Accuracy Tolerance & Dimensions

Accuracy Tolerance & Dimensions

The following tolerances and dimensions are subjected according to standard IS 11166 
All dimensions in millimeters.

Permissible Deviations on Dimensions, Class 2

Nominal dimensions of Rough Castings Over all Dimensions
Over Up to Up to 6 Over 6 up to 10 Over 10 up to 18 Over 18 up to 30 Over 30 up to 80 Over 80 up to 180 Over 180 up to 300 Over 300 up to 500
6 ± 0.10 ± 0.12 ±0.15 ±0.20 ±0.25 ±0.25 ±0.30 ±0.35
6 10 —– ±0.12 ±0.15 ±0.25 ±0.25 ±0.30 ±0.35 ± 0.45
10 18 —– —– ±0.20 ±0.30 ±0.35 ±0.35 ±0.40 ±0.55
18 30 —– —– —– ±0.30 ±0.40 ±0.45 ±0.50 ±0.65
30 80 —– —– —– —– ±0.45 ±0.55 ±0.60 ±0.75
80 180 —– —– —– —– —– ±0.60 ±0.70 ±0.90
180 300 —– —– —– —– —– —– ±1.00 ±1.15
300 500 —– —– —– —– —– —– —– ±2.00

Permissible Deviations on Centre to Centre, Distance between Holes, Bosses etc.

Nominal Dimensions Nominal Dimensions Permissible Deviation
Over Up to Class 2
6 ±0.125
6 10 ±0.125
10 18 ±0.15
18 30 ±0.25
30 80 ±0.35
80 180 ±0.45
180 300 ±0.70
300 500 ±0.90

Permissible Deviations on Angles

 Permissible deviations on specified angles for Class 2 is ± 1º

Permissible Deviations on Surface Roughness

  Surface roughness would be between 3.0Ra to 6.0Ra

Permissible Machining Allowance

Nominal Dimension Overall Dimensions (mm/face)
over Up to 6 6-10 10-18 18-30 30-80 80-180 100-300
—– 6 0.3 0.35 0.4 0.5 0.7 1.0 1.0
6 10 —– 0.35 0.4 0.5 0.7 1.25 1.5
10 18 —– —– 0.5 0.6 0.7 1.25 1.5
18 30 —– —– —– 0.6 0.8 1.4 1.75
30 80 —– —– —– —– 1.0 1.6 2.00
80 180 —– —– —– —– —– 2.0 2.25
180 300 —– —– —– —– —– —– 3.00