Improving the efficiency of fabrication of AM parts by segmentation design in DLP process Mehdi Kazemi and Abdolreza Rahimi Department of mechanical engineering, Amirkabir University of Technology, Tehran, Islamic Republic of Iran Abstract Purpose – Additive manufacturing technology significantly simplifies the production of complex three-dimensional (3 D) parts directly from the computer-aided design (CAD) model. Although additive manufacturing (AM) processes have unexampled flexibility, they still have restrictions inhibiting engineers to easily generate some specific geometric shapes, easily. Some of these problems pertain to the consumption of materials as supports, the inferior surface finish of some surfaces with certain angles, etc. One of the approaches to overcome these problems is designing by segmentation. Design/methodology/approach – The proposed methodology consists of two steps: (1) segmentation of the 3 D model and (2) exploring the best orientation for each segment. In the first step, engineers consider the possible number of segments and the connection method of segments. In this paper, a series of segments, called a segmentation pattern (SP), is obtained by the recognition of features and separating them automatically (or manually when needed) with one or more appropriate planes. In the second step, the best fabrication orientation should be chosen. The criteria for choosing the best SP and OPs are minimizing the support volume, building time (directly affected by segments’ height in layer-wise AM processes) and surface roughness. Both steps are performed automatically (or manually when needed) by the algorithm created based on principles of particle swarm optimization (PSO) algorithm using Visual C#. Findings – Experimental tests show that the segmentation design improves AM processes from the aspects of building time, material consumption and the surface quality. Segmentation design empowers users of AM technologies to reduce consumption of material by decreasing the support structures, to decrease the time of building by lowering the segments height and to decrease the surface roughness. Originality/value – This paper presents an original approach in efficiency improvement of AM technologies, thus bringing the AM one step closer to maturity. Keywords Surface roughness, Additive manufacturing, Building time, DLP, Material consumption, Segmentation design Paper type Research paper 1. Introduction Recently, computer-aided design and manufacturing (CAD-CAM) has made a lot of progress, thus providing a researcher with the opportunity of not only designing and analyzing a virtual model of a product on a computer but also producing that functional product directly from its three-dimensional (3 D) model (Ilinkin et al., 2002). This technology is called additive manufacturing (AM). The fundamental principle of this technology is that a model can be directly fabricated with no need for process planning (Li et al., 2017). AM technologies significantly simplify the production of complex 3 D products directly from CAD model (Kazemi and Rahimi, 2015), whereas other manufacturing processes require a detailed analysis of the product geometry. In contrast, AM merely requires some primary dimensional data, in addition to a small amount of understanding regarding how the AM machine works and the material used to build the part (Gibson et al., 2015). Fabrication of parts with any amount of complexity in shape is the most crucial advantage of AM processes (Rosen, 2007). In traditional production processes, it is difficult to manufacture a complicated part as a single integrated part; thus, a part of a complex shape must be separated into several pieces (Thomas and Gilbert, 2014). Contrarily, AM allows designers to design without paying attention to assembly issues, given the capability of these processes to generate a part layer by layer (Gibson et al., 2015). However, on a mass production scale, given the higher production rate of traditional processes involved with mold/die such as injection molding as compared with AM processes, the ease of design in these processes as compared with their traditional counterparts does not ensure a reasonable production rate. This is why AM demands the integration of design and manufacturing engineering concepts as a means to enhance productivity. However, AM processes have unexampled flexibility compared with traditional processes; they still have restrictions that do not allow engineers to generate some specific geometric The current issue and full text archive of this journal is available on Emerald Insight at: www.emeraldinsight.com/1355-2546.htm Rapid Prototyping Journal 25/7 (2019) 1155–1168 © Emerald Publishing Limited [ISSN 1355-2546] [DOI 10.1108/RPJ-09-2018-0253] Received 25 September 2018 Revised 14 May 2019 Accepted 16 May 2019 1155