In the hardware industry, many of our customers may encounter such a problem: tolerance requirements for sheet metal processing? The dimensional tolerance of sheet metal processing refers to the level to determine the accuracy of dimensions. The national standard stipulates that there are 20 levels. From IT01, IT0, IT1, IT2 to IT18, the larger the number, the lower the tolerance level (processing accuracy), the larger the allowable variation range (tolerance value) of dimensions, and the smaller the processing difficulty. For general NC machining, the tolerance for each tool is basically within plus or minus 0.3.
General tolerance precision standard for sheet metal parts
1. Purpose
Adopt unified and standardized unmarked tolerance standards, standardize the design, production and acceptance standards of sheet metal parts, and ensure that sheet metal
Precision requirements for machined parts. (1) It can effectively simplify drawing, save design time, and exchange information efficiently.
2. The size with tolerance marked on the drawing shall be highlighted to facilitate production and manufacturing.
3. Simplifying inspection requirements is helpful to quality management. High quality and high efficiency production can be achieved.
2. Scope of application: trial run from the date of promulgation of the standard, applicable to newly designed sheet metal parts after promulgation
(The previously designed sheet metal parts are also manufactured and accepted according to the original standard.) The whole stage from design drawing, production and manufacturing to product acceptance is operated according to this standard.
Sheet metal processing
3 Responsibilities
3.1 Technical Center
The Technical Center shall design in accordance with this standard. See Appendix - for standard reference. No special requirements for functions
General tolerances are applied to elements,
The tolerance may not be indicated on the drawings, but only the technical requirements or technical documents shall refer to this
Standards. The tolerance grade of general tolerance without tolerance indicated on the drawing shall consider the general workshop accuracy.
1. For any single dimension, when the functional tolerance is equal to or greater than the general tolerance, a
General tolerance, which does not need to be marked.
2. When the function of the element allows a tolerance larger than the general tolerance, it is more economical than the general tolerance in manufacturing
The corresponding limit deviation value shall be indicated after the size.
3. Due to functional requirements, a certain element requires a tolerance value smaller than the general tolerance, and its corresponding limit deviation value should be noted after the size.
3.2 Manufacturing Center (mainly refers to sheet metal supplier)
The manufacturing center conducts production according to this standard. See Appendix I for standard reference. Tolerance items shall be marked in the design drawing according to
Produce according to the marked deviation value. For items without tolerance indications in the design drawing, the standard of the specification shall be followed
The deviation value shall be used for production.
If the supplier is unable to process the accuracy requirements of the design mark, it shall communicate with the main designer for settlement.
