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In the world of electrical machinery, there is an invisible hero that quietly powers countless devices and industrial systems: the motor shaft. Although often overshadowed by its more visible counterparts, the motor shaft plays a vital role in converting electrical energy into mechanical power and drives our modern world forward. The unassuming motor shaft is the critical link between the motor and the driven load, transmitting torque and enabling various mechanisms to operate seamlessly. In this article, we will explore the anatomy of a motor shaft, its function, and the key factors to consider when selecting the right shaft for optimal performance and efficiency.
A motor shaft is a crucial element in most rotating mechanisms. When determining the ideal material for producing motor shafts, various factors such as cost and material defects must be considered. Essentially, the motor shaft serves as the core component of a motor.
The motor shaft is a cylindrical structure that extends from the motor and its casing. Its primary function is to transfer energy from the motor to its intended application. Precision pin shafts function with speed and torque, and there are numerous options available from manufacturers, distributors, suppliers, and businesses.
Moreover, the motor shaft acts as the bearing component located at the center of the rotor stack, which facilitates the transmission of electrically generated torque through the corresponding positive configuration.
What is a Motor Shaft?
The main component in most rotating devices is the motor shaft. A shaft is a mechanical section for transforming the rotation and torque. Shaft size significantly influences the torque in these devices. Therefore, the precise modeling and prototyping of shafts are essential for all applications.
Apart from the need for fitting the rotor and various attachments, the design of the motor shaft depends heavily on the chosen cooling approach for the electric device. In particular, with larger electric motors and correspondingly longer and bigger motor shafts, a hollow shaft can offer new design possibilities for both lightweight construction and the cooling system.
Various mechanisms are employed to transfer torque from electricity to kinetic output in the transmission, thereby propelling the device. Given the high rotational speed exceeding 20,000 rpm and significant torques involved, motor shafts must withstand extremely high loads. This necessitates the use of heavy-duty components that also meet stringent requirements for lightweight design.
What is shaft grounding?
Shaft grounding prevents energy from harming delicate motor components. These devices provide a safer path to ground by diverting electrical energy away from vulnerable motor components with low resistance, such as motor bearings.
Construction of motor shafts
Choosing the right material can improve reliability. When considering the best material for the equipment and its shaft, cost should be the first consideration.
Typical materials used for motor shafts are mild steel, but once high strength is required, alloy steels such as chrome vanadium, nickel and nickel chromium steels are used.
Most motor manufacturers use hot rolled (HRS) or cold rolled (CRS) SAE 1045 steel.C1045 is a medium carbon, medium tensile steel available in forged or normalized form. This steel has the right amount of toughness, strength and wear resistance. Visit here to view its manufacturing process.
It can be used on bolts, axles, crankshafts, forged connecting rods, light gears, torsion bars, guide rods and more.
Other substances include vulcanized SAE 1137, SAE 1117, SAE 1144, cold rolled SAE 1018 and hot rolled SAE 1035. grinding slurries of any substance can be used on specific CNC lathes.
In general, vulcanized and cold-rolled steels may come at a higher cost, up to 15%, compared to hot-rolled steels, but they offer superior performance. It is essential to conduct machining tests to control any additional expenses. As each axle unit performs differently, there are no established substances or machining maintenance methods.
When considering cost per pound, hot-rolled plain carbon steel is more economical than cold-rolled vulcanized steel. However, certain challenges arise when using hot-rolled materials. Due to the lack of outside diameter (OD) monitoring during the rolling process, hot-rolled material typically requires larger sizing.
Motor manufacturers need to assess whether the increased size and lower material cost of hot-rolled bar stock outweigh the advantages of cold-rolled bar stock.
Hot-rolled materials often exhibit residual stresses, hard and soft spots, voids, and other material defects, which can lead to processing difficulties. Some high-strength steels have a hardened outer layer, making them less strong when used with shafts.
Conducting tests helps to choose the best substance between CRS, HRS, vulcanized and non-vulcanized materials.
Industrial Electro-Mechanical Repair Services, or IER Services, was established in 2011 to provide effective and fast repair services for all types of electromechanical instruments, including DC and AC motors, variable frequency drives, pumps, dynamic balancing, and more. They also support shaft calibration services.
They not only provide quality motor shaft fixing services to their customers, but also offer special motor shafts for other valves, pumps, motors and hydraulics.
Materials available for motor shaft construction
-Alloy steel
-Aluminium
-Beryllium copper
-Brass
-Bronze
-Carbon steel
-Copper
-Nickel
Motor Shaft Manufacturing
As mentioned earlier, most motor manufacturers use SAE 1045 in either cold rolled (CRS) or hot rolled steel (HRS.) On a cost per pound basis, hot rolled carbon steel material is less expensive than cold rolled material. However, factors such as size need to be considered in the rolling process.
Electrical equipment manufacturers need to estimate whether hot rolled bars with lower material costs and larger dimensions are more or less costly than cold rolled bars.
Hot rolled substances are more problematic to machine due to their characteristics of soft spots, hard spots, voids, residual stresses and other material defects. The main disadvantage of some high strength steels is that the hardest part is only the outer layer. Thus once the shaft is machined down, the system loses strength.
Machine testing is required to select the best option among the various materials. (Some motor manufacturers use vulcanized CRS due to the difficulties of using HRS).
The Importance of Motor Shaft Alignment
Proper motor shaft alignment increases the performance life of rotating equipment. This can only be accomplished by accurately designing the components most likely to fail to perform within acceptable design limits.
The Office of Advanced Manufacturing under the U.S. Department of Energy has provided guidelines and recommendations for critical factors relating to alignment and misalignment. The following is a summary of important tips to consider regarding motor shaft alignment:
Although misalignment does not have a significant impact on efficiency, ensuring proper shaft alignment can enhance the efficiency and smoothness of energy transfer from the motor to the driven equipment. Misalignment occurs when the center lines of the motor shaft and the driven device do not coincide. This can lead to additional noise, vibration, premature failure of bearings, couplings or shafts, and increased temperatures of bearings and couplings.
Types of motor shaft misalignment
Angular misalignment occurs when the motor is mounted at an angle to the driven equipment. If the centres of the follower equipment and the motor shaft are extended, they will actually cross each other instead of running along or superimposed on the standard centreline. In contrast to the skew of a fixed machine shaft, the “space” (difference in space between coupling surfaces) or skew difference of the motor shaft may occur vertically, horizontally or in both directions. Angular misalignment can especially lead to serious damage to driven equipment and motors.
Parallel misalignment occurs as soon as the centre lines of two shafts are in a parallel configuration, but not in the same line. Parallel misalignment can take two forms; the shafts may be offset vertically (located at different heights), horizontally (shifted to the left or right), or both.
Combined misalignment occurs when the motor shaft is both parallel and angularly misaligned. This is the most common misalignment in the system.
Recommended measures for motor shaft misalignment
Here, some recommended measures for motor shaft misalignment will be presented:
-Check the shaft alignment of all production-critical equipment annually.
-Check newly installed instruments for misalignment due to foundation settlement 3 to 6 months after they have been put into service.
-Control vibration and the tendency for increased vibration, which is the main sign of misalignment. Misalignment can be caused by insufficient bolt tightening, foundation settlement, or output shaft failure.
-Use predictive maintenance methods, including spectrum analysis and vibration testing, to distinguish between shaft misalignment, bearing wear or electrically induced vibration.
Characteristics of motor shaft
According to user requirements, the motor shaft can be made into a hollow shaft or a solid shaft.
-The lightweight design is available in tubes and as a built-in version.
-Various material combinations are possible.
-The motor shaft is ready for installation or as a semi-finished component near its final outline.
-Light weight (saving resources) and high transmission capacity
-Splines can be changed according to customer requirements
The motor shaft in permanent magnet synchronous motors plays a crucial role in ensuring efficient and reliable performance. Its design, including considerations for mounting, attachments, cooling, and load-bearing capacity, is essential for optimizing the motor’s functionality. By understanding the importance of proper shaft alignment and addressing any misalignment issues, motor manufacturers can mitigate problems such as increased noise, vibration, and premature component failure. Ultimately, a well-designed and properly aligned motor shaft contributes to the overall efficiency and longevity of permanent magnet synchronous motors, paving the way for advancements in various industries reliant on electric propulsion systems.
