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H2W Technologies linear stepper 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 stepper motors are capable of very precise position, velocity and acceleration control when coupled with a microstepping 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 step and direction signal from a microstepping drive, to the 2 or 4 phase forcer is supplied via a power cable. The motion achieved with a full step is .010” [250 microns] and with a microstep it’s .00004” [1 micron].
The linear stepper motor is 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 stepper provides a closed loop system.
- Low profile and small cross section
- High Speed
- Low cost positioning stage solution
- No servo tuning required
- Multiple forcers on a single platen
- Pick and Place
- Wire bonders
- Parts transfer
- Fiber optic
The Linear Stepper Motor consists 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.
The linear stepper motor requires a full step or microstepping driver with power supply that is rated with sufficient current and voltage to meet the motion requirements. With full stepping, the forcer will move .010" [.25 mm] for each step. With microstepping the forcer will divide the fullstep by the number of microsteps. With 256 microsteps / full step, the microstep will be .010" [.25 mm] / 256 = 0.00004" [1 micron]
The linear stepper motor is 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.
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.
Setting The Air Gap On Single Axis Linear Stepper with Roller Bearing:
The forcer air gap should be set to .0015-.002 inches [38 – 50 microns]. If the air gap is properly set, the stepper motor should be able to move freely along the entire length of the platen. If the forcer becomes difficult to move manually or it physically makes contact with the platen, the air gap will need to be reset. Instructions on how to properly set the motor airgap can be downloaded below: