The electromechanical linear actuators included in this section have a lead or ball screw. These actuators eliminate the noise, need for a quality air supply and cost associated with pneumatic actuators by only requiring electricity instead of electric wiring and tubing. In addition, in lower power density applications, electromechanical actuators have advantages over hydraulic actuators. The hydraulic actuators frequently have noise from pump pressure pulses and the potential for hydraulic fluid leakage that can cause pollution problems. While also supporting trends of smaller, more durable and flexible, the ball and non-ball lead screw driven linear actuators in this section specifically target precise positioning.
MOTOR-DRIVEN LINEAR STAGE
The ATS150 series motor-driven linear stages from Aerotech incorporate a brushless rotary motor and a precision non-contact linear encoder option. The unit's precision-ground ball screw is pre-loaded to eliminate backlash and the nut has wipers to prevent contamination and maintain high accuracy, up to ±1.0 µm (±40 µinch), throughout the life of the stage. Pre-loaded duplex bearings eliminate axial play. The linear stage's brushless motor produces zero cogging for accuracy and smooth motion. With the 2 mm/rev lead, the units have 0.5 µm (20 µinch) at 4,000 steps/rev motor resolution and with the 4 mm/rev lead, 1.0 µm (40 µinch) at 4,000 steps/rev motor resolution. The bidirectional repeatability of the ball screw (standard) is ±1.0 µm (±40 µin), which improves to ±0.5 µm (±20 µin) with the Halar option. Based on its high resolution and repeatability, the motor-driven linear stages target precision micromachining applications, semiconductor fabrication and wafer testing, as well as automated microscope inspection systems.
LEADSCREW-DRIVEN LINEAR ACTUATOR
Providing an electromechanical alternative to a pneumatic actuator, Kerk Motion Products' Kerk Linear Actuator incorporates long life, high precision technology in a rod-type actuator. The leadscrew provides precise movement to any position and the ability to vary the speeds within the stroke for flexible operation. Designed to accept NEMA size 17, 23 and 34 motors, the actuator uses a polytetrafluoroethylene (TFE) coating and composite polymers to provide maintenance free service without lubrication. The linear actuator targets positioning requirements in semiconductor, assembly equipment, automotive, packaging and medical applications.
SIZE 8 LINEAR ACTUATORS
Occupying only 0.8 inch˛ (21 mm˛) space, Haydon Switch & Instrument, Inc.'s smallest hybrid motor, the 21000 series (Size 8) linear actuators, are available in captive, non-captive and external linear versions. With resolutions ranging from 0.00006 inch (.0015 mm) per step to 0.00157 inch (0.04 mm) per step and thrust capability up to 10 lb (4.5 Kg), the linear actuators can be micro stepped for even finer resolution. The use of a stainless steel acme lead screw and engineering thermoplastics in the rotor drive nut make the unit both efficient and durable. Operating from 2.5 to 7.5V, the units consume 2.45W. The linear actuators target applications in semiconductor handling, valve control, medical equipment, X-Y tables and hand held instruments among others.