Tolerances

CASTING TOLERANCES 毛胚

U.S.			METRIC
	一般	特別	Up to 25mm	±.127 mm
0～5	±0.25	±0.07
5～10		±0.14	Up to 50mm	±.254 mm
10～25		±0.25
25～50	±0.40	±0.32	Up to 75mm	±.381 mm
50～75	±0.60	±0.50
75～100	±0.80	±0.70	Up to 100mm	±.483 mm
100～125	±1.1	±0.90
125～150	±1.4	±1.1	Up to 125mm	±.559 mm
150～175	±1.7	±1.3
175～200	±2.0	±1.5	Up to 150mm	±.635 mm
200～250	±2.5	±1.8
角度公差	±1°	±30°

WALL THICKNESS 厚度能力

	U.S.MINIMUM WALL		METRICMINIMUM WALL
Metal	Small Area	Normal	Small Area	Notmal
Series stainless	.045 in.	.070 in.	1.143mm	1.778mm
Carbon Steel	.050 in.	.080 in.	1.270mm	2.032mm

FLATNESS真平度公差
Flatness refers to single plane surface and is usually a function of volumetric shrinkage.

U.S.		METRIC
Thickness	Dish per 6 sq. inches of surface	Thickness	Dish per 42 sq.cm of surface
.251 in.to .500 in.	.004 in.	6.5 mm to 13 mm	.102 mm
.501 in.to 1.000 in.	.008 in.	13mm to 25mm	.201 mm
1.001 in.to 2.000 in	.016 in.	25mm to 50mm	.406 mm

STRAIGHTNESS 真直度公差
Tolerances for axial straightness:±.005 in. per inc .005 in per inch (±.127mmp)

CONCENTRICITY 同心度公差

1. Concentricity of diameters in a shaft is also a function of straightness. Centers will be concentric within .005 in. per inch (±.127mm per 25mm) of maximum separation.

2. Centers of I.D. to O.D. will be concentric within .003 in. per 1/2 in (.076 mm per 13 mm) of wall thickness. This disregards out-of-roundness, and assumes measurements in the same plane IF the concentricity is being measured in separate planes, the requirements of paragraph 1 above must be added.

ROUNDNESS-SOLID BARS 真圓度公差
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 ±.005 in per inch (.127 mm per 25mm)may be .005 in

Angles 角度公差
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 (PCD公差)
.005 in per inch(.127 mm per 25 mm)for many single reference paint.

PARALLEL SECTIONS 平行度公差
Controlling relationship is between length and width of the elements being checked. To establish a specific to lerance range for all combinations would be impossible, but a general to lerance of .010 in. TIR per inch (.254 mm per 25mm) may be used.

1.	Concentricity of diameters in a shaft is also a function of straightness. Centers will be concentric within .005 in. per inch (±.127mm per 25mm) of maximum separation.
2.	Centers of I.D. to O.D. will be concentric within .003 in. per 1/2 in (.076 mm per 13 mm) of wall thickness. This disregards out-of-roundness, and assumes measurements in the same plane IF the concentricity is being measured in separate planes, the requirements of paragraph 1 above must be added.