Standardized, roboticized, relocated: This is what the wiring system production of the future could look like. But only if the wiring system manufacturers work together.
Cable harnesses stretch for several kilometers through the vehicles, weighing a good 50 kg.
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If you compare a vehicle to a human body, the on-board network is the nervous system. It is responsible for the power supply as well as the flow of information between components and control units. Physically, the vehicle electrical system "consists of the wiring harness or several sub-harnesses," explain Springer authors Gerhard Babiel and Markus Thoben in the chapter Einführung Bordnetzstrukturen (page 1) of the German language book Bordnetze und Powermanagement. In the wiring harnesses of modern cars, several kilometers of cables and wires are installed and several thousand contact points are connected. The cable harnesses reach a weight of around 50 kg. With electric vehicles or, for example, future developments in self-driving systems, more and more electronics must be accommodated in as small a space and with as little weight as possible.
For wiring systems, electrification and automated driving represent a paradigm shift. "Whereas they used to be pure commodity products, they are now transforming into safety-critical components. This results in completely new requirements for the manufacturers of wiring systems in terms of the quality and traceability of their products", says Bernd Jost, Managing Director at DiIT, a specialist for integrated software systems in cable harness production. These requirements can be met with digital twins, as he explains in his guest commentary Automation of Wiring System Production Begins with Design from ATZelectronics worldwide 5-2022. These digital representations of the wiring systems should allow a continuous reconstruction of their product and process history.
No automation, no competitiveness
A key prerequisite for this is further automation in the production of wiring systems. In contrast to many other cable processing industries, the production of wiring systems is still characterized by numerous manual processes, explains DiIT. Although the cutting of the cables is highly automated, the pre-assembly of the wiring systems is then mostly done manually and their final assembly – mostly in "best cost countries" – is even carried out completely by hand.
According to DiIT, these manual processes prevent the digitization of the industry. They stand in the way of end-to-end data collection and processing – and without them, wiring system manufacturers would not be able to meet automotive groups' increasing demands for the quality and traceability of their products. "Wiring system manufacturers must automate their production end-to-end, otherwise they risk losing their competitive edge," DiIT says.
Automation starts with design
But what must the production of wiring systems look like in order to be well positioned for future requirements? For DiIT, the future wiring system is characterized by three aspects:
Standardization
One major reason for the lack of automation is the absence of standardization in wiring systems, which in turn is due to the fact that the architecture of today's wiring systems is designed for customer-specific equipment variants. "Therefore, the automated production of wiring systems begins with their design: they must be constructed in such a way that they can be produced automatically in the frst place. This requires modularisation and standardisation of the wiring system architecture", says Bernd Jost in his guest commentary.
For this reason, there is no way around the industry defining components that can be automated. These standards would have to drastically reduce the variance of components such as cables, contact parts and connectors and completely exclude non-automation-capable components such as shrink tubing or grommets. One project of the Arena2036 research campus (source in German), for example, is the development of a standard (DIN 72036) for wiring systems suitable for automation. However, "this approach contradicts previous competitive ideas of the wiring system manufacturers and can therefore only be realized on a cross-company basis," says Jost.
Robotization
On the basis of these standards, wiring system manufacturers could then rebuild their process chains piece by piece in order to automate their production from end to end. According to DiIT, final assembly of the wiring systems on the laying board is a particularly big challenge. This is because the cable cross-sections, the connectors and the connections have now become so small that manual processing is difficult and time-consuming. One obvious way to automate this process step would be to use robots.
For example, a process for the automated production and assembly of cable harnesses, as detailed in a German language article, has been developed at Karlsruhe University of Applied Sciences. By cooling the cables, a flexurally rigid state is achieved, allowing industrial robots to be used flexibly and economically to manufacture cable harnesses. According to the researchers, the advantages of the process are a significant reduction in production times as well as better planning and shortening of the supply chain, as production can be relocated back to industrialized countries due to cost optimization through automation. This in turn also has a positive effect on quality assurance. In addition, it should be possible to reduce lead times because the required cable harnesses do not have to be ordered long in advance. The "ProP4CableSim" project (detailed in a German language article), on the other hand, is working with simulations to facilitate the installation of cables in vehicles.
Relocation
Until now, according to DiIT, robots for final assembly of wiring systems were not economically feasible. But rising wages in "best cost countries" could change the calculus. Added to that, he said, are the geopolitical upheavals and the increasing risk of failure of suppliers there. Final assembly automated with robots in close proximity to carmakers could be more cost-efficient and safer in the future than current practice, says DiIT.
Wiring system manufacturers must join forces
One thing is certain: the growing complexity of the wiring system must go together with automated production. However: "The linchpin for the automation of wiring system production is standardization. Wiring systems must be designed in such a way that they can be produced automatically in the first place," explains Bernd Jost. He concludes: "However, the industry can only meet this challenge together, as it contradicts the previous competitive approach of the wiring system manufacturers. Companies must join forces and jointly develop standards suitable for automation."
