Brushless DC Motors

Installation Requirements

The rare earth magnets used on the motors do not require a keeper and the rotor may be assembled or disassembled at will with no loss of performance. The rotors, however, contain very strong magnets, which can easily attract themselves to a foreign magnetic material or vice versa. Therefore, care should be exercised in handling these rotors during the installation process. Installation fixtures are recommended.

The stators are intended to be epoxied inside of a smooth cylindrical housing on the host equipment. Individual mounting flanges can be manufactured and installed at Aeroflex if desirable.

The rotors have round I.D.s as specified in the catalogue. These can be mounted onto the customer's hub as needed. Individual side plates can be added or custom hubs can be machined to customer requirements.

The motor’s performance is independent of rotor position within the typical 0.15 radial air gap. Centering the rotor as best as possible is preferred in that “once around” torques on the bearing is eliminated. Commutation with a resolver is a popular commutation.

Installation Requirements for Aeroflex Zero Cogging Constant Reluctance Motors

General Handling Issues
Initial Handling of the Rotor: The rare earth magnets used for these motors do not require keepers allowing the rotor to be assembled or disassembled at will with no loss of performance. The magnets, however, are easily attracted to other magnetic materials or structures and can easily pull out of ones hands during installation. Therefore, care should be exercised in moving the rotor about…installation fixtures for assembly with the stator (to which it is attracted) are recommended.

Great care is taken to insure that the rotor is delivered free of any particulate
contaminant. After opening the seal, the rotor should be kept in a clean environment as it easily attracts debris from tables, etc.

Initial Handling of the Stator: The motor is designed to have as minimum a mass as possible. Towards this end the radial cross section of the stator is very thin when compared to typical toothed stators. To avoid “egg-shelling” of the stator during shipment it is generally shipped with a support ring. During handling, excess unsymmetrical pressure on the O.D. should be avoided.

Although the coil I.D. is protected, the coil end turns are not. Keep all sharp objects away from these wires as in many cases the wire is fine and can be easily cut or abraded by screwdrivers, etc., even though it is impregnated with a hard clear material.

Installation Options
The stator design is primarily intended for epoxy bonding inside of a smooth
cylindrical housing. Several epoxy relief slots approximately 0.005 inches deep are recommended for maximum strength.

The stator O.D. can be seated against a shoulder and clamped on the opposite side. Due to the low-mass goals of this design there is only about 0.025 radial wall available for this approach.

The rotors have precision machined I.D.'s. This allows the customer to achieve weight goals and meet bearing configuration needs. (Custom hubs can be incorporated where needed.) As with the stator, the hub is designed primarily for epoxy bonding. Additional rotational constraints such as a dutchman pin can also be incorporated if desired.

When mounting the stator or rotor, the concentricity of each element is important.

Centering of the rotor eliminates a once around torque on the bearings. The motor can, however, operate with a relatively large radial or axial misalignment.

As with any permanent magnet motor, there is a strong attraction of the magnets to the stator laminations. The rotor will tend to pull to the side and jump into the stator during assembly of these components. It is therefore strongly recommended that a guide and jacking system be used to insert the rotor into the stator to prevent accidental contact. This fixturing will be unique to the customer’s ultimate design.

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