Interview: The cable with the smart core
Leuze intends to improve the availability of machines and systems with an intelligent sensor cable. The etz editorial team interviewed Michael Mayer-Rosa, Director of Product Center Accessories, and Felix Düllo, Product Manager of the Owen-based sensor technology expert to find out what this SmartCore technology is all about.
Where did the idea for "SmartCore" start?
M. Mayer-Rosa: As a specialist for connectivity and connection technology, we are naturally also involved in Industry 4.0. Here it is common practice for sensors, IO modules, and other components to send messages to higher-level systems. So we asked ourselves, why not also the interconnection cable? That's why we were looking for a way to integrate intelligence without installing additional electronics. We followed the principle of construction cranes. The interconnection cables of those cranes have a so-called sacrificial cable. This additional wire signals the cable has reached the end of its mission time. We wanted to adapt this approach to automation. Therefore, we developed an additional wire and incorporated it in a standard cable to make it Industry 4.0-compatible.
How is the life expectancy of the cables monitored?
M. Mayer-Rosa: We integrate a copper wire that was specifically developed by us into a PUR or TPE cable. This wire breaks after 80% of the minimum 5 million movement cycles guaranteed by us, while the other four wires continue to work. The user thus gets a warning in good time with a grace period of 20% of the life expectancy and can safely replace the cable without any production downtime. In addition, it is possible to plan future maintenance intervals more reliably by continuously evaluating the data.
F. Düllo: The challenge was to develop a wire that is no thicker than a standard wire, since it had to fit into a standard cable, and it had to be almost as flexible, so that it would break after 4 million movement cycles – no sooner and no later. Standard 5-wire cables do not have this red wire that carries 24 V. The color-coding also prevents mix-ups. If this voltage fails to arrive at the other end of the cable, a warning message is issued and the cable replacement can be scheduled: this is high level predictive maintenance, and not only for IO-Link, but also for other control systems.
What cables are available?
F. Düllo: PUR and TPE cables with four wires plus sacrificial wire including M12 connector, either on one or both ends, in lengths of 2, 5, 10, or 30 meters. The TPE cable including connector is even resistant against the effects of welding operations. Other lengths are available on request.
What faults are monitored with "SmartCore"? What happens with other sources of danger, such as excess temperature, overexpansion, overrotation, kinking, or crushing?
F. Düllo: We are monitoring a potential wire break of the sacrificial cable. Monitoring for other dangers is conceivable for Ethernet cables, for example, but this is not currently under development. Ultimately it is also a question of how much users are willing to pay for additional system monitoring. In the US, the level of acceptance is significantly higher, meaning the willingness to use standard cables without "SmartCore" is significantly lower than in Europe.
For whom is this a good investment?
M. Mayer-Rosa: Anyone with machines and systems with moving parts who consider not only the cost, but also the performance and the return on investment, or the total cost of ownership. Robotics, for example, is the perfect example. While "SmartCore" is twice as expensive as a standard cable, the investment pays for itself many times over if only a single unscheduled standstill is prevented.
F. Düllo: Surprisingly, the concept is much better received in the US than in Germany. It appears maintenance managers in the US get to have a say, whereas in Germany purchasers often order based on price only. Digitization is also more advanced in the US. And with "SmartCore," the entire system – including the interconnection cable – can be mapped to a cloud solution.
Other concepts available on the market monitor the cable condition with electronics. Why are you using a sacrificial wire?
M. Mayer-Rosa: Measuring electronics is much more expensive and complex to install. A ready-made cable with sacrificial cable is much less expensive. Additionally, it has also proved very efficient in practice, due to its simplicity. The costs are limited to incorporating the cable into the robot chain or replacing "regular" cables with those that have SmartCore technology integrated.
What are your further plans with "SmartCore"?
M. Mayer-Rosa: Depending on customer requirements, many things are possible, from eight- or twelve-pin solutions to power cables and the particularly favored Ethernet cables. The market will show us what it wants, and we will then develop, present, and offer this at the appropriate markets.
Leuze developed "SmartCore" specially for applications with moving cables, such as for robotics or handling axles. The cable contains an additional, special sacrificial cable that fails at approximately 80% of the possible movement cycles. To evaluate, the sacrificial cable is bridged with the supply voltage and, if the core breaks, gives early warning of the impending end of the cable's mission time. Unplanned system downtime caused by cable breakage can thus be effectively prevented, and the sensor cable at risk of breaking can be replaced during the next scheduled maintenance cycle. The "SmartCore" technology thereby contributes to increased system availability.
Appeared in the 5th issue of the etz in 2020. www.etz.de