Technical

Casting Tolerance

Metrics
Upto 25 mm	± 0.127 mm
Upto 50 mm	± 0.254 mm
Upto 75 mm	± 0.381 mm
Upto 100 mm	± 0.508 mm
Upto 125 mm	± 0.635 mm
Upto 150 mm	± 0.762 mm

Flatness

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

Metrics
Range of nominal dimension (mm)		For starightness / 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

Metrics
Range of nominal dimension (mm)		for Roundness / Concentricity (mm)
Over	upto	As cast TIR	Machined TIR
0	0	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	0.50	0.35
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.

HOLE POSITIONING

0.127 mm per 25 mm from any single reference point.

BLIND HOLES

Blind holes can be cast if length does not exceed the diameter

SURFACE FINISH

Average Ra value generally ranges between 3.20 to 5.50 microns