From 3D Models to 3D Prints: an Overview of the Processing Pipeline <s> Survey contents and objectives <s> Abstract The 1980s witnessed the emergence of new manufacturing technologies that build parts layer by layer. These layered-manufacturing techniques can significantly reduce the design-to-product leadtimes. The paper overviews several procedures for generating the layers from a cad model such that the resulting part can be accurately manufactured using LMT. <s> BIB001 </s> From 3D Models to 3D Prints: an Overview of the Processing Pipeline <s> Survey contents and objectives <s> Layered manufacturing, also called rapid prototyping or additive manufacturing is a revolutionary development in the field of manufacturing processes in last two decades. Unlike material removed from a stock in the machining process, layered manufacturing builds the solid volume from a CAD model by successively adding material layer by layer. Since parts are fabricated layer by layer, build orientation plays a critical role in the layered manufacturing process as it can improve part quality in terms of accuracy and surface finish, reduce the support volume required, support contact area and build time. It also affects the part strength and cost of manufacturing. This paper presents review of various strategies developed to decide the optimum part build orientation based on different criteria and related issues. This paper also discusses the effect of build orientation on fabricated parts and future directions to improve part quality by selecting suitable and feasible build orientation. <s> BIB002
The objective of this report is to give the reader a comprehensive overview of the Process Planning pipeline in the context of Additive Manufacturing. We provide a deep picture of the algorithms, data-structures and shape representations that are involved in turning an input virtual model into a set of instructions that the AM machine can understand. We cover key publications from the infancy of AM to the most recent advances. We categorize algorithms based on the PP problem they solve, and discuss their impact on various desirable properties of the final parts. Process Planning only. Recent surveys cover AM in a much broader sense, from a user's perspective. In particular, the reader can refer to the excellent survey by Gao and colleagues that proposes an overview of the status and challenges of AM in engineering [GZR * 15]. It covers fundamental principles and available technologies, design and modelling for AM, and its impact on the industry and society at large. The survey by Medeiros and colleagues  provides a clear picture of recent contributions in functional fabrication that is, parts that embed a functionality (e.g. articulated or deformable). We do not cover these topics, or only mention them from the perspective of process plan-ning. We also do not cover topics regarding the design of the part. The reader can refer to [HPE16, TMV * 16, SAZ15] and references therein for recent discussions on the new trends in shape design for AM. Furthermore, we do not provide in depth technical reviews of the current 3D printing technologies. In Section 1.3 we briefly go through the most important AM paradigms available. Our goal, however, is not to provide a comprehensive list, but rather to discuss the main properties -and limitations -that impact the process planning pipeline. Motivation and timeliness. Researchers operating in the area of process planning have been quite active in recent years, producing a tremendous amount of publications. The last (and only) survey focusing on the process planning for AM was published sixteen years ago  and, although the process planning pipeline has not changed much from an ideal point of view, many advances in algorithms have been proposed since. The same goes for surveys that focus on a more specific subject, such as BIB001 and [PVRD03] , that review slicing procedures for AM and were published in 1994 and 2003, respectively. One exception is the recently released survey on the role of build orientation in layered manufacturing BIB002 which, however, reviews contributions coming from the mechanical engineering community, and does not cover recent literature coming from other fields (e.g. computer graphics). Target reader. Indeed, additive manufacturing poses problems that cross several fields. Among classical players, such as designers, mechanical engineers and material scientists, new communities have become interested in it. For instance researchers in computer graphics, with their expertise at creating and manipulating digital 3D objects; but also applied mathematicians, with their expertise in fields such as topology optimization which is becoming increasingly important in the generation of support structures and infills. This report aims to be an entry door for those who want to contribute to AM, avoiding to re-invent the wheel, and promoting more interdisciplinary approaches. Both industry people and academics are targeted. From an industry perspective, this survey wishes to be a support to answer questions such as: I have a design, which algorithms are suitable to process it? What geometric processes would I need to implement? From an academic perspective, scholars can use this report to validate the originality of their own ideas in the area, to look for existing solutions to similar problems, and to know which open challenges deserve their attention.