# Sheet Metal Tolerances: The Key to Precision Engineering

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## 1. Dimensional Tolerance of Flat Stamping Parts and Formed Stamping Parts

Unit: mm

### (2) Dimensional Tolerance of Formed Stamped Parts

Unit: mm

Note:

1. Flat stampings are stampings formed by plane punching. Formed stampings are stampings made by bending, deep drawing, and other forming methods.
2. The dimensional tolerance of flat stampings applies to flat stampings, and also to dimensions formed by punching operations on formed stampings.
3. The limit deviations of the dimensions of flat stampings and formed stampings are selected according to the following rules:
1) For hole (internal shape) dimensions, the limit deviation is taken from the tolerance values given in the table, with “+” used as the upper limit deviation, and the lower limit deviation is 0.
2) For shaft (external shape) dimensions, the limit deviation is taken from the tolerance values given in the table, with “-” used as the lower limit deviation, and the upper limit deviation is 0.
3) For hole center distance, hole edge distance, and the length, height, and untolerated dimensions formed by bending, deep drawing, and other forming methods, the limit deviation is half the tolerance value given in the table, with “±” used as the upper and lower limit deviations.

## 2. Unnoted Coaxiality and Symmetry Tolerances Are

Coaxiality, symmetry, and primary parameters (L, H, D) are indicated in firgure below.

Unit: mm

## 3. Limit Deviation of Unnoted Tolerances (Punching, Forming) Dimensions

Unit: mm

Note:

1. Tolerances should be marked for dimensions 0.5mm and below.
2. This table is applicable to untoleranced dimensions of hole center distance, hole edge distance, and lengths and heights formed by bending, deep drawing, and other forming methods.

Unit: mm

## 6. Angular Tolerance

Unit: mm

Note:

1. The shearing angle of a stamped part refers to the angle created by the stamping or forming process in the planar part of the stamped component.
2. The bending angle of a stamped part refers to the angle created by the bending process in the stamped component.
3. The difference in the maximum values of the shearing angle and the bending angle of the stamped part should be selected according to the following criteria:
1) A unidirectional deviation is chosen based on usage requirements.
2) For unstated tolerance of angle limit deviations, half of the tolerance value given in the table is taken, denoted with a “±” sign as the upper and lower limit deviations.

Unit: mm

Unit: mm

## 9. Unnoted Flatness and Straightness Tolerances

The primary parameters (L, H, D) for flatness and straightness are indicated as shown in Figures 1-3.

Unit: mm

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