Two bolts, with a centre distance of 50 mm, are used to assemble two plates. The recommended class of fi t between bolts and holes is 12H11-d11. Specify tolerance for the centre to centre distance between bolts.
Chapter 3
Q. 3.4
Step-by-Step
Verified Solution
Step I Maximum and minimum diameters of hole and bolt
Hole: 12H11 (Table 3.2)
Table 3.2 Tolerances for holes of sizes up to 100 mm (H5 to H11)
| H | Diameter steps in mm |
||||||||
| 5-11 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | ||
| ei | es | to | over | ||||||
| 0 | +60 | +40 | +25 | +14 | +10 | +6 | +4 | 3 | 0 |
| 0 | +75 | +48 | +30 | +18 | +12 | +8 | +5 | 6 | 3 |
| 0 | +90 | +58 | +36 | +22 | +15 | +9 | +6 | 10 | 6 |
| 0 | +110 | +70 | +43 | +27 | +18 | +11 | +8 | 18 | 10 |
| 0 | +130 | +84 | +52 | +33 | +21 | +13 | +9 | 30 | 18 |
| 0 | +160 | +100 | +62 | +39 | +25 | +16 | +11 | 50 | 30 |
| 0 | +190 | +120 | +74 | +46 | +30 | +19 | +13 | 80 | 50 |
| 0 | +220 | +140 | +87 | +54 | +35 | +22 | +15 | 100 | 80 |
12^{\overset{+0.110}{_{+0.000}}} \text { or } \frac{12.110}{12.000} mm .
Bolt: 12d11 (Table 3.3a)
Table 3.3a Tolerances for shafts of sizes up to 100 mm (from d to h)
| h | g | f | e | d | Diametersteps in mm |
||||||||||||||||||||
| 10 | 9 | 8 | 7 | 6 | 5 | 5-10 | 7 | 6 | 6-7 | 8 | 7 | 6 | 6-8 | 9 | 8 | 7 | 6 | 6-9 | 11 | 10 | 9 | 8 | 8-11 | ||
| ei | es | ei | es | ei | es | ei | es | ei | es | to | over | ||||||||||||||
| -40 | -25 | -14 | -10 | -6 | -4 | 0 | -12 | -8 | -2 | -20 | -16 | -12 | -6 | -39 | -28 | -24 | -20 | -14 | -80 | -60 | -45 | -34 | -20 | 3 | 0 |
| -48 | -30 | -18 | -12 | -8 | -5 | 0 | -16 | -12 | -4 | -28 | -22 | -18 | -10 | -50 | -38 | -32 | -28 | -20 | -105 | -78 | -60 | –48 | -30 | 6 | 3 |
| -58 | -36 | -22 | -15 | -9 | -6 | 0 | -20 | -14 | -5 | -35 | -28 | -22 | -13 | -61 | -47 | -40 | -34 | -25 | -130 | -98 | -76 | –62 | -40 | 10 | 6 |
| -70 | -43 | -27 | -18 | -11 | -8 | 0 | -24 | -17 | -6 | -43 | -34 | -27 | -16 | -75 | -59 | -50 | -43 | -32 | -160 | -120 | -93 | –77 | -50 | 18 | 10 |
| -84 | -52 | -33 | -21 | -13 | -9 | 0 | -28 | -20 | -7 | -53 | -41 | -33 | -20 | -92 | -73 | -61 | -53 | -40 | -195 | -149 | -117 | –98 | -65 | 30 | 18 |
| -100 | -62 | -39 | -25 | -16 | -11 | 0 | -34 | -25 | -9 | -64 | -50 | -41 | -25 | -112 | -89 | -75 | -66 | -50 | -240 | -180 | -142 | –119 | -80 | 50 | 30 |
| -120 | -74 | -46 | -30 | -19 | -13 | 0 | -40 | -29 | -10 | -76 | -60 | -49 | -30 | -134 | -106 | -90 | -79 | -60 | -290 | -220 | -174 | –146 | -100 | 80 | 50 |
| -140 | -87 | -54 | -35 | -22 | -15 | 0 | -47 | -34 | -12 | -90 | -71 | -58 | -36 | -159 | -126 | -107 | -94 | -72 | -340 | -260 | -207 | –174 | -120 | 100 | 80 |
12^{\overset{-0.050}{_{-160}}} \text { or } \frac{11.950}{11.840} mm .
Step II Calculation of x
From Eq. (3.1),
x=\left(D_{\min .}-d_{\max }\right) (3.1).
x=\left(D_{\min .}-d_{\max }\right)=(12.000-11.950)=0.05 mm .
Step III Tolerance for the centre distance
The tolerance for the centre distance is given as
50 ± 0.05 mm.