T. Tanaka, Furukawa Techno Material Co., Ltd., Hiratsuka-city, Kanagawa pref, Japan
NiTi-based wire expands and contracts between its Martensite and Austenite phase transformation. The physical transformation is achieved by heating the wire while it is under a fixed load. Due to the electrical resistance being high this wire is heated by simply applying electric current. Therefore by controlling the electric current, the expansion and contraction cycle form an actuator device. However, there is a problem that this material results some degree of permanent strain after repeating the above-described reciprocating movements many times, thereby causing a certain degree of residual strain at room temperature that finally leads the material to failure in recovery of its original memorized length at a temperature of Af or higher. Furukawa have developed the new NT-H7-TTR wire (using a NiTiCu based alloy), which has much more stable property than the conventional NiTi-based wire, in spite of the number of repetitions. The stability is achieved by a special training process. The NT-H7-TTR wire has been used for portable equipment applications, such as a camera.
Summary: Furukawa’s new NT-H7-TTR wire for actuator applications, manufactured from NiTiCu base alloy. The property of NT-H7-TTR wire is more stable than conventional NiTi-based wire in spite of the number of repetitions.
