## 2 Background Work  
### Adoption of AM in the Industry  
The adoption of AM in the industry is becoming significant and it is pushed by the Industry 4.0 digitalization trend [1; 7; 8]. The benefits offered by this technology will continue to grow with the efficient processing of digital data for process and product improvements, especially when low production quantities or sophisticated geometric shapes are required [9]. The fast evolution of technical solutions, as well as the expiration of principal patents, has enormously expanded the choice on the market of systems for each process type.  
A few different knowledge related spaces need to be considered and faced for an effective application in companies. The first area concerns technology awareness. AM techniques have been classified by the type of process, by how the final construct is obtained and by the source of energy which is used for the phase change of the raw material. Seven categories have been defined so far according to the deposition method used to build the parts, i.e., VAT Polymerization, Fused Deposition Modelling, Powder Bed Fusion (PBF), Sheet Lamination, Material Jetting, Direct Energy Deposition and Binder Jetting [10].  
Secondly, the possible application fields to be identified in the specific business being run can be recognised in:  
1. Structural components, whose goal is to maximize stiffness while reducing weight;
2. Products that need a complex and specific shape, aimed at increasing fluid dynamic efficiency or temperature distribution, such as in conformal cooling;
3. Rapid tooling, using additive techniques to produce tools for other parts, for instance moulds;
4. Parts where high customization is required, such as in fashion or biomedical prostheses and braces requiring lattice structures and specific superficial texturing [1];
5. Prototypes, which are used for physical design evaluations, even if the production of the final product uses other techniques.  
Even though AM machines are already used on the shopfloor to produce prototypes and complex parts, they are still not applied systematically and extensively. Like any other production system, AM presents strengths and limitations [11], as summarized in the following Table 1.  
Finally, some design organization issues must be faced. In fact, the wide and mostly unexplored design space that AM offers is a very attractive landscape for the industry. However, the complexity and novelty of reasoning patterns could result in significant factors to impede the implementation of AM techniques in practice.  
Leaving the design teams to evaluate the possibilities of adopting AM technology based on subjective and unstructured considerations may lead to skewed considerations and a loss of opportunities. Designers have reported that, in many cases, extensive evaluations and design attempts have concluded without feasible solutions. Such failures have had a negative impact on the management due to the poor rate of success in AM adoption. In particular, design leaders complain about [13; 14]:  
1. The effort required to identify the right components to be redesigned;
2. The effort required to obtain new designs which need to face novel geometric shapes and careful structural and thermal simulations;
3. The variability of metallurgical properties of 3D printed materials makes the quality and reliability of new products uncertain;
4. Necessity of dealing with a new supply chain and the relative logistic aspects.  
The method presented in the paper aims to provide a framework to systematically operate in such a complex environment.