Planar Motors

Overview

Planar motors (linear stepper motors) are integrated positioning stages designed for precise open-loop positioning applications with light payloads. Capable of speeds up to 80 in/sec [2 m/sec] and strokes extending to 144″ [3.6 m], these motors deliver exceptional position, velocity, and acceleration control when paired with microstepping drives and indexers.

The compact moving assembly (forcer) travels along a precision ground track (platen) guided by roller or air bearings that maintain the critical 0.001″ [0.025 mm] gap. With full-step resolution of 0.010″ [250 microns] and microstepping capability down to 0.00004″ [1 micron], planar motors offer complete positioning solutions with motor, bearings, and positioning system integrated into one package.

How Planar Motors Work

Planar motors operate on the electromagnetic principle of stepper motor technology adapted for linear motion. The system consists of two primary components working in precise coordination.

The forcer contains motor windings, lamination stacks, and permanent magnets housed in an aluminum assembly. Its active surface features teeth with 0.040″ [1 mm] pitch. The platen is a precision ground steel bar with 0.020″ [0.50 mm] teeth, hard chrome plated and epoxy-filled for optimal bearing surface performance.

When step and direction signals from a microstepping drive energize the 2-phase or 4-phase forcer coils, electromagnetic forces interact between the forcer teeth and platen teeth to generate precise linear motion. Full-step operation moves the forcer 0.010″ [250 microns] per step. Microstepping divides this motion—at 256 microsteps per full step, resolution reaches 0.00004″ [1 micron].

The bearing system (roller or air) supports the payload and maintains the precise gap between components, eliminating physical contact during operation. Multiple forcers can operate independently on a single platen for multi-head applications.

Key Components

Forcer (Moving Assembly)

Aluminum housing containing motor windings, lamination stacks, and permanent magnets. Active surface features slotted teeth at 0.040″ [1 mm] pitch. Coil connections via D-connector or flying leads. Top-mounted holes for payload attachment.

Configurations: Available in multiple widths and lengths based on force requirements. Multiple forcers supported on single platen for independent moving heads.

Platen (Stationary Track)

Precision ground steel bar or tube with 0.020″ [0.50 mm] teeth. Hard chrome plated with epoxy fill for smooth bearing surface.

Dimensions:

• Width: 1.25″ to 3.0″ [31.8 mm to 76.2 mm]
• Length: Single piece up to 144″ [3.6 m]; sectioned for longer strokes
• Threaded mounting holes on bottom surface

Bearing Systems

Roller Bearings: Support payload while maintaining 0.0015-0.002″ [38-50 microns] air gap. Forcer slides when power fails in vertical mounting.

Air Bearings: Provide ultra-smooth motion and superior gap maintenance. Locks forcer position when air supply is deactivated.

Performance Specifications

Speed & Resolution:

• Maximum velocity: 80 in/sec [2 m/sec]
• Full-step resolution: 0.010″ [250 microns]
• Microstep resolution: 0.00004″ [1 micron] at 256 microsteps/step

Stroke & Gap:

• Maximum stroke: 144″ [3.6 m] single piece platen
• Required air gap: 0.001″ [0.025 mm] (forcer to platen)
• Roller bearing gap: 0.0015-0.002″ [38-50 microns]

Configuration: Complete integrated stage with motor, bearings, and positioning system in compact package

Advantages & Limitations

Control Options

Required Electronics: Microstepping driver with power supply rated for sufficient current and voltage to meet motion requirements.

Step Division:

• Full-step: 0.010″ [0.25 mm] per step
• Microstepping: Divides full-step by number of microsteps (e.g., 256 microsteps = 0.00004″ resolution)

Closed-Loop Option: Integrate linear encoder for closed-loop position feedback and verification.

Operating Considerations

Environmental: Precision device requiring clean, dry environment. Prevent debris accumulation on platen surface.

Mounting: Install platen on flat surface (better than 0.003″/ft [246 microns/m]) with adequate stiffness. Use threaded holes on platen bottom for secure mounting. Attach payload to threaded holes on forcer top surface. Any orientation supported.

Vertical Operation: Additional force required for gravity compensation. Roller bearing forcers slide down when unpowered; air bearing forcers lock when air supply is off.

Air Gap Setting (Roller Bearings): Maintain 0.0015-0.002″ [38-50 microns] gap. Forcer should move freely along entire platen length. Contact or binding indicates gap adjustment needed.

Applications

Planar motors excel in precision positioning applications requiring open-loop control with light payloads:

Electronics Manufacturing:

• Pick and place operations
• Wire bonders
• Component transfer systems

Fiber Optics:

• Fiber alignment and positioning
• Optical assembly
• Photonics manufacturing

Semiconductor:

• Wafer handling
• Die sorting
• Precision inspection systems

Laboratory & Research:

• Automated testing equipment
• Sample positioning
• Material characterization

Why Choose Planar Motors

Planar motors deliver complete positioning solutions in compact, integrated packages. The combination of motor, bearings, and positioning system eliminates complex assembly while providing micron-level precision through microstepping technology. Open-loop operation removes servo tuning requirements, reducing complexity and cost. Multiple forcers on a single platen enable independent multi-head operations for increased throughput.

Ordering Information

Available in various widths and lengths based on force requirements. Roller or air bearing configurations offered. Single-piece platens up to 144″ [3.6 m]; sectioned platens for longer strokes. Custom configurations available for specific application needs.