NASA’s Langley Research Center has created a collection of innovations for rapid, precise, and verified crimps. Wiring crimp failures can be a threat to safety and may lead to a loss of critical functions in high-risk applications, such as aerospace. In addition to the safety concerns, diagnosing and repairing poor crimp connections can be costly. Langley’s crimping innovations increase quality and reduce risk by using ultrasound to provide real-time, nondestructive verification of wire-crimp integrity while the crimp is being formed. This technology can be applied to electromechanical crimping machines, where the appropriate force required to form a crimped connection is determined in real time. Such an application prevents over- or under-crimping, and prevents excessive tool wear. Langley has also created a means and method to calibrate and verify the mechanical and electrical settings for an ultrasonically enhanced crimp tool.
The crimping innovations are based on traditional, ultrasonic, nondestructive evaluation methods. The quality of the contact between the connector and wire is determined by sending an acoustic wave through the crimp assembly. As the applied pressure increases and the crimp terminal deforms around the wire, the ultrasonic signature passing through the crimp is altered. The system analyzes the changes in the signal, including the amplitude and frequency content, as an indication of the quality of both the electrical and mechanical connection between the wire and terminal.
Various crimp quality issues such as under-crimping, missing wire strands, incomplete wire insertion, partial insulation removal, and incorrect wire gauge have been tested using this technique, and results show that the instrumented crimp tool consistently discriminates between good and poor crimps for all of these potential quality issues. This information can be used to provide a pass or fail indication for instant verification of the crimp quality, and to give a better prediction for the service life of the crimp.
This technology can improve safety and reduce costs related to installing and/or overhauling crimp/wire connections in applications with critical wire terminations, such as marine and automotive systems, industrial plants, nuclear power plants, and medical devices.