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Materials Science in Additive Manufacturing Base shape generation for HAM

reducing the layer thickness to achieve a better surface application needs, we define this problem as the base shape
quality may extend the printing time. On the contrary, the generation and optimization for the process planning in
advantages of traditional manufacturing processes, such as HAM. At present, this problem is handled manually with
high speed and high quality of finish surface, can greatly many uncertainties, but there is no decision support tool to
compensate for the disadvantages of AM . In light of this, help automatically generating an optimal base shape for a
[7]
the combination of additive and subtractive manufacturing given computer-aided design (CAD) model to be processed
processes is regarded as a hybrid solution to compensate by a HAM process in the process planning. To solve this
[8]
the limitations of both AM and traditional processes , problem, this paper introduces a geometric computational
spurring a variety of new applications . The combined method that automatically generates an optimal base
[9]
approach is now increasingly employed for producing or shape, taking into account the processing cost, quality, and
remanufacturing functional parts . manufacturing constraints.
[6]
The term “hybrid” has been widely used in many The contents of this paper are organized as follows:
areas of manufacturing . It is used to describe several Section 2 reviews the related woks; Section 3 introduces
[10]
hybrid techniques: (i) hybrid processes; (ii) hybrid the proposed method in detail; Section 4 demonstrates
machines, which refer to the machine platform rather the method with computation examples; and Section 5
than the constituent processes; and (iii) hybrid materials, concludes the paper with perspectives on future work.
structures, or functions, combining one or more materials
to yield a product with hybrid composition, structure, 2. Related work
or function [11,12] . The definition of hybrid additive In the domain of manufacturing, the crux of process
manufacturing (HAM) was proposed by Sealy et al. planning is about how to organize and make a full use of
[10]
as follows: “The use of AM with one or more secondary the existing processes and the corresponding machines with
processes or energy sources that are fully coupled can appropriate parameters . In AM, there are some differences
[14]
synergistically affect part quality, functionality, and/ since the printing planning is usually done for one machine,
or process performance.” The authors also defined the the AM printer, if post-processing is not considered. The
three key features of HAM: (i) fully coupled processes, main function of the so-called process planning for AM is
(ii) synergy, and (iii) part and/or process improvement. actually to transfer a design model, such as a CAD model,
More descriptions and definitions have also been into a processing model, called the printing toolpath model,
proposed in the literature [9,12,13] . In this paper, we consider to complete the AM processing chain . Four main planning
[15]
HAM as a type of specific hybrid process, where AM is tasks were defined as the model transformation steps for
the principle process, and other processes, integrated in rapid prototyping, the initial form of AM . Recently, with
[16]
one machine with AM or separated as modular processing the rapid development of AM technologies and increased
units, are assistive processes involved in shape formation availability of material options, the process planning for AM
procedure with AM working in a sequential, parallel, or has become widely explored. Some researchers proposed to
iterative fashion. include the manufacturability analysis, process selection,

Although the hybridization idea of the two types of model clustering, and printing prediction as additional
processes seems simple, the process of combining them planning tasks to adapt to the AM evolution [15,17-19] since
is more difficult than imagined since both of the existing these tasks are critical for analyzing the feasibility and
[15]
constraints of AM and non-AM (NAM) processes are suitability of using AM before printing . In general,
introduced and couple with each other. Therefore, the process these planning tasks are divided into two main classes:
[19]
planning for HAM is critical for the implementation of process macroplanning and microplanning . Microplanning not
combination. A few researchers noticed the importance only includes the four classical planning tasks, namely,
[21]
[20]
of this and had already conducted a set of investigations as orientation determination , support structure design ,
[22]
[23]
reviewed in Nassehi et al. . However, a plethora of problems slicing, and toolpath planning but also contains two
[13]
remain to be resolved, such as the selection of candidate additional new tasks, namely, part clustering/grouping and
process for combination, manufacturability analysis, nesting, to meet the needs of simultaneous printing for
processing from zero volume or existing volume, hybrid group components [24-26] .
operation sequence planning, hybrid toolpath planning for In conjunction with the emergence of HAM, more
AM, and NAM, etc. In this paper, we focus on the question NAM processing operations and machines are introduced
of manufacturing from zero or an existing subvolume since in the processing chain. Hence, the process planning
this rarely discussed topic is important for the feasibility contents should be adjusted again. However, the current
and efficiency of HAM. Based on the analysis of industrial computer-aided process planning (CAPP) in AM domain

Volume 2 Issue 4 (2023) 2 https://doi.org/10.36922/msam.2103