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Introduction Aluminum electrolysis multi-functional cranes generally operate in harsh environments characterized by high currents, strong magnetic fields, high temperatures, heavy dust levels, as well as corrosive gases and high concentrations of HF. Additionally, due to the large weight of these cranes and their high inertia during operation, the electrical components used must have strong resistance to interference. To prevent damage from collisions, inductive switches should be used as much as possible. Due to the characteristics of hall switches such as contactlessness, low power consumption, long service life, high response frequency, and the ability to operate reliably in various harsh environments, they can be effectively utilized in electrolytic production equipment. Therefore, this paper takes aligned material feeding as an example to provide a detailed explanation of the working principle and control process of the 80020C hall switch. 1 Principle of operation of Hall switches When a metal or semiconductor sheet carrying an electric current is placed vertically in a magnetic field, a potential difference is generated across the two ends of the sheet; this phenomenon is known as the Hall effect. The potential difference between the two ends is called the Hall voltage U, and its expression is: U = KIB/d (1). Here, K is the Hall coefficient, I is the current flowing through the thin sheet, B is the magnetic field strength of the external magnetic field (Lorentz force), and d is the thickness of the thin sheet. It can be seen that the sensitivity of the Hall effect is directly proportional to the magnetic induction intensity of the applied magnetic field. Hall switches are active magnetoelectrical conversion devices. Based on the principle of the Hall effect, they are manufactured using integrated packaging and assembly techniques, enabling the easy conversion of magnetic input signals into electrical signals for practical use. At the same time, they meet the requirements for ease of operation and reliability in industrial applications. Hall switches feature no contacts, low power consumption, a long service life, and a high response frequency. Their internal components are sealed together with epoxy resin, enabling them to be used reliably in various harsh environments for applications such as proximity switches, pressure switches, and odometers; they represent a new type of electrical component. Its internal schematic is shown in Figure 1. 2 Material analysis Aluminum electrolysis multi-functional cranes generally come equipped with storage bins; insulating material is added during electrolysis operations to replace the anodes or after work is completed on the sides of the electrolytic cells. However, the silo can be supplied with fresh alumina from the purification feed system; therefore, a feeding port is designed at the top of each aisle in the electrolysis workshop. When it is necessary to feed material into the silo of the overhead crane, the crane must first be moved to the nearest feeding port to align it properly, after which the fan of that purification feed system is started, and finally the alumina is delivered to the silo of the overhead crane. The manufacturing process of a certain company previously relied on manual control, which led to issues such as delayed closure of bins when they were full, inaccurate alignment, and waste caused by alumina scattering on the floor. This solution employs Hall switches to enable an automated material handling process, thereby highlighting its advancement, superiority, and rationality. The tank on the top of the main cart of the multi-functional aerial work platform serves as a material bin. The original material alignment system was controlled manually; thus, when the multi-functional crane needed to align materials, it would be moved to the nearest material alignment point. First, align the main crane in position; then move the main trolley carrying the material bin right below the material feeding port. Manually lower the dust cover for material alignment so that it covers the discharge opening of the bin. Next, manually start the supply fan of the purification system to convey alumina to the crane’s material bin via the pneumatic chute. Once the indicator light indicating that the bin is full comes on, turn off the supply fan to complete the entire material alignment process. Due to the human factors involved in this material mixing process, there are various drawbacks such as material leakage after the containers are filled to capacity, increased workload for workers, and a low level of automation; therefore, it is essential to design an automatic material mixing control system. 3 Design of the automatic material feeding control circuit The Hall switch of type 80020C used in this design operates at a DC voltage of 5–24 V, with a detection range of 8–12 mm. Figure 2 shows the PIC control schematic diagram of this crane automatic material alignment system. This design uses a Hall switch as the link between the crane material handling system and the purification feeding system. Figure 3 shows the ladder diagram of the control system for the alignment mechanism of this crane. When the end limit switches XK1 and XK2 of the main frame, along with the limit switch XK3 of the auxiliary frame, are in the correct positions, the electromagnet DT is energized; as a result, the normally open contact of the Hall switch HK in the purification and feeding section closes, thereby causing the intermediate relay JD to engage. The XD1, XD2, and XD3 indicator lights correspond respectively to the indicator lights for the crane being in the correct position, high material level, and low material level. Once the crane is in the correct position and sends a signal to the purification feeding control system via the electromagnet and Hall switch, the system will send an output signal to the PLC of the crane’s material-feeding and purification unit. The PLC control and the ladder diagrams for the purification feeding section in this system are shown in Figures 4 and 5 respectively. When the system is in operation, first, the solenoid valve DQ of the dust cover is energized and drops down; after a 30-second delay, the intermediate relay JD is activated, and the contactor KM of the fan motor is energized, causing the feeding fan to start and begin feeding material. When the material level in the vehicle’s storage bin reached its maximum level, the electromagnet lost its magnetic field as a result of power being cut off; the Hall switch was deactivated, the intermediate relay JD lost power, the fan stopped operating, and material supply was halted. At the same time. The PLC delays the activation of the dust cover for 30 seconds; once all the remaining material in the chute has flowed into the crane’s storage bin, the dust cover rises. Then the crane is removed, and the material handling process is completed. 4 Conclusion The design of this overhead crane automatic material feeding system is entirely based on the actual production processes. It not only eliminates the negative effects on production caused by human errors or defects in the equipment itself, but also prevents waste resulting from material spillage during feeding. As well as its safety and reliability.