !! Ms*nt openin+ len+th > ) > ) H H 2u 2u > 00 H 2(:.58) > ,42/4+ !! Ms*nt openin+ %idth > * H H 2u 2u > 200 H 2(:.58) > *42/4+ !! $dius on "orners > " > " H H u > 15 H :.58> +/0, !! 25.1;

(DSS units) units) n  "he!i" "he!i"ll !illin+ !illin+ opertion opertion on  flt !ild !ild steel plte, it it is desired desired to "ut "ut n ellipse& ellipse& shped po"*et to  depth of 0.25 in. -he se!i&es of the ellipse re a > 12.0 in nd b > :.0 in. 6 solution of hydro"hlori" nd nitri" "ids %ill be used s the et"hnt. onsult -ble 25.2 for the penetrtion penetrtion rte rte nd et"h f"tor f"tor.. eter!ine eter!ine () !etl re!ovl re!ovl rte in in in /hr, (b) ti!e reuired to et"h to depth, nd (") reuired di!ensions of the openin+ in the "ut nd peel !s*nt reuired to "hieve the desired po"*et si@e on the prt. Soution? =ro! -ble 25.2, the penetrtion rte for this "o!bintion > 0.001 in/!in nd the et"h f"tor ( f"tor ( e > 2.0.

() e+le"tin+ the f"t tht the initil re %ould be sli+htly less thn the +iven di!ensions of 12 in by : in, in, nd tht tht the !teril !teril re!ovl re!ovl rte ( " #") %ould therefore in"rese durin+ the "ut s the re in"resed, re of n ellipse A ellipse A > > ab > ab > (12.0)(:.0) > ;7  > 01.7 in 2 " #" > (0.001 in/!in)(01.7 in 2) > 0.017 in /!in > *4/.1+ in,-(r (b) -i!e to !"hine (et"h) ' m > 0.25/0.001 > 25. !in 3 0/*+ (r. (") Given ( Given ( e > 2.0, under"ut u > d / ( ( e > 0.25/2.0 > 0.125 !! -his !ust be doubled to deter!ine the effe"t on a nd b. Ms*nt openin+ aI > a H u > 12.0 H 2(0.125) > **/5 in Ms*nt openin+ bI > b H u > u > :.0 H 2(0.125) > /5 in 25.20

(S units) units) n  "ertin "ertin "he!i"l "he!i"l bln*in bln*in+ + opertion, opertion,  sulfuri" sulfuri" "id "id et"hnt et"hnt is used used to re!ove re!ove !teril fro!  sheet of !+nesiu! lloy. -he sheet is 0.25 !! thi"*. -he s"reen resist !ethod of !s*in+ %s used to per!it hi+h produ"tion rtes to be "hieved. 6s it turns out, the pro"ess is produ"in+ produ"in+  lr+e lr+e proport proportion ion of s"rp. Spe"ified Spe"ified tolern"es tolern"es of 0.025 !! re not bein+ "hieved. -he fore!n in the M deprt!ent "o!plins tht there !ust be so!ethin+ %ron+ %ith the sulfuri" "id. CPerhps the "on"entrtion is in"orre"t,C he su++ests. 6nly@e the proble! nd re"o!!end  solution. Soution? -he proble! in this "he!i"l bln*in+ opertion is tht the s"reen resist !ethod of !s*in+ "nnot "hieve the tolern"es spe"ified. -he photoresist !ethod should hve been used, nd the pro"ess should be "hn+ed over to dopt this !ethod.








Soution? =ro! -ble 25.2, ( 25.2, ( e > 1.85. n "he!i"l bln*in+, et"hin+ %ill o""ur on both sides of the prt. -herefore, the effe"tive hole depth on e"h side > one&hlf of the sto"* thi"*ness > 0.015/2 > 0.0085 in. Dnder"ut u > 0.0085/1.85 > 0.00 in i!eter of pttern holes > 0.100 & 2(0.00) > ./.1*0 in

ch25

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