Precision alloys for aircraft: high technology in action

For aircraft, be they modern airplanes, helicopters, or spacecraft, modern materials able to withstand extreme service conditions are required. One such solution is precision alloys, which have found wide application in active parts of rotors of hysteresis motors used in gyroscopic instruments.

Rotor and stator: the basis of an electrical machine

To understand operating principles and purpose of materials, let us start with the basics. A rotor is the rotating part of an electrical machine, be it a motor or generator. It consists of a ferromagnetic material that has hysteresis loops determining its magnetic properties. Depending on motor type the rotor may be a permanent magnet, electromagnet, or short-circuited winding. Its function is converting energy — electrical into mechanical or vice versa.

A stator is the stationary part of the machine that creates a magnetic field interacting with the rotor. It consists of a core and a winding through which electric current flows. Exactly this interaction between the stator magnetic field and the rotor sets the latter in motion, ensuring motor operation.

Rotor rotation speed depends on magnetic field magnitude, alternating current frequency, and properties of the ferromagnetic material. It is also conditioned by load on the motor shaft. When load increases rotation speed decreases.

Gyroscopic instruments: accuracy and stability

Gyroscopic instruments are used to determine object motion parameters, for example orientation angles. They are in demand in various areas, from aviation to the navy and space technology. Examples of such instruments are:

1. Artificial horizon — measures aircraft position relative to the horizon.
2. Gyrovertical — determines the object’s tilt angle relative to the true vertical.
3. Gyrocompass — helps establish course relative to the geographic meridian.

At the heart of these devices’ operation lies the gyroscope’s property of retaining the direction of the rotation axis, which makes them indispensable in navigation and stabilization systems.

Operating principle of a hysteresis motor

A hysteresis motor is an electric motor in which the hysteresis effect in the ferromagnetic material of the rotor is used to create torque. The operating principle is as follows:

1. Creating a magnetic field. The motor stator generates an alternating magnetic field that acts on the rotor.
2. Generating eddy currents. The alternating magnetic field causes a change of magnetic flux through the rotor, which leads to appearance of eddy currents in the rotor material.
3. Field interaction. Eddy currents create their own magnetic field that interacts with the stator field, creating a force rotating the rotor.
4. Lag. Due to hysteresis the rotor cannot instantly follow the change of the stator magnetic field, which creates the necessary torque.

Hysteresis motors, thanks to their reliability and overload resistance, are widely used in gyroscopic instruments with low power and constant rotation speed.

Precision alloys: 27KKh and 49K2FA-VI

Rotors and stators of hysteresis motors are manufactured from special precision alloys possessing unique magnetic and mechanical properties.

27KKh

A precision alloy based on iron, cobalt, and chromium. Characterized by high induction in medium and strong magnetic fields, as well as a high Curie point (950°C). Possesses excellent mechanical properties, including high strength (1080 MPa in the work-hardened state). Used to manufacture stators and rotors that operate at extreme temperatures and under significant mechanical loads.

49K2FA-VI

A soft magnetic alloy consisting of iron, cobalt, and vanadium. Characterized by a high level of magnetic saturation, elevated Curie point (950°C), and good mechanical properties, with tensile strength up to 1320 MPa in the work-hardened state. Used to create transformers, magnetic amplifiers, rotors and stators of electrical machines.

Advantages of using precision alloys

Using high-quality precision alloys of type 27KKh and 49K2FA-VI in aircraft designs ensures:

• High reliability and durability of motors and gyroscopic instruments.
• Resistance to extreme service conditions, including high temperatures and mechanical loads.
• Accuracy and stability of navigation systems, which is critically important for safe control of aircraft.

PZPS specializes in developing and releasing precision alloys of the highest quality matching all modern requirements of the aviation and space industry. We produce materials that serve as the basis for creating reliable and efficient systems in demand in the most advanced areas of science and technology. For supply of precision alloys, as well as development of new materials, contact us at the listed phones or leave a request on the website. Our specialists will contact you and answer your questions in detail.

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