Helping to realise the smart and flexible ambitions of Mercedes-Benz’s Factory 56 project, Conductix-Wampfler describes its system for the conveyance solutions installed at the plant
Back in February 2018, Mercedes-Benz held a groundbreaking ceremony for its Factory 56 facility at Sindelfingen near Stuttgart in the company’s heartland. In the words of Markus Schäfer, then Mercedes’ divisional board member for production and supply chain, Factory 56 is to “define a new way of building cars”.
The initiative combines three trend-setting features in that it is comprehensively digital, flexible and it brings the term green production to life. ‘As the inventor of the car, we are reinventing production,’ Mercedes-Benz asserts.
In 2020, Factory 56 will start production of passenger cars and electric vehicles in the premium and luxury segments. These include the new generation S-Class as well as the first electric vehicle of the product and technology brand EQ ‘made in Sindelfingen’.
For Mercedes-Benz, flexibility and efficiency have been the guiding principles of the entire project. Flexibility in terms of production processes comes with the implementation of AGVs in selected areas, working into so-called TecLines for cycle operations (for example, sliding glass roof installation).
Flexibility for the employees of the Factory 56 comes in various ideas to help them manage the complexity of their tasks, this can be through individual ergonomic adjustments of the conveyors or access to process information with PDAs and AGVs bringing components kits to the assembly line. Flexibility will mean major efficiency improvements with, for example, the implementation of paperless production but also a strong focus on data collection to enable predictive maintenance operations, supported by artificial intelligence and big data analyses.
Conveyance solutions
Those are the general concepts but how is Factory 56 looking in terms of industrial equipment? Beside the AGVs for the TecLines, mentioned earlier, the production will be supported by a significant amount of conveyors provided by Dürr Systems AG as system integrator. All these conveyors will integrate Conductix-Wampfler solutions, including LJU controls and electrification, namely:
• Skillet line: total of approx. 1,000 metres with 179 platforms
• Doors EMS: approx. 2,500 metres with 270 carriers
• Heavy EMS with tilt function: approx. 1,500 metres with 120 carriers
For the best integration with the plant controls architecture, all these conveyors are equipped with the latest LJU controls and communication solution iDM – intelligent Data Management system. This iDM system opens a wide range of possibilities in term of flexibility of integration and predictive maintenance.
As head of the iDM system, the Master Control Unit (MCU) is a central processing unit that regulates, controls and manages all components and vehicles within a conveyor. It communicates with the carrier controllers through several Track Control Units (TCU) installed along the track, in multiple track segments due to the large amount of carriers in the system.
The TCUs are connected to the MCU via EtherCAT and to the carriers via a proprietary bus system over the conductor rails. This topology means only the MCU is integrated with the plant’s Ethernet-based network, avoiding the use of critical Wi-Fi channels and multiple IP addresses, which then remain available for other systems, like PDAs or AGVs.
At the same time, the bus over conductor rails can provide sufficient data rates to transfer information from the carrier controllers to the plant’s predictive maintenance database, such as carrier number, hours of operation, travel distance, inverter currents, number of relay switching and temperatures of drives.
Using a dedicated Ethernet interface on the MCU, separated from the process PLC interface, all of this data is gathered by the cloud solution implemented on factory level based on a MQTT architecture.
On-board safety and flexibility
In the conveyors, the on-board controls are different due to various power requirements, diverse motions to be controlled, different safety requirements and associated sensors. Nevertheless, they share the same design principle: on-board intelligence, thanks to a compact integrated controller with embedded drives, dedicated safety PLC, and on-site configuration by parameters setting among the main characteristics.
With the help of the freely available software iDM System Manager (iDM-SyMa) and its virtual commissioning and Soft PLC capabilities, all controllers have been commissioned off-site in the carriers at the system integrator’s assembly facility, before being transferred to the plant. The on-board intelligence enables powerful flexibility management to adapt the conveyors’ motions to several parameters like pitch-length based on the load (vehicle length), height or angle variation of the heavy EMS based on the workstation and associate currently working on the line.
Mobile electrification
All these conveyors and their advanced mobile and stationary safety and controls solutions would not operate properly without one basic feature: a reliable energy and data management system. The choice has been made to provide energy and data to these conveyors using the traditional technique of conductor rails, in their state-of-the-art versions for EMS and skillet line conveyors. Indeed, specific attention must be given to several details in order to fulfil this basic expectation with the adequate level of reliability.
ProEMS 0815 has been specifically designed for the electrification of EMS focusing on eliminating the most recurrent pitfalls of the integration and on-site installation as increase the long-term reliability of the system. The current collectors are designed to have the maximum freedom of movement in all axes, a blocking position when not engaged in the rails (eg. for maintenance operations) and integrate the cable routing to an interface with a spring-loaded cable clamp. On the rail itself, the transfer points have been reworked to ensure smooth and proper transfer of the collector shoes at all aluminium rail cuts, such as track switches and elevators.
At floor level, the conductor rails installed in the skillet line face quite different technical requirements and integration conditions. Unlike in an EMS, the collector shoes on skillet platforms are engaged and disengaged to and from the conductor rails several times during one production cycle, as the line is divided in several sections. This puts a lot of mechanical stress on the current collector arms and guide funnels.
At the same time, the mechanical tolerances of skillet systems are higher and access to the conductor rail components in the shallow pit is much more limited in a skillet system. That requires a robust and reliable solution which is found with SingleFlexLine 0811. The specific funnels are designed using stainless steel ramps to reduce mechanical wear as much as possible and guarantee smooth engagement of the copper-graphite collector shoes. The integration of the long arm current collectors inside the platforms guarantees extended tolerance range and maximize service intervals.
Installation and services
A significant part of the performance of an electrification system with conductor rails is directly related to proper installation and maintenance operations. For this reason, Conductix-Wampfler took responsibility to provide services covering the entire electrification scope: starting with expertise during the engineering phase, supporting OEMs and end users, providing installation services, and last but not least training for maintenance crews. Later on, conductor rail systems will require regular inspection and maintenance, services that Conductix-Wampfler can conduct on-site based on predictive or preventive maintenance demand from the plant operation crew.
