Linear Stepper Motors

 

OES' linear step motors are ideal for open loop positioning applications with light payloads. They can be used at speeds up to 80 in /sec (2 m/sec) and strokes up to 144" (3.6 m). Linear step motors are capable of very precise position, velocity and acceleration control when coupled with a micro-stepping drive and indexer.

The short moving assembly called a "forcer" is guided by either roller or air-bearings along he precision ground track called a "platen". The bearings are designed to support the customer's payload and to maintain the required .001" (0.025 mm) gap between the platen and the forcer.

The forcer  conveniently connects to any commercially available 2-phase micro-stepper driver. The motion achieved with a full step is .010" (250 microns) and with a micro-step of 250 it's 0.00004" (1 micron).

These motors are also available with 4 windings to be used with a 4 phase step motor driver s. The advantage of using a 4-phase motor is higher resolution and lower velocity ripple.

The linear step motors a complete positioning stage with the motor, the bearings and the positioning system all built into one compact package.

Integrating a linear encoder with the stepping provides a closed loop system.

Advantages:

  • Low profile and small cross section
  • High Speed
  • Low cost positioning stage solution
  • No servo tuning required
  • Multiple forcers on a single platen

 Applications:

  • Pick and Place
  • Wire bonders
  • Parts transfer
  • Fiber optic

The Linear Stepper Motorconsists of 2 main parts

  • Moving Forcer Assembly: The forcer is made up of an aluminum housing that contains the motor windings, lamination stacks, and permanent magnets. The active surface of the lamination is slotted to form teeth with a pitch of .040" (1 mm). The ends of the coil are brought out to either a "D" connector or to flying leads. Mounting holes on the top surface of the forcer are for attaching the customer's payload. The forcer comes in different widths and lengths, depending on the required force. Multiple forcers can be supplied with a single platen to allow for independent moving heads.

  • Long Stationary Platen: The platen is a precision ground steel bar or tube that is slotted to form .020" (0.50 mm) wide teeth on the surface. The bar is hard chrome plated and filled with epoxy to provide a flat air-bearing surface for the platen. The platen is available in widths from 1.25" to 3.0 " (31.8 mm to 76.2 mm). The length of the platen is a function of the stroke. Single piece platens are available as long as 144 inches (3.6 m). For longer strokes the platens will be supplied in sections.

Operating Information:

Required Electronics:
With full stepping, the forcer will move .010" (0.25 mm) for each step. With micro-stepping the forcer will divide the full step by the number of microsteps. With 256 microsteps per full step, each micro-step will be .010" (0.25 mm) / 256 = 0.00004" (1 micron)

Environmental Considerations:
The linear stepper motors a precision device and should not be mounted in an environment that is wet or excessively dirty. Debris should not be allowed to accumulate on the platen.

Mounting:
The platen should be mounted to a flat (better than .003"/ ft (246 microns / m) and stiff surface. Threaded holes on the bottom of the platen are present for mounting to the customers system. The forcer has threaded holes on the top surface for attaching the payload. The linear stepper motor may be mounted in any orientation. When mounting the platen with the forcer moving vertical, it should be noted that the forcer will be required to generate additional force due to gravity and that the ball bearing forcer will slide down to the bottom when power fails. Turning off the air to an air bearing forcer will lock the forcer in place.

Product Information:

Travel
144 inches
(3.6 m)
Velocity
80 inches/sec
(2 m/s)
Acceleration
1 G's
1 G's
Peak Force
65 lbs
(289 N)
Continuous Force
50 lbs
(222 N)

 Dimensions:

 
5-lb Linear Stepping
 
 

Ordering Information:

Model #

Force cont
lbs   (N)

Force peak
lbs   (N)

# of Phases

Bearing Type

STPM-SL-05-Length-R
5   (22)
8   (36)
2
Roller

For example, STPM-SL-05-10-R  is a 5.0 lbs continuous force stepping with 10.0 inches of travel.

Note: This is a partial listing; other models with different forces and strokes are available. Optimal Engineering Systems, Inc. single axis linear stepper motors can be custom designed to meet your specifications.

please contact us for a prompt quotation. 



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