Software Traceability now a must

Author / Editor: Bernd Jost / Steffen Donath

Manufacturers of wire harnesses will soon be faced with new quality requirements. Find out how using digital twins can ensure vertical and horizontal traceability of products.

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Bernd Jost is the Managing Director of DiIT GmbH in Krailling near Munich.
Bernd Jost is the Managing Director of DiIT GmbH in Krailling near Munich.
(Source: DiIT GmbH)

The dawn of the electrified, self-driving car represents a paradigm shift for manufacturers of wire harnesses. Once seen solely as commodity products, wire harnesses are now increasingly becoming safety-critical components. They are used for running an increasing number of energy, signal and communication flows that support safety-critical functions such as steering, lane changes or braking. Problems with the electric systems can lead to serious malfunctions that not only result in the possibility of significant material damages, but also a risk to life and limb, not to mention hazards for the environment and the public.

It will thus become more important than ever for manufacturers of wire harnesses to identify the causes of a problem quickly, rectify them and be able to start immediate, targeted product recalls. Only then is it possible to restrict potential hazards quickly and minimise image damage — both in terms of the reputation of the manufacturer of wire harnesses at the vehicle manufacturers and the reputation of the vehicle manufacturers at the end customer. Of course, the best option is to avoid the problems in the first place. This not only enables manufacturers of wire harnesses to eliminate the possible dangers, but also the risk of paying heavy fines. This is because liability in the era of autonomous driving is now shifting from the driver to the manufacturer, its suppliers and even individuals within the value chain. If a malfunctioning wire harness causes an accident in an autonomous vehicle, the manufacturer can expect a fine that could reach hundreds of millions of euros.

Digital replicas of wire harnesses enable continuous traceability

With this in mind, seamless product traceability is now unavoidable for manufacturers of wire harnesses. This can be achieved with the help of digital twins. These are digital replicas of wire harnesses that contain interlinked, consistent data records and enable manufacturers to trace their products across their entire life cycle. Digital twins cover two dimensions here: Firstly, they cover the product history, which allows the composition of a wire harness to be reconstructed and thus ensures vertical traceability. Secondly, they also cover the process history, meaning the value chain can be reproduced and thus ensures horizontal traceability.

In terms of the product history, the digital twin compiles the raw materials, parts produced in house and purchased parts that have been used during the production of a wire harness. This allows the manufacturers to localise errors, rectify them and provide the vehicle manufacturers with data for fast and very specific product recalls. With the process history, the digital twin receives information on how the wire harness has been created, including the process steps and process parameters that have been implemented in order to produce the wiring system. This includes the force used during crimping, tool changeovers, post processing measures or the results of quality tests. Based on this holistic data, the quality of the wire harnesses can be continually improved with the help of predictive analytics. As error patterns can be uncovered and their causes identified using methods such as machine learning, manufacturers can take steps to prevent these errors in future.

Implementing digital twins with manufacturing execution systems

These digital twins can be implemented with manufacturing execution systems (MES), which communicate with the machines, employees and ERP systems involved in the process. The role of the MES has always been to control, inspect and document the production process, which makes it predestined for use with digital twins. However, the quality here also depends to a large extent on the configuration of the actual physical procedure that provides the system with data. In order to provide the necessary information, this process has to be adjusted on an operative, technical and organisational level.

Diagram of the process: Continuous traceability
Diagram of the process: Continuous traceability
(Source: Kuhn und Jost)

In terms of operation, the procedure has to be expanded to include steps such as the scanning of products or the documentation of quality inspection results. Ideally, this is made by stationary scanning systems or automated documentation via the machines. This ensures only minimum extra work is needed in the workflows and human intervention is kept to a minimum. Furthermore, the introduction of principles such as FIFO (‘first in, first out’) and poka-yoke significantly reduces the number and complexity of additional process adjustments. Nonetheless, the digital twins still require suitable devices in order to capture the data relevant for traceability. In terms of technology, this can mean the installation of scanners or updates and the reconfiguration of machines. Additionally, trace objects have to be selected and equipped with traceability technology such as barcodes or RFID. Last but not least, organisational awareness also plays a decisive role when it comes to the quality of the digital twins. Employees can no longer scan several products in advance instead of each individual product during assembly or scan the same product multiple times in place of the different parts that are actually used. If there is a lack of discipline when carrying out the processes, this will lead to incorrect and inaccurate records.

MES solutions have to offer flexible support for smooth transitions

It goes without saying that the necessary adjustments to the process and the resulting modernisation and further automation of production cannot be achieved overnight. Nonetheless, manufacturers of wire harnesses should not put off this step any longer. Taking the necessary steps to ensure a smooth transition will probably take years and is something that should be put into action today. It is the responsibility of the MES providers to develop solutions that can offer flexible support to manufacturers on each step of the transition process.