Terminal Crimp Defects: Causes, Inspection and Corrective Actions

A crimp can look acceptable and still fail electrically or mechanically. Troubleshooting should compare the result with the terminal manufacturer’s crimp specification wherever one is available.

Match the symptom to the inspection method

Symptom	Possible causes	Useful inspection
Low pull force	Missing strands, wrong compression, short conductor insertion	Visual, crimp height, pull force, cross-section
High or low crimp height	Wrong setup, tool wear, terminal variation, debris	Micrometer trend and tool inspection
Cut strands	Strip damage, terminal edge, wire misposition	Magnification before and after crimp
Missing bellmouth	Terminal position or applicator timing	Side-profile visual inspection
Insulation inside conductor crimp	Strip length or wire position error	Side view and cross-section
Split insulation support	Excess compression or wrong terminal-wire match	Visual and dimensional inspection
Terminal feed instability	Carrier damage, pitch mismatch, applicator feed setting	Observe feed through several cycles

Do not correct every defect with more force

Increasing compression may raise pull force while damaging strands or producing excessive conductor compression. First confirm terminal, wire and applicator compatibility. Then verify strip length, insertion and terminal position. Adjust crimp height only within the approved process window.

The WM-3130T servo press provides a controlled press platform, but tooling and setup still determine the finished geometry.

Use complementary tests

• Visual inspection finds position, strand, brush, bellmouth and insulation-support defects.
• Crimp-height measurement monitors a controlled dimension but does not reveal internal distribution.
• Pull-force testing measures mechanical retention under the stated test method.
• Cross-section analysis reveals compression, symmetry, strand distribution and voids.

The WM-817 pull-force tester and WM-813 cross-section system support different parts of this inspection plan.

Correction workflow

1. Quarantine the affected production interval.
2. Preserve terminal reel, wire lot, applicator and machine settings.
3. Compare a failed part with the last approved sample.
4. Identify whether the defect starts before crimping, during terminal feed or during compression.
5. Change one setting or worn component at a time.
6. Re-approve using the original acceptance criteria.
7. Record the correction and resulting sample measurements.

The EV harness and control-panel wiring pages show why acceptance differs by termination type. Public measured examples appear only in the case library after evidence approval. For a terminal-specific diagnosis, send the terminal drawing, applicator details and failed samples.