What quality problems may occur in the process of automobile stamping die processing?

During the processing of automobile stamping die, there may be some problems such as dimensional accuracy, surface quality, shape and position accuracy, and die performance. The following are specific introductions:

Dimensional accuracy problem

Dimensional deviation: there is a deviation between the size of the processed mold and the design size. This may be caused by insufficient precision of processing equipment, tool wear, improper setting of process parameters or programming errors. For example, in NC milling, if the tool radius compensation is set incorrectly, the size of the die cavity will be larger or smaller.

Unstable size: the size of different parts of the same mold or different batches of molds fluctuates. It may be due to factors such as poor stability of equipment, poor consistency of materials or changes of processing environment during processing. For example, the vibration of the equipment during machining will lead to a slight change in the size of the mold.

Surface quality problem

Poor surface roughness: the surface of the mold is not smooth enough, and there are defects such as knife marks, scratches and pits. This is mainly caused by unreasonable selection of cutting parameters, poor tool quality, vibration during machining or insufficient cooling and lubrication. For example, if the cutting speed is too low or the feed rate is too large, obvious tool marks will be left on the die surface, which will affect the surface roughness.

Surface burn: In the process of machining, the cutting heat is too high, which leads to local overheating of the die surface and burns. This may be caused by improper cutting parameters, severe tool wear or cooling system failure. For example, in grinding, if the linear speed of grinding wheel is too high or the grinding feed is too large, it is easy to burn the mold surface and affect the performance and life of the mold.

Surface crack: Micro cracks appear on the surface of the mold, which may be caused by defects in the material, stress concentration during processing or improper heat treatment process. For example, in the process of die quenching, if the cooling rate is too fast, large internal stress will be generated on the die surface, which will lead to the appearance of surface cracks.

Shape and position accuracy problem

Out-of-tolerance: the shape and position accuracy of the mold do not meet the design requirements, such as flatness, straightness, verticality, parallelism and other shape and position tolerances beyond the specified range. This may be caused by the decline in the accuracy of processing equipment, inaccurate clamping and positioning or unreasonable processing technology. For example, when machining a large stamping die, if the clamping is not firm, the die will shift during the machining process, which will lead to the shape and position tolerance of the die exceeding the tolerance.

Mold deformation: the mold is deformed during or after processing. This may be caused by the release of internal stress in the die material, excessive cutting force during machining, improper heat treatment process or unreasonable die structure design. For example, after the rough machining of the die, if there is no effective stress relief treatment, the release of internal stress will lead to the deformation of the die in the subsequent finishing process.

Mold performance problem

Hardness does not meet the requirements: the hardness of the die is an important index affecting its wear resistance, strength and life. The hardness does not meet the requirements, which may be caused by improper material selection and inaccurate heat treatment process control. For example, if the quenching temperature is too high or too low, the hardness of the die will be too high or too low, which will affect the performance of the die.

Poor wear resistance: the surface of the mold is prone to wear during use, which leads to the shortening of the service life of the mold. This may be caused by insufficient wear resistance of materials, improper surface treatment technology or poor surface quality after processing. For example, uneven nitriding treatment on the surface of the mold will make the local wear resistance of the mold poor and easy to wear.

Lack of toughness: the mold is prone to crack or fracture under impact load, which shows that the toughness of the mold is insufficient. It may be caused by insufficient toughness index of materials, unreasonable heat treatment process or defects in die structure design. For example, when designing a mold, if the hardness of the mold is excessively pursued while the toughness is neglected, the mold will be prone to brittle fracture during use.