Question

A hole and mating shaft are to have a nominal assembly size of 70 mm. The assembly is to have maximum clearance of 0.2 mm and minimum clearance of 0.1 mm and hole tolerance is 1.5 times the shaft tolerance. The tolerance on hole, based on basic hole standard, is

• A. 0.16 mm
• B. 0.04 mm
• C. 0.06 mm
• D. 0.3 mm

Answer 1

The correct option is C 0.06 mm

$\text{Max. clearance}$
$=\text{U.L of hole - L.L of shaft = 0.2 mm}$

$\text{Min. clearance}$
$=\text{L.L of hole - U.L of shaft =0.1 mm}$

$\text{Hole tolerance = U.L of hole - L.L of hole}$

$=1.5\text{times shaft tolerance}$

$=1.5\text{[U.L of shaft -L.L of shaft]}$

$\text{Hole basis system}$,

$\text{Therefore, L.L of hole =70 mm}$

$70-0.1=\text{U.L of shaft}$

$69.9=\text{U.L of shaft}$

$\text{Let U.L of hole =X}$

$\text{X}-70=1.5[69.9-(\text{X}-0.2\left)\right]$

$\text{X}-70=105.15-1.5\text{X}$

$\text{X}=70.06$

Therefore,

$\text{Hole tolerance}=70.06-70.0$

$=0.06\text{mm}$