Vehicles are becoming increasingly reliant on electronics. Electric vehicles (EVs), in particular, are packed with sensors and actuators that regulate and protect every aspect of the drivetrain. A vehicle’s wiring harness — which connects all these electrical and electronic circuits — is one of the largest and heaviest components purchased by EV makers. It’s also the last barrier to fully automated manufacturing and the benefits that could bring.
Vehicle wire harnesses are safety-critical components in vehicles, especially in EVs equipped with advanced driver-assistance systems (ADAS) and autonomous driving technologies. Wire harnesses also feed signals and power for driver convenience functions, such as heated seats, navigation, as well as infotainment and communications systems.
Figure 1. EV drivetrain parts contain hundreds of temperature, pressure, position, speed, current, voltage, gas concentration, level, humidity, and speed sensors — all of which require electrical connectivity.
However, there are problems arising from manual wire harness production, as follows:
- Manual processing: produced by hand, harnesses are increasingly complex and costly to manufacture.
- Supply chain complexities: production is labor intensive, so most harnesses are produced in countries with lower labor costs. Final assembly, however, typically occurs thousands of miles away from production, adding significant transportation costs, complexity, and risk to the supply chain. The war in Ukraine, where many wire harnesses are made for the European vehicle market devasted supply chains and throttled overall vehicle sales.
- Quality testing: every circuit must be tested in every manually produced wire harness. This is because the process is so prone to errors. Automated wiring would likely only require sample testing because of the more consistent quality that’s achievable.
- Over-ordering: quality issues are so common that some vehicle maker executives have stated they need to “over-order” to ensure sufficient inventory that’s of acceptable quality. Each harness costs approximately $1,000 to $2,000 for a typical mid-range EV, so there’s a significant loss (and waste) with every order.
- Over-specifying: every conventional harness wire must use insulated wires to prevent short circuits, adding insulation weight and cost. Also, the wires typically must be heavier than the electrical requirement demands so they can withstand the physical pressures encountered during assembly and use in vehicles. Adding unnecessary weight to an EV compromises its range, and a shorter range means consumers expect to pay less for vehicles.
- Assembly rework: quality issues are often encountered when harnesses are manually bent and twisted during final assembly.
- Repairs and recalls: warranty claims are costly and vehicle recalls are even more costly. In 2022, CNET reported that Nissan had recalled nearly 700,000, 2014-2016 Rogue SUVs over fire risk. The issue was caused by a poorly sealed wiring connector. That same year, the US National Highway Traffic Safety Administration (NHTSA) cited that electrical system faults and failures accounted for 20% of all vehicle recalls.
- Reputation: the cost to a vehicle’s brand reputation when a recall occurs is incalculable but can run into tens of millions of dollars.
Figure 2. This five-axis additive manufacturing cell can automatically and securely add bare or insulated conductors into components with simple or complex 3D shapes.
Given the above concerns, research financed by the European Regional Development Fund and published in March 2023, concluded that “automation in the wiring harness industry still constitutes the biggest deficiency. Despite research findings and patents, to our knowledge, none of these solutions have been implemented in the field and the state-of-the-art manufacturing process is still highly labor-intensive.”
Overcoming production challenges
There have been many attempts to address wire harness challenges. Some manufacturers have attempted to automate wire harness production but with limitations. Most automation machines simply bundle wires together and, in some instances, affix connectors to the ends of the wires. Inevitably, there’s still manual work involved, such as visually checking the terminations, fixing the bundles together to make the complete harness, and ensuring that wires do not become entangled or otherwise damaged in the process.
Additionally, conventional automation has not solved concerns related to weight, fragility, or supply chain logistics. But there is a new hybrid additive manufacturing and automation process that’s offering a higher degree of automation and reliability.
It uses an “electrical function automation” robot cell, which enables the full or partial replacement of traditional wire harnesses. It’s eliminating, or at least mitigating, the need for manual processes — adding electrical conductors to EV battery packs, infotainment systems, and more.
A new type of automation
A precision five-axis robot with interchangeable tools can add 3D polymeric features to metal, ceramic, or polymer surfaces. It can handle complex shapes, add bare or insulated wires, and attach electrical connectors to make the components functional. The robot can also route wires with conductors up to 3mm in diameter, which is approximately 13 AWG. This means each conductor can carry over 20 amps, sufficient for low-level signals and functions that include powering relays or fans.
Figure 3. Bare or insulated wires with conductors up to 3mm in diameter can be automatically secured onto complex 3D components.
Anchoring each wire to a substrate is fast, cost-effective, and flexible. The substrate can also be the component. For example, it can be a battery pack, or a part designed to carry the wiring for attachment to the component. It can be rigid or flexible. Because each wire is individually secured, it might not require insulation, saving cost and weight. It’s also less prone to environmental and mechanical damage because it’s securely positioned.
The finished products or components with integrated wiring also lend themselves to robotic final assembly. The reduces labor and supply chain risks by co-locating the integration of electrical conductors and components with the vehicles’ final assembly.
The automation race
In EV manufacturing, automating wire harness production can reduce the size and weight of sub-assemblies and their parts, enabling onshore manufacturing. It can also increase vehicle reliability, cut after-sales warranty and recall costs, and protect the value of the brands in which automakers invest so much to build.
The five-axis robotic cells described here are expected to be integrated into EV manufacturing lines within the next 12 to 18 months. Who will take pole position, we wonder?
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