Comprehensive Guide to Designing Electrical Wire Harnesses

Introduction to Electrical Wire Harness Design

What is an Electrical Wire Harness?

Often referred to as cable assemblies, wire harnesses are a unified diverse arrangement of leads, wires, cables, and connectors. A typical wire harness consists of a non-conductive sheath or housing wrapped around a collection of integrated but separate conductors.

Even modern home appliances and electronics have become so advanced that they require different cables with different connectors – just like computers. Wire harnesses allow you to streamline these connections and make cable management easier. However, this is only one facet of their usefulness…

Importance of Proper Wire Harness Design

Well-designed wire harnesses facilitate signal integrity by mitigating interference or loss. Because they must distribute power and signals to different components, it’s important that they do so without any cross-interference or intrusion.

High-stress environments like factories require robust wire harnesses to ensure safety and meet industry standards. Sub-standard wire harness design can make maintenance and installation more difficult. 

By optimizing the design, you can make faults and issues easier to identify. This along with the streamlining of resources and materials can lead to greater cost savings in the long run.

Fundamental Principles of Wire Harness Design

Here are a few design principles you can refer to determine and ensure the quality of a wire harness design. 

Design Efficiency

First, the designer needs to highlight the requirements of the wire harness. This includes the environmental conditions and voltage, current, and signal requirements. The designer can then use these properties to compile a specification to guide the design process. 

This guide can then be used to minimize the complexity of the design while maximizing its functionality.

Reliability and Durability

Designers and manufacturers can ensure the durability and reliability of the harness by selecting the appropriate materials based on the specifications. This includes wire types, connectors, and terminals. 

Sharp bends and abrasions must be avoided at all costs. Thus, the designer must carefully plan the cable routing paths for assembly. The wire harness design should implement the necessary stress reliefs, clamps, ties, and sleeves to bolster the structure. 

The automotive industry is an example of an industry that was revolutionized by the improved designs and reliability of wire harnesses.  

By simplifying the design and optimizing the material selections, automotive manufacturers managed to increase the output and development of wire harnesses. It’s a good idea to follow this example. 

Cost-Effectiveness

Another cost-saving advantage is how optimal design also ensures that the resources and materials used to create the harness are implemented optimally. This reduces waste and overall costs. A good wire harness designer can tailor the design to meet specific use cases and requirements. 

Electricity, chemicals (for cleaning), water, and manpower are all resources that can be saved by implementing efficient electric wire harness design. 

WellPCB performs quick Design for Manufacturing (DFM) checks for orders. This ensures that the design can be manufactured as smoothly as possible. 

Design approaches fall into four key categories:

Best Practices for Designing Efficient and Reliable Wire Harnesses

The following are some of the approaches designers must use to produce high-quality electric wire harnesses.  

Material Selection

The materials in electric wire harnesses fall into three categories:

• Conductors (wires)
• Insulation
• Connectors

Materials should meet the specified current capacity, insulation, and the harness’s operating environment. Let’s break down all the materials: 

Cable Management

Wire harnesses must avoid incurring damages from bunches, bends, and other structural impediments. There are three main techniques to prevent tangles and organize your wires with your design:

• Wire Bundling: Leverage cable ties and lacing cords to organize and hold wires together. Some usage tips include:
  • Always ensure cable ties are not applied too tightly. 
  • Lacing cards are preferable as they are more flexible and provide looser bundling. 
• Protective Sleeves and Conduits: Use a braided sleeve to guard wires from abrasions and environmental factors. Alternatively, you can house the wires in conduits which can make wires easier to organize. 
• Strain Relief: Adding strain relief boots at connection points can protect wires from excessive pulling and bending. Grommets should be applied to wires that pass through panels and bulkheads to protect them from abrasions. 

It’s a good idea to plan and define specific routing paths before bundling. You can also use clips and clamps to secure wire bundles along their routing paths.

Connector Selection and Placement

Your wire harness’s connectors must be able to handle the voltage and current requirements of its use case. Different connectors are compatible with different signal types. For instance, if your wires are responsible for transferring power signals, your connectors should be able to facilitate this signal type too. 

Other considerations include:

• Temperature range
• Moisture
• Dust resistance
• Vibration and shock (caused by the operating environment) 

When positioning connectors, make sure that they are easy to access for assembly, maintenance, and troubleshooting. External and internal components or structures should not impede the connectors. 

Additionally, it’s important to avoid placing connectors near heat sources while ensuring that connectors have access to necessary ventilation. 

Shielding and Protection

Keep power and signal wires apart to prevent electromagnetic interference (EMI) and ensure strong signal integrity. Make sure to apply EMI shielding techniques and materials to sensitive wires.

Documentation and Labeling

Each wire should feature a label denoting its function and destination. This makes installation, troubleshooting, and maintenance easier. Consider using colored labels or wires to indicate different functions or circuits. 

Keeping well-written documentation is crucial. Your design documentation should include detailed schematics and diagrams illustrating the routing and connection of all the wires within the cable assembly.  

Common Challenges in Wire Harness Design and How to Overcome Them

There are a variety of factors that may make wire harness design challenging. Fortunately, there are ways to manage and overcome these complexities. 

Managing Complexity

Designers must ensure that all connections are routed correctly. The harness will likely be used in a tight space. This should not impair its function. 

Using modular design is one of the best ways to manage complexity in wire harness design. It involves separating the harness into smaller sections or sub-harnesses which can be easily attached and detached. This eases maintenance and repair. 

Ensuring Traceability and Quality Control

Being able to trace the history, location, and usage of wire harnesses is important. If a design or manufacturing defect is discovered, it enables the manufacturer to recall the wire harnesses. It also allows the manufacturer to keep track of each process the wire harness goes through during assembly. 

Manufacturers must establish a continuous feedback loop that allows them to gather information from clients and customers. They can then use this information to improve the wire harness’s design.

In addition to keeping an up-to-date compilation of the necessary documentation, manufacturers must ensure that they perform the necessary inspections and tests. This includes incoming inspections, in-process inspections, and final inspections. 

Three main testing types exist for wire harnesses:

• Electrical: This includes insulation resistance tests, continuity, and voltage deep tests which are all designed to verify the integrity of the wire harness.
• Environmental: Tests designed to assess the wire harness’s ability to withstand environmental conditions.
• Functional: Test the wire harness in its intended application to verify that it runs as expected.  

Manufacturers must always consult the latest guides, regulations, and standards to ensure that the manufacturing process along with the final product complies as it should. 

Balancing Cost and Performance

Simply using the highest quality materials you can find isn’t realistic. While high-quality materials can enhance performance, they can also increase costs. The best approach is to select materials that will match the specified design properties as closely as possible.

Because prices and quality levels from suppliers may vary, manufacturers must be discerning when sourcing materials.

Advanced Technologies and Tools in Wire Harness Design

Through technological advancement, manufacturers and designers have managed to increase the reliability, durability, and functionality of wire harnesses. Some examples of important technology are:

Computer-Aided Design (CAD) Software

Digitalization has increased the productivity and output of designers with the most common form being computer-aided design (CAD) software.

It allows designers to outlay and plan the structure of the wire harness in a virtual environment. This grants them more precision. 

Simulation and Testing Tools

Digital twin and simulation software is another form of digitalization that enables engineers to simulate real-world functional tests. The performance and behavior of wire harnesses can be simulated under a variety of operating conditions. This allows for virtual prototyping and validation before production.  

Automation and Robotics in Manufacturing

Robotic machines have improved the efficiency and accuracy of wire harness fabrication. Manufacturers use these machines to attach terminal and strip insulation from wires. 

Because of these machines’ ability to accurately replicate each step, they produce wire harnesses with more consistent quality than manual operators. Moreover, they can reduce errors, cycle times, and overall labor costs. This allows for higher-quality wire harnesses. 

WellPCB’s Approach to Wire Harness Design and Fabrication

WellPCB is primarily known for the manufacture of high-quality PCBs. We’ve transferred these capabilities, knowledge, and expertise to the manufacture of wire harness PCBs. 

Proprietary Design Methodologies

PCBs are the foundation of all advanced electronic devices and systems. Wire harnesses allow us to interface, power, and connect these systems, essentially expanding the functionality and uses. 

In addition to understanding the core fundamentals, WellPCB knows how to produce wire harnesses that complement large high-frequency applications. If you know how to design and power a PCB, you know what it takes to power and connect an entire network of devices.

Customization Capabilities

WellPCB handles the entire process from drawing, sourcing, and processing to ensure high-quality custom wiring harnesses. Over the years, we’ve established a flexible and responsive communication infrastructure that allows us to keep our clients up-to-date each step of the way.

We create wire harnesses for computer systems such as servers and personal computers (PCs), automobiles, motor cables, light fixture cables, ground lug cables, and more. 

Commitment to Quality and Compliance

WellPCB is highly committed to ensuring the quality and compliance of our products. All wire harnesses undergo continuity tests, failure probing, and high potential (hipot) tests to assess and ensure their quality.

Our materials and components are sourced from reputable suppliers such as Amphenol, JST, Molex, and Tyco Connectivity.

Some of our accreditations and certificates include:

• IPC-A-620
• IPC-A-610
• IPC-6011, 6013, and 6017
• ISO 9001
• RoHS Compliance

Step-by-Step Guide to Designing Electrical Wire Harnesses

The following are the required steps for designing an electrical wire harness:

Step 1: Requirements Gathering

First, gather information to determine the voltage, current, signal types, and other electrical specifications. Next, use space constraints, flexibility, and environmental conditions to identify the mechanical requirements. 

Step 2: Conceptual Design

This step involves creating a wiring diagram that outlines the connections between components. This will help you determine the basic structure of the wire harness.

You’ll also use this information to select the appropriate wires, connectors, terminals, and protective sleeves based on the material requirements. 

Step 3: Detailed Design and Layout

Once you’ve established a concept of the design, this step requires you to “codify”. This involves using CAD software to draft the physical layout of the harness with its routing paths.  

Step 4: Prototyping and Testing

This step involves fabricating the prototype to validate the design. The prototype should undergo electrical and environmental testing to ascertain that the design does not require any adjustments before full-scale production.

Step 5: Final Design and Documentation

The final design is confirmed before manufacturing occurs. Detailed documentation including the assembly instructions, parts lists, and testing procedures must be compiled to help guide the manufacturing process. 

The manufacturer must implement rigorous quality control measures at each pivotal step of the fabrication process. This ensures that the final product is free from defects and meets tall design specifications. 

Conclusion

Wire harnesses connect and bind complex electronic systems. The design process can be complex but made more manageable through the practice and suggestions highlighted in the above guide. For all your PCB and wire harness needs, contact WellPCB today to see how we can help you cut costs on your next project. 

Frequently Asked Questions (FAQ)

What are the key principles of electrical wire harness design?

Design efficiency, durability, reliability, and cost-effectiveness are primary principles of electrical wire harness design. 

What materials are best for designing durable wire harnesses?

The best materials for designing wire harnesses are copper (as a conductor) and PVC.

What are the common challenges in wire harness design and how can they be addressed?

Some challenges include complex design and material requirements, environmental factors, and documentation and traceability. Many of these challenges can be overcome by simply following the best practices for designing wire harnesses. 

How does WellPCB ensure quality in wire harness design and fabrication?

WellPCB uses design for manufacturability checks, quality assurance, and functional tests to ensure the quality of wire harness designs. 

What industries can benefit the most from WellPCB’s wire harness design services?

Any industry that uses wire harnesses can stand to benefit from WellPCB’s design and manufacturing capabilities. This includes companies with on-premise servers and networks, aerospace systems, electric vehicles, and medical and industrial equipment.