Undercrimp

Undercrimp is a quality defect in crimped connections in which the crimp is not fully compressed around the conductor, resulting in an inadequate mechanical grip and poor electrical contact. The defect can cause loose connections, increased electrical resistance, heating, intermittent operation, or complete failure, especially under vibration or dynamic load.

The term is used across industries that rely on crimped terminations, including electrical and electronic assemblies, automotive wiring, and related manufacturing. Indicators of undercrimp include visible gaps between the crimp feature and the conductor or insulation, strands that are not fully captured by the crimp, or a connector that can be detached with hand force.

Common causes include using the wrong terminal for the conductor size, incorrect or worn crimping tools or dies, damaged insulation or conductor preparation, and attempts to re-crimp a previously crimped terminal. Poor tool maintenance, improper crimp height, and using damaged or counterfeit components can also contribute.

Prevention and detection rely on proper process control. Use the correct terminal and tool for the conductor, ensure dies and tools are within specification and in good condition, and verify crimp height with manufacturer guidelines. Visual inspection and non-destructive tests, such as pull tests, can help identify undercrimps; go/no-go gauges and standardized inspection criteria (for example, IPC/WHMA-A-620 and related manufacturer specs) are commonly employed. If a crimp is suspected of being undercrimped, it should be rejected and replaced to maintain reliability.