Operating principle of an electro-spindle

Operating phases and advantages of electro-spindles in machine tools

Electro-spindles represent the heart of modern machine tools, enabling high-speed machining with extreme precision. Their operation is based on a system that converts electrical energy into rotational movement, guaranteeing high performance and accurate control. To understand their operation, we analyze in detail their main operational phases.

1. Electrical Power Supply and Magnetic Field Generation

The process begins with the electrical power supply, provided by an inverter which is in turn controlled by a CNC numerical control system. Inside the electro-spindle, the motor can be synchronous with permanent magnets, or asynchronous with induction. In synchronous motors, the magnetic field of the rotor is generated directly by permanent magnets, while in asynchronous motors the rotor generates its own current through electromagnetic induction.

The windings present in the stator generate a rotating magnetic field, which induces the movement of the rotor, located at the center which in turn is directly connected to the tool. The rotation speed varies based on the input current. The rotation can then be regulated with extreme precision thanks to the use of position sensors called encoders, which constantly monitor the rotation to guarantee optimal performance.

2. Direct Motion Transmission to the Rotor

Unlike traditional spindles, which use belts or gears to transmit rotation, in electro-spindles this is transferred directly to the rotor. This eliminates energy dispersion and reduces the need for maintenance, increasing overall efficiency.

The rotor performs its rotation supported by high-precision bearings, often made of ceramic or special steel, which reduce friction and guarantee stability even at high speeds. In some advanced and complex industrial applications, a speed reduction or variation system can be inserted into the rotor rotation, such as elastic or transmission joints.

3. Speed and Torque Control

One of the greatest advantages of electro-spindles is the ability to regulate, based on machining requirements, the rotation speed and related torque. This is possible thanks to the frequency converter (inverter), which modulates the voltage, current, and frequency input to the electro-spindle motor.

Speed control occurs in real-time, allowing to:

• Optimize machining based on the type of tool and hardness of the material to be machined.
• Reduce the risk of vibrations and damage.
• Improve surface finish quality.

In more advanced models, position sensors (encoders) contribute to even more precise regulation of speed and torque, further improving performance.

4. Thermal Management and Cooling

The rotation of an electro-spindle generates heat, which must be dissipated to guarantee constant and prolonged performance and consequently improve component life. For this reason, electro-spindles are equipped with cooling systems, which can be:

• Liquid cooling, with internal circuits that convey a cooling fluid around critical components. This liquid must necessarily be cooled externally to maximize thermal efficiency.
• Forced air cooling, through fans or turbines that direct air flow toward the hottest parts and thus dissipate heat.

Some models adopt dielectric cooling fluids, which protect components from dust or chips and guarantee more effective heat dissipation.

These systems maintain stable operating temperature, improve overall reliability, and extend bearing life, avoiding harmful overheating.

5. Real-Time Monitoring and Diagnostics

Latest generation electro-spindles are equipped with intelligent sensors that monitor critical parameters in real-time, such as:

• Temperature, to prevent overheating.
• Vibrations, to detect any rotation anomalies and preserve bearings, or prevent their wear.
• Current absorption, to prevent overloads or malfunctions.

This data is sent directly to the CNC control system or diagnostic software, allowing performance optimization and preventive maintenance scheduling, reducing the risk of sudden machine downtime. All these types of monitoring aim to identify anomalies before they can cause serious damage, improving operational efficiency and machining safety.

To discover how OMLAT electro-spindles can improve the performance of your machine tools, visit our official website. Our team of experts is at your disposal to provide customized solutions that meet your production needs. Contact us for personalized consultation!