A common question we receive is related to the barrel crimps for the Datamate (M80 and M83 series) cable connectors. The individual crimp part numbers are:
For all these contacts, there is a cross-hole in the side of the crimp bore, in the back half of the contact. This hole is commonly believed to be an inspection hole, to see the cable conductor wires are correctly located in the crimp bore. However, this is not its purpose. The hole is designed to allow plating materials (nickel, gold and/or tin) to reach the inner end of the crimp bore. Without this hole, plating coverage at the base of the crimp bore is compromised by trapped air - increasing the risk of corrosion and potential for variable electrical performance.
The hole can be used for inspection purposes, but it is not its intent. Therefore, it does not compromise the inspection criteria as specified in IPC-620, which states that crimping should not overlap inspection holes. As it is not an inspection hole, this criteria does not apply.
A correct crimp can overlap the hole - and would typically look like this:
This is documented in the Instruction Sheet for the M22520/2-01 hand crimp tool, IS-01.pdf, and also within the Datamate Female Crimping Video.
Because of the compact nature of the Datamate product, and to keep the overall height of the crimp connector to a minimum, it would not be possible to redesign these contact to move the crimped area away from the plating hole.