GB/T 37057-2019Multi-way precision die forgings—Quality control criterion (English PDF)

4.1 Process design

4.1.1 Multi-way die forging technology is generally applied to forge complex structural forgings which have inner holes and multiple branches or bosses externally.

4.1.2 Forging design shall minimize the surface machining allowance on the premise of satisfying the structural dimensions and mechanical properties of the part. The final forming part and cavity of the forging shall retain sufficient process margin; if necessary, the demander's opinion shall be asked for the design result.

4.1.3 The process design process shall comply with the requirements that are specified in GB/T 35079; process specification (card) shall be prepared to guide the production process. The process specification (card) shall include at least the requirements and control methods for the processes such as cutting, heating, mold, forging, multi-way die-forging hydraulic machine control parameters, post-forging treatment.

4.1.4 For the process design process, numerical simulation technology should be used to optimize the process and process parameters. The forging steps should meet the requirements that are specified in GB/T 35079.

4.1.5 Each stage of the process design shall be reviewed; the design results shall also be reviewed by professionals of design, process, quality, and production; if necessary, demander's opinion shall be asked for the design result.

4.2 Raw material

4.2.1 The raw materials shall have valid quality certification documents that are provided by the manufacturer; the chemical composition, appearance, size, mechanical properties and internal quality of the raw materials shall comply with the process requirements.

4.2.2 The raw materials shall be free of defects such as cracks, crusting, folding or inclusion on the surface.

4.2.3 After the raw materials are delivered to the factory, they shall be re-inspected by the quality inspection department. The items and requirements for re-inspection shall be implemented in accordance with GB/T 33879.

4.2.4 The raw materials shall be stored in sections according to materials, specifications, inspection status, and clearly marked. Materials and furnace batches shall be confirmed before the raw materials are shipped out, so as to prevent mixing.

4.3 Blanking

4.3.1 The raw materials should be sawed and blanked; the blanking shall meet the requirements of GB/T 35079. The precision of the sawing equipment shall meet the requirements of JB/T 4318.2. […]