67071_11.pdf

CHAPTER

11 METAL FITS, TOLERANCES, AND SURFACE TEXTURE

S Y M B O L S 1,2,3

E E~ E~ F l

L M~ p pc t

oz

6 Ad //

o

#

area of cross section, m 2 (in 2) diameter of shaft, m (in): ' diameter of cylinde r, m(in) ' modulus of elasticity, GPa (Mpsi) modulus of elasticity of cast iron, GPa (Mpsi) modulus of elasticity of steel, GPa (Mpsi) force, kN [lbf or tonf (pound force or tonne force)] length, m (in) length of hub, m (in) effective length of anchor, m (in) original length of slot, m (in) torque or twisting moment, N m (lbf in) pressure, MPa (psi) contact pressure MPa (psi) temperature, °C (°F) coefficient of linear expansion, (m/m)/°C [(in/in)/°F] total change in diameter (interference), m (in) change in diameter, m (in) Poisson's ratio stress, MPa (psi) coefficient of friction factor of safety

SUFFIXES

a

b c

d f h i 0

r

axial bearing surface contact surface, compressive design final hub internal, inner original, external, outer radial, rim

11.1

11.2 CHAPTER ELEVEN

s shaft 0 tangential or hoop 1 initial 2 final

Particular Formula

P R E S S A N D S H R I N K FITS

Change in cylinder diameter due to contact pressure

The change in diameter

The change in diameter of the inner member when subjected to contact pressure Pc (Fig. 11-1)

The change in diameter of the outer member when subjected to contact pressure Pc (Fig. 1 l- 1)

The original difference in diameters of the two cylinders when the material of the members is the s a m e

The total change in the diameters of hub and hollow shaft due to contact pressure at their contact surface when the material of the members is the same

I ", T

1' ,1 ,

FIGURE 11-1

Ad = deo

Adi E ~, d2c-d 2

pcdc ( dz + d2 ) A d o = - ~ d2o_d~ +~,

= Ado +/X4

-pcdc ( d2° +d2 ) - e d2o-4+~'

pcdc ( d2 + d2 ) + - / - 4 - d ~

= a 4 + ~ad~ = 4 - dh

pcds (d.Z +d2 V~ ) E, 4 - 4 ~

pcdh ( d,Z + d 2 +-~ d~o - d~

+ Uh) exactly

6 - pod,, E,(d 2 _ d2 ) d0~+4 +

E~(do ~ -d~ )

(approx.)

(11-1)

(11-2)

(11-3)

(11-4)

(11-5a)

-EZ

(ll-Sb)

Particular

/

Formula

The shrinkage stress in the band

The contact pressure between cylinders at the surface of contact when the material of both the cylinders is same (Fig. 11-2)

The tangential stress at any radius r of outer cylinder (Fig. 11-2a)

The tangential stress at any radius r of inner cylinder (Fig. 11-2a)

The radial stress at any radius r of outer cylinder (Fig. 11-2a)

The radial stress at any radius r of inner cylinder (Fig. 11-2a)

The tangential stress at oUtside diameter of outer cylinder (Fig. 11-2)

The tangential stress at inside diameter of outer cylinder (Fig. 11-2)

The tangential stress at outside diameter of inner cylinder (Fig. 11-2)

The tangential stress at inside diameter of inner cylinder (Fig. 11-2)

The radial stress at outside diameter of outer cylinder (Fig. 11-2)

E 5 or° = 4 (11-6)

~E(d~ - d~)(do 2 -d~) Pc = 2 4 (do 2 - d 2) (11-7)

~0-O-do2 4 1 + ~ (11-8)

Cro_ i = d 2 _ d2 1 + ~ r 2 (11-9)

_ ) O'r_ o - - d2 _ 62 ~ r 2 - 1 ( 1 1 - 1 0 )

C r r - i - d2c _ d 2 ] ---~r 2 (11-11)

2pc~ cr0_oo = d 2 _ d 2 (11-12)

d2+d2 (11-13) o 0 - o i -- Pc d2 _ d2

p e ( d 2 + d 2) O o _ i o - - - d 2 _ d 2 i (11-14)

2pc~ O ' o _ i i --- d 2 _ d 2 i ( 1 1 - 1 5 )

O'r-oo - -0 (11-16)

METAL FITS, TOLERANCES, AND SURFACE TEXTURE 11.3

(a) Tangential stress, % (b) radial stress, o r

FIGURE 11-2 Distribution of stresses in shrink-fitted assembly.

11.4 CHAPTER ELEVEN

Part i cu lar F o r m u l a

The radial stress at inside diameter of outer cylinder (Fig. 11-2)

The radial stress at outside diameter of inner cylinder (Fig. 11-2)

The radial stress at inside diameter of inner cylinder (Fig. 11-2)

The semiempirical formula for tangential stress for cast-iron hub on steel shaft

Timoshenko equation for contact pressure in case of steel shaft on cast-iron hub

The allowable stress for brittle materials

O'r- oi - - - -Pc (11-17)

O'r- io --- - -Pc (11-18)

O'r_ii - - 0 (11-19)

Eo6 (11-20) or° = dc + 0.14do

Ec6 ( 1 - (dc/do) 2 ) Pc = ~ 1.53 + 0.47(dc/do) 2

& f°r ~ 7 = 3

(11-21a)

as. E~6[1 + (4.~do) 2] O'a// -- - - - - (11-21b)

n d,.[1.53 + 0.47(dc/do) 2]

I N T E R F E R E N C E F I T S

P r e s s

The axial force necessary to press shaft into hub under an interface pressure Pc

The approximate value of axial force to press steel shaft into cast-iron hub with an interference

The approximate value of axial force to press steel shaft in steel hub

Fa = 7rdfl#pc (11-22a)

where # = 0.085 to 0.125 for unlubricated surface = 0.05 with special lubricants

F = 4 1 3 7 x 104 (d° -+-0"3dc)/t5 S I ( 1 1 - 2 3 a ) do + 6.33dc

where do, de, l and 15 in m, and F in N

F = 6000 (do + 0.3dc)I/5 do + 6.33dc

USCS (11-23b)

where do, de, l and ,5 in in, and F in tonf

F = 28.41 x l 0 4 (d2° - d2)l¢5 a~ SI (11-24a)

where do, dc, l and 8 in m, and F in N

F = 4120 (d2 - d2)16 d2 USCS (11-24b)

where do, de, l and 6 in in, and F in tonf


Particular Formula

The transmitted torque by a press fit or shrink fit without slipping between the hub and shaft

The temperature t 2 in °C to which the shaft or shrink link must be heated before assembly

7r d21#p c Mt= 2

where # -- 0.10 for press fit -- 0.125 for shrink fits

t2 --> ~ c -k- tl (11-26)

where tl -- temperature of hub or larger part to which shaft or shrink link to be shrunk on, °C

(11-25)

Shrink links or anchors (Fig. 11-3)

The average compression in the part of rim affected according to C. D. Albert

3_ I"

FIGURE 11-3 Shrink link.

The tensile stress in link

The total load on link

The compressive stress in rim

The original length of link

The necessary linear interference 6 for shrink anchors

The force exerted by an anchor

F cr c = v/AbAr (11-27)

o t = L f - L o E (11-28) Lo

F = (Lu - L o ) E A (11-29) Lo

ac = Lu - Lo EA (11-30) Lo x/'AbAr

L L ° = ( A E ) o r (11-31)

1+ I + Er v~ A b A----------~ -g

= ael (11-32) E

F = abcr d (11-33)

b - = 2 t o 3 a

cra = design stress based on a reliability factor of 1.25

11.6 CHAPTER ELEVEN

Particular Formula

For letter symbols for tolerances, basic size deviation and tolerance, clearance fit, transition fit, interference fit

For press-fit between steel hub and shaft, cast-iron hub and shaft and tensile stress in cast-iron hub in press-fit allowance

Refer to Figs. 11-4 to 11-8

Refer to Figs. 11-9 to 11-11

T O L E R A N C E S A N D A L L O W A N C E S

The tolerance size is defined by its value followed by a symbol composed of a letter (in some cases by two letters) and a numerical value as

A fit is indicated by the basic size common to both components followed by symbols corresponding to each component , the hole being quoted first, as

For grades 5 to 16 tolerances have been determined in terms of s tandard tolerance unit i in micrometers (Refer to Table 11-1).

Values of s tandard tolerances corresponding to grades 01, 0, and 1 are (values in gm for D in mm)

45 g7

45H8

g7 or 4 5 H 8 - g 7 or 45

i -- 0.45D 1/3 + 0.001D

where D is expressed in mm

IT 01 0.3 + 0.008 D

IT 0 0.5 + 0.012 D

IT 1 0.8 + 0.020 D

H8

g7

(11-34)

(11-35)

TABLE 11-1 Relative magnitudes of standard tolerances for grades 5 to 16 in terms of standard tolerance unit " i " [Eq. (11-34)]

Grade IT 5 IT 6 IT 7 IT 8 IT 9 IT 10 IT 11 IT 12 IT 13 IT 14 IT 15 IT 16

Values 7 i l0 i 16 i 25 i 40 i 64 i 100 i 160 i 250 i 400 i 640 i 1000 i

Source: IS 919, 1963.

TABLE 11-1A Coefficient of friction,/~ (for use between conical metallic surfaces)

Contacting surface Nature of surfaces Coefficient of friction,/~

Any metal in contact with another metal Lubricated with oil 0.15 Any metal in contact with another metal Greased 0.15 Cast iron on steel Shrink-fitted 0.33 Steel on steel Shrink-fitted 0.13 Steel on steel Dry 0.22 Cast iron on steel Dry 0.16

Source: Courtesy J. Bach, "Kegelreibungsverbindungen," Zeitschrift Verein Deutscher Ingenieure, Vol. 79, 1935.

M E T A L F I T S , T O L E R A N C E S , A N D S U R F A C E T E X T U R E 11.7

TABLE 11-2 Formulas for fundamental shaft deviations (for sizes _<500 mm)

Upper deviations (es)

Shaft designation In ttm (for D in ram) Shaft designation

Lower deviation (ei)

In ~tm (for O in mm)

= - ( 2 6 5 + 1.3D) j5-j8 a for D < 120 k4-k7

- - 3 . 5 D k for grades <3 and _>8

for D < 120

~- - (140 + 0 .850) m

f o r D < 160 n

- 1.8D p

f o r D > 160 = - 5 2 D °'2 r

c f o r D < 40

= - ( 9 5 + 0.8D)

for D > 40 s = - 16D 044

= - l l D °41 t

= - 5 . 5 D T M U

= - 2 . 5 D TM v

X

Y = 0 z

z a

zb ZC

IT F o r js: The two devia t ions are equal to + - ~ -

, , , ,

Source: IS 919, 1963.

N o fo rmu la

= +0 .6~fD

= 0

= + ( I T Y-IT 6) = _+_5D T M

-- IT 7 + 0 to 5

= geomet r ic m e a n of values

ei for p and s

= + I T 8 + I t o 4

for D < 50

= + I T 7 + 0.4D

for D > 50

= IT 7 + 0.63D

= + I T 7 + D

= + I T 7 + 1.25D

= + I T 7 + 1.6D

= + I T 7 + 2D

= + I T 7 + 2.5D

= + I T 8 + 3.15D

= + I T 9 + 4D

= + I T 10 + 5D

1 1 . 8 C H A P T E R ELEVEN

T A B L E 11-3 Rules for rounding off values obtained by the use of formulas

Above 5 45 60 Values in l~m Up to 45 60 100

100 200 300 560 600 800 1000 2000 200 300 560 600 800 1000 2000

Rounded in multiples of

For standard 1 1 1 tolerances for Grades II and finer

For deviations es, 1 2 5

from a to g

For deviations ei, 1 1 1

from k to zc

5 10 10

5 10 10 20 20 20 50

2 5 5 10 20 50 1000

Source: IS 919, 1963.

~ m

+350 +300 +250 +200 +150 +100 + 50

0 -50

-100 -150 -200 -250 -300

~tm +300 +250 +200 +150 +100 + 50

-100 -150 -200 -250 -300 -350

s = a . c . , z .

II o==.c =ize

I ~ Shafts C

oil FIGURE 11-4 Letter symbols for tolerances.

M E T A L FITS, TOLERANCES, A N D S U R F A C E T E X T U R E 11.9

T A B L E 11-4 F u n d a m e n t a l to l erances o f grades 01, 0, and 1 to 16

Values of tolerances in pm (1 Jim = 0.001 mm)

Diameter Tolerance grades steps in mm 01 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 a 15 a 16 a

<3 0.3 0.5 0.8 1.2 2 3 4 6 10 14 25 40 60 100 140 250 400 600 >3 <6 0.4 0.6 1 1.5 2.5 4 5 8 12 18 30 48 75 120 180 300 480 750 >6

<10 0.4 0.6 1 1.5 2.5 4 6 9 15 22 36 58 90 150 220 360 580 900 >10 <18 0.5 0.8 1.2 2 3 5 8 11 18 27 43 70 110 180 270 430 700 1100 >18 <30 0.6 1 1.5 2.5 4 6 9 13 21 33 52 84 130 210 330 520 840 1300 >30 <50 0.6 1 1.5 2.5 4 7 11 16 25 39 62 100 160 250 390 620 1000 1600 >5O <80 0.8 1.2 2 3 5 8 13 19 30 46 74 120 190 300 460 740 1200 1900 >8O

<120 1 1.5 2.5 4 6 10 15 22 35 54 87 140 220 350 540 870 1400 2200 > 120 <180 1.2 2 3.5 5 8 12 18 25 40 63 100 160 250 400 630 1000 1600 2500 >180 <250 2 3 4.5 7 10 14 20 29 46 72 115 185 290 460 720 1150 1850 2900 M

>250 <315 2.5 4 6 8 12 16 23 32 52 81 130 210 320 520 810 1300 2100 3200 >315 <400 3 5 7 9 13 18 25 36 57 89 140 230 360 570 890 1400 2300 3600 >400 <500 4 6 8 10 15 20 27 40 63 97 155 250 400 630 970 1550 2500 4000

a Up to 1 mm grades 14 to 16 are not provided. Source: IS 919, 1963.

(1) O N E

o O (1> (~ ~" ~.'~= o =~ _,=~

o (~ Hole ~ ~_ "~ ~ ' - ; . - , o o o o

Basic hole system

Hole K////////J Z e ro l i n e

Shaft .~

m

FIGURE 11-5 Basic size deviation and tolerances. F IGURE 11-6 Clearance fit.

11.10 CHAPTER ELEVEN

T A B L E 11-5 Clearance fits (Fig. 11-6) (hole basis)

Quality of fit

Large clearance

Slack running

Loose running

Easy running

Normal running

Close running or sliding

Precision sliding

Combination of shaft and hole Remarks and uses

H l l a 9 } H l l b 9 coarse

H l l a l l normal

H 9 a 9 "~ fine H 8 b 8 J H 11 c 9 coarse

H 11 c 11 "~ normal f H 9 c 9

H 8 c 8 "~ fine H 7 c 8 J H 11 d 11 ) H 9 d 9 J~c°arse

H 8 d9 normal

H 8 d 8 "~ fine H 7 d 8 J H 8 e 9 } H 9 e 9 coarse

H 8 e 8 ~normal H 7 e 8 J

H 7 e 7 '~ fine H 6 e 7 J

H 8 f 8 coarse H 7 f 7 normal H 6 f 6 fine

H 8 g 7 coarse H 7 g 6 normal

H 6 g 6 "~ fine H 6 g 5 J

H 11 h 11 H 8 h 7 H 8 h 8 H 7 h 6 H 6 h 5

Not widely used

Not widely used

Suitable for plummer block bearings and loose pulleys

Recommended for general clearance fits, used for properly lubricated bearings requiring appreciable clearance; finer grades for high speeds, heavily loaded bearings such as turbogenerator and large electric motor bearings

Widely used as a normal grease lubricated or oil-lubricated bearing having low temperature differences, gearbox shaft bearings, bearings of small electric motor and pumps, etc.

Expensive to manufacture, small clearance. Used in bearings for accurate link work, and for piston and slide valves; also used for spigot or location fits

Widely used for nonrunning parts; also used for fine spigot and location fit

T A B L E 11-6 Values of standard tolerances for sizes >500 to 3 1 5 0 m m

IT 6 IT 7 IT 8 IT 9 IT 10 IT 11 IT 12 IT 13 IT 14 IT 15 IT 16

10 I *a 16 I 25 I 40 I 64 1 100 I 160 I 250 I 400 I 640 I 1000 I

a , Standard Tolerance Unit I (in pm) -0.004D + 2.1 for D in mm.

Hole Shaft

Shaft Basic hole system

Source: IS: 2101-1962.

FIGURE 11-7 Transition fit.

Shaft Zero line

I / / / / , / , / / / / A Zero line

Hole

FIGURE 11-8 Interference fit.

T A B L E 11-7 Transition and interference fits (hole basis)

Quality of fit Combination of shaft and hole Remarks and uses

Push H 8 j 7 coarse H 7 j 6 normal H 6 j 5 fine

True transition H 8 k 7 coarse H 7 k 6 normal H 6 k 5 fine

Interference transition

True interference

Light press fit

Medium drive fit

Heavy drive fit

Force fit

Heavy force fit or shrink fit

H 8 m 7 coarse H 7 m 6 normal H 6 m 5 fine

H 8 n 7 } H 7 n 6 coarse

H 6 n 5 fine

H 7 p 6 normal H 6 p 5 fine

H 7 r 6 normal H 6 r 5 fine

H 8 s 7 "[ normal H 7 s 6 J

H 6 s 5 fine

H 8 t 7 ~ normal H 7 t 6 J

H 6 t 5 fine

H 8 u 7 ; normal H 7 u 6 J H 6 u 5 fine

Transition fit (Fig. 11-7) Slight clearance--recommended for fits where slight interference is permissible, coupling spigots and recesses, gear rings clamped to steel hubs

Fit averaging virtually no clearance-recommended for location fits where a slight interference can be tolerated, with the object of eliminating vibration; used in clutch member keyed to shaft, gudgeon pin in piston bosses, hand wheel, and index disk on shaft

Fit averages a slight interference suitable for general tight-keying fits where accurate location and freedom from play are necessary; used for the cam holder, fitting bolt in reciprocating slide

Suitable for tight assembly of mating surfaces

Interference fit (Fig. 11-8) Light press fit for nonferrous parts which can be dismantled when required; standard press fit for steel, cast iron, or brass-to-steel assemblies, bush on to a gear, split journal bearing

Medium drive fit with easy dismantling for ferrous parts and light drive fit with easy dismantling for nonferrous parts assembly; pump impeller on shaft, small-end bush in connecting rod, pressed in bearing bush, sleeves, seating, etc.

Used for permanent or semipermanent assemblies of steel and cast- iron members with considerable gripping force; for light alloys this gives a press fit; used in collars pressed on to shafts, valve seatings, cylinder liner in block, etc.

Suitable for the permanent assembly of steel and cast-iron parts; used in valve seat insert in cylinder head, etc.

High interference fit; the method of assembly will be by power press

1 1 , 1 1

11 ,12 CHAPTER ELEVEN

TABLE 11-8 Preferred basic and design sizes Linear dimensions (in mm)

Shaft basis Hole basis

A B Priority 1 Priority 2 Priority 3

1.6 5.0 1.0 22.0 110.0 1.2 2.5 8.0 1.6 25.0 125.0 2.0 4.0 12.0 2.5 28.0 140.0 3.2 6.0 14.0 4.0 32.0 160.0 4.5

10.0 18.0 5.0 36.0 180.0 5.5 16.0 20.0 6.0 40.0 200.0 7.0 25.0 22.0 8.0 45.0 220.0 9.0 40.0 32.0 10.0 50.0 250.0 11.0 63.0 50.0 12.0 56.0 280.0 13.0

100.0 80.0 14.0 63.0 320.0 15.0 16.0 71.0 360.0 17.0 18.0 80.0 400.0 19.0 20.0 90.0 450.0 21.0

100.0 500.0 23.0 26.0 30.0

34.0 170.0 145.0 38,0 190.0 155.0 42.0 210.0 165.0 48.8 230.0 175.0 53.0 240.0 185.0 58.0 260.0 195.0 65.0 270.0 290.0 75.0 300.0 310.0 85.0 340.0 330.0 95.0 380.0 350.0

105.0 420.0 370.0 115.0 430.0 390.0 120.0 470.0 410.0 130.0 480.0 135.0 150.0

440.0 460.0 490.0

Angular dimensions (in deg)

Priority Preferred angles

1 1 3 6 10 16 2 2 4 5 8

30 45 60 90 12 20

TABLE 11-9 Formulas for shaft and hole deviations (for sizes >500 to 3150mm)

Shafts Formulas for deviations in pm (for D in mm) Holes

12o

d

e

f (g)

h

j s

k

m

n

P r

s

l

U

e s

es

e s

es

es

ei

el

el

el

el

el

el

el

el

16 D °44 + E1 D

11 0 0'41 + E1 E

5.5 0 041 + E1 F

2.5 D °34 + E1 (G)

0 E1 H

0.5 ITn + E S J S

0 E S K

0.024 D + 12.6 E S M

0.04 D + 21 - - E S N

0.072 D + 37.8 ~ E S pa

geometric mean between p and s or P and S E S R a

IT 7 + 0.4D ~ E S S a

IT 7 + 0.63D E S T a

IT 7 + D E S U

a It is assumed that associated shafts and holes are of the same grade contrary to what has been allowed for the dimensions up to 500 mm (see IS 919, 1959), Source: IS 2101, 1962.

METAL FITS, TOLERANCES, A N D SURFACE T E X T U R E 1].]3

• ~ 19,000

~ 1 7 , 0 0 0 - ¢- .

"o 15,000 c -

.~ 13,000 e . -

= 11,000

~, 9,000

• 7,000 L

co 5,000 L_

3,000

1,000

o~b'qy

I I Unitpressure /~//// betweenstee, ~ / / / hub and shaft ~ /

/ /

~ / / / ~ / . ~ ~ . . / - I _...-.~ / ..~ 0.90

0 0 0 0 ' , - ~-- ' , - C) (D (D (D 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Allowance per inch of shaft diam. e

0.40

0.50 0.55 0.60

0.65

0.70

0.75 "o

F I G U R E 11-9 Press-fit pressures between steel hub and shaft (1 psi = 6894.757Pa; 1 in = 25.4mm). (Baumeister, T., Marks' Standard Handbook for Mechanical Engineers, 8th ed., McGraw-Hill , 1978.)

19,000

17,000

8 15,000

" 13,000 t -

11,000 ¢/}

m 9,000 (t) • 7,000 t~0

= 5,000

3,000

1,000

uootnO o~ o~0000 .... o o o o

0.75 I I I I ~/~/,~ 0.70

_Max . t e n s i l e s t r e s s i n ~ ~ / ~ , ~ , uou0"60 hub for steel shaft n . = n O and cost iron-hub 0.40 ~

/ 0.20

&v Iv

O~1 "~" ~ OO 0 04 ~l" O O O O '~- v - T- O O O O O 0 O O O O O O O O o o o o o o c5


F I G U R E 11-10 Variation in tensile stress in cast-iron hub in press-fit allowance (1 psi=6894.757 Pa; 1 i n = 2 5 . 4 m m ) . (Baumeister, T., Marks" Standard Handbook for Mechanical Engineers, 8th ed., McGraw-Hill , 1978.)

. m (/)

= 14 000

= 12,000

"~ 10,000 A::: ~- 8,000

.~ 6,000

" 4,000

= 2,000

0 t _

i

f f l

L._

Cost iron hub and / 0 0.20 steel shaft ; "

~ , - 0.30 ] , l, / . / 0.40

0.50 . / 0.55

0.60 o I 0 . 6 5 ~ -" 0.70

0 7 5 ~ ~ ~ ~ ~ ; ~ / / / ~ ~ -- 0 1850"80 ~-~__ . ~ 2_... ~ - 0.90

. . . . . . 0.95

0 0 0 0 v- T- v- 0 0 0 0 0 0 0 0 C) 0 (D C) (D C) O O O O O O O


F I G U R E 11-11 Press-fit pressure between cast-iron hub and shaft (1 ps i -6894 .757Pa ; l i n = 2 5 . 4 m m ) . (Baumeister, T., Marks" Standard Handbook for Mechanical Engineers, 8th ed., McGraw-Hill , 1978.)

=3 r.g} ~a N

o~

li..

,,~%

.<,,~ ~

[,-

e',.I

e,,I e,,l

¢",,1

¢',,I

| ""

m

(',t

~a

~ ~1"

~:~ ~

L ~- ~

(~ ~

t",,I t"4

(',1

~

(",1 ~

~ ~

~ ~

.. ~

('4

I ,

I ,

I i

I ,

i ,

~ ,

i i

"7 "7

-~

-~

-'

*

..

..

..

.

~ I

"7 "7

r-..- ~

~ ~

~ ~

~ ~

(--.,i ~

-- ~

-- ~

-- ~

1

I I

I I

I .

..

..

..

i

I I

i I

I I

~1 I

t I

I ~"

I I

..

..

_

~ ~

~ ~

~ o

~

II

II

~

~

..

..

.

~ ~

,,

,

~7

,,

,,

,

~7

77

,

m m--

~ I

I I

I I

I I

I I

I~ I

I I

~ I

"~ I

I I

I I

I I

I I

I I

I I

I I

I I

I

I ~1

--I --I

I I

I I

I ~

I I

I I

I I

I I

I I

I I

I I

I I

I I

I I

I I

I I

11.14

oJ.

t..

~F ¢~

¢.,

t.m

~..

~,I ,or

-.~ rq

~ ~

~ ~

~ ~

-~ ~

"~+

+

+ +

++

++

++

++

++

+

~o

~~

-o

oo

oo

o~

_

_ _

7 I

I I

I i

i I

I I~

I

I +

7+

7+

i

++

++

++

++

++

++

7 7

?+

+ +

++

++

++

++

++

++

7 7

+ +

+ +

++

++

++

++

++

+

~ 7 ~

~ ~

~ ~

~ 7 ~

7 ~ 7

+7 +7

+7 +

++

++

++

++

++

+

"~ +

+ ÷

÷ +

÷ ÷

+ ÷

+ ÷

+ +

÷ ÷

"~ ~

~ "~

~ "~

~ ~

~ ~

~ i

~ 7

~ 7+

~

+ ~

+7

~°

~°

~-

'*

-~

"~

+

++

++

++

++

++

+

I I

"7 17

I I

I i

i i

17 17+

i

+ i

+7

++

++

++

++

++

++

|

~ ÷

+ ÷

÷÷

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11.18

METAL FITS, TOLERANCES, AND SURFACE TEXTURE l l .19

T A B L E 11-12 Tolerances a for shafts for sizes 500 to 3 1 5 0 m m

System Diameter steps, mm of basic 500 560 630 710 800 900 1000 1120 1250 1400 1600 1800 2000 2250 2500 2800 shaft Limits 560 630 710 800 900 1000 1120 1250 1400 1600 1800 2000 2250 2500 2800 3150

dlO

e8

f9

g6

g7

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hl l

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c s

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-260 -290 -320 -350 -390 -430 -480 -520 -540 -610 -680 -770 -890 -1030 -1180 -1380 -145 -160 -170 -195 -220 -240 -260 -290 -255 -285 -310 -360 -415 -470 -540 -620

-76 -80 -86 -98 -110 -120 -130 -145 -251 -280 -316 -358 -420 -490 -570 -685

-22 -24 -26 -28 -30 -32 -34 -38 -66 -74 -82 -94 -108 -124 -140 -173 -22 -24 -26 -28 -30 -32 -34 -38 -92 -103 -115 -133 -155 -182 -209 -248

0 0 0 0 0 0 0 0 -44 -50 -56 -66 -78 -92 -110 -135

0 0 0 0 0 0 0 0 -70 -80 -90 -105 -125 -150 -175 -210

0 0 0 0 0 0 0 0 -110 -125 -140 -165 -195 -230 -280 -330

0 0 0 0 0 0 0 0 -175 -200 -230 -260 -310 -370 -440 -540

0 0 0 0 0 0 0 0 -280 -320 -360 -420 -500 -600 -700 -860

0 0 0 0 0 0 0 0 -440 -500 -560 -660 -780 -920 -1100 -1350

±87.5 ~100 ±115 ±130 ±155 ±185 ±220 ±270

+44 + 50 + 56 +66 + 78 +92 + 110 + 135 0 0 0 0 0 0 0 0

+70 +80 +90 +106 +126 +150 +178 +211 +26 +30 +34 +40 +48 +58 +68 +76 +88 +100 +112 +132 +156 +184 +220 +270 +44 +50 +56 +66 +78 +92 +110 +135

+122 +139 +156 +186 +218 +262 +305 +375 +78 +88 + 100 + 120 + 140 + 170 + 195 +240

+220+225+255+265 +300 +310 +355 +365 +425 +455 +520 +550 +615 +635 +760 +790 +150+155+175+185 +210 +220 +250 +260 +300 +330 +370 +400 +440 +460 +550 +580 +350+380+420+460 +520 +560 +625 +685 +765 +845 + 9 7 0 + 1 0 7 0 + 1 1 7 5 + 1 2 7 5 + 1 4 6 0 + 1 6 1 0 +280+310+340+380 +430 +470 +520 +580 +640 +720 +820 + 9 2 0 + 1 0 0 0 + 1 1 0 0 + 1 2 5 0 + 1 4 0 0 +470 +520 +580 +640 +710 +770 +885 +945 +1085 +1175 +1350 +1500 +1675 +1825 +2110 +2310 +400 +450 +500 +560 +620 +680 +780 +840 +960 +1050 +1200 +1350 +1500 +1650 +1900 +2100 +570 +730+820 +920+1031 +1140 +1255 +1405 +1575 +1725 +2000 +2150+2475 +2675 +3110 +3410 +600 +660 +740 +840 +940 +1050 +1150 +1300 +1450 +1600 +1850 +2000 +2300 +2500 +2900 +3200

a Tolerances in gm (1 gm = 1 0 - 3 mm). b es = upper deviation. c e i - - lower deviation. Source: IS 2101, i 962.


TABLE 11-13 Tolerances a for holes for sizes 500 to 3150ram

System of

Diameter steps, mm

basic 500 560 630 710 800 900 1000 hole Limits 560 630 710 800 900 1000 1120

i120 1250 1400 1600 1800 2000 2240 2500 2800 1250 1400 1600 1800 2000 2240 2500 2800 3150

E S ~ D I O E S b

ES E8

E1

ES F9

E1 ES

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E1

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E1

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E1

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E1

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K6 El

ES M6 El

ES N6

E1

ES P6

E l ES

R7 E1

ES $7

E1

ES T7

E1

ES U7

E1

+540 +610 +680 +770 +890 +1030 +1180 +1380 +260 +290 +320 +350 +390 +430 +480 +520 +255 +285 +310 +360 +415 +470 +540 +620 +145 +160 +170 +195 +220 +240 +260 +290 +251 +280 +316 +358 +420 +490 +570 +685

+76 +80 +86 +98 +110 +120 +130 +145 +66 +74 +82 +94 +108 +124 +144 +173 +22 +24 +26 +28 +30 +32 +34 +38 +92 +103 +115 +133 +155 +182 +209 +248 +22 +24 +26 +28 +30 +32 +34 +38 +40 +50 +56 +66 +78 +92 +110 +135

0 0 0 0 0 0 0 0 +70 +80 +90 +105 +125 +150 +175 +210

0 0 0 0 0 0 0 0 +110 +125 +140 +165 +195 +230 +280 +330

0 0 0 0 0 0 0 0 +175 +200 +230 +260 +310 +370 +440 +540

0 0 0 0 0 0 0 0 +280 +320 +360 +420 +500 +600 +700 +860

0 0 0 0 0 0 0 0 +440 +500 +560 +660 +780 +920 +1100 +1350

0 0 0 0 0 0 0 0

+87.5 +100 +115 +130 -1-155 -1-185 +220 +270

0 0 0 0 0 0 0 0 -44 -50 -56 -66 -78 -92 -110 -135 -26 -30 -34 -40 -48 -58 -68 -76 -70 -80 -90 -106 -126 -150 -178 -211 -44 -50 -56 -66 -78 -92 -110 -135 -88 -100 -112 -132 -156 -184 -220 -270 -78 -88 -100 -120 -140 -170 -195 -240

-122 -138 -156 -186 -218 -262 -305 -375 -150 -155 -175 -185 -210 -200 -250 -260 -300 -330 -370 -400 -440 -460 -550 -580 -220 -225 -255 -265 -300 -310 -355 -365 -425 -455 -520 -550 -615 -635 -760 -790 -280 -310 -340 -380 -430 -470 -520 -580 -640 -720 -820 -920 -1000 -1100 -1250 -1400 -350 -380 -420 -460 -520 -560 -625 -685 -765 -845 -970 -1070 -1175 -1275 -1460 -1610 -400 -450 -500 -560 -620 -680 -780 -840 -960 -1050 -1200 -1350 -1500 -1650 -1900 -2100 -470 -520 -580 -640 -710 -770 -885 -945 -1085 -1175 -1350 -1500 -1675 -1825 -2110 -2310 -600 -660 -740 -840 -940 -1050 -1150 -1300 -1450 -1600 -1850 -2000 -2300 -2500 -2900 -3200 -670 -730 -820 -920 -1030 -1140 -1255 -1405 -1575 -1725 -2000 -2150 -2475 -2675 -3110 -3410

a Tolerances in x ttm (1 ~tm = 10 - 3 mm). b ES = upper deviation. c E1 = lower deviation. Source: IS 2101, 1962.

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11.24

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11.25

11 .26 CHAPTER ELEVEN

T A B L E 11-19 Surface finish a values (CLA)

High quality Normal quality Coarse quality

Machining process Tolerance grade Finish (ltm) Tolerance grade Finish (ttm) Tolerance grade Finish (ttm)

Drill 11 1.6-3.2 12 Mill, slot, plane 9 0.4-0.8 11 0.8-1.6 Turn, bore 8 0.4-0.8 9 0.8-1.6 Ream 7 0.4-0.8 8 0.8-1.6 Commercial grind 7 0.4--0.8 8 0.8-1.6 Fine turn, bore 6 0.2-0.4 7 0.4-0.8 Hone 6 0.1-0.2 7 0.2-0.4 Broach 6 0.1-0.2 7 0.2-0.4 Fine grind 5 0.1-0.2 6 0.2-0.4 Lap 3 0.05-0 1 4 0.1-0.2

12 1.6-3.2 11 1.6-3.2

9 1.6-3.2

a The Roughness Number represents the average departure of the surface from perfection over a prescribed "sampling length" normally 0.8 mm, and is expressed in micrometers (lam). The measurements are normally made along a line at right angles to the general directions of tool marks or scratches on the surface.

1 ~t = 0.001 mm

Old machining Surface symbols Description roughness

O

V L !

v ~ w

Unmachined surface, cleaned up by sand blasting, brushing, etc.

Surface to be rough machined if found necessary (to prevent fouling)

Surface obtained by rough machining under turning, planing, milling etc. Quality coarser than 9

Finish-machined surface obtained by turning, milling etc. Quality 12-7

Fine finish-machined surface obtained by boring, reaming, grinding etc. Quality 9-6

Super finish-machined surface obtained by honing, lapping, super finish grinding. Quality 7-4

5-80 ~t

8-25 ~t

1.6-8 kt

0.25-1.6 ~t

0-0.25 ~t

FIGURE 11-12 Machining symbols.


TABLE 11-20 Lay symbols

Lay symbol

l

_L

X

M

C

R

P

Interpretation

Lay parallel to the line representing the surface to which the symbol is applied

Lay perpendicular to the line representing the surface to which the symbol is applied

Lay angular in both directions to line representing the surface to which symbol is applied

Lay multidirectional

Example showing direction of tool

marks

i

I

IrllllI, II!,ll! I

i i

I i

Lay approximately circular relative to the center of the surface to which the symbol is, applied

Lay approximately radial relative to the center of the surface to which the symbol is applied

Pitted, protuberant, porous, or particulate nondirectional lay

,(~,~c .... i

I ! ' I

il I

11 .28 CHAPTER ELEVEN

Drill re,depth r21!_~_ ,depth+~ ~

3.5oo ±o.oo..~ ~-mo2

T i 1'1 4.000 - ;

Waviness Typical flow width

( s c ~

Roughness'r I ~, !! V . height Lay~ !I Waviness

(direction of predominate J I~eight surface pattern) I"

Roughness width

. m 16 ~" Ream 0750 : ! : 0 . 0 0 ~ ~-Top_,depth_ / - - Waviness

Roughness / _ height ,=ight 7 n n02 / " Roughness

_ 63 r / ~ u . , " 0.005 Width "j" ~ Lay direction

" ' - - -r- (perpendicular to _ / line shown, hence

- ~ circumferential) . . ~ l a g

optional

C

Symbol for Machining prohibited. machining Indicated surface allowance must be produced

without removal of material

f3x • ' 3x r "1.5x " ~ F - approx, r . 3 x oo,1 oo ~ o.

Bo°-~ V" oo

Letter height = x

FIGURE 11-13 Application and use of surface-texture symbols. (Baumeister, T., Marks' Standard Handbook for Mechanical Engineers, 8th ed., McGraw-Hill, 1978.)

TABLE 11-21 Preferred series roughness average values (Ra) (in pm and pin)

pm pin lttm pin pm pin pm pin Ittm pin

0.012 0.5 0.125 5 0.50 20 2.00 80 8.0 320 0.025 1 0.15 6 0.63 25 2.50 100 10.0 400 0.050 2 0.20 8 0.80 32 3.20 125 12.5 500 0.075 3 0.25 10 1.00 40 4.0 160 15.0 600 0.10 4 0.32 13 1.25 50 5.0 200 20.0 800

0.40 16 1.60 63 6.3 250 25.0 1000

Source: Reproduced from Baumeister, T., Marks' Standard Handbook for Mechanical Engineers, 8th ed., with permission from McGraw-Hill Book Company, New York, 1978.

TABLE 11-22 Preferred series maximum waviness height values

mm in mm in mm in

0.0005 0.00002 0.008 0.0003 0.12 0.005 0.0008 0.00003 0.012 0.0005 0.20 0.008 0.0012 0.00005 0.020 0.0008 0.25 0.010 0.0020 0.00008 0.025 0.001 0.38 0.015 0.0025 0.0001 0.05 0.002 0.50 0.020 0.005 0.0002 0.08 0.003 0.80 0.030

Source: Reproduced from Baumeister, T., Marks' Standard Handbook for Mechanical Engineers, 8th ed., with permission from McGraw-Hill Book Company, New York, 1979.

M E T A L FITS, TOLERANCES, A N D S U R F A C E T E X T U R E 1 1 . 2 9

T A B L E 11-23 Surface roughness ranges of production processes

Process

Flame cutting Snagging Sawing Planing, shaping

Drilling Chemical milling Elect, discharge roach. Milling

Roughness height rating,/~ m (/~ in) Ra 50 25 12.5 6.3 3.2 1.8 0.80 0.40 0.20 0.10 0.05 0.0250.¢12

(2000)(1000)(500)(250)(125) (63) (32)(16) (8) (4) (2) (1) (0.5)

ZZZZ; i ZZZZ; ZZZZ; m ~ z z z z ; z z ~ m m ~ ~ z ~

ZZZZ ~ ~ ~

t ~ m ~ ~ - ~

zzzz; 7777: ~ ~ ~ 7777~ 7777:

Broaching Reaming Electron beam Laser Electro-chemical Boring, turning Barrel finishing

m7777: ~ ~ 7777:

z ~ m ~ z ~

m ~ ~ z ~ ~ z z

I / / / / , 7 / / / / / / / , ~ / / / _

~T~. ~-~ m m T~ ~7-~

Electrolytic grinding Roller burnishing Grinding Honing

Electro - polish Polishing Lapping Superfinishing

ZZZZ ZZZZ ~ ZZZZ;

ZZZZ;

Sand casting ~ m zz~ Hot rolling ~ m zzzz

Forg)ng z ~ m ~ ~ - ~ Perm. mold casting Z Z Z Z ; ~ ZZZZ;

~ m zzzz

m m m ~ z ~

m m m ~J-~ zz~ mmmzzzm~ z z z z : m ~ ~ 7 7 - ~ z z 2 z ~ ~ m 7 7 - ~

Investment casting 7777:, i ZZZZ2ZZZZ; Extruding ZZZZ 7777;, i m 7777:. Cold rolling, drawing 7777:, m m zzzz; 7777;, Die casting ZZZZ; m

The ranges shown above are typical of the processes listed. ~ Average application Higher or lower values may be obtained under special conditions. ~/ / / / ,~ Less frequent

application

Source: Reproduction from Baumeister, T., Marks' Standard Handbook for Mechanical Engineers, 8th ed., with permission from McGraw-Hill Book Company, New York, 1979.


TABLE 11-24 Application of surface texture values to surface symbols

(63 ) 1 .~- - - Roughness average rating is (63 ) 3 . 5 1 . ~ - placed at the left of the long leg; the specification of only one rating shall indicate the maximum value and any lesser value shall be acceptable

(63) 1.6 The specification of (63 ) 1 . ~ - maximum value and

(32) 0.8/----- minimum value roughness 0.8 % ,

average ratings indicates (32) ~/--~ permissible range of value

v

rating

Machining is required to produce the surface; the basic amount of stock provided for machining is specified at the left of the short leg of the symbol

Removal of material by machining is prohibited

Lay designation is indicated by the lay symbol placed at the right of the long leg

0.05 (32) 0 . 8 / ~ Maximum waviness height (32) 0"8 2/~. 5 (0.100)

v

rating is placed above the v

horizontal extension; any lesser rating shall be acceptable

Roughness sampling length or cutoff rating is placed below the horizontal extension; when no value is shown, 0.80 mm is assumed

0.05- 100 0 8 (32) 0.~/ Maximum waviness spacing (32) "~/±__ 0.5

rating is placed above the horizontal extension and to the right of the waviness height rating; any lesser rating shall be acceptable

Where required, maximum roughness spacing shall be placed at the right of the lay symbol; any lesser rating shall be acceptable

Source: Reproduction from Baumeister, T., Marks' Standard Handbook for Mechanical Engineers, 8th ed., with permission from McGraw-Hill Book Company, New York, 1979.


TABLE 11-25 Typical surface texture design requirements

(250 ~tin) 6.3/--- Clearance surfaces I ¢

Rough machine parts

(125 ~tin) 3.2/-----

(63 ~tin) 1 .6~-- -

(32 ~in) 0.80/-----

Mating surfaces (static) Chased and cut threads Clutch-disk faces Surfaces for soft gaskets

Piston-pin bores Brake drums Cylinder block, top Gear locating faces Gear shafts and bores Ratchet and pawl teeth Milled threads Rolling surfaces Gearbox faces Piston crowns Turbine-blade dovetails

(16 ~tin) 0 .4~- - -

(13 ~tin) 0.3~-----

(8 ~tin) 0 .2~ - - -

Broached holes (4 gin) 0. l~/r m Bronze journal bearings Gear teeth Slideways and gibs Press-fit parts Piston-rod bushings (2 gin) 0.050/---

x/ Antifraction-bearing seats Sealing surfaces for hydraulic tube fittings (1 gin) 0.025 F - -

V

Motor shafts Gear teeth (heavy loads) Spline shafts O-ring grooves (static) Antifraction-bearing bores and faces Camshaft lobes Compressor-blade airfoils Journals for elastomer lip seals

Engine cylinder bores Piston outside diameters Crankshaft bearings

Jet-engine stator blades Valve-tappet cam faces Hydraulic-cylinder bores Lapped antifriction bearings

Ball-bearing races : Piston pins Hydraulic piston rods Carbon-seal mating surfaces

Shop-gauge faces Comparator anvils

Bearing balls Gauges and mirrors Micrometer anvils

• ;.,." ;. ,~!. .... • .


TABLE 11-26 Range of surface roughness a

Manufacturing process With difficulty Normally

Manual Hack saw cut Chipping Filing Emery polish

Casting Sand casting Permanent mold Die casting

Forming Forging Extrusion Rolling

Machining Drilling Planing and shaping Face milling Turning Boring Reaming Cylindrical grinding Centerless grinding Surface grinding Broaching Superfinishing Honing Lapping

Gear manufacture Milling with form cutter Milling, spiral bevel Hobbing Shaping Shaving Grinding Lapping

Surface process Shot blast Abrasive belt Fiber wheel brushing Cloth buffing

0.8-1.6 0.1-0.4

0.8-1.6

1.6-3.2 0.4-0.8 0.4-0.8

3.2-6.3

0.8-1.6 0.2-1.6 0.2-1.6 0.4-0.8 0.025-0.4 0.05-0.4 0.025-0.4 0.2-0.8 0.025-0.1 0.025-0.1 0.006-0.05

1.6-3.2 1.56-3.2 0.8-3.2 0.4-1.6 0.4-0.8 0.1-0.4 0.05-0.2

1.6-3.2

0.1-0.2 0.012-0.05

6.3-50 3.2-50 1.6-12.5 0.4-1.6

6.3-12.5 1.6-6.3 0.8-3.2

3.2-25 0.8-6.3 0.8-3.2

6.3-25 1.6-12.5 1.6-12.5 1.6-6.3 1.6-6.3 0.8-6.3 0.4-3.2 0.4-3.2 0.4-3.2 0.8-3.2 0.1-0.4 0.1-0.4 0.05-0.4

3.2-12.5 3.2-12.5 3.2-12.5 1.6-12.5 0.8-3.2 0.4-0.8 0.2-0.8

3.2-50 0.1-6.3 0.2-0.8 0.05-0.1

a Surface roughness in l~rn (lpm = 10-3mm = 10-6m).

Roughing

1.6-3.2

12.5-25

12.5-50 6.3-50 6.3-50 6.3-12.50 3.2-6.3

3.2-6.3 3.2-6.3

12.5-50 12.5-25 12.5-50 12.5-250

0.8-1


Rivet Symbol

Characteristics to be toleranced Symbol

Shop snap headed rivets

Shop Csk (near side) rivets

-I-

Straightness Shop Csk (far side) rivets ..~

Flatness Circularity 0 Shop Csk (both sides)rivets ..~

Accuracy of any profile ~ Site snap headed rivets _ ~ Accuracy of any surface Pai'allelism / / Site Csk (near side) rivets

Perpendicularity • I Site Csk (far side) rivets Angularity i ~

Position 0 Site Csk (both sides)rivets . ~

Concentricity or coaxiality 0 Open hole , Symmetry ~-

IS • 696-1960

FIGURE 11-14 Symbols for tolerances of form and position.

IS • 696-1960

FIGURE 11-15 Rivet symbols

R E F E R E N C E S r

1. Lingaiah, K., and B. R. Narayana Iyengar, Machine Design Data Handbook, Engineering College Co- operative Society, Bangalore, India, 1962.

2. Lingaiah, K., and B. R. Narayana Iyengar, Machine Design Data Handbook, Vol. I, Suma Publishers, Bangalore, India, 1986, ,

3. Lingaiah~ K., Machine Design Data Handbook, Vol. II (SI and Customary Metric Units), Suma Publishers, Bangalore, India, 1986.

4. Black, P. H., and O. Eugene Adams, Jr., Machine Design, McGraw-Hill Publishing Company, New York. 5. Baumeister, T., Marks' Standard Handbook for Mechanical Engineers, 8th ed., McGraw-Hill Publishing

Company, New Yorkl i978. 6. Maleev, V. L., and J. B. Hartman, Machine Design, International Textbook Company, Scranton, Pennsylvania,

1954 . . . . 7. Shigley, J. E., Machine Design, McGraw-Hill Publishing Company, New York, 1956. 8. Vallance, A., and V. L. Doughtie, Design of Machine Members, McGraw-Hill Publishing Company, New

York, 1951. 9. British Standard Institution.

10. Bureau of Indian Standards.

67071_11.pdf

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