Machine Drawing

228 Machine Drawing

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d:\N-Design\Des15-1.pm5

than the hole and still be within the prescribed tolerances. It results in a clearance fit, when

shaft diameter is 29.95 and hole diameter is 30.05 (+ 0.10 mm) and interference fit, when shaft

diameter is 30.00 and hole diameter 29.95 (– 0.05 mm).

Maximum size of shaft

Shaft tolerance

Max. clearance

Min. clearance (Allowance)

Min dia. of shaft

f29.90

f29.85

f29.95 Min. size of hole =

basic size

f30.00

Hole tolerance

Max. dia of hole

Fig. 15.10 Clearance fit

Max. size of shaft

Shaft tolerance

Max. clearance

Max. interference (Allowance)

Min. dia. of shaft

f30.00

f29.95

f29.95 Min. size of hole =

basic size

f30.05

Hole tolerance

Max. dia. of hole

Fig. 15.11 Transition fit

15.4.3 Interference Fit

If the difference between the hole and shaft sizes is negative before assembly; an interference

fit is obtained.

15.4.3.1 Minimum Interference

It is the magnitude of the difference (negative) between the maximum size of the hole and the

minimum size of the shaft in an interference fit before assembly.