General Tolerances

These tolerances apply as a general rule of thumb. Closer tolerances can be obtained depending on part design or the use of special procedures or secondary operations

Casting Tolerances

Metric
Meta Up to 25 mm	± 0.127 mm
Up to 50 mm	± 0.254 mm
Up to 75 mm	± 0.381 mm
Up to 100 mm	± 0.508 mm
Up to 125 mm	± 0.635 mm
Up to 150 mm	± 0.762 mm

Flatness

Flatness refers to single plane surface and is usually a function of volumetric shrinkage

Metric
Range of nominal dimension (mm)		For Straightness / Flatness (mm)
Over	Upto	As cast TIR	Machined TIR
0	10	0.12	0.08
20	25	0.15	0.10
25	50	0.20	0.15
50	75	0.30	0.20
75	100	0.40	0.25
100	150	0.55	0.35
150	200	0.70	0.50
200	300	0.95	0.70

Concentricity

Metric
Range of nominal dimension (mm)		For Straightness / Flatness (mm)
Over	Upto	As cast TIR	Machined TIR
0	10	0.12	0.08
20	25	0.15	0.10
25	50	0.25	0.15
50	75	0.40	0.25
75	100	0.50	0.35
100	150	0.70	0.45
150	200	0.85	0.55
200	300	1.00	0.70

Roundness - Solid Bars

Roundness is a function of normal shrinkage variations in the metal. Shrinkage variation increases with diameter and the tolerance required increases proportionately. A general rule of 0.127 mm per 25 mm may be applied.

Angles

As-cast tolerances of angles depend on their location in casting. They range from ± 1/2° for well supported positions to ± 2° where inherent distortion could be expected. Inclusion of gussets and ribs often minimizes distortion and many sections can be mechanically straightened.