‘Environmentally sealed’ linear actuator stands up to harsh world

Designers and engineers looking for compact linear actuators suitable in medical, food processing, cleanroom, and related applications now have an added solution with Ultra Motion LLC’s recent launch of a new series of such devices offering washdown and autoclaving capability.

By Control Engineering Staff July 22, 2004
ESLA-17 actuator measures only 1.72 in. (44 mm) square at the motor end times 2.30 in. (58.4 mm) long. Overall dimension is just 5.8 in. more than the stroke length.

Designers and engineers looking for compact linear actuators suitable in medical, food processing, cleanroom, and related applications now have an added solution with Ultra Motion LLC ’s recent launch of a new series of such devices offering washdown and autoclaving capability. Available in 2, 4, or 8 in. stroke lengths, ESLA (Environmentally Sealed Linear Actuators) is powered by either a NEMA 17 or NEMA 23 size stepper motor. The device also is said to be quiet.

ESLA’s sealing provision consists of polyolefin shrink tubing and polyurethane adhesive at the motor end, while the polished stainless-steel shaft has a low-friction Buna-N U-cup seal. The actuator’s tube body is made of clear anodized aluminum (6061-T6).

These actuators feature a choice of lead-screw options. Three Acme-type screws (0.0833, 0.2500, and 0.400-in. pitch) and either single-nut or double-nut ball screws (0.1250-in. pitch) are available. The smallest pitch Acme lead screw cannot be back driven. Depending on the lead screw selected, the two actuator models—ESLA-17 and ESLA-23—have some common characteristics: Linear step resolution of 2,400 steps/in.; backlash of 0.0005 in.; and maximum speed of 16 in./s. ESLA-17 develops 97 lb max. force, while the larger ESLA-23 unit outputs 392 lb. max. force.

ESLA units come with matching controllers and drives for full-step, half-step, and microstepping operation. Externally adjustable reed switches provide home position sensing. Analog absolute position feedback is a further option, says Ultra Motion.

Frank J. Bartos, executive editor, Control Engineering, fbartos@reedbusiness.com