L i n e a r

M o t i o n

Linear actuators

based on shape-memory alloys

Now, one new actuator uses bundles of SMA wire made of specialty nickel-titanium alloy for reliable linear motion.

Dean Pick, P.Eng. | President | Kinitics Automation

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Lisa Eitel | Motion Editor

Shape-memory alloys (SMAs) are those materials that respond to temperature changes by changing form factor. Originally funded by the U.S. Navy, SMA technologies were first commercialized by Raychem Corp. (now of TE Connectivity) during the 1950s. But the unpredictable nature of early material versions proved a challenge. So over the decades, manufacturers investigated ways (with mixed success) to boost the durability, consistency, and applicability of SMA-based designs. Now one new SMA-based linear-motion offering uses advanced SMA material for repeatable and predictable motion. The manufacturer bundles wires made of SMA and anchors them to an actuator housing. Current through the (electrically resistive) SMA generates this heat; when warmed past a transition temperature, the wires’ atoms realign to another crystalline structure. This results in wire contraction when heated and re-extension when cooled — which in turn makes for linear motion output.

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September 2018 www.designworldonline.com

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DESIGN WORLD

9/6/18 11:28 AM