Car rearview mirror die-casting mold custom processing faces harsh working conditions such as high temperature, high pressure and metal liquid flushing during the production process. Surface nitriding treatment is an important means to improve its wear resistance, corrosion resistance and demolding performance, and process stability is directly related to the consistency and reliability of the nitriding effect.
First of all, the precise control of nitriding process parameters is the basis for ensuring stability. The nitriding temperature has a key influence on the diffusion rate of nitrogen atoms and the formation of the compound layer. Generally speaking, the temperature between 480℃ and 580℃ is more suitable. If the temperature is too low, the nitrogen atoms diffuse slowly, the thickness of the nitriding layer is insufficient and the hardness is insufficient; if the temperature is too high, it may cause the mold matrix structure to be coarse, reduce the mold strength and toughness, and affect its service life. Nitriding time should not be ignored. If the time is too short, the ideal nitriding layer depth and hardness gradient cannot be formed. If the time is too long, the nitriding layer may be loose and easy to peel off. For example, in a car rearview mirror die-casting mold custom processing nitriding treatment, when the temperature is controlled at 520℃ and the time is set to 10-15 hours, a relatively stable and good nitriding layer can be obtained. In addition, the ammonia flow rate and decomposition rate also need to be precisely controlled. Excessive ammonia flow rate or unstable decomposition rate will make the nitriding layer uneven.
Secondly, the pretreatment of mold materials is crucial to process stability. Before nitriding, the mold should be thoroughly stress-relieved annealed to eliminate the internal stress generated during the processing and prevent mold deformation due to stress release during the nitriding process. For example, stress-relieved annealing at 550℃-650℃ and heat preservation for 2-4 hours can effectively reduce the risk of mold deformation. At the same time, the cleanliness of the mold surface will also affect the nitriding effect. Impurities such as oil and rust need to be removed to ensure that nitrogen atoms can be evenly adsorbed and diffused.
Furthermore, the performance and operating status of the nitriding equipment affect the process stability. The temperature control accuracy of the equipment should be within ±5℃, and the error of the ammonia flow control system should be as small as possible to ensure the stable output of process parameters. Regular maintenance and calibration of the equipment, checking the working status of components such as heating elements, thermocouples, and gas flow meters, and timely replacement of aging or damaged parts are necessary measures to ensure the stability of the nitriding process. For example, if the thermocouple is inaccurate, it may cause temperature measurement deviation and make the nitriding process out of control.
Finally, the quality inspection and monitoring system is an important link to ensure process stability. During the nitriding process, hardness testing, metallographic analysis and other methods can be used to monitor the nitriding layer in real time. Through regular sampling, establish a quality data file, analyze the fluctuation of the nitriding layer performance, and adjust the process parameters in time. For example, if the hardness of the nitriding layer is found to be low, the nitriding temperature can be appropriately increased or the nitriding time can be extended, but it needs to be operated with caution to avoid other problems caused by excessive adjustment. Only by establishing a complete inspection and monitoring system can the unstable factors of the process be discovered and solved in time, the long-term stability and reliability of the surface nitriding treatment process of Car rearview mirror die-casting mold custom processing can be ensured, and the comprehensive performance and service life of the mold can be improved.
