Linear servo motors essentially work the same as rotary motors, only opened up and laid out flat. Each motor is made of only two parts - a coil assembly and a magnet assembly as shown below.

The coil assembly encapsulates copper windings within a core material (e.g. epoxy, steel). The copper windings conduct current (I). The magnet assembly consists of rare earth magnets, mounted in alternating polarity on a steel plate, which generate magnetic flux density (B). When the current and the flux density interact, force (F) is generated in the direction shown above, where F = I x B.

The coil assembly is typically attached to the moving portion of the machine. The magnet channel is usually fixed to the machine base. The air gap between the two motor elements is typically 0.6mm (0.024"). The gap can vary as much as ± 0.3 mm (± 0.012") without appreciable loss of performance.

There are two basic classifications of permanent magnet servo motors: epoxy core (i.e. non-ferrous, slotless) and steel core. Variation of these classifications include an epoxy/steel core. Anorad's epoxy core motors have coils wound within epoxy support. Therefore, these motors produce extremely smooth motion and have no magnetic attraction. Anorad's steel core coil assembly motors use the steel to focus the magnetic flux, thus producing very high force density. The steel in the coils is attracted to the permanent magnets in a direction perpendicular (normal) to the operated motor force. Magnetic attraction is a constant force and is present whether or not the motor is electrically energized. Depending on the motor type, the normal force of the magnetic attraction can be up to 10 times the continuous force rating of the motor.

Cogging is a form of magnetic "detenting" that occurs when a coil's steel laminations cross the alternating poles of the motor's rare-earth magnets. Cogging is negligible in non-ferrous motors (LEU, LEM, LEA, LEB, LEC). Cogging in steel core motors (LC-30/50/100/150/200, LCK) is typically +/-5% of the motor's continuous force rating.

The magnetic flux density within the air gap of linear motors is typically several thousand gauss. The non-ferrous motors (LEU, LEM, LEA, LEB, LEC), have a closed magnetic path through the gap since two magnet plates "sandwich" the coil assembly. With these motors, very little flux exists outside the motor. Steel core motors, on the other hand, have only one magnet plate. High flux density therefore exists in the vicinity of the exposed magnets. This flux rapidly diminishes to a few gauss as the point of measure is moved a few centimeters away from the magnets. When needed, special shielding is used to further reduce the level of flux outside steel core motors.

Linear Motors are routinely used in vertical applications. To avoid motor overheating and to inhibit carriages from falling when power is removed, gravitational load offsets are typically achieved with pulleys and weights, springs, or air cylinders.

In cases of a power loss, servo control is interrupted. Stages in motion tend to stay in motion; those at rest tend to stay at rest. The stopping time and distance depend on the stage's initial velocity and the system friction. Use of the motor's back EMF for dynamic braking and positive friction brakes are often used to rapidly attenuate motion. It is also strongly advised that a system of positive stops and travel limits be built into a motion stage to prevent damage under emergency conditions (power loss, loss of feedback, and controller or servo driver failure).

Anorad linear motors are frameless type motors. The motor is supplied in kit form, designed to be integrated into a customer provided structure. The motors themselves have no bearings. The machine structure in which the motors are mounted must include bearings of sufficient precision to maintain the air gap, and sufficient load rating to support the normal force of the magnetic attraction (if present).

Anorad linear motors are servo motors designed to be used in a closed loop servo positioning system. Most applications will require a linear position feedback sensor. Typical feedback sensors include linear encoders or laser interferometers. LVDT's, and linear inductosyns can also be used. The motors themselves do not have a position sensor.