Advances in Manufacturing

Microscale shaping and rounding of ridge arrays and star pattern features on nickel mould via electrochemical polishing

Sana Zaki, Nan Zhang, Michael D. Gilchrist

2024, 12(2): 207-226. doi:10.1007/s40436-023-00474-w

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High quality micro mould tools are critical for ensuring defect-free production of micro injection moulded products. The demoulding stage of the micro injection moulding can adversely affect the surface integrity due to friction, adhesion and thermal stresses between the metallic mould and polymeric replicated part. In the present work, we propose the use of precision electropolishing (EP) as a shaping and polishing process to control the draft angle and fillet radius of micro features in order to ease demoulding. Typical defects that occur in replicated polymer parts include cracks, burrs and distorted features. A nickel mould having multiple linear ridges and star shape patterns was designed for the present investigation to have characteristic dimensions ranging from 10 μm to 150 μm and with various aspect ratios to study the effect of electropolishing on modifying the shape of micro features and surface morphology. A transient 2D computational analysis has been conducted to anticipate the effect of shaping on the Ni mould after electrochemical polishing with non-uniform material removal rates, based on the distribution of current density. The experimental results indicate that after shaping using EP, the draft angle of starpatterns and linear patterns can be effectively increased by approximately 3.6°, while the fillet radius increases by up to 5.0 μm. By controlling the electropolishing process, the surface roughness can be maintained under 50 nm. This work uses a green and environmental friendly nickel sulfamate electrolyte which can be effective for shaping of nickel micro features without causing any surface deposition.

The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-023-00474-w

Energy-efficient buffer and service rate allocation in manufacturing systems using hybrid machine learning and evolutionary algorithms

Si-Xiao Gao, Hui Liu, Jun Ota

2024, 12(2): 227-251. doi:10.1007/s40436-023-00461-1

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Currently, simultaneous buffer and service rate allocation is a topic of interest in the optimization of manufacturing systems. Simultaneous allocation problems have been solved previously to satisfy economic requirements; however, owing to the progress of green manufacturing, energy conservation and environmental protection have become increasingly crucial. Therefore, an energy-efficient approach is developed to maximize the throughput and minimize the energy consumption of manufacturing systems, subject to the total buffer capacity, total service rate, and predefined energy efficiency. The energy-efficient approach integrates the simulated annealing-non-dominated sorting genetic algorithm-II with the honey badger algorithm-histogram-based gradient boosting regression tree. The former algorithm searches for Pareto-optimal solutions of sufficient quality. The latter algorithm builds prediction models to rapidly calculate the throughput, energy consumption, and energy efficiency. Numerical examples show that the proposed hybrid approach can achieve a better solution quality compared with previously reported approaches. Furthermore, the prediction models can rapidly evaluate manufacturing systems with sufficient accuracy. This study benefits the multi-objective optimization of green manufacturing systems.

The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-023-00461-1

A condition-based maintenance policy for reconfigurable multi-device systems

Shu-Lian Xie, Feng Xue, Wei-Min Zhang, Jia-Wei Zhu

2024, 12(2): 252-269. doi:10.1007/s40436-023-00465-x

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The exploration of component states for optimizing maintenance schedules in complex systems has garnered significant interest from researchers. However, current literature usually overlooks the critical aspects of system flexibility and reconfigurability. Judicious implementation of system reconfiguration can effectively mitigate system downtime and enhance production continuity. This study proposes a dynamic condition-based maintenance policy considering reconfiguration for reconfigurable systems. A double-layer decision rule was constructed for the devices and systems. To achieve the best overall maintenance effect of the system, the remaining useful life probability distribution and recommended maintenance time of each device were used to optimize the concurrent maintenance time window of the devices and determine whether to reconfigure them. A comprehensive maintenance efficiency index was introduced that simultaneously considered the maintenance cost rate, reliability, and availability of the system to characterize the overall maintenance effect. The reconfiguration cost was included in the maintenance cost. The proposed policy was tested through numerical experiments and compared with different-level policies. The results show that the proposed policy can significantly reduce the downtime and maintenance costs and improve the overall system reliability and availability.

The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-023-00465-x

Research on feed-pulse collaborative control method in micro-electrical discharge machining

Qiang Gao, Ya-Ou Zhang, Xue-Cheng Xi, Yuan-Ding Wang, Xiao-Fei Chen, Wan-Sheng Zhao

2024, 12(2): 270-287. doi:10.1007/s40436-023-00471-z

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Reducing the short-circuit rate and increasing the effective discharge rate are important targets for improving the servo control effect of micro-electrical discharge machining (micro-EDM), as these two indicators are closely related to the machining efficiency and quality. In this study, a feed-pulse collaborative control (FPCC) method is proposed for micro-EDM based on two dimensions (space and time). In the spatial dimension, a feed control strategy with a discharge holding process is adopted. Meanwhile, in the time dimension, a forward-looking pulse control strategy is adopted, in which the pulse interval is adjusted based on a sequence analysis of feed commands and discharge states. Process experiments are carried out to determine the key parameters used in this method, including the discharge holding threshold and pulse interval adjustment value (T_{off _adj}). The feed smoothness and discharge sufficiency analyses of the experimental results show that compared to the traditional double threshold average voltage method, the FPCC method reduces the number of long-distance retreats by 64 % and improves the effective discharge time by 40 %.

The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-023-00471-z

Study on a probabilistic algorithm for the forming and 3D characterization of special-shaped surfaces under profile grinding

Zhao-Qing Zhang, Kai-Ning Shi, Yao-Yao Shi, Yi-Hui Song, Zhe He, Ya-Song Pu

2024, 12(2): 288-299. doi:10.1007/s40436-023-00467-9

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Abstract Profile grinding is the most crucial method for the ultra-precision machining of special-shaped surfaces. However, profile grinding produces a unique machining profile, and many random factors in the machining process lead to complex surface characteristics. In this study, the structural and probabilistic characteristics of the profile grinding of a special-shaped surface were analyzed, and a probabilistic algorithm for the forming and 3D characterization of special-shaped surfaces under profile grinding was developed. The forming process of a GH738 blade tenon tooth surface was considered as an example to demonstrate the algorithm. The comparison results showed that the simulation results had similar surface characteristics to the measurement results, and the relative error range of the 3D roughness parameter was 0.21 %-19.76 %, indicating an accurate prediction and characterization of the complex special-shaped surface under the action of multiple factors.

The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-023-00467-9

Universal and efficient hybrid modeling and direct slicing method for additive manufacturing processes

Sen-Lin Wang, Li-Chao Zhang, Chao Cai, Ming-Kai Tang, Si Chen, Jiang Huang, Yu-Sheng Shi

2024, 12(2): 300-316. doi:10.1007/s40436-023-00468-8

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Model design and slicing contour generation in additive manufacturing (AM) data processing face challenges in terms of efficiency and scalability when stereolithography files generated by complex functionally graded structures have millions of faces. This paper proposes a hybrid modeling and direct slicing method for AM to efficiently construct and handle complex three-dimensional (3D) models. All 3D solids, including conformal multigradient structures, were uniformly described using a small amount of data via signed distance fields. The hybrid representations were quickly discretized into numerous disordered directed lines using an improved marching squares algorithm. By establishing a directional HashMap to construct the topological relationship between lines, a connecting algorithm with linear time complexity is proposed to generate slicing contours for manufacturing. This method replaces the mesh reconstruction and Boolean operation stages and can efficiently construct complex conformal gradient models of arbitrary topologies through hybrid modeling. Moreover, the time and memory consumption of direct slicing are much lower than those of previous methods when handling hybrid models with hundreds of millions of faces after mesh reconstruction.

The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-023-00468-8

Cutting performance of saw blades with microtextured rougher and finisher sawteeth

Yang Lu, Jian-Xin Deng, Zhi-Hui Zhang, Jia-Xing Wu, Ran Wang, Yi-Chen Bao

2024, 12(2): 317-334. doi:10.1007/s40436-023-00470-0

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The problems of severe sawtooth wear, harsh sawing noise, and low surface quality during the processing of circular saw blades need to be solved. To improve the cutting performance of TiC-based cermet saw blades, microtextures parallel to the cutting edge were fabricated on rough and fine sawteeth by laser machining. The cutting tests were performed on a sawing platform under lubricated conditions. Models of the sawing arc length and working sawtooth cutting force variations were developed for sawing steel pipes, and the accuracy of the sawing force model was verified experimentally. The results indicate that the variations in the sawing force are proportional to the sawing arc length. The circular saw blades with microtextures that did not penetrate the sawtooth rake face exhibited the lowest cutting force, sawing noise, and highest machined surface quality. Furthermore, the worn-out distance of the rougher and finisher sawteeth was reduced by approximately 7.4 % and 44.1 %, respectively, compared with conventional circular saw blades. The main failure modes of sawteeth were tip wear, rake face adhesion, and oxidative wear. In addition, the mechanism by which the textures improve the cutting and wear properties of TiC-based circular saw blades was discussed. This study provided a significant concept for enhancing the cutting performance of circular saw blades and improving the machined surface quality.

The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-023-00470-0

A novel weld-pool-length monitoring method based on pixel analysis in plasma arc additive manufacturing

Bao-Ri Zhang, Yong-Hua Shi

2024, 12(2): 335-348. doi:10.1007/s40436-023-00466-w

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The real-time monitoring of the weld pool during deposition is important for automatic control in plasma arc additive manufacturing. To obtain a high deposition accuracy, it is essential to maintain a stable weld pool size. In this study, a novel passive visual method is proposed to measure the weld pool length. Using the proposed method, the image quality was improved by designing a special visual system that employed an endoscope and a camera. It also includes pixel brightness-based and gradient-based algorithms that can adaptively detect feature points at the boundary when the weld pool geometry changes. This algorithm can also be applied to materials with different solidification characteristics. Calibration was performed to measure the real weld pool length in world coordinates, and outlier rejection was performed to increase the accuracy of the algorithm. Additionally, tests were carried out on the intersection component, and the results showed that the proposed method performed well in tracking the changing weld pool length and was applicable to the real-time monitoring of different types of materials.

The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-023-00466-w

Surface quality investigation in high-speed dry milling of Ti-6Al-4V by using 2D ultrasonic-vibration-assisted milling platform

Jin Zhang, Li Ling, Qian-Yue Wang, Xue-Feng Huang, Xin-Zhen Kang, Gui-Bao Tao, Hua-Jun Cao

2024, 12(2): 349-364. doi:10.1007/s40436-023-00473-x

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Ultrasonic-vibration-assisted milling (UVAM) is an advanced method for the efficient and precise machining of difficult-to-machine materials in modern manufacturing. However, the milling efficiency is limited because the ultrasonic vibration toolholder ER16 collet has a critical cutting speed. Thus, a 2D UVAM platform is built to ensure precision machining efficiency and improve the surface quality without changing the milling toolholder. To evaluate this 2D UVAM platform, ultrasonic-vibration-assisted high-speed dry milling (UVAHSDM) is performed to process a titanium alloy (Ti-6Al-4V) on the platform, and the milling temperature, surface roughness, and residual stresses are selected as the important indicators for performance analysis. The results show that the intermittent cutting mechanism of UVAHSDM combined with the specific spindle speed, feed speed, and vibration amplitude can reduce the milling temperature and improve the texture of the machined surface. Compared with conventional milling, UVAHSDM reduces surface roughness and peak-groove surface profile values and extends the range of residual surface compressive stresses from -413.96 MPa to -600.18 MPa. The excellent processing performance demonstrates the feasibility and validity of applying this 2D UVAM platform for investigating surface quality achieved under UVAHSDM.

The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-023-00473-x

Shock effects on the upper limit of the collision weld process window

Blake Barnett, Anupam Vivek, Glenn Daehn

2024, 12(2): 365-378. doi:10.1007/s40436-023-00472-y

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The maximum flyer impact velocity based on a dynamic solidification cracking mechanism is proposed to describe the upper limit of collision welding process windows. Thus, the upper limit of the weld window is governed by the evolution of dynamic stresses and temperatures at the weld interface. Current formulations for the upper limit of the collision weld window assume that both the flyer and target are made of the same material and approximate stress propagation velocities using the acoustic velocity or the shear wave velocity of the weld material. However, collision welding fundamentally depends on the impacts that generate shockwaves in weld members, which can dominate the stress propagation velocities in thin weld sections. Therefore, this study proposes an alternative weld window upper limit that approximates stress propagation using shock velocities calculated from modified 1-D Rankine-Hugoniot relations. The shock upper limit is validated against the experimental and simulation data in the collision welding literature, and offers a design tool to rapidly predict more accurate optimal collision weld process limits for similar and dissimilar weld couples compared to existing models without the cost or complexity of high-fidelity simulations.

The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-023-00472-y

Optimizing mechanical properties of HIPS fabricated with low-cost desktop 3D printers: investigating the impact of process parameters

Jin-Ting Xu, Guang-Wei Zhang, Man-Man Chen

2024, 12(2): 379-395. doi:10.1007/s40436-023-00475-9

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Recently, low-cost desktop three-dimensional (3D) printers, employing the fused deposition modeling (FDM) technique, have gained widespread popularity. However, most users cannot test the strength of printed parts, and little information is available about the mechanical properties of printed high-impact polystyrene (HIPS) parts using desktop 3D printers. In this study, the user-adjustable parameters of desktop 3D printers, such as crisscross raster orientation, layer thickness, and infill density, were tested. The experimental plans were designed using the BoxBehnken method, and tensile, 3-point bending, and compression tests were carried out to determine the mechanical responses of the printed HIPS. The prediction models of the process parameters were regressed to produce the optimal combination of process parameters. The experimental results showcase that the crisscross raster orientation has significant effects on the flexural and compression strengths, but not on the tensile strength. With an increase in the layer thickness, the tensile, flexural, and compression strengths first decreased and then increased, reaching their minimum values at approximately 0.16 mm layer thickness. In addition, they all increased with an increase of infill density. It was demonstrated that when the raster orientation, layer thickness, and infill density were 13.08°/-76.92°, 0.09 mm, and 80 %, respectively, the comprehensive mechanical properties of the printed HIPS were optimal. Our results can help end-users of desktop 3D printers understand the effects of process parameters on the mechanical properties, and offer practical suggestions for setting proper printing parameters for fabricating HIPS parts.

The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-023-00475-9

Evolution of inner wall wrinkle defects in the sinking zone of a thick-walled steel tube during radial forging

Yu-Zhao Yang, Cheng Xu, Li-Xia Fan

2024, 12(2): 396-408. doi:10.1007/s40436-023-00462-0

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An axial wrinkle defect was observed in the inner wall of the sinking zone of a thick-wall steel tube processed by cold radial forging. Wrinkles can evolve into fissures. The present study focuses on the evolution of wrinkles and the effects of process parameters on them using a three-dimensional radial forging process finite element model, radial forging experiments, and surface morphology observations. The results indicated that the vertical section angle of the hammer die and the size of the tube blank significantly affect the evolution of wrinkles. The height-towidth ratio λ was introduced to describe the morphology of wrinkles. It had an approximately linear relationship with the radius reduction in the sinking zone. There was a linear correlation between the growth slope of λ and the axial to circumferential strain ratio|ε_r/ε_θ|, which can predict the λ under few process parameters. For the 30SiMn2MoVA steel, at the junction of the forging and sinking zones, the threshold of λ of the wrinkle that can evolve into a fissure is approximately 1.123.

The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-023-00462-0

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