Additive Manufacturing: innovation and applications in metallic materials

Additive Manufacturing (AM) represents a set of advanced production technologies that enable the creation of three-dimensional objects through the successive deposition of material layers, guided by a CAD-CAM system. The ISO/ASTM 52900-15 standard identifies seven main categories. For metallic materials, AM is based on the use of metal powders or wires as raw materials.

Unlike traditional subtractive machining methods, AM allows the production of highly complex geometries that are often unachievable with other processes. A notable example is the possibility of producing a large gold ring with a hollow interior, reducing its weight without compromising aesthetics. Furthermore, the additive approach minimizes material waste, as the generation of scrap is drastically reduced compared to subtractive processes. Despite its potential, AM poses several challenges related to materials, costs, and component quality, including the possible formation of structural defects. However, numerous industrial sectors — from aerospace to biomedical, automotive to energy — have successfully adopted AM technologies based on laser or electron beam processes. Innovation in this field is continuously evolving, with new materials and manufacturing techniques currently under development.

Industrial Applications and Development of Functionalized Punches

Research on AM at the Department of Industrial Engineering began in the early 2000s. In recent years, one of the most innovative applications pursued within the Metallurgy Laboratory has been the development of functionalized punches for pressing metal powders, a project carried out in collaboration with Officine Meccaniche Pontillo of Scafati (SA). The traditional method of die lubrication involves adding lubricant to the powder, requiring a subsequent removal step before sintering. This approach negatively affects costs, sustainability, and carbon footprint
The project introduced a substantial innovation: punches equipped with internal channels for the direct delivery of lubricant during pressing, eliminating the need for subsequent treatments and improving process efficiency. The geometric complexity of such punches makes the creation of these channels impossible with conventional techniques, while AM offers an ideal solution, enabling the production of non-linear internal structures with high precision.

The Three Main Axes of the Project

The project is structured along three main lines:

1. Selection of the Optimal Material
   Choosing the appropriate steel is crucial to ensure the mechanical strength and wear resistance of the punches. An extensive screening activity was carried out on five different alloys, evaluating their microstructure, hardness, tensile strength, impact, and fatigue resistance, varying both manufacturing parameters and heat treatments.
   
2. Production and Validation of Prototypes
   Initial prototypes were produced and analyzed to verify geometric tolerances and the surface quality of the internal channels. Special attention was paid to the precision and finish of the lubricant delivery surfaces, key parameters for the system’s effectiveness.
   
3. Optimization of Surface Treatments
   To enhance hardness and wear resistance, duplex surface treatments were tested based on plasma nitriding followed by PVD coatings. These treatments, already used on traditional tools, must be adapted to the specific microstructural characteristics of AM materials.
   

Results and Future Perspectives

The project, which is expected to conclude by the end of 2025, has already produced tangible results: an effective solution has been identified and validated through testing under real conditions. However, further improvements are under study, including the use of a next-generation steel currently being evaluated. The research has involved a PhD student, Tugce Tekin, who continued with a postdoctoral research grant, and a master’s student, Marianna Mondini, who is developing her thesis on the subject. The collaboration between university and industry has yielded significant benefits: Officine Meccaniche Pontillo has gained new skills in AM processes and materials, while academic research has produced noteworthy results, published in international scientific journals.

AM and the Future of Advanced Manufacturing

One aspect still unexplored in the project is the integration of machine learning techniques for optimizing AM processes. Although such methodologies have great potential, they require a solid knowledge base, which for some materials and processes is still being established. AM cannot be considered a mere extension of CAM techniques: effective use of these technologies demands a deep understanding of metallurgy and the solidification dynamics of materials.

The evolution of additive manufacturing is the result of intense research activity, which has enabled the development of applications in highly demanding sectors. Investing in the understanding of materials and process optimization will be crucial to further expand the potential of these technologies in the near future.