Dimensional Tolerance Standards for Metal Stamping Parts

The tolerance size of metal stamping parts is related to the size and the selected tolerance class. The selection of tolerance grades must not only meet the design requirements, but also consider the possibility and economy of the process. That is to say, in the case of meeting the requirements of use, try to add to the tolerance value, that is, choose a lower tolerance level.

The dimensional tolerance value of the stamping part is related to the size of the stamping part and the thickness of the plate, and on the other hand, it is related to the accuracy level.

Ⅰ. Dimensional tolerance of metal stamping parts

1. Dimensional tolerance of flat stamping parts: divided into 11 grades, indicated by ST1 to ST11, among which ST indicates the dimensional tolerance of flat stamping parts, and the tolerance grade code is indicated by Arabic numerals. From ST1 to ST11, the accuracy grades decrease sequentially.

2. Dimensional tolerance of formed stamping parts: Formed stamping parts are divided into 10 precision grades, indicated by FT1 to FT10, among which FT indicates the dimensional tolerance of formed stamping parts, and Arabic numerals indicate the tolerance level. From FT1 to FT10, the accuracy grades decrease sequentially.

Ⅱ. Limit error of metal stamping parts

The press error of the hole size is 0, the upper error is the lower error plus the dimensional tolerance; the upper error of the shaft size rule is the fundamental error, the value is 0, and the lower error is the upper error minus the dimensional tolerance. For hole center distance, hole edge distance, bending, stretching length, height, etc., the upper and lower error rules are half of the dimensional tolerance.

Tolerance is the range of dimensional changes. The larger its value, the lower the precision and the less difficult the processing; the smaller the value, the higher the precision and the greater the processing difficulty. So what should be paid attention to in production?

1. Bending angle: the angle size of metal stamping parts formed by bending;

2. Punching point of view: the size of the point of view formed by punching at the plane of the flat plate or formed part;

3. Punching fillet radius: the linear dimension of the fillet radius of metal stamping parts processed through punching, blanking and separation processes;

4. Forming size: the linear size of stamping parts processed by bending, stretching and other processes;

5. Punching size: the linear size of metal stamping parts processed through punching, blanking and separation processes.

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