Aluminium casting rotor: manufacturing process and technical conditions

According to the material characteristics filled in the rotor slot of the motor, there are winding rotor, aluminium casting rotor and permanent magnet rotor. In comparison, aluminium casting rotors are the most widely used, of course, due to some cost and process advantages of this type of rotor.

With the development of new energy vehicle technology, aluminium casting rotors have been widely used in squirrel-cage induction motors. Aluminium casting rotors can make induction motors lighter, improve power/mass density, have a small moment of inertia, and release greater starting torque. Due to the low melting point of aluminum, the manufacturing process of aluminium casting rotors is mature and the manufacturing cost is low, which is one of the reasons why it is widely used.

The groove shape of the aluminium casting rotor is not limited by the profile, and the best groove shape can be selected arbitrarily to improve the starting performance of the motor; the copper row of the rotor accounts for about 40% of the copper used in the entire motor, and the use of the aluminium casting rotor can greatly reduce the motor's cost. Material cost; cast aluminum conductors fill the entire rotor slot, and the slot full rate is close to 100%, which is conducive to heat dissipation; the rotor blades and end rings are cast together to increase the heat dissipation capacity, and there is no need to install additional fans, saving some Processing process; the structure of the aluminium casting rotor is symmetrical and compact, the balance column and the end ring are cast together, and it is easy to achieve balance mechanically; the production cycle is short, the labor hours are short, and the cost is low, which is suitable for mass production.

At present, centrifugal casting aluminum and die casting aluminum have been adopted by most motor manufacturers.

The working principle and characteristics of centrifugal cast aluminum

The molten metal is injected into the rotating aluminum casting mold, so that it fills the cavity and solidifies under the action of centrifugal force

(1) Centrifugal force plays an important role in the molding of castings and the process of metal crystallization, and it helps to discharge the gas and non-metallic impurities (lighter than metal) in the molten metal. More importantly, it affects the metal crystallization process and plays a role in strengthening feeding and crystallization refinement.

(3) The equipment for centrifugally aluminium casting rotor is relatively simple. However, there are many manual operations in the casting process, which are labor-intensive.

Die-cast aluminum working principle and characteristics

The molten metal is injected into the cavity with pressure, and it becomes a casting after cooling and solidification

(1) Pressure plays a major role throughout the die casting process.

(2) During die casting, during the high-speed filling process of the molten metal, if the gas in the cavity cannot be discharged in time, it will be involved in the metal, causing pores in the casting.

(3) Since the metal filling process is carried out under pressure, the rotor core can be die-cast in a cold state.

(4) The production efficiency is high, and it is easy to realize mechanization and automation, which can reduce labor intensity and improve labor conditions.

NIDE Group supplies a variety of rotor pressure-casting aluminum equipment, which can realize the integrated production of fully automatic rotors. The efficiency of die casting machine can reach 10-12 seconds/piece, 300-400 pieces per hour, and one person can operate several devices at the same time. The die-casting machine has an automatic splash-proof system to prevent the splash of aluminum water during the aluminum casting process and ensure the safety of operators.