metrology basics

7/24/2019 Metrology basics

1/113

METROLOGY & TOLERANCE ENGINEERING(MAE 622)

K.Srinivasulu Redd!e"ar#$en# % Me'ani'al & ei'le

En*ineerin*Ada$a S'ien'e & Te'n%l%* +niversi#

,


2/113

2

Unit I INTRODUCTION:

Metrological concepts - Abbe's principle - need for high precision measurements -

problems associated with high precision measurements.

Unit II MEASUREMENT, GAUGING AND GEAR & THREAD MEASUREMENT

Standards for length measurement - Shop floor standards and their calibration -Method of coincidence - Slip gauge calibration - Measurement errors. Angular

measurements - principles and instruments. Gear and Thread measurements.

Various tolerances and their specifications, gauging principles, selective assembl,

comparators.

Unit III SURFACE AND FORM METROLOGY

Surface and form metrolog - flatness, roughness, waviness, roundness,clindricit, etc.

Unit IV COMPUTER AIDED METROLOGY

!omputer Aided Metrolog - "rinciples and interfacing, software metrolog. #aser

metrolog - Applications of #asers in precision measurements - #aser

interferometer, spec$le measurements, laser scanners.

Unit V CMM, IMAGE PROCESSING AND ITS APPLICATIONS!oordinate Measuring Machine - Tpes of !MM - "robes used - Applications - %on

contact !MM using &lectro optical sensors for dimensional metrolog - %on

contact sensors for surface finish measurements. mage processing and its

application in Metrolog.


3/113

-

Unit VI LIMITS AND FITS

Tpes of (its, #imits, #imits and (its in Metric Sstem, )esignation of standard

tolerances, Tolerance Grades, "osition of Tolerance, Sstem of (its* +ole asisand Shaft asis sstems, relation between the sstems, (undamental relationship

between fits and tolerances, Selection of (its* General Method using common fits,

!ompatible tolerances with the methods of manufacturing.

Unit VII TOLERANCE ANALYSIS

ntroduction to interchangeabilit and selective assembl, Addition of Tolerances,

Subtraction of Tolerances, Tolerancing )imensions between centers of two holes

using series, parallel and combination methods,

Unit VIII GEOMETRICAL TOLERANCES

h use GT hat is Geometric )imensioning and Tolerancing/G)T0,

Geometric !haracteristics, Smbols of GT, Ma1imum

Material !ondition /MM!0, #east Material !ondition /#M!0, 2egardless of (eature

si3e /2(S0, )atum, )atum dentification and smbol.


4/113

When you can measure what you are speaking

about and express it in numbers, you know

something about it, but when you cannotmeasure it, when you cannot express it in

numbers, your knowledge is of a meager and

unsatisfactory kind.

-#ord 4elvinritish Scientist

/5678-59:;0


5/113

What is Met!"!#$%

Metrolog is the science of measurement ofdimensions, and measurement is the language of

science.

f science is measurement, then without

metrolog, there is no science.

/

Measurementcan be defined as the determinationof a dimension


6/113

+istorearin*s? Sa# in #e 0us is %i$"r%"er di$ensi%ns 3i'resul#s insu@'ien# #in 4l$: anden'e ri'#i%n: 3ear: lu0ri'a#i%nas"e'#s e#'.


9/113

ACCI!ENT O ALASKA AIRLINES LIG9T 26,

1

B $e#r%l%* is i$"%r#an#

Te $%s# seri%us "r%'ess err%r resul#ed in #e l%ss% Alasa Airlines %n Danuar -,:2 3i# 8-

"assen*ers.


10/113

E'essive #read 3ear %n #e Fa's're3 asse$0lresul#ed in l%ss% #e %ri=%n#al s#a0ili=er.

Te $e'ani' 3%r 'ard s#a#ed #a# #read 3ear 3aswithin allowable limitsH. In a'#: #e #reads %n#ejackscrew nut were almost completely wornaway.

Te "r%'ess (4#ures) used 0 #e $e'ani' 3eren%# 3a# >%ein* s"e'i4ed and #ere%re #e$easure$en# resul#s 3ere dieren# and 8-"e%"leJ're3 l%s# #eir lives

,


11/113

Re'%vered Fa's're3 7 #e s"iral

3ire 3%und ar%und #e #readed"%r#i%n is #e re$ains % #e a'$enu# in#ernal s're3 #read #a# as0een s#ri""ed r%$ #e nu#: 3i':

reein* #e Fa's're3.

,,

Rand%$ "r%'edures "r%du'e

rand%$ resul#s.


12/113

Su04eld !e4ni#i%n

S'ien#i4' %runda$en#al$e#r%l%*

'%n'erns #e es#a0lis$en# % uan#i#ss#e$s: uni# ss#e$s: uni#s %$easure$en#: #e devel%"$en# % ne3$easure$en# $e#%ds.

A""lied %rindus#rial $e#r%l%*

'%n'erns #e a""li'a#i%n % $easure$en#

s'ien'e #% $anua'#urin* and %#er"r%'esses and #eir use in s%'ie#: ensurin*#e sui#a0ili# % $easure$en# ins#ru$en#s:#eir 'ali0ra#i%n and uali# '%n#r%l %$easure$en#s.

Le*al $e#r%l%*

'%n'erns re*ula#%r reuire$en#s %$easure$en#s and $easurin* ins#ru$en#s%r #e "r%#e'#i%n % eal#: "u0li' sae#:#e envir%n$en#: "r%#e'#i%n % '%nsu$ersand air #rade.

T"es %Me#r%l%*

,2


13/113

Process of measurement:,.Measurand 2.Reeren'e -.C%$"ara#%r

1.Measurand? Measurand is #e "si'al uan#i# %r

"r%"er# lie len*#: an*le: dia$e#er: #i'ness e#'. #%0e $easured.

2.Reference: I# is #e "si'al uan#i# %r "r%"er# #%

3i' uan#i#a#ive '%$"aris%ns are $ade.

3.Comparator: I# is #e $eans % '%$"arin* $easurand3i# s%$e reeren'e

E? i##er as #% $easure MS a# 3i# s#eel rule

,.Ali*ns #e =er% end % s#eel rule 3i# %ne end % MS a#.2.C%$"ares #e len*# % a# 3i# #e *radua#i%ns %n #e rule

0 is ees.9ere:,-


14/113

Basicdenitions

1.Nominal size(Basic size: I# is #e si=e % a "ar#s"e'i4ed in #e dra3in* as a $a##er % '%nvenien'e.

li$i#s % si=e are0ased %n n%$inal si=e. I# $a 0e a3%le nu$0er %r de'i$al nu$0er.!. "rue size? I# is #e #e%re#i'alsi=e % a di$ensi%n:3i' is ree r%$ an err%rs % $easure$en#

#.$ctual size? I# is #e value % si=e %0#ained #r%u*$easure$en# 3i# #e "er$issi0le$easurin* err%r

%.&'act size? I# is #e value % si=e %0#ained 3i# #ei*es# $e#r%l%*i'al a''ura'a##aina0le in "ra'#i'e

.&rror of measurement? I# is #e dieren'e0e#3een #e #rue value % #e si=e 0ein* $easured

and #e value %und 0 $easure$en#(a'#ual %r ea'#),


15/113

).*ensiti+ity? Te s$alles# 'an*e in a $easure$en##a# an ins#ru$en# is 'a"a0le % de#e'#in*.

Sensi#ivi# reers #% #e a0ili# % $easurin* devi'e #%de#e'# s$all dieren'es in a uan#i# 0ein*$easured.

Sensi#ivi# $a 0e de4ned as #e ra#e %dis"la'e$en# % #e indi'a#in* devi'e % anins#ru$en#: 3i# res"e'# #% #e $easured uan#i#.

Sensi#ivi# s'ale s"a'in*


16/113

,6

hich is more sensitive


17/113

,.-alibration? Te '%$"aris%n % a devi'e 3i#unn%3n a''ura' #% a devi'e 3i# a n%3n: a''ura#es#andard #% eli$ina#e an varia#i%n in #e devi'e 0ein*

'e'ed.

I# is 'arried %u# 0 $ain* adFus#$en#s su' #a# #eread %u# devi'e "r%du'es =er% %u#"u# %r =er%

$easured in"u#.

Cali0ra#i%n is a "re$easure$en# "r%'ess: *enerall'arried %u# 0 $anua'#urers.

Te a''ura' % an ins#ru$en# de"ends %n #e'ali0ra#i%n. C%ns#an# use % ins#ru$en#s ae'# #eira''ura'.

I #e a''ura' is #% 0e $ain#ained: #e ins#ru$en#s,;


18/113

./ysteresis? Te dela 0e#3een #e a'#i%n andrea'#i%n % a $easurin* ins#ru$en#.

Te "en%$en%n % s#eresis is due #% #e"resen'e % dry frictionas 3ell as #e "r%"er#ies %elastic elements.

I# resul#s in #e l%adin* and unl%adin* 'urves% #eins#ru$en# 0ein* se"ara#ed 0 a dieren'e 'alledhysteresis error.

I# als% resul#s in #e "%in#er n%# re#urnin* '%$"le#el#% =er% 3en #e l%ad is re$%ved. 9s#eresis is"ar#i'ularl n%#ed in ins#ru$en#s avin* elas#i'ele$en#s.

Te "en%$en%n % s#eresis in $a#erials is $ainl,8


19/113

,1


20/113

0.epeatability? I# is #e a0ili# % #e $easurin*

ins#ru$en# #% re"ea# #e same results %r #e

$easure$en#s %r #e sa$e uan#i#: 3en #e

$easure$en#s are 'arried %u#

70 #e sa$e %0server73i# #e sa$e ins#ru$en#7under #e sa$e '%ndi#i%ns73i#%u# an 'an*e in l%'a#i%n73i#%u# 'an*e in #e $e#%d % $easure$en#7and #e $easure$en#s are 'arried %u# in s%r#in#ervals % #i$e.

I# $a 0e e"ressed uan#i#a#ivel in #er$s %2


21/113


22/113

22

11.Precision 3 $ccuracy

Pre'isi%n and a''ura' are used in '%nne'#i%n 3i##e "er%r$an'e % #e ins#ru$en#.

Pre'isi%n is de4ned as #e repeatability % #e

$easurin* "r%'ess: 3ile #e a''ura' is #ea*ree$en# % #e resul# % a $easure$en# 3i# #e#rue value % #e $easured uan#i#.

In $%s# $easure$en#s: i# is #e "re'isi%n 3i' is

% *rea# i$"%r#an'e.

I #e ins#ru$en# is n%# "re'ise: i# 3ill *ive dieren#resul#s %r #e sa$e di$ensi%n 3en $easureda*ain and a*ain.


23/113

1!.$ccuracy: A''ura' is #e de*ree #% 3i' #e$easured value % #e uali# 'ara'#eris#i' a*rees 3i##e #rue value.

Te dieren'e 0e#3een #e #rue value and #e$easured value is n%3 as err%r % $easure$en#.

I# is "ra'#i'all di@'ul# #% $easure ea'#l #e #rue

value and #ere%re a se# % %0serva#i%ns is $ade 3%semean +alue is taken as the true +alue % #e uali#$easured.

!i$e

nsi%

n

Ex: Several measurements are made on a component ydi!erent types of instruments and results are plotted

2-


24/113

2


25/113

2/

"Excessive accuracy is a si#n of poor reedin#$ % Socrates.


26/113

26


27/113

2;

%ormal distribution is also called the Gaussian distribution.

The most widel $nown and used of all distributions is thenormal distribution. t fits man human characteristics,

such as height, weight, performance etc.

Man living things in nature, such as trees, animals and

insects have man characteristics that are normalldistributed.

Man variables in business and industr are also normall

distributed.

%ormal )istribution


28/113

28

(re>uenc distribution and %ormal distribution/Gaussian0

5?@?6?58?5?9?8?5=

people weight distribution


29/113

Q

21

Q is S#d. devia#i%n


30/113

-

The formula for Normal distribution


31/113

Te se# % %0serva#i%ns 3ill s'a##er a0%u# #e$ean. Te s'a##er % #ese $easure$en#s is

desi*na#ed as si*$a(Q): #e standard de+iation:Q

S#andard devia#i%n is used as inde' of precision.

Te less #e s'a##erin* $%re "re'ise is #eins#ru$en#. Tus: lower the +alue of 45 themore precise the instrument.S#andard devia#i%n (r%%# $ean suare devia#i%n)s%3s %3 $u' varia#i%n %r dis"ersi%n eis#sr%$ #e avera*e ($ean: %r e"e'#ed value).

A l%3 s#andard devia#i%n indi'a#es #a# #e da#a"%in#s #end #% 0e ver 'l%se #% #e $ean: 3ereasi* s#andard devia#i%n indi'a#es #a# #e da#a

"%in#s are s"read %u# %ver a lar*e ran*e % values.-,

Stan4a4 De8iati!n


32/113

In#er'an*ea0ili# & Sele'#ive asse$0l

,.C%$"le#e in#er'an*ea0ili# %r rand%$ asse$0l?

An '%$"%nen#: asse$0les 3i# an %#er

'%$"%nen# '%s#l

-2

Inte*han#eai"it$: The abilit to replace the components,

parts, or e>uipment of one manufacturer with those of another,

without losing function or suitabilit.

&1amples of !omplete nterchangeabilitualit, precision and

trouble free products but also he wants them at attractive prices.

This has become possible onl b adopting automatic gauging

for se"e*ti8easse-"$whereb parts manufactured to rather

wide tolerances fit and function as though the were precisel

manufactured in precision laborator to ver close tolerances.

"arts are graded according to si3e and onl matched grades of

mating parts are assembled.

n se"e*ti8easse-"$the components produced b a machine

are classified into several groups according to si3e. This is done

both for hole and shaft and then the corresponding groups will

match properl.


34/113

-

f some parts /shaft and holes0 to be assembled are manufactured

to normal tolerances of :.:5 mm /and both are within the curve of

normal distribution0, an automatic gauge can segregate them into

ten different groupswith a :.::5 mm limit for se"e*ti8easse-"$of

the individual parts.

Thus parts with tolerances of :.::5 mm are obtained /due tosegregation0 and both the conditions of high >ualit and low cost

can be served b selective assembl techni>ue.

Re9+ie-ent: Two component parts to be fitted together must be

$ept within the normal distribution, the process capabilit of two

machines producing shafts and holes must be identical.


35/113

-/

!esired $ean value %%le

!esired $ean value %sa#

Pr%'ess 'a"a0ili# %%le(9) $ain*$a'ine

Pr%'ess 'a"a0ili# %sa#(S) $ain*$a'ine

"rocess capabilit inde1BS#=Bpper Specification #imit

#S#=#ower Specification #imit


36/113

-6

(ig. shows a case in which the process capabilit of both

shaft and hole producing machines is same but tolerances on

parts are desired as one-tenth of process capabilit of machines.

n such a case the parts are segregated b automatic inspectioninto ten groupsand parts in shaft region are matched with parts in

hole region.

This results in matching of parts having tolerances lC5:th of

machine capabilit.

n this case as the process capabilit of both machines is same,

e>ual number of parts are available in each segregated

3one and no wastage will be there.

"rocess capabilit is the abilit of a processCmachineto produce

output within specification limits
http://en.wikipedia.org/wiki/Process_(engineering)http://en.wikipedia.org/wiki/Process_(engineering)http://en.wikipedia.org/wiki/Specification_(technical_standard)http://en.wikipedia.org/wiki/Specification_(technical_standard)http://en.wikipedia.org/wiki/Process_(engineering)http://en.wikipedia.org/wiki/Process_(engineering)


37/113

-;

N%. % *r%u"s "r%'ess 'a"a0ili#< #%leran'e desired


38/113

-8

nterchangeabilit< nterchangeabilit of parts made possible mass production of

identical products.

Se"e*ti8e asse-"$


39/113

-1

Se"e*ti8e asse-"$

This is often used to avoid high costs of tight tolerancing b classifing small shafts

with small holes, etc.

LIMITS, FITS &TOLERANCES


40/113

Te-s & Deiniti!ns


41/113

,

TERMS & DEFINITIONS C!nt4

Dero deviation


42/113

2

Shaft< The term shaft refers not onl to the diameter of a circular

shaft but to an e1ternal dimension on a component

+ole< +ole refers not onl to the diameter of a circular hole but toan internal dimension on a component

asic or %ominal si3e< The si3e from which the limits of si3e are

derived b the application of upper and lower deviation.

asic si3e is the 3ero line.

asic si3e is same for both the hole and its shaft.

asic si3e can be a whole number or a decimal number.&1< @7,5,6.; mm etc

An si3e more than the basic will be above the 3ero line and an

si3e less than basic si3e will be below the 3ero line and si3e e>ual

to basic si3e will be at 3ero line.


43/113

-

Tolerance< The difference between the upper and lower limits is called

the tolerance. /Er0 The algebraic difference between upper and lower

deviations, and it is an absolutevalue.

Shaft of dia. 8:.:: F :.: = 8:.: mm and 8:.:: :.: = @9.9 mm

The dimension 8:.: mm is called the upper limit and the dimension

@9.9 mm is called the lower limit.

Tolerance = upper limit lower limit = 8:.: @:.9 = :.5: mm

Tolerance is alwas a positive>uantitative number(or a shaftasi' Si=e) #% su"eri%r si=e % sa#.ei: =er% line (>asi' Si=e) #% ineri%r si=e % sa#.&*: =er% line (>asi' Si=e) #% su"eri%r si=e % %le.&;: =er% line (>asi' Si=e) #% ineri%r si=e % %le.

Fen*h te- e*at s+)eie+ & e*at ineie+

asic shaft and asic hole< The shafts and holes that have 3ero

fundamental deviation.

asic hole has 3ero lower deviation where as basic shaft has 3ero

upper deviation

TOLERANCES ON COMPONENTS


49/113

Tolerance is permissible variation in the dimension of the

component.

)ue to inherent inaccuracies in Manufacturing processes

tolerances have to be provided.

Concepts of asic si&e' limits' deviations and tolerances

% Shaft 1



50/113

Concepts of asic si&e' limits' deviations and tolerances

% Hole

/



51/113

;asi* Shat:

Bpper deviation /es0 = asic si3e Bpper limit = :

/,



52/113

;asi* H!"e:

#ower deviation /&0 = asic si3e #ower limit = :

/2


53/113

(7ve) >el%3 #e =er% line

/-

(undamental deviationwhich is closest to the 3ero line


54/113

(Jve) A0%ve #e =er% line

/


55/113

//

:C:!:E::G:9:DS: D: K: M:

N:P:R:S:T:+::U:Y::A:>:C

S#andard Li$i# Ss#e$? - de'idin*


56/113

S#andard Li$i# Ss#e$? - de'idin*a'#%rs

,.un'#i%nal reuire$en#(Ba# i# is reuired #% d%)

2.In#er'an*ea0ili#(Ease % re"la'e$en# in #eeven# % ailure)-.E'%n%$i's(Mini$isa#i%n % "r%du'#i%n #i$e and'%s#)

a. >ri#is S#andard >S7/7,1610. Te In#erna#i%nal S#andard ISO?2867,188

In %rder #% ave universal in#er'an*ea0ili# i# is

essen#ial #% %ll%3 a uni%r$ s#andard #r%u*%u##e 3%rld.

T% assis# #e desi*ner in #e '%i'e % li$i#s & 4#s and#% en'%ura*e uni%r$i# #r%u* %u#: s%$e s#andard

%n: li$i# and 4# is es#a0lised.

/6

All #ese s#andards 0asi'all $ae use % #e


57/113

/;

All #ese s#andards 0asi'all $ae use % #e%ll%3in* #% *ive innu$era0le 4#s

,.S#andard #%leran'e (unda$en#al #%leran'e)2.unda$en#al devia#i%n

=rade of "olerance: ;t is an indication of thele+el of accuracy.

"here are 1*rades % #%leran'es IT,: IT: IT, #%IT,6

IT, #% IT 7 %r "r%du'#i%n % *au*es: "lu* *au*es:$easurin* ins#ru$en#s

IT/ #% IT; %r 4#s in "re'isi%n en*ineerin*a""li'a#i%nsIT8 #% IT,, %r General En*ineerin*IT,2 #% IT, %r See# $e#al 3%rin* %r "ress

3%rin*IT,/ #% IT,6 %r r%'esses lie 'as#in eneral

T%leran'es ave "ara0%li' rela#i%nsi" 3i# #e si=e %#e "r%du'#s.

As #e si=ein'reases: #%leran'e3i#in 3i' a "ar# 'an


58/113

*tandard "olerance: >arious ?rades of tolerancesare dened usin? the Vstandard tolerance unit@5

(i) in (m' )*ic* is a function of asic si&e.

i+ ,.,,- / 2.1 for 0,, mm

3ere: mm is t*e #eometric mean of t*e lo)er andupper diameters of a "ar#i'ular dia$e#er s#e" 3i#in3i' #e '%sen #e dia$e#er lies.

!ia$e#er s#e"s in I.S.I are? (a70: 3ere ais a0%ve and0is u" #%)

,7-: -76: 67,: ,7,8: ,87-: -7/: /78: 87,2:,27,8: ,872/: 2/7-,/: -,/7 and 7/ $$

%r !W/$$

/8

Grades % #%leran'e C%n#d..


59/113

=rades

;"

;")

;", ;" ;"0 ;"12

;"11

;"1!

;"1#

;"1%

;"1

;"1)

alues

;i ,i ,6i 2/i i 6i ,i ,6i 2/i i 6i ,i

%r IT,: T%leran'e .- J .8!%r IT: T%leran'e./J.,2!

%r IT,: T%leran'e.8J.2!

IT2 #% IT are re*ularl s'aled a""r%i$a#el:*e%$e#ri'all 0e#3een #e values % IT, and IT/

(IT, is *iven a0%ve and IT/ *iven in #a0le 0el%3)Bere ! is in $illi$e#ers

/1

0le27Aunda$en#

l devia#i%ns


60/113

;N"&N$";AN$7 "A7&$N-& =$9&*

>alues ;n6icrons

IT, IT IT,

>alues


61/113

+""er !evia#i%n (es) L%3er !evia#i%n (ei)

Sa#

!esi*na#i%n

In $i'r%ns

(%r ! in $$)

Sa#

!esi*na#i%n

In $i'r%ns

(%r ! in $$)

a

7(26/ J ,.-!)

%r ! X,2

and -./2!%r ! ,2

D/ #% F8 N% %r$ula

#% 8 J .6 !,


62/113

62



63/113

S$-!"i* e)esentati!n ! t!"ean*es !n shats an4 h!"es

6-

%r sa#s VaZ #% VZ #e u""er devia#i%n is 0el%3 =er%


64/113

6

%r sa#s a #% #e u""er devia#i%n is 0el%3 =er%line(7ve) and %r sa#s VZ #% V='Z i# is a0%ve #e =er%line(Jve)

Te devia#i%n % #e sa# r%$ VFZ #% VZ ei#er Jve %rve

%r %les VAZ #% V9Z: #e l%3er devia#i%n is a0%ve #e=er% line(Jve) and %r VKZ #% VCZ: i# is 0el%3 #e =er%line(7ve)

Te devia#i%n % #e %le r%$ VDZ #% VKZ ei#er Jve %rve

%r$ulas are *iven #% de#er$ine #e unda$en#aldevia#i%n.

Te %#er devia#i%ns(u""er & l%3er) $a 0e deriveddire'#l usin* #e #%leran'e IT.

Standard tolerances

18 grades: IT01 ,IT0

and IT1-1T16

(undamental devations

25 types: A- ZC (For holes)

a- ! (For sha"ts)


65/113

6/

+""er devia#i%n % sa#s r%$ VaZ #% V*Z are ve and%r VZ i# is =er% and l%3er devia#i%n % #e re$ainin*sa#s is Jve.

%r %les: l%3er devia#i%n is Jve %r %les VAZ #% VGZand %r V9Z i# is =er% and u""er devia#i%n %re$ainin* %les is ve.

ce 6a'. metal condition of hole C 6a'. metal condition

7ow limit of hole C /i?h limit of shaft

All%3an'es? Te dieren'e 0e#3een #e %le

di$ensi%n and sa# di$ensi%n %r an #"e % 4# is'alled all%3an'e.


66/113

66

i #i 9 l S # d i#


67/113

esi*na#i%n % 9%les: Sa#s and i#s

A %le %r a sa# is '%$"le#el des'ri0ed i #e

0asi' si=e: %ll%3ed 0 #e a""r%"ria#e le##er and#e nu$0er % #%leran'e *rade is *iven.

,. A / $$ 97%le: 3i# #e #%leran'e *rade % IT;: is

/ 9;.2. A / $$ 7sa# 3i# #e #%leran'e *rade IT8 is / 8

.A4# is desi*na#ed 0 #e 0asi' si=e '%$$%n #% 0%##e %le and

#e sa# %ll%3ed 0 s$0%ls '%rres"%ndin* #% ea'ele$en#: #e

%le is u%#ed 4rs#.

. Tus: i #e 0asi' si=e is /$$: #e %le is 9; and6;


68/113

APPLICATIONS IT Grade Ran*e

Measurin* Ins#ru$en#s andPr%du'#i%n % Gau*es IT,: IT: IT,: IT2: IT-:IT: IT/: IT6

General En*ineerin*


69/113

T!"ean*es !taina"e !- 4ieent -an+a*t+in# )!*esses:

61

FITS


70/113

The e"ati!n es+"tin# !- the 4ieen*e et


71/113

;,ll%3an'e is Jve %r 'learan'e 4# and ve %r in#ereren'e 4

(undamental deviationsStandard tolerances18 grades: IT01 IT0


72/113

25 types: A- ZC (For holes)

a- ! (For sha"ts)

18 grades: IT01 ,IT0

and IT1-1T16

;2

FITS


73/113

Ben #3% "ar#s are #% 0e asse$0led: #e rela#i%nresul#in* r%$ #e dieren'e 0e#3een #eir si=es

0e%re asse$0l is 'alled a 4#.

!e"endin* %n #e a'#ual li$i#s % %le %r sa#: #e 4#$a 0e 'learan'e 4#: #ransi#i%n 4# %r an in#ereren'e

4#.

;-

Clearan'e 4#? Te lar*es# "er$i##ed sa# dia iss$aller #an #e dia % #e s$alles# %le: s% #a#sa# 'an r%#a#e %r slide #r%u* 3i# dieren#de*rees % reed%$ a''%rdin* #% #e "ur"%se % #e

$a#in* $e$0ers

I # 4# T i i## d di # #


74/113

In#ereren'e 4#? Te $in. "er$i##ed dia. % #e sa#is lar*er #an #e $a. all%3a0le dia. % #e %le.

Te sa# and #e %le $e$0ers are in#ended #% 0ea##a'ed "er$anen#l and used as a s%lid'%$"%nen# 0u# a''%rdin* #% #e a""li'a#i%n % #is'%$0ina#i%n: #is #"e % 4# 'an 0e varied.

Transi#i%n 4#? Te dia. % #e lar*es# all%3a0le %leis *rea#er #an #a# % #e s$alles# sa#: 0u# #es$alles# %le is s$aller #an #e lar*es# sa#: s%#a# a s$all Jve %r ve 'learan'e 0e#3een #e

sa# and %le $e$0ers are e$"l%a0le.

;

FITS C!nt477


75/113

Clearan!e F#t

;/

Mai$u$ sa# di$ensi%n W Mini$u$ %ledi$ensi%n

Clearan'e i# C%n#d[


76/113

In a 'learan'e 4#: #e #%leran'e =%ne % #e %le isen#irel a0%ve #e #%leran'e =%ne % #e sa#.

;6Al3as 'learan'e

Clearan'e i# C%n#d[

Clearan'e i# C%n#d


77/113

;;

Min. 'learan'eMin. si=e % %le 7 Ma. si=e % sa#

Ma. 'learan'eMa.si=e % %le 7 Min.si=e % sa#

In #is #"e % 4#: #e si=e li$i#s %r $a#in* "ar#s ares% sele'#ed #a# 'learan'e 0e#3een #e$ al3as

%''ur.

Clearan'e 4#s $a 0eslide 4#: eas slidin* 4#: runnin* 4#: sla' runnin* 4#and l%%se runnin* 4#.

E? Pull r%#a#es %n sa#

!learance fit in various engine components

Clearan'e i# C%n#d[

Clearan'e i# C%n#d[


78/113

E>E?ha+st 8a"8e

S>S)a@ P"+#

I>In"et 8a"8e

V>Va"8es

P>Pist!n

R>C!nne*tin# R!4

C>Can@ shat

W>Wate *!!"in#


79/113

;1

Mai$u$ 9%le si=e W Mini$u$Sa# si=e

Alwas interference for all si3es

In#ereren'e 4# C%n#d..


80/113

Min. In#ereren'eMa. si=e % %le Min si=e % sa#Ma. In#ereren'eMin. si=e % %le Ma. si=e % sa#

8

In #is #"e % 4# #e si=e li$i#s %r #e $a#in*



81/113

8,

In #is #"e % 4#: #e si=e li$i#s %r #e $a#in*"ar#s are s% sele'#ed #a# in#ereren'e 0e#3een#e$al3as %''ur.

In an in#ereren'e 4#: #e #%leran'e =%ne % #e%le is en#irel 0el%3 #e #%leran'e =%ne % #esa#.

Te a$%un# % in#ereren'e de#er$ines #e de*ree% %r'e reuired #% asse$0le %r $a#e #e sa# #%#e %le.

Te uali# % sura'e 4nis % #e $a#in* "ar#s:#e si=e % #e dia$e#ers: #e $e#als r%$ 3i'#e are $ade: all ae'# #e uali# % #e 4#%0#ained.

E? ,.>earin* 0uses in #eir %usin* 2.S$all end % #e '%nne'#in* r%d & "is#%n

"ypes of ;nterference ts? Tese are 'ea" and@ i # # d F i i # # # #


82/113

e@'ien# $e#%d % F%inin* #%*e#er #3% '%$"%nen#s.

1.7i?ht press t(/,p): i#s use is '%n4ned #% #e

asse$0l % err%us '%$"%nen#s 3i' reuirere$%val %r "ur"%ses % rene3al %r re"la'e$en# a#a la#eral da#e.E? !rill 0us in Fi* "la#e

##"?


83/113

8-

"ress (it- ush in a frame "ress (it- ush in a housing

!.Press t(medium press or li?ht dri+e tD



84/113

!.Press t(medium press or li?ht dri+e t/,Es): Inv%lves ea#in* %r reri*era#i%n % %ne "ar#:"%3erul %r'es are 0r%u*# in#% "la: resul#in* in a

"er$anen# F%in# 0e#3een #e #3% '%$"%nen#s.

E? >earin* 0uses in all% %usin*s %r 'as#in*s:"u$" i$"eller sa#

#./ea+y dri+e t: E? Clinder liner in a 'as# ir%n0l%': "r%du'in* a "er$anen# %r se$i7"er$anen#asse$0l 0e#3een liner and 0l%'.

lar*e si=es reuire ea#in* and srinin* #% av%id #e8



85/113

C$"in4e Line Shin@ it

Shring (it- #ocomotive wheel



86/113

86

Steel tire on a steam locomotive's

driving wheel is heated with gas

flames to e1pand and loosen it so it

ma be slipped over the wheel.



87/113

8;

ooden wheel of bulloc$ cart with iron rim



88/113

88

A))"i*ati!ns

FITS C!nt477Trans#t#on F#t


89/113

81

O0#ained 0 %verla""in* % #%leran'e =%nes % sa#and %le [[!%es n%# *uaran#ee nei#er 'learan'e n%r

in#ereren'e 4#

Trans#t#on F#t Contd&&


90/113

In #is #"e % 4#: #e si=e li$i#s %r #e $a#in* "ar#s are

s% sele'#ed #a# ei#er a 'learan'e %r in#ereren'e $a%''ur de"endin* u"%n #e a'#ual si=e % #e $a#in*"ar#s. I# $a 0e n%#ed #a# in a #ransi#i%n 4#: #e#%leran'e =%nes % %le and sa# %verla".

1

Transition fit !ontd..


91/113

1,

Ma1imum clearance= Ma1imum limit si3e of hole Minimum limit si3e of shaft

Ma1imum interference = Minimum limit si3e of hole Ma1imum limit si3e of shaft

Te #ransi#i%n 4#s $a 0e force t5 ti?ht t and pusht.

In#ereren'e is s% li*# #a# and "ressure is su@'ien# #%'ause en#r % #e sa#.E? 9and 3eel and indein* dial eed #% sa# (La#e$a'ine 3i# lead s're3)

A))"i*ati!ns

Transition fit !ontd..


92/113

12

A))"i*ati!ns


93/113

"ush (itTransition fit !ontd..


94/113

1


95/113

1/

L%3er devia#i%n % %le is =er%

+""er devia#i%n % sa# is =er%#ow limit of hole=basic si3e

+igh limit of shaft = basic si3e

"o obtain diFerent types of ts5 it is ?eneralpractice to +ary tolerance zone of one of the


96/113

9OLE >ASE! SYSTEM7

Si=e % %le is e"# '%ns#an#:sa# si=e is varied#% *e# dieren# 4#s.

practice to +ary tolerance zone of one of thematin? parts

S9AT >ASE! SYSTEM7Si=e % sa# is e"# '%ns#an#:%le si=e is varied

#% *e# dieren# 4#s.

16

asic hole is chosen I

)ifferent (its are obtained

b changing shaft si3e

)ifferent (its are obtained

b changing hole si3e

/ole basis system *haft basis system


97/113

,.Si=e % %le 3%se l%3erdevia#i%n is =er%(97%le) isassu$ed as #e 0asi' si=e.

Si=e % sa# 3%se u""erdevia#i%n is =er%(7sa#) isassu$ed as 0asi' si=e

2.Li$i#s %n #e %le are e"#'%ns#an# and #%se % sa# arevaried #% %0#ain desired #"e %4#.

Li$i#s %n #e sa# are e"#'%ns#an# and #%se %n #e %leare varied #% ave ne'essar 4#

-.9%le 0asis ss#e$ is "re"ared

in $ass "r%du'#i%n: 0e'ause i# is'%nvenien# and less '%s#l #%$ae a %le % '%rre'# si=e due #%availa0ili# % s#andard drills andrea$ers

Tis ss#e$ is n%# sui#a0le %r

$ass "r%du'#i%n 0e'ause i# isin'%nvenien#: #i$e '%nsu$in*and '%s#l #% $ae a sa# %'%rre'# si=e

.I# is $u' $%re eas #% var

#e sa# a''%rdin* #% #e 4#reuired

I# is ra#er di@'ul# #% var #e

%le si=es a''%rdin* #% #e 4#reuired

/.Gau*in* % sa#s 'an 0e easiland '%nvenien#l d%ne 3i#adFus#a0le *a" *au*es.

>ein* in#ernal $easure$en#:*au*in* % %les 'ann%# 0e easiland '%nvenien#l d%ne.

1;

FITS

e!o''ended F#ts *ased on $an+"a!t+r#ng ro!esses and Appl#!at#on:


98/113

e!o''ended F#ts *ased on $an+"a!t+r#ng ro!esses and Appl#!at#on:

18


99/113


100/113

,


101/113

,,


102/113

,2


103/113

,-


104/113

Euivalen# 4#s %n #e 9%le70asis and sa#,


105/113

,/


106/113

,6


107/113

,;

Assume dia. Step of 56 I 78 I

() of " hole is TJ ? : to


108/113

,8

Te 4# is in#ereren'e.

!ieren'e 0e#3een T%leran'e & All%3an'e


109/113

"olerance $llowance

I# is #e "er$issi0le varia#i%n in#e di$ensi%n % a "ar#(ei#era %le %r sa#)

I# is #e "res'ri0ed dieren'e0e#3een #e di$ensi%ns % #3%$a#in* "ar#s(%le and sa#)

I# is #e dieren'e 0e#3een

i*er and l%3er li$i#s % adi$ensi%n % a "ar#

I# is #e in#en#i%nal dieren'e

0e#3een #e l%3er li$i# % %leand i*er li$i# % sa#

Te #%leran'e is "r%vided %n#e di$ensi%n % a "ar# as i# isn%# "%ssi0le #% $ae a "ar# #%

ea'# s"e'i4ed di$ensi%n

All%3an'e is #% 0e "r%vided %n#e di$ensi%n % $a#in* "ar#s#% %0#ain desired #"e % 4#

I# as a0s%lu#e value 3i#%u#si*n

All%3an'e $a 0e"%si#ive('learan'e 4#) %rne*a#ive(in#ereren'e 4#)

,1

Ge!-eti* Di-ensi!nin# an4 T!"ean*in# .GD & T3


110/113

,,

Geometric tolerancing reading helps to understand to specif and

control the form, location and orientation of the features ofcomponents and manufactured parts.

Geometric )imensioning and Tolerancing is an efficient method

for describing the tolerancing mandated b the designer of the

part.

The )atum a1is or )atum planes are to be used for locating other

features.

ith G)IT all inspection will result in the same result. t will helpto understand if the dimension is within or out of tolerance.

Geometric )imensioning and Tolerancing forces the designers to

totall consider functions, manufacturing processes, and

ins ection methods.

T!"ean*e Feat+e In4i*ati!nBFeat+e C!nt!" Fa-e S$-!"7


111/113

,,,

T!"ean*e Feat+e In4i*ati!nBFeat+e C!nt!" Fa-e S$-!"7

Pi-a$ Dat+-, Se*!n4a$ Dat+-, an4 Tetia$ Dat+- P"anes: )atums

must be perpendicular to each other.


112/113

,,2

Pi-a$ Dat+- P"ane:The primar datum is selected to provide functional

relationships, standardi3ations and repeatabilit between surfaces. A

standardi3ation of si3e is desired in the manufacturing of a part. !onsiderationof how parts are orientated to each other is ver important. The chosen primar

datum must insure precise measurements.

Se*!n4a$ Dat+- P"ane: Secondar datums are produced perpendicular to

the primar datum so measurements can be referenced from them.

Tetia$ Dat+- P"ane:Tertiar datum is alwas perpendicular to both the

primar and secondar datums ensuring a fi1ed position from three related

parts.


113/113

metrology basics

Documents