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1. Integrating robotic wire arc additive manufacturing and machining: hybrid WAAM machining

   https://doi.org/10.1007/s00170-023-12517-4  

   Li, Benquan; Nagaraja, Kishore M.; Zhang, Runyu; Malik, Arif; Lu, Hongbing; Li, Wei (October 2023, The International Journal of Advanced Manufacturing Technology)

   Andrew Yeh-Ching Nee, editor-ion-chief (Ed.)

   Wire arc additive manufacturing (WAAM) has received increasing use in 3D printing because of its high deposition rates suitable for components with large and complex geometries. However, the lower forming accuracy of WAAM than other metal additive manufacturing methods has imposed limitations on manufacturing components with high precision. To resolve this issue, we herein implemented the hybrid manufacturing (HM) technique, which integrated WAAM and subtractive manufacturing (via a milling process), to attain high forming accuracy while taking advantage of both WAAM and the milling process. We describe in this paper the design of a robot-based HM platform in which the WAAM and CNC milling are integrated using two robotic arms: one for WAAM and the other for milling immediately following WAAM. The HM was demonstrated with a thin-walled aluminum 5356 component, which was inspected by X-ray micro-computed tomography (μCT) for porosity visualization. The temperature and cutting forces in the component under milling were acquired for analysis. The surface roughness of the aluminum component was measured to assess the surface quality. In addition, tensile specimens were cut from the components using wire electrical discharge machining (WEDM) for mechanical testing. Both machining quality and mechanical properties were found satisfactory; thus the robot-based HM platform was shown to be suitable for manufacturing high-quality aluminum parts. 

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2. Parametric and theoretical study of hole quality in conventional micro-machining and rotary ultrasonic micro-machining of silicon

   https://doi.org/10.1016/j.precisioneng.2025.01.008  

   Li, Yunze; Pei, Zhijian; Cong, Weilong (January 2025, Precision Engineering)
3. Ultra-Precision Machining: Cutting With Diamond Tools

   https://doi.org/10.1115/1.4048194  

   Lucca, D. A.; Klopfstein, M. J.; Riemer, O. (November 2020, Journal of Manufacturing Science and Engineering)

   null (Ed.)

   Abstract This article is written as a tribute to Professor Frederick Fongsun Ling 1927–2014. Single-point diamond machining, a subset of a broader class of processes characterized as ultraprecision machining, is used for the creation of surfaces and components with nanometer scale surface roughnesses, and submicrometer scale geometrical form accuracies. Its initial development centered mainly on the machining of optics for energy and defense related needs. Today, diamond machining has broad applications that include the manufacture of precision freeform optics for defense and commercial applications, the structuring of surfaces for functional performance, and the creation of molds used for the replication of a broad range of components in plastic or glass. The present work focuses on a brief review of the technology. First addressed is the state of current understanding of the mechanics that govern the process including the resulting forces, energies and the size effect, forces when cutting single crystals, and resulting cutting temperatures. Efforts to model the process are then described. The workpiece material response when cutting ductile and brittle materials is also included. Then the present state of the art in machine tools, diamond tools and tool development, various cutting configurations used, and some examples of diamond machined surfaces and components are presented. A discussion on the measurement of surface topography, geometrical form, and subsurface damage of diamond machined surfaces is also included. 

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4. Transfer learning for autonomous chatter detection in machining

   https://doi.org/10.1016/j.jmapro.2022.05.037  

   Yesilli, Melih C.; Khasawneh, Firas A.; Mann, Brian P. (August 2022, Journal of Manufacturing Processes)
5. Stability Performance of a Stochastic Toolpath in Machining

   Grimm, Tyler; Kharat, Nilesh; Potthoff, Nils; Mears, Laine; Wiederkehr, Petra (November 2021, Proceedings of ASME International Mechanical Engineering Conference and Exposition)

   null (Ed.)

   The overall quality of a machined part relies heavily on the tool path that is used. Several methods of toolpath generation are currently employed. A more recently developed toolpath method is known as trochoidal milling, which is also known by several other terms, such as adaptive milling. This type of path benefits the machining process by attempting to reduce chip thickness on entry and exit to the workpiece. In doing so, utilization of this type of path can reduce tool wear and enables higher feed rates, thus improving machining efficiency.\par Another advantage of the trochoidal approach is that it often creates paths which are relatively more smooth compared to traditionally designed paths. In order to follow the contours of the final geometry, the path can yield a significant number of direction changes which result in constantly changing forces directions on the tool. Chatter, or self-excited vibration that occurs in the tool or workpiece, can therefore be mitigated or avoided since resonance does not have time to increase the vibration’s amplitude. The trochoidal milling tool path strategy typically operates on the XY plane. The operator will assign a step-down value, which defines the Z-depth at each pass. This strategy can create issues during freeform milling: because of this step-down effect, the trochoidal path may only be able to perform clearing and not finishing. This is due to the excess material left on the workpiece when a large step-down value is used. A significant and randomized variation range of the trochoidal path is tested in this research. Using this new proposed method, stochastic behavior of the toolpath is implemented. The toolpath consists entirely of circular arcs which drive the tool in a pseudo-random fashion. As the tool nears completion of the pass, the generator will give heavier probabilistic weight to points which have not yet been machined, thereby improving the efficiency of the process. It is hypothesized that this toolpath can generate the same chip-inhibiting properties of the trochoidal path while granting the ability to perform finishing cuts. The stability of such a path is determined in this work. A key parameter of this path is the allowable radius range of the circular arcs. For example, short, tight arcs or long, relatively straight arcs can be used. The influence of these arcs is analyzed against several different metrics, such as generation time, path efficiency, and chatter. The stability lobes for several radii parameters were determined. It was found that the most efficient path utilized a median parameter value, signifying a negative parabolic relationship between path efficiency and tool path radius. It was also discovered that smaller arcs result in decreased chatter. Future studies will explore the behaviors of this path when milling 3D surfaces. 

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