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SMT007-Apr2024

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82 SMT007 MAGAZINE I APRIL 2024 Figure 7. erefore, due to the exposed con- ductor ends, stamped and formed contacts are typically only used for ground systems at NASA because in a microgravity environment, conductor strands have the potential to float inside the system and cause short circuits. For this reason, NASA primarily uses machined contacts for space flight hardware. Addition- ally, as a result, stamped and formed contacts were excluded from this study. Contacts are sized in accordance with the AWG size of the largest diameter wire that the contact can accept. However, adjustable crimp tools allow the modification of the crimp depth of the indenter blades, allowing a larger contact to be crimped to a wire a size or two smaller, e.g., a 20 AWG wire is able to fit into a larger 16 AWG contact. e size of the contact in a crimped connection is irrelevant for crimp pull testing, instead, the size and composition of the wire is the dominant factor in the tensile strength of the connection. Furthermore, it is recommended to select the correct size of wire and contact combination (C/W) pair to avoid excessive compression of the wires that will result in extensive compaction of the conduc- tor strands as shown in Figure 8 3 . Conclusion is analysis on crimp pull force testing has concentrated on past NASA project data from multiple NASA centers. ese results may offer some validation into the relaxation or revision of the pull force test requirements, but only assuming good training, process doc- umentation, calibration, and tool verification procedures are in place. e measures to mit- igate the risk should be formulated if pull test requirements are relaxed. If the frequency of pull force testing is being reduced, additional process control methods should be followed, such as incoming material inspection, tool and equipment calibration, and tool verification during crimp process. Periodic training to identify bad practices and lack of attention to details will also help pre- vent crimped termination defects. An allow- ance to reduce pull force testing frequency Figure 7: Stamped and formed contact components. The crimped contact is showed at the bottom with exposed wire brush.

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