**5. Conclusions**

The present study articulates and utilizes a methodology and a cost frame for assessing the potential impact of a switch in the production technologies from conventional strategies to AM strategies. The methodology consists on a taxonomy product analysis, the engineering case study analysis, the discussion of the results and the extrapolation of the findings to the potential impact in the company overall.

The taxonomy analysis is undertaken in detail to (i) select a relevant product for the case study analysis, as well as to (ii) quantify the hierarchical and economic parts catalog of the company. The engineering case study analysis covers the analysis of the product manufacturing both in the conventional process and in the AM process. The latter is evaluated in the manufacturing of the original design and of a specific product redesign implementing DfAM techniques. Being a single-case design with a single unit of analysis, the engineering case study has been screened to make sure of its validity and reliability in the context of a real engineering case from a company.

The cost frame articulated formalizes a method for calculating the impact of a product modification based on the TIMC and of several factors affecting the inventory costs, which are divided into manufacturing costs, transportation costs, holding costs, and management costs. The factors affecting the costs are dependent on basic cost generators; namely: Processing time, material weight, and material dimensions.

The engineering case study part selected is a support for an automatic valve that it is required in a volume of 2000 parts. Following the taxonomy analysis performed, it is considered a representative part of the inventory in terms of weight and demand. The original design, weighting 0.862 kg has been assessed in its costs of manufacturing. Then, topological optimization has been undertaken reaching a weight of 0.237 kg without modifying the external shape. The DfAM has been validated experimentally both in virtual and physical conditions. This enormous reduction in mass has led to cost reductions in terms of material and processing times. The estimation within the category analyzed yields that a cost reduction of 69.22% of the manufacturing costs of 'Plastics' parts could be achieved. When considering this impact in the company overall, it is found that a reduction of 13.69% of inventory costs could be feasible to obtain.

The methodology and the cost frame in the article are applied to a company dedicated to the provision of spare parts for fluid conduction systems. However, both methodology and cost frame could be applied to any other industrial company. The specific figure of the reduction of a 13.62% in the inventory costs can be extrapolated to other companies operating in similar contexts. In addition, analogous analysis could be done assessing different product fractions to incorporate AM technologies

to other product categories. For example, it could be used in the category of 'Kits' for AM plastic technologies or in other categories for example with metal technologies.

Concerning the cost frame, the factors affecting the inventory costs have been specifically split into the presented division to ease the treatment of the effect of costs of the use of materials, technology, regional locations and human factor. Therefore, the same kind of study that has served to evaluate a topological optimization that has led to savings in different cost factors (volume and weight), could be undertaken with the same cost frame model for a change on the regional change in location affecting the product value chain from manufacturing to inventory.

**Author Contributions:** Conceptualization, J.M.-C. and J.R.G.A.; Methodology, J.M.-C., J.R.G.A. and S.M.P.; Software, S.M.P.; Validation, J.R.G.A. and M.A.d.l.S.L.; Formal Analysis, J.M.-C., S.M.P. and M.A.d.l.S.L.; Investigation, J.M.-C., S.M.P. and M.A.d.l.S.L.; Resources, S.M.P.; Data Curation, J.M.-C. and S.M.P.; Writing-Original Draft Preparation, J.M.-C., S.M.P. and M.A.d.l.S.L.; Writing-Review & Editing, J.M.-C.; Visualization, J.M.-C. and S.M.P.; Supervision, J.M.-C. and J.R.G.A.; Project Administration, J.M.-C. and S.M.P.; Funding Acquisition, J.M.-C. and M.A.d.l.S.L.

**Funding:** This research was cofounded by the "Agència de Gestió d'Ajuts Universitaris i de Recerca" (AGAUR) of the "Generalitat de Catalunya", under the schema "Programa de Doctorats Industrials", with grant number 2015DI 29.

**Acknowledgments:** For the present study, the authors want to acknowledge the manufacturer *Nexeo Solutions Spain SL*, suppliers of the filament used in the physical tests (*Novamid® ID1070*), for the material and its characterization information. Also, the authors want to thank the partner company Krotwaar CAE for the execution of the finite element calculations.

**Conflicts of Interest:** The authors declare no conflict of interest.

#### **References**


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