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Advantages and disadvantages of closed slot motor cast aluminum rotor

Release time:2024/03/07

Advantages and disadvantages of closed slot motor cast aluminum rotor

Cast aluminum rotors have been widely used in squirrel cage induction motors. The cast aluminum rotor can make the induction motor lighter, increase the power/mass density, reduce the rotational inertia, and release greater starting torque. Due to the low melting point of aluminum, the manufacturing process of cast aluminum rotors is mature and the manufacturing cost is low, which is one of the reasons why it is widely adopted.

There are five ways to cast aluminum rotors: vibration cast aluminum, gravity cast aluminum, centrifugal aluminum cast, pressure cast aluminum and low pressure cast aluminum. Due to the vibration cast aluminum and gravity cast aluminum rotors, it is difficult to replenish the aluminum water when the lower end ring is solidified, and shrinkage holes often occur, so they are rarely used. Low-pressure cast aluminum has not yet been widely used by professional motor manufacturers. Centrifugal cast aluminum and pressure cast aluminum have been used by most motor manufacturers.

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The slots on the induction motor rotor are mainly used to fix the windings. There are three common forms: open slots, semi-closed slots and closed slots. An open slot refers to one side that is open along the rotor core, a semi-closed slot refers to a slot design with a partially closed top on the rotor core, and a closed slot refers to a slot that is closed on both sides.

With people's continuous pursuit of motor efficiency, closed slot rotors are gradually recognized by motor manufacturers. For three-phase asynchronous motors, due to the existence of stator and rotor cogging, pulse vibration loss will occur during rotation. If the rotor adopts closed slots, the effective air gap will be shortened and the pulsation of the air gap magnetic field will be weakened, thereby reducing the excitation magnetic potential, reducing the loss of the harmonic magnetic field, and helping to improve the performance of the motor.

The arch direction is an important parameter of the closed slot rotor. When the rotor slot shape is the same, choosing different arch heights will have varying degrees of impact on the motor performance. When the closed-groove rotor is laminated, it cannot be seen due to the lack of grooves, making it difficult to check the uniformity, prone to hidden sawtooth problems, and increasing uncontrollable factors.

The use of rotor closed slots will not only reduce the stray losses and iron losses of the motor, but also increase the rotor leakage reactance, causing the power factor to decrease, the stator load current to increase, the stator losses to increase; the starting torque and starting current to decrease, and the slip rate to increase. increase. Therefore, when using a closed slot, changes in various performance data should be considered at the same time to optimize the overall performance of the motor.


Ningbo Nide Mechanical Equipment Co., Ltd., is committing to provide customers with highly automated, intelligent, and flexible motor manufacturing solutions, and focusing on the production line of stator, rotor and final assembly of various motors. Our electric motor aluminum rotor die -casting machine is suitable for casting aluminum of various of motor rotors, and can realize the integrated production of fully automatic rotors. Easy to operate. It only takes one day for green hands becoming practician. It takes about 10min to change mold. It is high working efficiency and equipped with 4 aluminum casting stations, 300-500pcs/hour.

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