Discussion on the casting blow hole defect of motor shell

Motor housing is one of the most important components of electric vehicle motor. ZHY casting produces a motor shell blank, in which the defective blow hole defect account for more than 40% of the total production, which seriously affects the reliability and appearance quality of the product. With the company’s need to reduce production costs and improve production efficiency, relevant improvements are made for the problem of blow hole defect.

Fig. 1 motor shell Fig. 2 pouring method

Brief introduction of motor shell structure and process

(1) The motor shell is of cylindrical structure and the overall dimension is Φ 250mm, inner cavity size Φ 218mm, height 186mm.

(2) The main sand core structure is two spiral structures, which are composed of coated sand material j4k.

(3) The blank material is ZL101A aluminum, the pouring temperature of molten aluminum is 730 ℃, and the blank weight is about 18kg. Gravity casting process is adopted for reverse pouring. The schematic diagram of blank is shown in Figure 1, and the pouring method is shown in Figure 2.

In the daily production process of ZHY casting, the casting blow hole defects of gravity casting are common. According to different casting structure requirements, in the early stage of product development, the gating system design is optimized through casting software analysis to reduce the occurrence of defects in the process. At the same time, according to the requirements of casting structure and internal quality, reasonable casting process is adopted to improve the quality of castings.