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Linear Servo Motors

Linear servo motors produce direct linear thrust without rotary-to-linear mechanical conversion, eliminating the backlash, compliance, and wear associated with ballscrews, rack-and-pinion drives, and belt systems in precision motion applications. PLC Direct supplies linear servo motors from leading automation manufacturers as surplus sealed, refurbished, and used hardware, supporting replacement and lifecycle maintenance of installed linear motor systems in high-precision manufacturing, semiconductor, and machine tool environments.

Where Are Linear Servo Motors Used in Industrial Environments?

Linear servo motors are used on machine axes where direct linear force, high acceleration, and sub-micron positioning accuracy are required and where mechanical transmission elements would introduce unacceptable compliance or wear. They are most common in high-speed, high-precision discrete manufacturing and semiconductor equipment, where the axis stroke, force, and velocity profile cannot be achieved with conventional ballscrew or belt drives.

Facilities and operations that depend on linear servo motors include:

CNC machining centers and grinding machines using SIMOTICS L linear motors on high-speed axis drives, where the elimination of ballscrew compliance improves surface finish and contouring accuracy.

Semiconductor wafer handling and inspection equipment where ironcore linear motors provide the thrust and positioning repeatability required for sub-micron stage control.

Electronics assembly and PCB placement machines, where high-cycle linear direct drive axes deliver the acceleration and throughput that rotary servo and ballscrew systems cannot sustain.

Laser cutting and waterjet systems using linear servo motors on gantry and cross-slide axes, where high traverse speeds and accurate positioning are required simultaneously.

Metrology and inspection equipment where the absence of mechanical transmission elements in a linear motor system eliminates position error sources introduced by ballscrew backlash and thermal expansion.

When a linear servo motor forcer or secondary fails on an installed axis, sourcing a matched replacement by part number is essential, as the forcer is sized and matched to the magnetic track it operates on.

Which Brands of Linear Servo Motors Does PLC Direct Stock?

PLC Direct stocks linear servo motors from major automation manufacturers.

Siemens SIMOTICS L 1FN Series: The SIMOTICS L 1FN series is a three-phase synchronous linear motor for high-dynamic axis applications, with primary sections (forcers) including water-cooled variants rated at 2200 N peak force for CNC and high-speed machine tool installations.

Yaskawa SGLTW Series: The SGLTW series is a moving-coil linear servo motor with Hall sensor feedback, rated force outputs including 130 N continuous and 380 N peak, for precision positioning and motion control applications requiring direct linear drive without mechanical transmission.

All linear servo motors at PLC Direct are available as surplus sealed, refurbished, and used, depending on current inventory.

What Should You Know Before Ordering Linear Servo Motors?

Hardware condition options: PLC Direct supplies linear servo motors as surplus sealed, refurbished, and used hardware. Surplus sealed units are factory-sealed stock in original packaging; refurbished units have been tested and restored to operational condition. Used hardware has been previously installed and carries the same 1-year PLC Direct warranty as all other condition grades.

Compatibility and part identification: Linear servo motors consist of a primary section (forcer or moving coil) and a secondary section (magnetic track or platen), which must be matched by manufacturer, series, and pole pitch. A forcer from one series will not operate correctly on a secondary from a different series, and the full part number of both components is required to confirm compatibility. For SIMOTICS L 1FN series motors, the primary section part number encodes the cooling configuration, force rating, and connector type; for Yaskawa SGLTW series motors, the part number encodes the coil stack length and voltage rating. Confirm both primary and secondary part numbers from the installed system before ordering a replacement.

Warranty: All linear servo motor hardware purchased from PLC Direct carries a standard 1-year warranty covering defects and functionality, applicable to surplus sealed, refurbished, and used products.

PLC Direct supplies linear servo motor hardware for replacement and maintenance purposes and does not provide system design, programming, or integration services.

Frequently Asked Questions

An ironcore linear motor uses a steel-laminated primary section that produces higher force density and is more efficient, but it also generates a cogging effect from magnetic attraction between the forcer and the track, which must be compensated by the drive. An ironless linear motor uses a winding without a steel core, eliminating cogging entirely for smoother low-speed motion, but at lower force density and higher cost, making it the preferred choice for applications such as metrology and semiconductor stages where cogging-induced position ripple is unacceptable.

Linear servo motors require a linear position encoder rather than a rotary encoder, since there is no shaft to attach a rotary feedback device to. Glass scale or magnetic linear encoders are the standard feedback devices, mounted parallel to the motor track and read by a read head attached to the moving forcer; the encoder resolution directly determines the positioning accuracy achievable by the axis.

The most common failure modes are winding insulation breakdown from thermal cycling or contamination ingress, and Hall sensor failure that causes the drive to lose commutation reference. Water-cooled primary sections, such as the Siemens 1FN series, are also subject to coolant circuit leaks that can cause winding contamination if the cooling circuit is not properly maintained.

A linear motor axis has no mechanical transmission elements to wear, lubricate, or preload, eliminating the maintenance tasks associated with ball screw replacement and periodic nut preload adjustment. The primary wear items in a linear servo motor system are the linear guide bearings that support the moving element, which can be maintained independently of the motor itself.

Yes, provided the replacement forcer matches the pole pitch and series of the installed secondary track. The forcer is the active component and the more likely failure point; the secondary track is passive and typically remains serviceable for the life of the machine. Confirm full part-number compatibility between the replacement forcer and the installed secondary before ordering.