A conceptual, holistic framework to overcome limitations and constraints of design in laser based powder bed fusion of metals: Case novel separation and purification units

Abstract

The advancements of digitization and the fourth industrial revolution has introduced several modern technologies, among which additive manufacturing (AM), known also as industrial 3D printing, has significant role. Additive manufacturing has the potential to revolutionize products, production, and businesses in various fields of engineering, such as in chemical engineering industry. AM enables the creation of such designs that improves performance and functionality of products but introduces faster, more costeffective manufacturing which are beneficial also in industrial separation and purification application.

The markets for additive manufacturing have experienced rapid growth offering opportunities for the production of lighter, stronger, and more functional parts. Globally, the AM industry is constantly evolving and used in mass production in many industrial fields, such as in aerospace, automotive and medical applications. The technological innovations and continuous development of AM is leading to new solutions; new applications, materials, and techniques are developed all the time.

The chemical engineering industry, both domestically and internationally, has not yet fully utilized the potential of AM which AM can offer. Traditional manufacturing methods, such as casting and machining, continue to dominate the industry. One common thought preventing wider used of AM is idea that AM is slow process, both in the production of large components and high-volume products. This mindset overlooks the economic savings achieved during the lifetime of the product, such as reduced pumping energy, especially when considering components optimized for fluid dynamics. It is also easily forgotten that the entire product may not need to be additively manufactured, but AM could be suitable for critical components, such as nozzles, which can be welded onto a larger assembly.

Additive manufacturing of metals, more closely laser-based powder bed fusion of metals (PBF-LB/M) is a revolutionary technology, but it has its constraints and limitations, as any other fabrication method has. These limitations can significantly impact product design. For example, support structures are generally required for geometries with building angles of less than 45 degrees. These supports are essential, ensuring proper bonding of each new layer to the one below. However, support structures have also challenges: supports increase the complexity of the AMed part and the manufacturing process itself, and fabrication of them needs material, and takes time. Supports needs also to be removed in a separate step, and thus removing supports can be labour-intensive and time-consuming.

This thesis examined ways to improve the performance of chemical engineering applications (such as separation and purification technologies) through advanced metal additive manufacturing. This refers in this thesis to the integration of modern automated product design tools into simulation-based optimization and real-time monitoring of the AM process by utilizing artificial intelligence (AI) algorithms. Furthermore, this thesis discussed that this solution helps to overcome current limitations in industrial AM.

The combination of modern simulation and advanced modeling tools is needed to use optimize product designs for AMed parts. This will reduce the number of iterations required in product development and also guarantee successful production. In-situ detection of the process signature in PBF-LB/M, such as the temperature, emitted radiation and high-speed images, gives a deeper understanding of process optimization and defect prevention. When this can be fully integrated with product design and modern simulation tools, such geometries that were not possible to be produced earlier due to existing process constraints can be fabricated.

Existing limitations and constraints in AM can be avoided by understanding the fundamentals of the process phenomena involved, and this leads to an evolution in the designs which are manufactured by PBF-LB/M. For example, smaller feature sizes than those known by the limitation of existing technology can be produced, thus enabling a larger surface area to volume ratio, an essential feature, e.g., for the performance of products used in the separation and purification industry. Larger surface area to volume ratio leads to an enhanced performance, functionality and energy-efficiency.

It was also concluded that PBF-LB/M is a suitable fabrication method for manufacturing customized unit systems for industrial separation and purification applications. A thorough understanding is needed about the capabilities and possibilities of both separation and purification processes and PBF-LB/M. Collaboration between experts in unit processes, product design, and additive manufacturing is essential to achieve this understanding.

This thesis study found that simulation-assisted product design using optimization methods, such as computational fluid dynamics (CFD), enhance the performance of the unit systems for separation and purification by fine-tuning design parameters and fluid dynamics. A lattice structure that maximizes the surface area to volume ratio enhances the performance of components, such as in AMed electrodes. When AM is combined with new lattice structures enables by AM, such as, triply periodic minimal surfaces (TPMS) based lattices, design flexibility and high surface area to volume ratio are gained. This could benefit various applications in separation and purification. For example, optimized electrode design enhances the mass flow and the electrochemical performance. TPMS structures enable also graded structures relevant to fluid dynamics, providing, e.g., improved control over flow resistances and distribution patterns.

In future studies, a comprehensive understanding of separation and purification processes in the manufacturing industry, simulation-assisted product design and using PBF-LB/M technology should be a focus. Investigating the impact of PBF-LB/M on sustainability and its potential in these industries is valuable.