Engineering

Synchronous motors (spindles) have permanent magnet rotors that produce back EMF when rotating. Back EMF increases with speed. The drive inverter has a fixed rated output voltage. When motor back EMF exceeds the drive rating, the drive must apply field weakening - generating additional current to counteract back EMF. The higher the speed, the greater the field-weakening current, raising coil temperature. This is normal physics for high-power, high-speed motors.

For high-precision spindles, slightly higher coil current and temperature are acceptable (as long as within insulation limits). Our design approach is to increase cooling flow and heat dissipation, promptly removing coil heat so it does not transfer to bearings and other components.

Synchronous spindles/servo motors/permanent magnet motors all have permanent magnet rotors. Permanent magnets produce voltage when rotating - this output is called back EMF. Back EMF directly relates to rotor magnetism. If the rotor heats up, approaches strong magnetic fields, or otherwise loses magnetism (demagnetization), motor power/torque/current/speed will change. Measuring and understanding back EMF is critical for high-end synchronous spindle design, production, repair, and operation. The Swiss e+a synchronous rotor tester can conveniently and accurately measure back EMF of various brands of synchronous motors.

Most common motorized spindles use rolling bearings (steel balls, ceramic balls for high speed). Rolling bearings provide maximum rigidity due to hard contact. Rolling bearing spindles can achieve 2um nose runout; Swiss brands like TDM achieve under 1um. Maximum speed reaches 180,000 rpm. Rolling bearing spindles are widely used for general industry, especially heavy-load applications.

Aerostatic (air) bearings: the shaft is supported by air, no hard contact. Theoretically very long life. Runout can be controlled to 0.1um or better. Another advantage: contamination-free, ideal for pharmaceutical, food, and clean-environment applications.

Hydrostatic (liquid) bearing spindles work similarly but use hydraulic oil. They achieve similar high precision (0.1um) but with significantly higher load capacity and rigidity - about 5-8 times that of aerostatic bearings of similar size. Without rolling bearing linear speed limits, they can achieve higher speeds and power at the same size.

Most hydrostatic spindles max out at 30,000-40,000 rpm due to hydraulic oil heating. However, Swiss TDM, with its superior hydrostatic technology, has achieved 250,000 rpm while maintaining 0.08-0.1um precision. We offer models like 6kW/120,000rpm, 3.5kW/140,000rpm, 1.7kW/200,000rpm, and 1.2kW/250,000rpm for high-precision, high-speed applications.

Stators and rotors are the core components of motors and generators, determining speed, power, and torque. Since they are components (not complete machines), they cannot run at high speed on their own. Inexperienced manufacturers may find that actual electrical parameters fall short of design targets. e+a has over 40 years of R&D and production experience, with over 1.5 million sets applied across industries. This expertise ensures our stators and rotors meet or exceed design specifications.

Furthermore, we focus exclusively on stators and rotors. Unlike companies that also produce motors, drives, and systems, our motors are compatible with virtually all drives and CNC systems on the market. e+a stators and rotors cover nearly all high-speed application areas.

Third, regarding technical parameters: at the same power and torque, our stators and rotors have smaller outer diameters and larger inner diameters. Thermal losses are approximately 8%, significantly lower than competitors.

Finally, we offer a rich variety of specifications: winding connections can be delta, star, or star-delta switchable; stators come in standard, epoxy-sealed, and metal-sealed versions; rotors include aluminum, copper, alloy, surface-mounted permanent magnet, and interior-mounted asynchronous types. We also offer outer-rotor motors, rotor synchronous analyzers, and stator voltage testers.

Asynchronous motors are lower cost and simpler to manufacture, assemble, and commission. Synchronous motors offer superior technical performance: smaller size, lower heat generation, and higher precision.

First, e+a offers a wide variety of synchronous motor configurations: surface-mounted, interior-mounted, and magnets directly mounted on customer shafts.

Second, our synchronous rotors have a unique mounting structure. Customers can mount the rotor onto the shaft without heating the rotor or cooling the shaft. This offers several advantages:

(1) Ensures tight fit between shaft and rotor, enabling higher motor speeds.

(2) Avoids the risk of demagnetization from improper rotor heating.

(3) Our synchronous rotors can be repeatedly assembled and disassembled.

Based on our years of experience: heating the water jacket, inserting the stator coil, then allowing the jacket to cool and shrink-fit tightly around the stator is the better method. This maximizes contact between the coil and jacket, improving cooling efficiency. However, it requires skilled experience to control heating temperature and time, and interference tolerances. We provide technical support to customers who purchase our products.