Coil Actuators and Brackets

NiTi Coil Actuators

An NiTi coil actuator is fabricated by wrapping a strand of thin NiTi wire around a shaft and setting its shape. Each 22mm coil uses about 34cm of straight wire. A single 5m spool has enough wire to make 10-12 actuators.

Manufacturing procedure of NiTi coil actuators.	Clamp 150um NiTi wire to a core of 0.024in music wire. Insert into drill press. Slide 3D printed pieces onto the core and push up against the NiTi. Place NiTi into V channel of the piece and pull taught. Turn on drill press and push up lightly on the 3D printed piece. This forms the coil. After coil is complete, clamp the free end using a nut and bolt. Set the shape of the coil by annealing it at 390 degrees Celsius for 20 minutes. After shape setting is complete, remove coil and cut into 22mm sections.

HowToSMA — Manufacturing procedure of NiTi coil actuators.

Clamp 150um NiTi wire to a core of 0.024in music wire. Insert into drill press.
Slide 3D printed pieces onto the core and push up against the NiTi. Place NiTi into V channel of the piece and pull taught.
Turn on drill press and push up lightly on the 3D printed piece. This forms the coil.
After coil is complete, clamp the free end using a nut and bolt.
Set the shape of the coil by annealing it at 390 degrees Celsius for 20 minutes.
After shape setting is complete, remove coil and cut into 22mm sections.

Point Brackets

Music wire is considerably stiffer than the NiTi wire and therefore must be secured more firmly. To create the point brackets, use steps 2-4 above, using 0.029" music wire in place of the NiTi and a 0.042" core. Keep fingers away from the winding coil. If released, the remaining wire can whip around and cause injury. After the spring is compete, cut every three coils using a dremel. Do not cut the wire with pliers. This will cause burrs that can puncture the FFT membrane.
Manufacturing procedure of steel point brackets.

Music wire is considerably stiffer than the NiTi wire and therefore must be secured more firmly. To create the point brackets, use steps 2-4 above, using 0.029" music wire in place of the NiTi and a 0.042" core. Keep fingers away from the winding coil. If released, the remaining wire can whip around and cause injury. After the spring is compete, cut every three coils using a dremel. Do not cut the wire with pliers. This will cause burrs that can puncture the FFT membrane.

PBs — Manufacturing procedure of steel point brackets.