Wiring Harness Quality Assurance (5-Step Guide)

With wire harnesses being used across many industries, manufacturers must implement effective quality assurance strategies to ensure product reliability and drive continuous improvement.

The key challenge is integrating quality control seamlessly into the manufacturing process. This guide will explain what wiring harness quality assurance involves, why it matters, and how to assess it effectively.

The Importance of Quality Assurance in Wire Harness Manufacturing

Quality assurance processes help manufacturers ensure wiring harnesses are fully operational, safe, and reliable. 

Create Reliable and Durable Products

Wiring harnesses are used in critical applications, where faults can cause electrical failures or fire hazards. Thorough quality assurance at each stage helps manufacturers detect issues early and ensure long-term performance and safety.

Comply with Industry Regulations

Wiring harnesses must comply with strict industry standards and regulations. The primary consideration for manufacturers is where the wiring harness will be used. 

Safety standards

Regulatory and safety standards tend to be regional. For instance, wiring harnesses designed for North American markets must adhere to guidelines and rules set by the Underwriters Laboratories (UL) or the Canadian Standards Association (CSA). 

Likewise, many territories feature installation standards specific to their countries. A large segment of these areas bases their guidelines on regulations set by:

• International Commission for Rules for the Approval of Electrical Equipment (CEE)
• International Electrotechnical Commission (IEC)
• European Committee for Electrical Standardization (CENELEC)

Environmental standards

Manufacturers must aim to limit the environmental impact of their processes and products. Two regulations are most concerned with this: the European Union’s Registration, Evaluation, Authorization, and Restriction of Chemicals (REACH) and Restriction of Hazardous Substances (RoHS). 

Manufacturers must comply with these directives and the UK’s Waste Electrical and Electronic Equipment (WEEE), which provides guidelines on how electronic components and devices should be broken down, recycled, and disposed of.

Assembly Standards

The IPC/WHMA-A-620 is the benchmark for assembling wire harnesses. It is the primary guideline for wiring harnesses intended for U.S. markets. Under the intended application, cable assemblies may also be required to meet additional connection standards and specifications, such as:

• SFP+u
• HDMI
• QSFP
• TIA/EIA 568-C.2

It’s also common for assemblies to undergo review and testing by independent third-party services like the ETL.

Note: These standards can only be met by manufacturers who implement and maintain high wiring harness quality assurance standards.   

Reduce Costs and Waste

Quality assurance makes troubleshooting and fault detection much easier. This, in turn, saves time and reduces excess material consumption, enhancing sustainability.

5 Steps For Quality Assurance

When implementing a quality assurance strategy, manufacturers often must evaluate their entire approach to production. To do this properly, they must observe five key areas.  

Design for Manufacturability (DFM)

Traditionally, DFM’s main goal was to ensure that the final product would function well and meet performance requirements. DFM has expanded its focus to include other manufacturing process parameters like cost, efficiency, and complexity. 

Manufacturers could streamline assembly, reduce errors, and improve the overall reliability of products by simply optimizing the wiring harness design.  

A Clear Manufacturing Process

Although the manufacturing process can vary significantly, manufacturers should plan multiple standardized processes to accommodate these differences. For example, more steps are required to produce braided wire harnesses than their non-braided counterparts. Further, they typically need different testing measures. 

Manufacturers can track the various steps and requirements by recording them in clear, well-written documentation. They should also implement monitoring systems, which should flag any activity that strays away from the documented processes and rules.

Strict Inspection and Testing Procedures

Manufacturers can detect and fix errors by comprehensively testing wiring harnesses. 

Inbound inspection

Before starting production, manufacturers check wires and other components for materials, gauge, connector damage, and terminal space. If any of the products look unsatisfactory, they ask for replacements.

Prototyping: 

Manufacturers create a real-world demo product to test the real-world viability of a wiring harness design. This can identify flaws and assess whether the design is fully optimized for manufacturability. 

In-process testing

This process includes inspection and testing at multiple stages of manufacturing. Manufacturers work closely with the customer’s engineering team to perform the required tests. High-quality testing equipment is essential, as it affects both accuracy and efficiency. Technicians follow specifications and custom drawings to minimize errors.

Final inspection and testing 

Each harness undergoes a thorough visual inspection to verify physical dimensions, workmanship, labels, and electrical properties. Upon request, manufacturers conduct high-potential tests and continuity tests on 100% of the manufactured harnesses. Additionally, some typically construct a wire harness mate to ensure precise alignment with the customer’s specifications, facilitating accurate electrical testing based on their drawings.

Note: Manufacturers can hire an independent entity specializing in wire harness testing.  This would fill in any inspection or testing gaps that the manufacturer missed.  

Professional and Highly Trained Staff

Manufacturers must update workers at all levels on the latest procedures.

• Step 1: Cut and prepare wires using custom processing equipment to meet specified length preferences and compliance. 
• Step 2:  Label, after which wires are laid out for design matching.
• Step 3: Peel the insulation at the wire ends with automated equipment to make production faster and more cost-effective.
• Step 4:  Crimp with specific tools meant for that particular contact.
• Step 5:  Fit pins and terminals to the wires.
• Step 6:  Bundle the wires into a harness to meet specific design specifications.

Note: More technical employees are supposed to be IPC/WHMA-A-620 REV C certified. 

Precision Equipment & Testing Technology

During the wire processing process, steps can be automated, making the process easier and more efficient. 

Wire preparation

Fully automated wire processing machines and benchtop equipment can cut, strip, and terminate ribbon cables, battery cables, coax cables, and FFC cables. 

With completely automated wire processing machinery, we can cut, strip, and terminate both ends of a wire at rates of up to 10,000 wires per hour.

Crimping

You can apply automation when crimping terminals and plugging in wires already fitted with end terminals into the connector housing. You can also solder wire ends via automation.

Wiringo performs millions of crimps per year. We use automatic wire processing equipment, hand tools, benchtop equipment, and hydraulic and pneumatic presses to crimp terminals.

Wire Marking

In the wire processing industry, authentication is important. 

At Wiringo, we employ four wire marking methods.

• Heat shrink labels
• Machine-wrapped vinyl labels
• Hand-placed vinyl labels
• Inkjet printing directly on wire insulation

Testing

After every job, a complete electrical continuity test ensures no open, short, or faulty wiring. The testing step is slightly automated since you’ll use a teddy board designed for the wire harness, allowing it to plug into the board and check for any electrical malfunctions.

How to Evaluate Wiring Harness Quality Assurance?

Key indicators for evaluating a manufacturer’s wire harness quality assurance capabilities include:

Manufacturing Certifications

Various certifications can show a manufacturer’s competency and dedication to quality assurance. These certificates indicate that the manufacturer complies with recognized industry rules and regulations, and they can be used to gauge the manufacturer’s trustworthiness. 

Wiringo is rigorously certified, such as ISO 9001 for general quality control and IATF 16949 for automotive quality. 

Rich Industry Experience

A manufacturer with a long track record will likely have a strong reputation for wiring harness quality assurance. Their experience often means they have the tools and expertise to execute your design and ensure its quality.

Trusted Suppliers

As mentioned in the previous section, some regulations, like REACH, require manufacturers to source materials only from REACH-compliant manufacturers. Regardless of whether they aim to be REACH compliant, manufacturers must source all raw materials from reputable industry-recognized suppliers.

Wiringo prides itself on sourcing materials from trusted RoHS-compliant suppliers. Over the last few years, we have established strong strategic partnerships with many global component suppliers. Some notable examples include Future Electronics, Arrow Electronics, and Element 14. Our purchasing department balances cost with quality. 

Clients and Testimonials

Many manufacturers prominently feature past customer testimonials and reviews on their websites. It’s important to take the time to read some of these reviews. It’s also vital that you search for reviews from third-party sources. You can find client interactions and reviews on social media sites like Facebook, YouTube, and Reddit.  

Ensure Wiring Harness Quality With Wiringo

With over ten years of experience in the industry, Wiringo leverages the latest precision equipment and specialized manufacturing techniques to deliver wiring harnesses with quality assurance. Our Outgoing Quality Control (OQC) department performs comprehensive testing featuring cross-section analysis, 100% online, and IEC spotting tests. 

Contact us and speak to a one-on-one representative who will walk you through our quality assurance measures and capabilities.