In order to ensure that the flange forgings have the dimensional accuracy and mechanical properties required by the design, the quality of the forgings must be controlled, that is, the whole production process from the selection of raw materials to the heat treatment after forging must be controlled to ensure stable product quality.
Forging quality control includes inspection of raw materials, intermediate inspection (semi-finished products), final inspection (finished forgings) and control of production tools, such as molds, measuring tools, and adjustment and inspection of equipment and instruments.
The pre-forging heating process and the post-forging heat treatment process are special processes, and the quality characteristics cannot be measured accurately or economically, but they are mainly ensured by strict process parameter control.
1. Quality control of raw materials
- 1) check the warranty and standards of materials.
- 2) check whether the identification of materials is correct to avoid material mixing.
- 3) check material specifications.
- 4) check the surface quality of materials for defects such as cracks and crusts.
- 5) chemical composition test
- 6) test with spectrometer, spark test, etc., to avoid material mixing
2. Mold quality control
- 1) check mold warranty or manufacturing inspection report (including non-destructive testing)
- 2) mold inspection (re-inspection), including shape, size and hardness
- 3) mold adjustment and sample inspection
- 4) mold repair
3. The temperature
- 1) use a device similar to an infrared thermometer to detect the heating temperature
- 2) accelerate heating when using coal or oil stove.
4. Forging process
- 1) the first inspection
- 2) it shall be inspected by the workers themselves, and then re-inspected by the inspectors, and records shall be filled in.
- 3) equipped with necessary inspection tools and measuring tools
5. Heat treatment
- 1) strictly control parameters and keep records in the heat treatment process.
- 2) the worker should check the hardness, and then the inspector should check and record the hardness.
- 3) if necessary, use magnetic hardness sorter or hardness tester to test 100% hardness.
- 4) use the corresponding nondestructive testing method to check whether there are cracks.
6. Product identification and traceability
- 1) label management shall be implemented from raw materials to the workshop.
- 2) label management, label management of each item in the process, quantity, name, material grade and quantity, specification, operator and inspector shall be transferred to the processing unit.
- 3) if necessary, print the serial number and material number on the forging.
Method of forging defects
- 1. Burr, cracking, folding – smoothed by grinding wheel or air digger or rotating burr.
- 2. For small pits – they can be reforged in a new die or modified by a fusion joint.
- 3. Forgings with insufficient die forging – can be modified through pre-processing in the machining workshop. For this kind of forging, it is better not to forge again. This can become an irreparable waste as the newly produced scale presses the forgings. Sometimes they can be modified by grinding. The unimportant forgings can be reheated, and the excess metal can be turned into oxide, and finally modified with a shot blasting machine.
- 4. Error – the wrong way is to fake again. If it is relatively severe, the error cannot be corrected. If the error is not serious, it can be modified by grinding.
- 5. Bend – can be modified by pressing at trim temperature or cold.
- 6. Overheating – overheating forgings can be modified through standardization.
- 7. Unqualified forging hardness – when the hardness is too high, it can be reduced by annealing again; When the hardness is too low, it can be increased by quenching again.
- 8. Overfired, hardened-cracked, severely folded and severely unqualified forgings shall be deemed to be beyond repair.