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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. Structure and Deformation of Gradient Metal Foams Produced by Machining

   https://doi.org/10.1115/1.4043768  

   Qiao, Haipeng; Murthy, Tejas G.; Saldana, Christopher (July 2019, Journal of Manufacturing Science and Engineering)

   The effects of surface structure on mechanical performance for open-cell aluminum foam specimens were investigated in the present study. A surface gradient for pore structure and diameter was introduced into open-cell aluminum foams by machining-based processing. The structure changes in the strut and pore network were evaluated by computed tomography characterization. The role of structure gradients in affecting mechanical performance was determined using digital volume correlation and in situ compression within the computed tomographic scanner. These preliminary results show that the strength of these materials may be enhanced through surface structural gradients. 

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4. In Situ Observations of Shear Localization and Fracture in Machining

   https://doi.org/10.1115/MSEC2024-124723  

   Yadav, Shwetabh; Chawla, Harshit; Sagapuram, Dinakar (June 2024, American Society of Mechanical Engineers)

   Using direct high-speed imaging, we study the transition between different chip formation modes, and the underlying mechanics, in machining of ductile metals. Three distinct chip formation modes — continuous chip, shear-localized chip, and fragmented chip — are effected in a same material system by varying the cutting speed. It is shown using direct observations that shear-localized chip formation is characterized by shear band nucleation at the tool tip and its propagation towards the free surface, which is then followed by plastic slip along the band without fracture. The transition from shear-localized chip to fragmented chip with increasing cutting speed is triggered by crack initiation at the free surface and propagation towards the tool tip. The extent to which crack travels towards the tool determines whether the chip is partially fragmented or fully fragmented (discontinuous). It is shown that shear localization precedes fracture and controls the crack path in fragmented chip formation. Dynamic strain and strain-rate fields underlying the each chip formation mode are quantified through image correlation analysis of high-speed images. Implications for using machining as an experimental tool for fundamental studies of localization and shear fracture in ductile metals are also discussed. 

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5. Investigating the differences in human behavior between conventional machining and CNC machining for future workforce development: A case study

   https://doi.org/10.1016/j.jmapro.2023.04.037  

   Jarosz, Krzysztof; Chen, Yan-Ting; Liu, Rui (June 2023, Journal of Manufacturing Processes)