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HomeTips & GuidesCable Assembly Manufacturing: A Detailed Guide to the Wiring Harness Manufacturing Process

Cable Assembly Manufacturing: A Detailed Guide to the Wiring Harness Manufacturing Process

About Cable Assembly Manufacturing: Many electronic devices use wire harnesses to transmit electric or power signals. 

As these harnesses play a critical role, you must always pick one made from high-quality materials. 

Further, it is equally essential for wiring harnesses to meet all sorts of safety standards. 

Only a reputed and reliable wiring harness manufacturer understands this fact and ensures to deliver you premium quality products through a specific cable assembly manufacturing process.

Cable Assembly Manufacturing Understanding:

When the cables, wires and connectors assemble together in a complicated structure to transmit electricity and power signals, it results in a wire harness. 

The companies involved in assembling cables and wires are wire harness manufacturers. As a part of their manufacturing, a large number of processes such as crimping, soldering, stripping and wire assembling are available at their site.

Every wire harness is assembled for a specific application using innumerable wires and connectors. 

However, the complexity of each harness may differ based on its use application. 

Mostly, these harnesses are widely used in industrial, aerospace, automotive and other such sectors. 

Due to their critical use in all these major industries, they must deliver optimal performance with high durability.

 Premium quality cable assemblies

 Premium quality cable assemblies

Designing a wire harness assembly:

A very basic structure of a wire harness comprises very few cables and wires with essential terminals connected.

For more complex electrical systems requiring multiple operations, it’s a complex assortment of wires, cables and connectors, which otherwise would have looked messy in their applications.

The wire harness designing process starts with the basic design that is framed on the basis of the electrical and geometrical requirements of the equipment.

 Using designs, technicians work on preparing documents on the manufacturing and assembly board of the wire harness. 

Also called a Pinboard, an assembly board is a full-size diagram showing the location of all the components used in harness manufacturing.

Several factors impact the wire harness designs, such as:

  • Will the harness need continuous flexing?
  • What will be the working conditions of the harness, whether it’s indoors or outdoors?
  • Required voltage
  • Number and characteristics of conductors and circuits required by the assembly
  • Operating temperature information (maximum, minimum and average), potential fluctuations in the temperature.
  • Exposure to any harmful substances, be it corrosive chemicals, moisture, heat or other weather conditions.
  • Local regulations regarding safety and the environment help the manufacturer determine the components.
  • Routing and breakouts.

Schematic prewired cable assembly

What does your Contract Manufacturer (CM) need for the manufacturing process?

For wire harness manufacturing, contract manufacturers use a panel with pegs positioned on them. 

Wires and cables are laid out on this panel, and the location of pegs determines their branching out. 

These pegs also indicate the position of connectors. A CM needs to be very careful with the dimensions during laying out wires.

 Based on your information, the contract manufacturer creates information in the form of notes or 3D CAD models to determine the exact dimensions for wiring and connections.

So, the preciseness of the information helps a contract manufacturer create a harness most appropriate to the application’s use.

 It would be best for you to provide the following information to the contract manufacturer for precise and accurate manufacturing.

  • Wire lists specifying their colors, nets and connectors
  • Comprehensive information regarding connectors with images showing their pin locations
  • BOM with part numbers
  • Assembly drawing with instructions, label locations and tolerances
  • Final test specifications

Cable assembly manufacturing process:

The cable assembly manufacturing process can be categorized into the following steps:

Design review:

As soon as the CM receives the design and Bill of Materials, he first reviews it to ensure everything is good to go. 

All the specified parts and components will be evaluated for cost, performance, and availability. In case of any issue, the CM will first look for its replacement.

Materials preparation:

Once the CM gives the green flag to the Bill of Materials, procuring materials and components starts to kick off production.

Assembly documentation:

Based on the customers’ input, the CM simultaneously starts preparing assembly documentation for manufacturing. 

This documentation contains strategically listed assembly steps, illustrations, images and test procedures. 

Along with it, technicians will also prepare an assembly panel with the pegs installed at the specified points.


The working model of a wire harness design is its prototype. The manufacturers test this prototype for its use in the intended application. 

This prototype is inspected properly and through measurement tools, its design is compared with the CAD models. 

This prototype should meet all the specifications of the drawing and the model. Any failure means reworking the project.

 Ensuring the accuracy and precision at the prototype stage saves time and cost in the mass production.

Inbound inspection:

Before the wire harness assembly process, the manufacturer inspects and tests the wires, cables, and other components from the suppliers. 

Using a digital system, inspecting officials maintain data related to wire gauges, damages in connectors, correct spacing of the connectors, etc. 

All the information should be properly documented.


If the prototype passes all the parameters, it’s time to assemble the wire harness. 

During assembly, a couple of quality checks and inspections are done to ensure good quality in the end products. 

The accuracy ensured at this stage saves time in production, builds the company’s reputation and prevents losses.

The basic process of wire assembly includes cutting wires to the desired lengths, stripping off the insulation, crimping wire contacts and finally, connecting the connector. 

As the assembly process involves so many steps, the chances of errors also increase. 

Thus, each step must be carried out professionally with high precision.

Wire stripping-To assemble wires, insulation is stripped off to reveal the central metal conductor. 

Care is taken to keep the wires and the insulation undamaged, as otherwise, it can lead to safety issues. 

It’s better to use magnification during wire stripping to ensure a smooth, clean and safe stripping process.

 Wire crimping: Manual or automatic crimpers crimp contacts at the wire ends. In case of any error, it can lead to discontinuity of the signal. 

Excess crimping can damage the wire, while insufficient crimping may leave the wire loose. 

The manufacturing team inspected the finished crimped wires through an inspection system to prevent defects.

Wire termination: After crimping, terminal pins are attached to the wires either through soldering or by directly inserting the wire into the terminal.

 As the electrical devices are becoming more compact day by day, the assembly boards become further tiny. 

Manufacturers often use microscopes to ensure correct termination to avoid defects and damages.


After completing the assembly process, it’s time for final testing. This testing phase ensures that the wire harness functions as intended. 

The final testing procedures include continuity tests, pull tests and megohm tests

Further, some visual testing is also done using a microscope. If any adjustments need to be made, they are done at this stage only. 

After final testing, the wire harness moves to the mass production stage.

Factory worker assembles cable connections.

Factory worker assembles cable connections.

Why is there a need for the manual assembling of wiring harnesses?

Although automation has overtaken almost all sectors, wire harness manufacturing is the only one left. 

To date, the process is much more efficiently done manually than by machines. It’s because of the several intricate processes in manufacturing that require manual precision.

Some of these processes are:

  • Taping breakouts
  • Installing cables and wires through conduits and sleeves
  • Binding wires and cables with cable ties, clamps, and tape
  • Installation of terminated wires in varying lengths
  • Crimping wires multiple times

All these processes are still difficult to automate, and manual processing only seems to be the cost-effective solution. 

For the same reason, the time taken to manufacture wire harnesses is often more than any other cable assembly, ranging from a few days to weeks. 

The complexity of the designs may further extend the production times.

Manual processing does not mean that everything is done by hand. Nowadays, there are fully automated machines and devices for wire stripping, cutting and crimping.

Some of the pre-production processes that are done through automated machines include:

  • Crimping one or both sides of wires using crimping machines
  • Soldering ends of wires
  • Using automated machines for cutting and stripping wires
  • Twisting wires through different tools
  • Plugging terminated wires into connector housings

Wiring harnesses manufacturing machine

Wiring harnesses manufacturing machine


Cloom manufactures cable and wiring harnesses for general applications, but there are customization options, too. 

For instance, we can cut, strip, twist and color the wires as you choose. We can use zip ties or cable wraps for binding harnesses, as you request. 

We give you a choice of labeling services, either by heat shrink tubing or laser-printed stickers.

Furthermore, whether you connect to us for the first time or need another set of previously delivered wiring harnesses, our attention and quality to our customers remain the same.

Contact us for your cable assembly requirements right from prototyping to final delivery.

Hi I am Christa, sales manager of Cloom.

I have extensive expertise and experience in wiring harnesses and I believe I can help you.

And we have a very professional technical team who can clearly understand the customer’s needs and give professional suggestions and solutions after receiving the drawings.

If you also have wiring harness needs, please send me the drawing so that we can give you our quote and start our business.

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