AlCoCrFeNi2.1, a new class of eutectic high entropy alloy (EHEA) has drawn significant interest owing to the lamellar structure of alternating face-centered cubic (FCC) and B2 phases. Properties such as high strength and high plasticity render the machining of this alloy challenging. Addressing this issue, the milling experiments were conducted under dry conditions to investigate the machining quality of AlCoCrFeNi2.1 EHEA as well as the tool wear. The cutting temperature and cutting force were measured to explain the changes in tool wear and machining quality. The tool wear mechanisms and evolution modes were clarified. Finally, the change of surface roughness and surface morphology under different parameters were analyzed and the characterization method of plastic flow marked by B2 phase was proposed. Results showed that both the cutting temperature and cutting force increase as the milling parameters become larger. The width of flank wear increases with the increase of the cutting speed and the feed rate when the volume of material removal volume is constant. The tool wear modes evolved differently with different cutting parameters, for instance, abrasive wear dominated while the cutting speed was less than 80 m/min, but for higher speeds up to 110 m/min, adhesive wear and coating peeling occurred. As the cutting speed increases further, crater wear on the rake face starts to arise in addition to the flank wear. Abrasive wear and adhesive wear with increasing feed rate were dominant until a certain threshold (0.10 mm/tooth) beyond which the coating peels off the tool. Furthermore, chipping occurred for a higher feed rate of 0.14 mm/tooth. In particular, the formation of tool adhesive wear is mainly caused by the FCC phase adheres. In terms of machining quality, larger cutting parameters will worsen the surface roughness and morphology as well as lead to deeper subsurface plastic flow. The research will be conducive to promoting the applications of AlCoCrFeNi2.1 HEA.

Double-sided lapping setup includes upper lapping plate (always floating rather than rigid coupling), lower lapping plate, sun wheel and gear ring. Besides, planetary wheels as the carriers can drive the workpieces rotation and the complex motion is intended to produce homogeneous profiles on both of the surfaces . Moreover, the planetary wheels revolve around sun wheel and the slurry is dropped from the holes on the upper plate while processing. As a result, both of the surfaces can be lapped at the same time, so the two surfaces are similar on profile, residual stress, surface roughness, subsurface defects and so on.

Fluid jet polishing (FJP) can achieve high surface quality and form accuracy in finishing freeform surfaces. Due to its advantages, FJP has been widely used in the ultra-precision manufacturing process of high-end components. However, the edge effect in FJP poses a great challenge to the uniform material removal control at the edge, which has not been investigated in depth hitherto. The non-uniform material removal at the edge deteriorates the form accuracy and affects the functional performance of components, especially in the field requiring extremely high precision. The traditional strategy for restraining the edge effect through the movement system is limited by the extremely high acceleration speeds within a small distance. To address this problem, the cause of the edge effect in FJP is first revealed by computational fluid dynamics (CFD) simulation. Hence, this study presents a pressure-dependent shape-adaptive multi-jet polishing (PDSAMJP) system to restrain the edge effect. The material removal discrepancies were compensated for by adjusting the jet pressure, rather than modifying the feed rate of the machine tool. A surface generation model at the edge was established to optimize the jet pressure distribution. The effectiveness of the PDSAMJP system was validated by jet pressure response measurements and a series of polishing experiments. Compared to traditional jet polishing, the PDSAMJP method enhanced the radius of curvature of the edge surface from 15.2-41.4 mu m to 73.2-143.9 mu m by mitigating edge collapse. The success of this study provides an approach to restraining the edge effect of FJP, thereby enhancing the manufacturing accuracy of ultra-precision freeform surfaces. Furthermore, the principles established herein can be applied to other polishing processes, such as bonnet polishing, to achieve uniform material removal by adjusting a parameter with a fast response, without compromising the stability of the movement system.

The structural optimisation is a crucial step in researching the CDC proportional pilot valve; however, the influence of its structure on key performance remains unclear. This study established the mapping relation between the key performance parameters and structural characteristics of CDC solenoid valves according to the concept of high-performance manufacturing. The simulation model was established and the accuracy was verified. Modelling simulations and theoretical analyses was adopted to optimise the structural parameters based on performance. Results demonstrated that reducing the air gap between the armature and magnetic conductive sleeve increased electromagnetic force and reduced response time. The optimised electromagnetic and response characteristics are obtained when the magnetic isolating ring is placed 0.5 mm below the end face of the valve seat. After optimisation, the average electromagnetic force is increased by 7.72 N, the standard deviation is reduced by 0.36, and the response time is reduced by 4.8 ms.

Fused silica glass, known for its exceptional physical and chemical properties, is widely used across diverse industries. Cerium oxide (CeO2), a common polishing abrasive, is extensively employed in polishing fused silica surfaces. Studies have revealed that chemical reactions occur on fused silica surfaces during polishing processes with CeO2 abrasives. While these chemical reactions have been studied in the context of chemical-mechanical polishing on fused silica surfaces, the chemical impacts of employing a small, compliant polishing tool on fused silica surfaces remain unclear. In this study, we use CeO2 abrasive and alumina (Al2O3) abrasive as polishing slurries and utilize a bonnet tool to polish fused silica surfaces. Through a comparative analysis of the removal efficiency of the tool influence function, alterations in surface hardness, and the sub-surface damage layer, we found that the primary factor governing material removal is the chemical reactions between CeO2 and fused silica. These reactions effectively soften the fused silica molecule layers and contribute to rapid material removal. This research fills the knowledge gap regarding the chemical effects during bonnet polishing with CeO2 abrasive. It offers valuable insights for efficient material removal control in the context of bonnet polishing fused silica surfaces. These insights will also be applicable to other computer-controlled polishing processes for fused silica glass utilizing CeO2 slurry.

The success of injection molding is restricted by the poor surface finish of the mold especially the poor finish of the structured edges significantly limits the performance of injection molded parts. To address this challenge, a non-contact polishing method was developed to achieve conformal polishing and experimentally applied to study the finishing of Fresnel microstructured molds. A complementary finite element simulation model involving nonNewtonian fluid was also developed to elucidate the mechanism of shape evolution during the polishing process. The findings revealed built up of stress intensity at sharp corners of the Fresnel microstructured surface due to the dynamic pressure from the polishing fluid which differs in distribution significantly from other areas such as the bottom and sides of the microstructures. This leads to inconsistent material removal from a microstructured surface which needs careful consideration. Using the proposed polishing method, it has been experimentally shown that the pre-existing defects on the Fresnel microstructured surface can successfully be removed without introducing new damage and a smooth surface with Sa of 1.6 nm and form error of less than 0.6 mu m can be obtained.

Ta-12W, a tantalum-tungsten alloy with high tungsten content, is utilized in the manufacturing of highperformance critical components due to its superior mechanical properties. However, the high strength, low thermal conductivity, and work hardening characteristics of Ta-12W pose significant challenges to achieving high-quality machining. Meanwhile, there is limited research on the Ta-12W machining characteristics, and no suitable constitutive model exists to support simulation-based studies of the material removal process. Addressing these issues, a polynomial-modified Ta-12W constitutive model was proposed to conduct numerical simulations of cutting. The material removal mechanism of Ta-12W has been revealed through a combination of simulation and experimental studies. The ScCO2 + MQL cooling strategy was introduced into the machining process of Ta-12W alloy, and the milling machinability of Ta-12W alloy has been systematically studied using this method, focusing on cutting forces, surface integrity, tool wear, and chip morphology, etc. Results showed that the proposed constitutive model exhibits good accuracy, with a cutting force error within 16.5 % compared to the experimental results. The superiority of ScCO2+ MQL hybrid cooling in the milling of Ta-12W alloy has been validated. Compared with conventional milling, the cutting forces Fx, Fy, and Fz were reduced by 23.5 %, 27.9 %, and 28.1 %, respectively, under specific process conditions. When the feed per tooth was set at 60 mu m/z, the surface roughness obtained under ScCO2 + MQL conditions decreased by approximately 42 %. Chip adhesion was minimized, tool wear was significantly alleviated, and the formation of microcracks and plastic flow on the workpiece surface was suppressed.

The quality of the internal surface plays a crucial role in the performance of parts with complex structures, which are widely used in aerospace, biomedical, and other fields. However, due to poor accessibility, the uniformity of the internal surface of multi-cross channels are low after finishing with existing methods. To address this issue, this paper proposes a step-by-step abrasive flow machining method according to the characteristics of multi-cross channel structures. By flexibly setting the positions of inlets and outlets and adjusting finishing parameters in each step, the material removal rate in different sections of the multi-cross channels can be regulated. Guided by simulation results, the material removal rate in each section becomes consistent after successive steps, achieving uniform finishing of the entire channel. To verify this method, a separatable stainless-steel part with six crossed channels was finished under an inlet pressure of 10 MPa for 40 minutes by using SiC abrasive with a size of 75 μm. The internal surface roughness of the workpiece was reduced from 1.919 μm to less than 1 μm, with variation in each section controlled to less than 12%.

A glycerol-based slurry was developed for the precision polishing of Cs2LiYCl6 (CLYC) crystals. Glycerol was chosen as the base liquid to minimize excessive deliquescence, while ethanol was added to enhance the slurry's fluidity. By incorporating a small amount of deionized water and SiO2 abrasives, the slurry effectively balances deliquescence with mechanical material removal. The material removal mechanism was elucidated through experimental results. Using the optimal parameter set, the surface roughness (Ra) was reduced from 900 nm to 85 nm. The energy resolution of the polished CLYC: 0.5% Ce crystal reached 5.73%, meeting the requirements for practical applications. (c) 2025 CIRP. Published by Elsevier Ltd. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

The double-sided lapping process is extensively employed in the manufacturing of wafers, optical windows, and seal rings due to its high efficiency and ability to achieve precise flatness. However, limited research has explored the thickness uniformity among different workpieces after double-sided lapping, and the underlying mechanism remains unclear. To address the demand for higher precision, this paper first analyzed the relative kinematic model between the workpiece and the lapping plate to clarify the causes of thickness variations among workpieces after double-sided lapping. Subsequently, a finite element method (FEM) model was developed to account for the pressure distribution on the workpiece surfaces at the initial stage of the process. The results indicate that the number of workpieces influences the final thickness variation. Then, various sets of thin copper plates with different thicknesses were lapped, and the findings revealed that five copper plates processed simultaneously exhibited more uniform thickness compared to the three plates. The experimental results align well with the theoretical analysis. Ultimately, a thickness variation of less than 6 μm was achieved on five copper plates measuring Φ100 × 2.9 mm. This study presents a comprehensive analysis of the mechanisms influencing thickness uniformity in the double-sided lapping process and provides practical guidelines for optimizing the process to achieve stringent precision standards in industrial applications.

Wiper tools are increasingly valued for their great potential in achieving high-quality and high-efficient machining. Cutting force is a significant physical parameter in the cutting process, serving as a crucial basis for the study of tool design, machining deformation, tool wear, and cutting vibration. Nevertheless, the cutting force formation mechanism of wiper tools remains unclear, and few studies on the cutting force analytical prediction model of wiper tools has been reported. In this study, the cutting process of wiper tools was firstly thoroughly analysed, and the cutting region was divided into double edge cutting region dominated by shear effect and wiper region dominated by plough effect. Then the cutting force model dominated by shear effect was established by using the energy method and the equivalent cutting edge method, the cutting force model dominated by the plough effect was established by the minimum cutting thickness, surface elastic recovery and slip line field theory. Finally, a cutting force analytical prediction model considering wiper edge structure was established. Compared to the experimental cutting forces, the maximum average absolute errors in the predicted forces are 13.87 %, 10.27 %, and 13.03 % in the x, y, and z directions, respectively. Furthermore, increasing the length of the wiper edge results in increasing cutting forces, especially radial forces. This study provides theoretical guidance and technical support for the design and practical application of wiper tools.

To promote the international cutting-edge technical exchange in the field of abrasives, the Group G (abrasive processing) papers in the 2024 CIRP Annals – Manufacturing Technology journal have been specially selected for introduction. A total of 9 papers on this topic have been published, numbered G1 to G9 in the order of submission. The research topics of these papers include grinding models (G1/G2), grinding machinability (G3/G4), polishing tools (G5), inner surface polishing (G6), chemical mechanical polishing (G7), polishing edge effects (G8), and electrochemical mechanical polishing (G9). This paper summarizes and introduces the main innovations and conclusions of each study to facilitate learning and communication among scholars in related fields.

The metallurgical bonding quality of bonded joints is affected by the substrate surface condition in metal additive forging process, and the surface roughness serves as a critical indicator for the surface condition. Nevertheless, the effect of surface roughness obtained by milling on interface bonding quality (IBQ) remains unclear, resulting in the lack of effective evaluation criteria for surface roughness in the milling process. This study prepared samples with various surface roughness through milling, and introduced three parameters, Ra, Rc, and Rsm, to quantify surface roughness. The interfacial morphology, elemental distribution, and mechanical properties were used to characterize the IBQ, and the influence of surface roughness on the IBQ was finally revealed. The results show that a reduction in surface roughness obtained by milling leads to an improvement in interfacial bonding, more uniform elemental distribution, and enhanced mechanical properties, all of which were related to the size of the initial voids and the dynamic recrystallization mechanism of the bonding interface. And the interface bonding process with various surface roughness involves grain boundary bulging and continuous dynamic recrystallization mechanisms. Finally, the Ra 1.2 mu m was recommended as the evaluation criteria in milling process, and a high-feed face milling cutter equipped with wiper edge was suggested for machining to achieve high-quality and high-efficiency cutting of the substrate. This study provide a theoretical basis and practical guidance for the efficient acquisition of substrate surfaces suitable for interface bonding in metal additive forging process.

While few phase bias streams are available from the IGS Real-time Service Phase, such products are essential to enable PPP ambiguity resolution. Satellite phase biases and clocks should be estimated when fixing undifferenced ambiguities in a network solution, which is troublesome in real time and thus usually not done in practice. This study estimates real-time GPS/Galileo/BDS ambiguity-fixed multi-frequency raw phase biases from GNSS observation modeling. Multi-frequency narrow-lane and wide-lane uncalibrated phase delays (UPDs) are first extracted from the float ambiguities of the stations. Multi-frequency raw ambiguities are then resolved to form unambiguous carrier-range observations. Finally, the satellite phase observable-specific signal biases (phase OSBs) are estimated directly from the real-time network data processing using carrier-range observations only. The approach has been applied to generate real-time phase bias products at the Wuhan IGS analysis center. Real-time products are routinely calculated by 180 globally distributed stations. This study validates the approach and associated products using one week of data. The results show that triple-frequency kinematic PPP-AR based on the ambiguity-fixed phase OSBs can converge in 7.2 min on average, while those based on UPD products take 11.2 min to converge. The other software, PRIDE PPP-AR is used to validate the high-precision static positioning performance of the real-time OSB products. The results show that 82%, 85% and 76% of GPS, Galileo and BDS-3 narrow-lane ambiguities can be resolved successfully among global stations, achieving a mean positioning accuracy of 3.1, 3.0 and 6.0 mm for the east, north and up components.

PPP-RTK (network-based real-time kinematic precise point positioning) can achieve instantaneous centimeter-level positioning using only a single GNSS receiver under the premise of precise satellite orbits, satellite clocks, satellite code/phase biases, and atmospheric corrections. It is usually reported that PPP-RTK needs two or more frequencies of measurements as the phase biases are conventionally defined in terms of wide-lane and narrow-lane combinations. Although single-frequency PPP-RTK has been proven achievable, the signals demonstrated in most open studies are usually limited to specific frequencies such as GPS L1 or similar. However, in GNSS challenging environments, satellite signal losses can repeatedly take place on any frequency, which is likely to disable conventional PPP-RTK algorithms prescribing particular signal frequencies. Therefore, we apply the observable-specific code and phase bias (OSB) concept to PPP-RTK and investigate whether the integer properties of PPP ambiguities on any frequency or frequency combination can be fully recovered after such OSB corrections, i.e. , all-frequency PPP-RTK, to address the satellite signal loss problem in GNSS adverse environments. In particular, all-frequency PPP-RTK is able to process any number, any choice, or any combination of GNSS signal frequencies rather than the prescribed frequencies. We carried out both static and vehicle-born experiments using a regional GPS/Galileo/BDS network over seven days. In the static experiment, six signal clusters across the three constellations ( i.e. , L1/E1/B1C, L5/E5a/B2a, E5b/B2I/B2b, B1I, B3I, and L2/E6) were tried to perform single-frequency single-epoch PPP-RTK. Each cluster of signals (except L2/E6) shares the same frequency ( i.e. , overlap frequency among constellations). We found that the average ambiguity fixing rate was 95.8% and the mean positioning precisions were 1.9, 1.6, and 5.4 cm in the east, north, and up components, respectively, in terms of RMS errors. In the vehicle-borne experiment, the ambiguity fixing rate at GNSS challenging epochs was improved by 15 percentage points and the horizontal positioning errors were reduced by over 30% when switching from conventional to all-frequency PPP-RTK.

Modern industrial equipment is increasingly characterized by miniaturization, integration, and high performance, necessitating the production of complex structural parts with exceptionally high internal surface quality. Direct manufacturing often leads to high internal surface roughness, which traditional finishing and measuring methods cannot adequately address due to the decreasing size and increasing complexity of internal structures. This is especially true for components like pipes with large aspect ratios, extremely small deep holes, multi-stage bends, cross pipes, and array holes. To meet the high-performance manufacturing demands of these parts, advanced internal surface finishing and roughness measurement technologies have gained significant attention. This review focuses on the challenges and solutions related to internal surface parts with various apertures and complex structures. Internal surface finishing methods are categorized into mechanical finishing, fluid-based finishing, and energy-field-based finishing based on their characteristics. Roughness measurement technologies are divided into tool-probing and non-probing methods. The principles, required equipment, and key parameters of each finishing and measurement approach are discussed in detail. Additionally, the advantages and limitations of these methods are summarized, and future trends are forecasted. This paper serves as a comprehensive guide for researchers and engineers aiming to enhance the internal surface quality of complex structure parts.