Reducing the mass of machine tool designs by 30 percent without compromising performance or quality

Striving for high-quality innovation

ROMI, an international manufacturer of machine tools, plastic processing machines and cast-iron parts, is known for its innovation, invests heavily in research and development (R&D) and holds numerous patents for a wide range of industries.

However, staying innovative and competitive while meeting customer demands for precision and quality can be challenging. Additionally, it is difficult to ensure machine tools meet stringent dimensional tolerances and geometric specifications during the manufacturing process and address thermal- and structural-related errors. This was especially true when it comes to the prototyping process.

To help with these challenges and more, ROMI used Siemens Digital Industries Software’s solutions, namely NX™ software, Teamcenter® software, Simcenter™ software and HEEDS™ software. These solutions are part of the Siemens Xcelerator business platform of software, hardware and services.

Overcoming prototyping challenges

Previously, ROMI relied heavily on physical prototypes for testing and validating products. This process was time-consuming and costly, often requiring multiple iterations before achieving the desired performance. Although the company used simulation methods, they were not advanced enough nor integrated into the design process. Additionally, ROMI engineers often identified issues during the physical testing phase or after deploying the machines in the field. Physical prototypes are still important in the process of developing new products; however, they become much more optimized with less iterations.

To overcome these limitations, ROMI needed more robust solutions that integrated computer-aided design (CAD), computer-aided engineering (CAE), computer-aided manufacturing (CAM) and project lifecycle management (PLM) functionalities. Additionally, the company started collaborating with universities and research institutions, creating new opportunities for innovation.

Thanks to these partnerships, ROMI could leverage external expertise and resources, allowing them to develop innovative solutions and methodologies to enhance the design and functionality of their machine tools and plastic processing machines.

As for solutions, ROMI chose Siemens due to their comprehensive suite of seamlessly integrated solutions, which offered more advanced CAE capabilities and more sophisticated simulations than their original tool. By switching to Siemens solutions, the company entered the foray into the cutting-edge domain of virtual prototyping, opening a world of new design process possibilities.

With more advanced simulation tools, especially topology optimization, as well as thermal and dynamic simulation capabilities, ROMI engineers could mitigate machining vibrations, which used to rely heavily on time-consuming prototype testing and trial-and-error processes. Now, they can accurately forecast a machine’s stability during the initial design phases, allowing engineers to benchmark designs against industry standard performance metrics, which significantly accelerated development processes and enhanced overall product quality.

“Thanks to Siemens solutions, we’ve moved from reactive prototype testing to proactive design optimization, predicting vibrations before they become issues,” says Alexandre Zoppellari, PhD in engineering and product engineer at ROMI. “We’re now able to model and compensate for thermal expansion with significant accuracy, enhancing the overall quality of our manufactured parts.”

Revolutionizing processes and design approaches

ROMI made a strategic decision to invest in the latest simulation methods, particularly the finite element method (FEM). This allowed the company to continually develop and refine its design processes, leading to improved machine performance and reliability.

“Finite element simulation plays a crucial role in our design process,” says Douglas Pedro de Alcantara, chief technology officer (CTO) at ROMI. “It allows us to test and optimize our machines virtually before they are built, helping us identify potential issues early on. This not only saves time and resources but also ensures we deliver high-performance products that meet our customers’ standards.”

With Simcenter, ROMI’s range of simulations grew significantly, introducing simulations, iterative testing and optimization to the design process, specifically for motion, thermal, frequency response and more. This allows engineers to identify and resolve potential issues earlier, enhancing overall machine performance, reducing costs and saving time.

ROMI also used Simcenter for thermal simulations to predict temperature distributions within machine tools. This is crucial because temperature changes can affect machining accuracy by causing thermal expansions and unintended relative tool and workpiece displacements. By simulating thermal effects, the company can compensate and design machines that maintain precision under varying thermal conditions.

One notable example is ROMI’s newfound understanding of thermal errors in machine tools. Previously, they could compensate for thermal expansion in real time using an error model the machine’s computational numerical control (CNC) calculates, which limited their insight into the affected parts. By leveraging Simcenter 3D and advanced design exploration techniques, ROMI developed a thermoelastic model of the machine that accurately mirrors the equipment’s behavior. This in-depth analysis of each component’s expansion not only empowers the company to formulate more sophisticated thermal compensation models but also drives significant innovations to the machine’s design.

One important area ROMI aimed to optimize was for topology. For this, the company used Simcenter, which involved determining the ideal material allocation within a predefined design area. For example, the goal may be to maximize structural stiffness or minimize dynamic displacement, which results in more efficient and lightweight designs.

“Using the Simcenter topological optimization tools has been a game changer for our sustainability initiatives,” says Zoppellari. “Using Simcenter, we’ve achieved a 30 percent mass reduction in our latest designs without compromising performance, simultaneously cutting costs and our environmental footprint.”

Although ROMI can estimate thermal loads and convection using analytical or empirical formulas, the difference in results between analytical and numerical calculations can be significant, even for simple geometry. Thus, engineers can adjust the value of these boundary conditions based on experimental tests. For this, the company used HEEDS software to identify the optimal set of values for the boundary conditions.

“With NX, we can quickly visualize and refine our designs, and bring those design iterations rapidly into the simulation model,” says de Alcantara. “Meanwhile, using our PLM system, Teamcenter, helps us manage every stage of the product lifecycle effectively. This comprehensive approach to digitalization allows us to adapt to market needs and stay competitive in the machinery industry.”

Achieving breakthrough improvements

Overall, thanks to their use of Siemens solutions, ROMI’s strategic initiatives yielded significant, measurable outcomes. The first major result was weight optimization. Without compromising performance, the company reduced mass in their latest machine tool designs by 30 percent when compared to previous generations. This breakthrough improves their energy efficiency and reduces material costs while maintaining robust capabilities.

Next, ROMI enhanced the structural integrity of their machine designs. Their injection molding plates demonstrate superior flatness under extreme load conditions, improving product quality and process reliability in high-stress manufacturing environments.

Lastly, they achieved advanced stability control by enhancing the dynamic and thermal stability of their machine tools. This results in higher precision, an increase in productivity and extended equipment lifespans.

“ROMI’s journey towards becoming a digital enterprise is highlighted by our use of advanced CAD and PLM software, namely NX and Teamcenter from Siemens,” says de Alcantara. “This combination helps us simplify our design processes and encourages better teamwork, ensuring every machine we create reflects our commitment to
innovation and precision.”

Planning for the future

In the future, ROMI plans on developing advanced automation solutions using NX Open within preprocessing and postprocessing workflows. By focusing on automation, the company aims to not only accelerate their design cycle but also minimize human error, allowing engineers to dedicate more time to critical analysis and innovative problem-solving rather than routine data handling tasks.

Additionally, ROMI is strategically allocating resources for cutting-edge computational fluid dynamics (CFD) simulation capabilities. Using this advanced technology will help the company further improve precision machine tools to accurately model and optimize coolant flow dynamics and chip management within the coolant tank and, for plastic processing equipment, CFD simulation provides a deeper understanding of plastic flow within machines, facilitating more efficient production processes.