GB/T 25747-2022Magnesium alloy die castings (English PDF)

4.3 Dimensions

4.3.1 The geometry and size of die castings shall conform to the requirements of the die casting drawings.

4.3.2 The dimensional tolerance of die castings shall meet the requirements of grade DCTG4 ~ grade DCTG7 in GB/T 6414-2017. For the dimensional tolerance, which is affected by the parting surface and the movable part of the mold, it needs to add an additional amount, please refer to Appendix B and Appendix C. When there are special provisions and requirements, they shall be marked on the drawings.

4.3.3 For the geometric tolerance requirements of die castings, please refer to Appendix D. Its labeling method shall comply with the provisions of GB/T 1182.

4.3.4 The machining allowance of die castings shall be implemented, in accordance with the provisions of GB/T 6414-2017. If there are special provisions and requirements, the machining allowance shall be indicated on the drawing.

4.4 Weight

When the buyer has requirements on the weight of die castings, its weight tolerance shall comply with the grade MT5 ~ grade MT7 requirements of GB/T 11351-2017.

4.5 Surface quality

4.5.1 The surface roughness of die castings shall conform to the drawings or customer requirements.

4.5.2 Die castings shall not have penetrating cracks, under-casting or other defects.

They are allowed to have scratches, dents, lack of flesh, mesh-shaped burrs, gray spots, flow marks and other defects.

4.5.3 There shall be no bulging phenomenon on the mating surface of die castings; the number and size of such defect, on the non-mating surfaces, which is allowed to exist, shall be determined, through negotiation between the supplier and the buyer.

4.5.4 If there is no special provision in the drawings, the settings of the die-casting process, such as the position of the ejector pin, the position of the parting line, the position of the gate and the overflow port, etc., shall be determined, through negotiation between the supplier and the buyer.

4.5.5 The surface of the die casting, that needs special treatment, such as polishing, shot blasting, chrome plating, coating, anodizing, chemical oxidation, etc., shall be indicated on the drawing. provisions of GB/T 231.1.

5.2.3 When sampling is required for die castings, the sampling location, specimen structure and size shall be agreed upon by both the supplier and the buyer.

5.3 Dimensions

5.3.1 The geometric dimension inspection of die castings shall be carried out, in accordance with the provisions of GB/T 3177.

5.3.2 The geometric tolerance inspection of die castings shall be carried out, in accordance with the provisions of GB/T 1958.

5.3.3 If the accuracy is met, general or special measuring tools can be used for inspection.

5.4 Weight

During mass production, it shall randomly take not less than 10 pieces of products from the blanks; use the average weight of the actual weight is taken as the nominal weight.

5.5 Surface quality

5.5.1 The surface quality of die castings shall be inspected by visual method or by other suitable methods.

5.5.2 The surface roughness of the die castings shall be tested by comparing the sample blocks.

5.6 Internal quality

5.6.1 The test methods for the internal quality of die castings may include non- destructive testing, pressure test, metallographic inspection, cutting inspection, etc.

5.6.2 Corresponding quality inspection shall be carried out for the die castings, after infiltration, repair, deformation correction.

6.1 Inspection items

The inspection of die castings is divided into type test and exit-factory inspection. The inspection items are as shown in Table 4.

6.4.3 When the size of any specimen is unqualified, it shall be judged as unqualified.

The rest of the products in the same batch are checked one by one.

6.4.4 When the weight of any specimen is unqualified, it shall be judged as unqualified.

The rest of the products in the same batch are checked one by one.

6.4.5 When the surface quality of any specimen is unqualified, it shall be judged as unqualified.

6.4.6 When the internal quality of any specimen is unqualified, it shall be judged as unqualified. Check the rest of the same batch one by one.

7.1 Product marking

The following marks shall be cast or engraved on non-machined surfaces of the die castings:

a) Raw material designation;

b) Part number;

c) Customer trademarks or symbols;

d) Manufacturer's brand or symbol;

e) Manufacturing year, month, mold number;

f) Other markings specified by the customer.

7.2 Packaging signs

The outer packaging of die castings shall have the following signs:

a) Part number;

b) Product code;

c) Date of packing quantity;

d) Internal system-specific traceability information;

e) The manufacturer's brand or symbol;

f) Other requirements specified by the customer.