PC-based control and OPC UA communication in a laser welding system for the electromobility sector
In order to serve the rapidly growing electromobility market, particularly efficient manufacturing processes are requiredwhen it comes to the production of lithium-ion battery systems. This is made possible by Manz’s BLS 500 laser weldingsystem, which allows individual battery cells to be contacted highly precisely and thus connected to form battery modules. High efficiency is ensured by a graphical programming tool and a virtual commissioning tool from Manz, as well as throughfast PC-based control technology from Beckhoff and the continuous OPC UA communication that can be achieved using it.
Manz AG, based in the German city of Reutlingen, is a globally operating hightechengineering company that focuses on production solutions for electromobility,battery production, electronics, energy, and medical technology. Its portfolioranges from customized single machines for laboratory production or pilot andsmall series production to standardized modules and systems or turnkey lines formass production. Consequently, the company has particularly high requirementsregarding the flexibility and performance of the automation technology used, ascan be seen in the production equipment for lithium-ion battery cells and batterysystems as well as capacitors, to name but a few examples.
Application-specific customizable laser platform
A prime example is the new Battery Laser System (BLS) 500, which is designedas a flexible platform for the various laser processes used in the manufacture oflithium-ion batteries. Starting from a standardized machine base, it can operateindividually as a single system where the workpiece is loaded manually or aspart of an integrated production line to achieve high-precision laser welding, aswell as laser cutting and drilling, or partial material removal.
In the BLS 500 application described here, a battery module consisting of roundbattery cells is inserted into the machine manually in a laboratory scenario, butotherwise this is an automated process. The individual cells are then welded tothe contacting elements by laser. As a graphical programming tool, the SmartLaser Assistant uses the CAD data of the underlying battery module to createthe associated recipe, i.e., the optimum path calculation for all welding pointsas well as the appropriate laser power in each case. Stephan Lausterer, Head ofSoftware Core Design and Product Development at Manz, describes the clearapplication advantage as follows: “Our programming tool makes it much easierto adapt the BLS 500 to diverse applications, i.e., to different cell types andmodule formats.” He adds that the result can then be conveniently examinedin Manz’s virtual commissioning tool, and not only that: “Commissioning isaccelerated and simplified by the fact that using the model the control programcan be tested in detail and realistically in advance, i.e., before the machine has actually been mechanically assembled. In addition, high precision is achievedby using image processing to compare the CAD data of the battery pack withreal-life data and to take any offset values into account during the weldingprocess. In all these aspects, we benefit from the TwinCAT control software withits convenient and powerful OPC UA integration.”
System advantages of PC-based control
The importance of high-performance and, above all, flexible control technologyhas also increased significantly at Manz in recent years, and it was this thatultimately led to the partnership with Beckhoff which has been sustained forover ten years now. Stephan Lausterer explains this in more detail: “Originally,Manz developed its own control technology; however, this became increasinglydifficult due to the growing relevance of electronics in mechanical engineeringand the exceptionally fast innovation cycles in this field. We therefore went insearch of a suitable specialist as a new control supplier. In a correspondingbenchmark, PC-based control proved to be the optimal solution, in particulardue to the PC-based concept and the flexible, open, and finely scalable systemarchitecture. In addition, there was the innovative strength of Beckhoff – afactor that we regarded highly even back then.”
Tilman Plaß, automotive industry manager at Beckhoff, adds the following froman automation perspective: “The high requirements of the Manz systems canbe met very well with PC-based control. These requirements include the shortcycle times that can be achieved with our control technology as well as a logicthat covers all processes throughout the application, an aspect which promotesspeed during format changeovers in particular. The comprehensive functionalityof TwinCAT up to OPC UA communication results in further advantages – andon both sides. For example, as a very early user of TwinCAT 3, Manz was able toprovide us with important user feedback as part of our partnership.”
The hardware core of the BLS 500 controller is formed by a C6030 ultra-compactIndustrial PC, whose main advantages Stephan Lausterer describes: “The C6030 is ideally suited to applications like this with limited installation space.In addition, the computer equipped with an Intel® CoreTM i7 CPU providessufficient computing power for both machine control and visualization. Thisalso holds true for future requirements, especially since Beckhoff is graduallyintegrating suitable new processor generations and – with the C6032 – also hasa compact device variant with more interfaces in its portfolio.” Such a versatileindustrial PC also makes sense for Stephan Lausterer from another perspective:“Purchasing and warehousing are significantly simplified as a result. The sameapplies to the entire test tool chain for hardware and software, something whichis hugely important to us at Manz. Accordingly, all the software is tested onvirtual machines as well as on the real hardware.”
All in all, the TwinCAT automation software meets Manz’s requirements verywell, as Stephan Lausterer confirms: “Among other things, we benefit from theintegration of TwinCAT in Visual Studio, as our software team also includeshigh-level language programmers. Added to this is the overall high level of flexibility,for example with the editors for the respective programming languagesand through the variety of functions up to Safety Editor, TwinCAT Scope, andTwinCAT HMI. In our view, this level of integration is a unique selling point ofTwinCAT.” He also adds that motion control can be programmed and simulatedvery conveniently in C++ and with the TwinCAT 3 NC PTP, NC I, and KinematicTransformation blocks, and then run as a TcCOM module in the real-time context.In addition, the TcCOM concept makes it easier to reuse program code andprovide suitable protection of intellectual property.
Higher-level communication via OPC UA
In addition to fast EtherCAT communication for the machine processes themselves,i.e., between the industrial PC and the EtherCAT terminals or drives, Manzrelies on data exchange via OPC UA throughout the BLS 500. This is realized viathe TwinCAT 3 function OPC UA (TF6100) for aspects including the transmissionof camera images to the HMI, integration into higher-level systems, andcross-control communication. The virtual commissioning tool also exchanges data with the TwinCAT controller via OPC UA. Tilman Plaß notes the followingin this regard: “The scope of OPC UA communication is very impressive. Manzrecognized the advantages of standardized, secure, and vendor-independentcommunication early on and uses the TwinCAT OPC UA server and client at aconsiderable scale and with high performance.” Stephan Lausterer confirms this:“Almost all external communication runs via OPC UA, both for our Industrie 4.0products and for customer applications. For non-OPC-UA-capable third-partycomponents, the TwinCAT 3 function TCP/IP (TF6310) or XML Server (TF6421)is used – options which demonstrate the high level of system openness offeredby PC-based control.”
In addition to manufacturer independence, IT security is an important aspect forManz. Here, OPC UA offers the clear advantage that the corresponding securitymechanisms are already integrated into the communication stacks, meaningthat the necessary security capabilities are already provided from the outset.According to Stephan Lausterer, this is a topic that will become increasinglyimportant in the future. Another benefit is that Beckhoff as an early adopterhas already implemented an OPC UA client on the control side at a very earlystage. Tilman Plaß also confirms this: “Beckhoff had already presented anapplication scenario of TwinCAT 3 in 2014 with the SOA PLC (SOA = serviceorientedarchitecture), which combines logic functions and OPC UA services fordata-consistent, secure, and standardized communication.”