# On the Impact of Additive Manufacturing Processes Complexity on Modelling
It is noted, though, the process and the machine related challenges are interrelated, since the delivery of the energy and/or the material are done by mechatronic systems [32]. The benefits, both per process and in general, have also been pinpointed by Deloitte in the aforementioned study; complexity of the part, time to market, cost reduction (in the strict sense of inventory minimization), customization, and eco-friendliness are some key features of AM, regardless of the mechanism. Additional benefits and challenges of a hybrid nature (both technical and business) can be found in other works in the literature, such as the tabular presentation of Ford and Despeisse [33], where even aspects like localized material recycling are mentioned, while per process, the generic features are well documented [34]. Another interesting classification of the technical issues come across in literature has been the 4M's, where the making, the material, the metrology as well as the market are mainly regarded [35]. This particular approach \begin{table}
\begin{tabular}{l l} \hline \hline \multicolumn{1}{c}{**AM Process Group**} & \multicolumn{1}{c}{**Typical Commercial Names**} \\ \hline \multirow{2}{*}{Vat Photopolymerization (VP)} & Stereolithography (SLA), Digital Light Processing, Solid Ground Curing, Projection \\  & Stereolithography \\  & Electron Beam Melting (EBM), Electron Beam Additive Manufacturing (EBAM), \\  & Selective Laser Sintering (SLS), Selective Heat Sintering, Direct Metal Laser Sintering (DMLS), Selective Laser Melting (SLM), Laser Beam Melting (LBM) \\  & Laser Metal Deposition (LMD), Direct Metal Deposition (DMD), Direct Laser Deposition (DLD), Laser Engineered Net Shaping, Electron-Beam Freeform Fabrication, Weld-based \\  & Additive Manufacturing \\ Binder Jetting (BI) & Powder Bed and inkjet Head, Plaster-based 3D Printing \\ Material Extrusion (ME) & Fused Deposition Modeling (FDM), Fused Filament Fabrication \\  & Multi-Jet Modeling, Aerosol Jet, Ballistic Particle Manufacturing, Drop On Demand \\ Material Jetting (MJ) & (DOD), Laser-Induced Forward Transfer, Liquid Metal Jetting (LMJ), Multi-Jet-Printing \\  & (MJP), Nano Metal Jetting, NanoParticle Jetting, Polyjet, Printoptical Technology \\ Sheet Lamination (SL) & Laminated Object Manufacturing (LOM), Ultrasonic Consolidation \\ AM for the Construction Sector & Cement AM/3D Printing, Concrete AM/3D Printing \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Classification of additive manufacturing (AM) processes (according to [14]). can help also as regards the material properties and hence the mechanisms that are present in industrial AM. This has a direct impact on industrial systems metamodeling, as from the cyber-physical system point of view the mechanism and the subsystems are of utmost importance [36]. Meanwhile, in the performance prediction through modelling, the key aspect is indeed the identification of the main mechanisms (process- and machine-wise) [37]. As a matter of fact, [PERSON] et al. [38] indicate five domains of modules; Energy deposition, motion control, stock feeder, material and geometry, while at the same time they discuss behavior at macro, meso and micro level (3m's). Thus, as one may be interested in studying in a unified matter the various mechanisms that there are available, a specific schematic (Figure 2, left diagram) could be created, in order for the conceptual modelling to be conducted. Then, a Bayesian network [39] could be used to elaborated quantification of the features. However, before this aspect, a more quantified approach for conceptual modelling could be elaborated. This is depicted in the right diagram of Figure 2, adopting the abstract notation of unified modeling language (UML), a general purpose modelling language providing the visualization of the design of a system [40]. In this case, the involved entities are engaged in an one-to-many relationship (denoted as 1-1. *), i.e., a machine may have more than one heads.