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What is An electric vehicle (EV) rotor shaft?

An electric vehicle rotor shaft is a crucial component within the electric motor of an electric vehicle (EV).

The correct design and quality of the rotor shaft are critical to ensure the efficient and reliable performance of the electric motor.  The shaft must be able to handle high rotational speeds, maintain its structural integrity under load, while minimizing energy losses due to friction and heat generation.

Historically, shafts have been manufactured from solid.  The more recent trend has been towards hollow rotor shafts, mainly driven by the need for weight savings.

However, an additional benefit of hollow shafts is greater flexibility in the area of thermal cooling.  The hollow shafts allow for the incorporation of coolant oil flow through the shaft, resulting in increased heat transfer. This reduces heat-related losses in the motor.

 What makes NETFORM’s rotor shaft different?

NETFORM has created a hollow rotor shaft design that works well for both low and high torque applications. This advanced, light-weight rotor shaft is made up of two flowformed half shafts that are laser-welded together in the center.

Each half shaft is manufactured using the flowforming process.  This process increases the material strength due to the work hardening that happens during the forming process itself. This strength increase is typically 2-3 times that of the base material.

This strength increase can be used to reduce the wall thickness of the shaft, which in turn will lead to a reduction in the overall shaft weight.

In applications where higher shaft stiffness is required, an optional center support component can be added.

This center support provides axial and radial support between both halves of the shaft, increasing the overall strength of the shaft, while still allowing coolant to flow through the shaft.

In cases where additional coolant flow control is required, inserts can be added to the center support as follows:

These inserts create a controlled gap between the insert and the shaft I.D. that can prevent coolant pooling in the lowest part of the shaft.