In batch production, this situation is often encountered: sometimes different defects appear due to seemingly the same reason, and sometimes the same defect occurs due to different reasons. This shows that the defects of the rotor are often the result of the combined effect of multiple unfavorable factors. Of course, there must be a main reason. When the conditions change, even if the same defect occurs, the main reason for the defect will change.

For example: rotor pores are often caused by poor mold exhaust or blocked mold exhaust slots. But sometimes, even if the exhaust slots are unobstructed, the residual gas cannot be discharged in time due to the pouring speed being too fast, which will also cause pores in the rotor. At this time, the main reason for the pores in the rotor is no longer the exhaust problem of the mold, but the pouring speed problem. Therefore, when analyzing the quality problems of cast aluminum rotors, it is necessary to conduct a comprehensive analysis based on the location and characteristics of the rotor defects and various conditions in order to more correctly find the main cause of the quality problems, so as to take corresponding measures to effectively prevent the occurrence of cast aluminum rotor defects.

Combined with the defects of thin rotor bars, broken bars, shrinkage holes, cracks, etc. mentioned above, Ms. Can focuses on the cold shut and rotor conformity problems of cast aluminum rotors with Baowei today. The failure of aluminum liquid to completely fill the mold cavity is called "incomplete pouring". The places where the rotor is not poured or the edges are unclear are mainly the fan blades and balance columns. Cold shut refers to the joints or pits where the aluminum liquid is not completely fused. The edges of the joints are smooth and are most obvious at the fan blades.

Causes of cold shut defects ● The aluminum liquid temperature is too low during pouring; the pouring speed is too slow or there is a flow interruption phenomenon. ● The mold and core temperature are low. ● Aluminum leakage or insufficient aluminum liquid. ● Insufficient rotation speed. ● The cross-section of the inner gate is too small or the mold is not vented smoothly. ● Separated by oxide scale or other inclusions. Cold shut defect control measures ● The aluminum liquid temperature should meet the specified value, and the pouring speed should be correctly controlled. It must be poured in one time. ● Appropriately increase the core temperature and the temperature of the tool, especially the upper root temperature (for low-pressure products, increase the lower mold ● Eliminate aluminum leakage. When pouring aluminum, use 10~20% more than the actual rotor. ● Control the speed. If the speed is too high at the beginning of overflow, it will cause ground voids. (5) Keep the exhaust unobstructed and the pouring date can be appropriately enlarged. ● Keep the mold and the core clean and free of debris. Pay attention to the stimulation and cleaning of the corresponding water. Rotor resistance exceeds the tolerance (1) Analysis of the reasons for the rotor resistance exceeding the tolerance ● The core is too long, or the slot slope is greater than the allowable value, which increases the cage bar resistance. ● The rotor is misaligned and serrated, which reduces the effective area of the aluminum bar. ● Aluminum water The cleaning or slag cleaning is not good, and contains a large number of pinholes and impurities. ●The quality of the rotor aluminum casting is poor, with defects such as pores, shrinkage cavities, shrinkage, slag inclusions, cracks or cold shuts. ●The wrong grade of aluminum ingot is used or the quality is poor, and the conductivity is low. (2) The rotor resistance is small, which mainly occurs in aluminum alloy rotors. It may be that high-purity aluminum ingots are used incorrectly, or the slot slope is less than the value, which reduces the cage bar resistance. Control measures for rotor resistance out-of-tolerance problems ●Before pressing and pouring the core, pay attention to check the core length and slot slope, which should meet the requirements of the drawing. ●Do a good job of cleaning and slag removal of the aluminum liquid. ●Eliminate the rotor's casting defects such as pores and shrinkage cavities. ●Use aluminum ingots of the specified grade.

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