Pull force testing is a quick, destructive method to evaluate the mechanical strength of a crimp termination. If the results of a pull force test fall outside of the allowable range, it’s a good indicator of problems in your manufacturing process. Wire strands in the stripping operation being cut or nicked, lack of proper bell mouth or conductor brushing, or incorrect crimping height or tooling will reduce pull force withstanding. Wire properties and stranding, and terminal design (material thickness and serration design) may increase or decrease the result of pull force testing.
If the result of the pull force test is within the allowable range, you can ensure that the proper crimping force is being applied during crimping. It is essential that when crimping, sufficient force is applied on the stripped conductor and the inside terminal clip. This is necessary to provide good metal-to-metal contact. Otherwise, a poor crimp may increase electrical resistance. Over-crimping will reduce the circular area of the conductor, which also increases resistance.
A Pull Tester is useful equipment to determine the mechanical strength of a crimp termination. One example is WT3-201M from Mark-10. This wire crimp pull tester is designed to measure pull-off forces of up to 200 lbF [1 kN] for wire and tube terminations. To learn more about this tester, please check its datasheet, here: Wire Crimp Pull Tester Model WT3-201M.