A reliable crimp connection is the foundation of every high-quality wire harness. Whether used in automotive, industrial automation, medical devices, or consumer electronics, a poorly crimped terminal can lead to electrical failures, overheating, intermittent signals, or even complete system shutdowns.

At Dongguan Quanlin Electronics Co., we manufacture custom wire harnesses for customers worldwide. Through years of production experience, we’ve found that most crimp failures can be traced back to a handful of preventable causes. Understanding these issues can help engineers, purchasing managers, and OEM manufacturers improve product quality while reducing warranty claims and maintenance costs.

In this guide, we’ll explain the most common crimp failure causes, how to identify them, and the best practices for preventing them.

---

What Is a Crimp Failure?

Crimping is the process of mechanically joining a wire conductor to a terminal without soldering. A proper crimp creates both an electrical connection and a strong mechanical bond.

A crimp failure occurs when this connection cannot reliably carry electrical current or withstand mechanical stress during the product’s service life.

Common symptoms include:

• Loose terminals
• High electrical resistance
• Overheated connectors
• Intermittent electrical signals
• Wire pull-out
• Broken conductors
• Equipment malfunction

---

1. Incorrect Crimp Height

One of the leading causes of crimp failure is improper crimp height.

If the crimp height is too high, the wire is not compressed enough, resulting in poor electrical conductivity.

If the crimp height is too low, excessive compression can damage the conductor strands.

Signs

• Loose wire
• High resistance
• Broken strands
• Failed pull test

Prevention

• Use calibrated crimping equipment.
• Measure crimp height regularly.
• Follow terminal manufacturer specifications.

---

2. Wrong Wire Size

Using a wire outside the terminal’s specified AWG range often causes unreliable crimps.

For example, placing a 22 AWG wire into a terminal designed for 18 AWG leaves excessive space, while forcing a larger wire into a smaller terminal damages both the conductor and terminal.

Prevention

• Verify wire gauge before production.
• Match wire size with the terminal specification.
• Use approved wire combinations.

---

3. Worn or Damaged Crimping Dies

Crimping dies gradually wear after thousands of production cycles.

Worn tooling creates inconsistent compression and poor terminal geometry.

Symptoms

• Uneven crimp shape
• Variable crimp height
• Increased rejection rate

Best Practice

Implement regular tool inspection and replacement schedules.

---

4. Poor Wire Stripping

Improper stripping can damage conductor strands before crimping even begins.

Common problems include:

• Nicked conductors
• Cut strands
• Excessive strip length
• Insufficient strip length

These defects reduce both electrical performance and tensile strength.

Prevention

• Use automatic wire stripping machines.
• Perform visual inspections.
• Verify strip length during quality control.

---

5. Incorrect Crimping Force

Every terminal requires a specific compression force.

Too little force results in loose connections.

Too much force damages the terminal barrel and conductor.

Modern servo crimping machines automatically monitor crimp force to detect abnormalities in real time.

---

6. Low-Quality Terminals

Not all terminals are manufactured to the same quality standards.

Inferior materials may have:

• Thin plating
• Inconsistent dimensions
• Poor conductivity
• Weak mechanical strength

Choosing certified terminals from reputable suppliers significantly improves long-term reliability.

---

7. Wire Contamination

Oil, dust, oxidation, or moisture on the conductor surface increases contact resistance.

Contaminated wires may initially pass testing but fail after long-term operation.

Prevention

• Store wire properly.
• Keep production areas clean.
• Avoid touching stripped conductors unnecessarily.

---

8. Improper Terminal Positioning

If the terminal is not correctly positioned inside the crimp die, the conductor and insulation crimps may not form properly.

Misalignment often causes:

• Bent terminals
• Open barrels
• Uneven compression

Automatic crimping machines help minimize positioning errors.

---

9. Operator Error

Manual crimping still plays an important role in prototype and low-volume production.

Without proper training, operators may:

• Use incorrect tools
• Select wrong settings
• Skip inspections
• Use damaged terminals

Continuous operator training is essential for maintaining product quality.

---

10. Inadequate Quality Inspection

Even a well-designed production process requires effective quality control.

Recommended inspections include:

• Crimp height measurement
• Pull force testing
• Cross-section analysis
• Crimp force monitoring
• Visual inspection
• Electrical continuity testing

Combining these methods significantly reduces the risk of defective products reaching customers.

---

How to Prevent Crimp Failures

The most effective way to prevent crimp failures is to establish a robust manufacturing process.

Key recommendations include:

• Use high-quality terminals and wires.
• Select the correct wire gauge.
• Calibrate crimping machines regularly.
• Replace worn crimping dies.
• Perform crimp height measurements.
• Conduct pull force testing.
• Train operators regularly.
• Follow IPC/WHMA-A-620 workmanship standards.
• Implement 100% electrical testing whenever possible.

---

Why Crimp Quality Matters in Custom Wire Harness Manufacturing

For OEMs, a single failed crimp can result in costly field failures, equipment downtime, warranty claims, or product recalls.

At [Your Company Name], every custom wire harness undergoes strict quality control procedures, including crimp height inspection, pull testing, visual inspection, and electrical continuity testing. Our production process is designed to ensure consistent crimp quality for industries such as automotive, industrial automation, medical equipment, renewable energy, and consumer electronics.

Whether you require prototype assemblies or high-volume production, our engineering team works closely with customers to deliver reliable wire harness solutions that meet international quality standards.

---

Conclusion

Crimp failures are rarely caused by a single factor. Instead, they often result from a combination of tooling, materials, equipment settings, and process control.

By understanding the most common crimp failure causes and implementing preventive quality measures, manufacturers can improve product reliability, reduce production defects, and extend the service life of electrical systems.

If you’re looking for a trusted custom wire harness manufacturer with strict crimp quality control, our team is ready to help. Contact us today to discuss your next wire harness project.