WorldWide WCE introduces its latest advancement in shape memory alloy (SMA) wire actuation devices. These devices utilize a specific Nitinol (nickel-titanium) alloy that shrinks by 4% when heated. Heat generation can be achieved by electrical current or thermal energy. Compared to conventional actuation methods such as motors or solenoids, SMA devices require less power and allow for lighter, more compact designs.

However, termination of SMA wires is not straightforward using standard joining techniques such as soldering, brazing, or mechanical methods. These techniques are often impractical due to the wire's metallurgy, its small size in complex actuation applications, and the need to terminate the SMA wire under tension. These connections must withstand a variety of electrical, mechanical, and environmental conditions demanded by the application.

Solution: Crimping Technology

Crimping technology solves these challenges by providing highly reliable and repeatable assemblies in high-volume manufacturing environments. Crimping, especially when using a sleeve over the joint, is the most widely used and effective joining technique for nitinol wire. The combination of the material properties of the swaging strip and the geometric configuration of the crimp provides the necessary mechanical grip around the nitinol wire.

Precise Monitoring

Crimp force monitoring systems analyze and process crimp signatures to detect acceptable ranges of crimp forces. Process capability indices (Cpk and Ppk) are used to monitor crimp reliability.

Efficient Packaging

Packaging of SMA actuators is crucial to prevent the nitinol wire from overstretching or tangling during the assembly process. Accuracy in the position of the electromechanical connectors relative to the wire and specific dimensions between the connectors are essential. This is achieved through tight tolerances and wire tension control.

Quality Control in Mass Production

Automated production of SMA assemblies requires a complex quality control system to validate critical parameters such as minimum crimp pull force, SMA wire length between crimps, and actuation amount.

Our inspection system uses fixtures to position and activate the SMA assembly. Precision optical microscopes, such as the OGP SmartScope® Flash™, measure all necessary control dimensions in automated mode.

Conclusion

Crimping is the most effective technique for joining nitinol wire and requires continuous monitoring of crimp forces and geometry to ensure a reliable electromechanical connection. WorldWide WCE offers highly repeatable and reliable assemblies for a variety of applications, employing efficient packaging methods.