Improving Cycle Time of Ni-Ti Shape Memory Alloy Actuators Using a Novel Cooling Technique

Abstract

Shape Memory Alloy (SMA) actuators require long cycle time due to slow cooling. Therefore, they are not suitable for applications that require fast operation. The research reported in this paper presents a novel technique of SMA actuator cooling. Using this technique, the Nickel-Titanium (Ni-Ti) based SMA wire actuator of diameter 0.15 mm was placed inside a PolyTetraFluoroEthylene (PTFE) tube of 0.5 mm outside diameter. The tube was filled with a grease to achieve faster cooling. The actuation behaviour was investigated in ambient air and in grease filled PTFE tube under various actuation currents. Compared to ambient air cooling, this technique resulted in up to 50% reduction in cooling time.