Automotive products remain the standard for coordinated manufacturing, and the emergence of electric vehicles (EVs) has created a new platform for collaborative design and engineering. From concept to production, every component of a new EV is an opportunity to demonstrate designers’ vision, manufacturers’ skills, and the potential for collaboration between them and with their technology partners.
In 2022 Siemens undertook to design and produce an EV – the Siemens eRod – drawing on its own advances in software and automation, manufacturing technology from DMG More USA and Trak Machine Tools, and cutting technology from Walter Tools.
The project also demonstrated the potential for integrating optimization into the design and engineering workflow, namely of combining additive manufacturing with more established manufacturing technologies. According to Siemens, manufacturing is “at a convergence point with these technologies, and it is only through projects like this that we can prove out, validate, and embrace that potential – whether from the perspective of reducing waste and maximizing resource utilization during design or as a way to reduce mass and energy consumption during use.”
Creating a “digital thread” among the partners made it possible to apply technologies from all four of them, beginning with Siemens NX™ software to generate the initial design, taking operating parameters of an electric vehicle, and using those to optimize the development of a critical suspension component for the EV, using with integrated generative engineering tools.
During the Design for Additive Manufacturing phase, the part concept was fully validated using structural simulation technologies and optimization is performed to ensure that its performance requirements are met, and to optimize the manufacturing processes available to produce it. In the Siemens eRod project, simulation-driven design ensured that the optimal part was produced using a minimal amount of material, resulting in a steering knuckle design that is 45% lighter than the standard, with improved stress-handling capability.
The next phase, Process Planning, demonstrated how comprehensive manufacturing plans are developed with Siemens Teamcenter® and Opcenter™ software platforms. These are programs that manufacturers can use to automate programming by applying their own standard CNC functions, inspection path methods, tools and program templates, with confidence that correct revisions of parts are programmed and measured on the shop floor. The result is a single source of data for the entire digital manufacturing process.
In the manufacturing phases, the Siemens eRod project showed how the component is manufactured using a combination of additive and traditional manufacturing methods, then finished to achieve the necessary dimensional accuracy and tolerances, with 60% less programming time thanks to task automation.
Advanced capabilities in Siemens NX CAM – such as five-axis simultaneous programming, cloud-based post-processing, and integrated simulation – helped to prepare the part for both additive manufacturing, using Ti6Al4V powder on a DMG Mori Lasertec 30 Dual SLM Selective Laser Melting machine; and finishing on a DMG Mori DMU 85 monoBLOCK five-axis machining center, equipped with the Sinumerik 840D sl CNC system for a two-step machining process.
Walter’s industry leading tooling hardware was adopted for the finishing and cut-off operations, to ensure the required tolerances are met. Machining of 3D printed titanium presents unusual challenges. While additive technology effectively generates complex components, finish machining can be more complicated because of the design complexity.
Among the challenges addressed in the machining solution developed for the component are 3D printed Ti6Al4V stock material, removing support structures that tend to be more brittle than the bulk material, difficult to access features, and minimizing vibration during machining where clamping for the component is weak due to the complex geometry.
Working with DMG Mori and Siemens, Walter developed an efficient machining process with a combination of tools to address all the challenges and resulting in a finished component that meets all dimensional accuracy and surface finish requirements.
When evaluating the entire assembly, the design team determined that certain components could still be manufactured more efficiently with traditional subtractive processes. Specifically, the spindle for the suspension component, designed in NX, is suitable for a traditional turning process; however, by applying the Siemens CNC’s Run MyVirtual Machine digital twinning function it was possible to add a TRAK Machine Tools TC820si turning center to the digital manufacturing process.
The spindle was virtually programmed in the Sinumerik One control with ShopTurn conversational programming, and validated with the TC820si’s 3D twin.
Closing the part’s development loop, the Quality Control and Production Preparation phases were be carried out using automated CMM processes driven by dimension and tolerance data captured and stored using PMI (Product Manufacturing Information) within NX CMM Inspection Programming software, to ensure that the part is within the tolerances expected and ready for assembly.
During final assembly, the spindle component produced by a standard turning step was combined with the optimized knuckle and installed on the Siemens eRod electric vehicle.