inter chang ibility

8/10/2019 Inter Chang Ibility

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Interchangeability andselective assembly

1/17/15Interchangeability and Selectiveassembly 1

Chirra Kumara swamy

Roll No.143503

M.Tech (MFG)

NIT ara!"al


2/20

Defnition#! i!$ercha!"ea%le &ar$ is o!e which ca! %e su%s$i$u$e' or

similar &ar$ ma!uac$ure' $o $he same 'rawi!".

he! o!e com&o!e!$ assem%les &ro&erly (a!' which sa$isies$he u!c$io!ali$y as&ec$ o $he assem%ly) wi$h a!y ma$i!"

com&o!e!$ %o$h chose! a$ ra!'om $he! i$ is *!ow! as

i!$ercha!"ea%ili$y.

+r

The &ar$s ma!uac$ure' u!'er similar co!'i$io!s %y a!y

com&a!y or i!'us$ry a$ a!y cor!er o $he worl' ca! %e

i!$ercha!"ea%le1/17/15Interchangeability and Selectiveassembly 2


3/20

,eore $he 1-$h ce!$ury &ro'uc$io! use' $o %e co!i!e' $o

small !um%er o u!i$s a!' $he same o&era$or coul' a'us$ $he

ma$i!" com&o!e!$s $o o%$ai! 'esire' i$.

/eices such as "u!s were ma'e o!e a$ a $ime %y "u!smi$h.

I si!"le com&o!e!$ o a irearm !ee'e' a re&laceme!$ $he

e!$ire irearm ei$her ha' $o %e se!$ $o a! e&er$ "u!smi$h or

cus$om re&airs or 'iscar'e' a!' re&lace' %y a!o$her irearm.


HistoricalBackground


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5/20

I!$ercha!"ea%ili$y o &ar$s are achiee' %y com%i!i!" a

!um%er o innovationsa!' improvementsi! machi!i!"

o&era$io!s so $ha$ we will a%le &ro'uce componentswi$h

accuracy.

Mo'er! machi!e $ools li*e !umerical co!$rol (NC) which

eole' i!$o CNC. 6i"s a!' i$ures.

Gau"es $o chec* $he accuracy o $he i!ishe' &ar$s. Thesehel&s i! ma!uac$uri!" $he com&o!e!$s wi$hi! i$s s&eciie'

limi$s.

1/17/15 I!$ercha!"ea%ili$y a!' elec$ie assem%ly 5


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I a &lo$ is 'raw! o $he ac$ual 'ime!sio!s o $he

similar com&o!e!$s &ro'uce' %y a well8co!$rolle'

machi!e i$ is ou!' $o ollow Normal 'is$ri%u$io!.

1/17/15 Interchangeability and Selective assembly6

= Standard deviationxmean X/N ,!!re"#ency


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eam&le we hae 100 parts each wi$h a hole a!' 100shaftswhich hae $o i$ i!$o $hese holes.

I we hae i!$ercha!"ea%ili$y $he! we ca! ma*e a!y o!e

o $he 100 shaft9 i$ i$ i!$o a!y hole 9 %e sure $ha$ $he

re:uire' i$ ca! %e o%$ai!e'.

Any M6 bolt will fit to any M6 nut randomly selected.



8/20

The a'a!$a"es o i!$ercha!"ea%ili$y

1. The assem%ly o ma$i!" &ar$s is easier. i!ce a!y

com&o!e!$ &ic*e' u& rom i$s lo$ will assem%le

wi$h a!y o$her ma$i!" &ar$ rom a!o$her lo$wi$hou$ a''i$io!al i$$i!" a!' machi!i!".

;. I$ e!ha!ces $he &ro'uc$io! ra$e.

3. I$ %ri!"s 'ow! $he assem%li!" cos$ 'ras$ically.

1/17/15Interchangeability and Selectiveassembly $


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4. Re&airi!" o eis$i!" machi!es or &ro'uc$s is

sim&liie' %ecause com&o!e!$ &ar$s ca! %e easily

re&lace'.

5. Re&laceme!$ o wor! ou$ &ar$s is easy.


10/20

&'am(leseys

!ouplings

"in #oints$cre%ed &asteners

'ears

!lutches

1/17/15Interchangeability and Selectiveassembly 1)
http://img.bhs4.com/12/9/1299072118b457bd117a115d0188f46f833a66c3_large.jpg


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Selective assemblyThe 'iscussio! so ar has %ee! i! co!!ec$io! wi$h ull

i!$ercha!"ea%ili$y or ra!'om assem%ly i! which a!y

com&o!e!$ assem%les wi$h a!y o$her com&o!e!$.

+$e! s&ecial cases o accuracy a!' u!iormi$y arises

which mi"h$ !o$ %e sa$isie' %y cer$ai! o $he i$s "ie!

u!'er a ully i!$ercha!"ea%le sys$em.



12/20

or eam&le i a &ar$ a$ i$s low limi$ is assem%le' wi$h $he

ma$i!" &ar$ a hi"h limi$ $he i$ so o%$ai!e' may !o$ ully

sa$isy $he u!c$io!al re:uireme!$s o $he assem%ly.

also machi!e ca&a%ili$ies are some$imes !o$ com&a$i%le

wi$h $he re:uireme!$s o i!$ercha!"ea%le assem%ly.

1/17/15 Interchangeability and Selective assembly 12


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For selec$ie assem%ly com&o!e!$s are measure' a!'

sorted intogroups by dimension &rior $o $he assem%ly&rocess. This is 'o!e or %o$h ma$i!" &ar$s.

Co!si'er a %eari!" assem%ly

7ole wi$h ha$ Cleara!ce shoul' %e 0.14mm

Ra!'omly i we $a*e a!' cleara!ce will %e 0.0-mm

7ole a!' ha$ &airi!" res&c$iely which "ies 0.14mm

cleara!ce ;4.=> a!' ;4.-3 ;5.0 a!' ;4.-


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I e$remely $i"h$ (!arrow) $olera!ce ra!"es are re:uire'

i$ may !o$ &ossi%le wi$h machi!i!" o&era$io!s. I! suchcase we use selec$ie assem%ly

?i! a!' 7ole wi$h sli'i!" i$.

7ole wi$h ?i! wi$hI &i!s comi!" wi$h over size ;0.003 !ee' !o$ %e

scra& $hey ca! %e ma$e' wi$h 7oles ;0.013

ame or com&o!e!$s wi$h u!'er si@e'.

1/17/15 Interchangeability and Selective assembly 14


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+rocess ca(ability

The mi!imum $olera!ce' com&o!e!$s which ca! %e

&ro'uce' o! a machi!e wi$h more $ha! ==A o

acce&$a%ili$y calle' as process capability

-0B0.1


16/20

+roblem,1For Cleara!ce Fi$

7ole Dha$D

Tolera!ce or %o$h D 0.1mm

Maimum cleara!ce D 7.E o hole 8 E.E o sha$ D ;0.18(1=.-5) D 0.;5 mm

Mi!imum cleara!ce D E.E o hole 8 7.E o sha$ D ;0.08(1=.=5) D 0.05 mm

?rocess ca&a%ili$y D 0.3Num%er o "rou&s D (&rocess ca&a%ili$y)Tolera!ce D 0.30.1D3

Ee$ $hose "rou&s %e 'e!o$e' %y # , C

1/17/15

Interchangeability and Selectiveassembly 16

Ty&e 7ole (mm) ha$ (mm)

#

,

C

Ty&e 7ole (mm) ha$ (mm)

#

,

C


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Grou& C holes wi$h Grou& C sha$

7ole Tolera!ce D0.1mmha$ Tolera!ce D0.1mm

Ty&e o i$ re:uire' is cleara!ce.

Maimum cleara!ce D 7.E o hole 8 E.E o sha$

D ;0.38;0.05

D 0.;5mm

Mi!imum cleara!ce D E.E o hole 8 7.E o sha$

D ;0.;8;0.15 D 0.05mm



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-dvantagesThere is a lar"er !um%er o acce&$a%le &ar$s as ori"i!al

$olera!ces are "rea$er

This i! $ur! allows $he ma!uac$ure o chea&er &ar$s as

less will %e co!si"!e' $o $he was$e %i!.

elec$ie #ssem%ly assures %e$$er a!' more accura$e

assem%ly o &ar$s %y i!suri!" closer $olera!ces %e$wee!

$he ma$i!" &ar$s.

Rise $he :uali$y a!' lower ma!uac$uri!" cos$s %yavoiding tight tolerances.

Re'uces $he reec$io! ra$e (scra& ra$e)

1/17/15Interchangeability and Selectiveassembly 1$


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.imitations/uri!" usa"e o $he assem%ly i o!e com&o!e!$ ails

irs$ we !ee' ma!ual o assem%ly a!' i'e!$iy $he "rou&

$o which ailure com&o!e!$ %elo!"s $o a!' search $he

com&o!e!$ i! s&are &ar$s.

,y ocusi!" o! $he i$ %e$wee! ma$i!" &ar$s ra$her $ha!

$he a%solu$e si@e o each com&o!e!$ so $here will small

'eia$io! i! si@e o com&o!e!$.

1/17/15Interchangeability and Selectiveassembly 1%


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e!erences1. A text boo of production engineering ,y ?. C.

harma

!. Metrology " Measurement ,y ,ewoor3. h$$&e!.wi*i&e'ia.or"wi*iI!$ercha!"ea%&ar$s

1/17/15Interchangeability and Selectiveassembly 2)
http://en.wikipedia.org/wiki/Interchangeabpartshttp://en.wikipedia.org/wiki/Interchangeabpartshttp://en.wikipedia.org/wiki/Interchangeabpartshttp://en.wikipedia.org/wiki/Interchangeabpartshttp://en.wikipedia.org/wiki/Interchangeabparts

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