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76 SMT007 MAGAZINE I APRIL 2024 e use of hand crimp tools and manual pull testers requires additional process controls that are needed to maintain consistency and limit the variability of the results. Hand Crimp Tools e quality of the finished crimp depends on the tooling setup and its operability with the contacts (i.e. terminals) being crimped. Tool manufacturers provide specification sheets for hand tools with defined parameters such as the manufacturer's contact type, wire size range, insulation diameter, and strip length. According to the MOLEX Quality Crimping Handbook, a typical crimping procedure using a hand crimp tool is as follows 5 : 1. Identify the appropriate crimp tool for the contact and wire being crimped. 2. Strip the wire and inspect for damage. 3. Select the appropriate positioner/color- coded crimp nest for the contact and tool being used and insert the crimp contact. 4. If a locator bar is used for the crimp design, ensure the locator bar is engaged properly with the contact and the contact is unable to move. 5. Insert the wire into the crimp contact. 6. Engage the ratchet by squeezing the actuation handle, following through for a full cycle. 7. Inspect for proper crimp location and inspect for damage. Not only does the technician need to operate the tool appropriately for consistent crimping action, the tool itself oen needs to meet cer- tain minimum process control requirements. For example, according to the NASA-STD- 8739.4A Change 2, Section (i.e., §) 12.3.1, crimp tools must contain a full-cycle ratch- eting mechanism and that calibration adjust- ments are made only by the tool manufacturer or by a calibration laboratory 1 . For commercial applications and some high- reliability applications, the cable/harness stan- dard levied is IPC/WHMA-A-620B, Require- ments and Acceptance for Cable and Wire Har- ness Assemblies, which defines three unique end product classes reflecting various lev- els of controls that need to apply to the man- ufacturing process. For aerospace applica- tions, these controls may not be sufficient for hardware safety, and as a result the aerospace industry has developed an addendum to the original IPC/WHMA-A-620B base document, titled IPC/WHMA-A- 620B-S, Space Applica- tions Electronic Hardware Addendum to IPC/ WHMA-A-620B. Furthermore, according to IPC/WHMA-A-620B-S §19.6.1, Mechanical Test—Selection, the "crimp tools shall not be used for longer than 30 days between verifi- cation testing" 6 . Periodic tool calibration is needed due to the wear-out of the indenter blades (Figure 4). Calibrated tools should have records and a quick verification method, such as sticker, on the tool. Figure 4: Typical crimp tool for machined contacts.