International Journal of Advanced Manufacturing Technology最新文献

Subtractive manufacturing is undergoing a transformative shift towards sustainability and zero-defect manufacturing. This shift is driving the need for more efficient machining strategies such as dynamic milling. The real-time implementation of dynamic milling toolpaths, composed of circular and cycloidal curve patterns, is challenging due to the kinematic constraints in computer numerically controlled machine tools. Resulting from a rigorous analytical analysis of kinematics, the limitations of current approaches to finite impulse response (FIR) interpolation of circular arc (G02/G03) motion are addressed. A novel hybrid FIR interpolation method is presented which modifies the interpolation style depending on the fundamental geometry of commanded circular motion. The method globally satisfies kinematic constraints and tool centre point position tolerances during circular motion and allows consideration of machine dynamics (i.e., resonant frequencies) within the interpolation strategy. The proposed method outperformed current state-of-the-art methods during benchmarking tests which included a high-performance machine tool and two commercial controllers. Reductions of up to 38% in manufacturing cycle times were demonstrated when interpolating high-speed trochoidal toolpaths with the proposed method.

The UK is the twelfth-largest manufacturing nation globally, yet its adoption of digital manufacturing technologies (DMTs) lags behind other European countries. In an era where industrial automation and digital transformation are essential for maintaining competitiveness, understanding the human factors influencing the acceptance and implementation of these technologies is critical. This study examines the perceptions of 313 UK manufacturing employees regarding the usefulness, ease of use, and workplace impact of DMTs. Findings indicate that while employees recognise the potential benefits of DMTs such as increased productivity, improved product quality, and enhanced competitiveness, concerns remain regarding ease of use, workforce upskilling, and physical interaction with new technologies. Notably, employees with lower educational qualifications expressed greater scepticism about the applicability of DMTs. Furthermore, those working in companies that had already implemented digital technologies reported more positive perceptions compared to non-users, emphasising the role of experience in shaping attitudes. The study highlights the need for targeted training and change management strategies to facilitate smoother workforce adaptation to digital advancements. These findings provide insights for policymakers, industry leaders, and system designers aiming to integrate human-centric approaches in the transition to Industry 4.0 and beyond.

Wire arc additive manufacturing (WAAM) is suitable for building large-scale engineering structures with high deposition rates and relatively low costs. However, in a typical plasma transferred arc (PTA)-based WAAM process using an inclined wire and vertical torch, keyhole defects can occur due to the high arc pressure, and the process is sensitive to the wire-feeding position with respect to the workpiece. Therefore, in this study, a PTA-based WAAM process with a new configuration employing a vertical wire and an inclined plasma torch was investigated for the potential of mitigation of keyhole formation and improvement of process tolerance. In particular, detailed investigations were carried out on the metal transfer mechanisms and bead formation characteristics under various processing conditions. The results show that the new configuration significantly reduces the likelihood of keyhole formation compared with the conventional approach due to the changes in arc pressure and heat distribution. Systematic analysis reveals that process parameters, including wire feed speed, arc current, and plasma gas flow rate, strongly influence droplet transfer stability, melt pool dynamics, and final bead morphology, which offer guidance for future process optimisation.

Abstract

This paper aims to develop a simulation-based chatter prediction system using relative entropy—Kullback-Leibler divergence (KLD), and the NC program can be modified to become non-chatter. Chatter is one of the major concerns when machining mechanical components on a CNC machine. In general, the majority of the previous research methods achieved non-chatter stable machining by assigning the appropriate machining parameters: (1) spindle speed, (2) feed rate, and (3) depth of cut based on the generated SLD (stability lobe diagram). Non-chatter stable machining can also be accomplished by manually adjusting the spindle override percentage on the operation panel or the values in the CNC controller via networking once chatter is detected during the machining processes. The creation of SLD must consider two essential parameters: cutting force coefficients (CFCs) and frequency response function (FRF). The CFCs can be obtained from cutting experiment data related to a paired tool and workpiece, and the FRF can be calculated from the tapping test experiment. Then, the CFCs and FRF are stored in the database of the developed system. The simulation-based chatter prediction calculates the KLD value based on the relativity of the dynamic cutting force and the static cutting forces so as to predict whether there is chatter in the NC program or not. The NC program can be adjusted to become non-chatter if there is chatter predicted. The proposed method has been successfully verified through on-site machining, showing very promising achievement.

Abstract

Niobium (Nb) is a transition metal commonly used as an alloying element for increasing strength, toughness, corrosion resistance, and other properties of steel and superalloys. Pure Nb, however, is a very interesting metal for its excellent superconductivity. This makes it suitable for producing superconducting magnets and devices for particle acceleration systems and particle physics research (e.g., superconducting resonant cavities). In this work, the production of Nb by the Laser-Based Powder Bed Fusion (PBF-LB/M, also known as Laser Powder Bed Fusion or LPBF) process was examined. Manufacturing parameters were investigated to achieve additively manufactured parts with a relative density higher than 99.5% and showing a down-skin surface roughness in the range of 20–70 μm, depending on the inclination angle. Studies related to the limiting angle of self-supported Nb parts were also conducted, and innovative non-contact supporting structures were successfully developed. These allowed to creation of parts with very small overhang angles, without compromising the downward-facing surfaces; indeed at the same time, the as-built surface finish was improved.

For weight reduction, multi-material designs comprising metal and fiber-reinforced plastic (FRP) components in vehicle body structures have been increasingly used. However, the commonly used resistance spot welding (RSW) technology for car body assembly cannot be employed to join sheet metal and FRPs, limiting the use of FRPs. To solve this problem, a novel resistance insert spot welding (RISW) technique was developed in this work for RSW of steel parts and FRP structure parts made by injection molding. Small inserts were developed by using finite element method and experiments that may be welded to different micro-alloyed and dual-phase sheet steels using the projection welding method. The usual flange width of original equipment manufacturers could be kept unchanged. Using the developed insert and welding parameters, the maximum temperature in the FRPs surrounding the inserts was limited to 255 °C, minimizing the damage to polyamide 6 (PA6) material (with 40 wt% glass fiber). A weldability range between 2.5 and 7 kA could be achieved. The joining strength of RISW between a micro-alloyed HC340 steel in 0.75 mm and 1.5 mm thickness and a 2.5 mm/3.0 mm PA6-GF40 material is 20 to 80% higher than self-piercing riveting (SPR). For high-speed loading, RISW strength increases by 39 to 56% further. Finally, RISW was successfully applied to an FRP–steel roof-frame sub-assembly that consists of 19 simultaneously integrated inserts, achieving 10% weight reduction.

The thermal characteristics of the motorized spindle significantly affect the machining accuracy and efficiency, and many thermal models have been developed to investigate the factors that affect the spindle thermal characteristics. However, the thermomechanical coupling of the bearings with constant pressure preload is rarely considered in the present works. Thus, this paper developed a transient temperature model of motorized spindle to study the influence of the radial thermal stress on the heat generation of the constant pressure preloaded bearings. In this research, an analytical thermal stress model was established first by simplifying the components of the bearings into a rotating ring geometry to calculate the thermal stress loaded on the bearings. Meanwhile, a transient temperature model of the motorized spindle was established based on the finite element method (FEM). Then, the analytical model was integrated into the spindle transient thermal model, so that the heat generated by bearings and the motorized spindle temperature can be revised constantly, through the iterative calculation between these two models. Finally, verification experiments with different work conditions clarify that the proposed transient thermal characteristic model of the motorized spindle is valid, and the study shows that it is necessary to consider the bearing heat generation induced by the radial thermal stress when the spindle runs at a high speed.

Abstract

To improve the reliability of the connection of various steel/aluminum dissimilar materials, an integrated optimization method of material-structure-process-performance is proposed to realize the optimal design of process parameters. First, the Johnson–Cook material model and failure fracture model are established to ensure the accuracy of the simulation model. Then, an integrated simulation analysis for self-piercing riveted joint forming and tensile mechanical performance is established considering the residual information of the joint forming process. Compared with the experimental results, the accuracy of the established model is higher than the model without considering the residual information. Finally, a hybrid sequence approximate optimization that comprehensively considers the forming quality and tensile mechanical performance is constructed to determine the optimal riveting parameters. Compared with the initial design, the maximum pull-out force, maximum shear force, and maximum peeling force of the optimized design for DC01 and 5754 rivets are increased by 35.66%, 8.6%, and 22.43%, respectively, and the maximum pullout force, maximum shear force and maximum peeling force of the optimized design for HC280 and 5754 rivets are increased by 1.490%, 1.292%, and 6.867%, respectively. Moreover, the accuracy and efficiency of self-piercing riveting process design are improved.

In industrial applications of laser welding of aluminum alloys, it is often a challenge to find optimal process parameters to produce welded joints of good quality. This study investigates the effect of changes in welding parameters on the resulting welding defects and tensile properties of laser-welded aluminum alloy joints. A high-power disk laser was used for welding 2.54 mm thick AA6061-T6 sheets with four different sets of process parameters. X-ray computed microtomography and full-field microhardness mapping were first used to characterize the as-welded joints. Surface strain mapping based on digital image correlation and a two-mirror optical setup was applied to tensile testing of welded joints up to ductile failure. It was found that the fusion zone of all four laser-welded joints has similar microhardness levels and spatial distributions. Small pores were detected in all four weld joints, except one had a few large pores. Both microstructural heterogeneities and surface geometric irregularities were found to induce highly non-uniform local tensile deformation in laser-welded joints. One set of laser welding parameters was identified to produce the aluminum welds with the best tensile properties even though its weld joint may contain a few relatively large pores.

This paper aims to investigate the contribution of tool wear and process parameters to the shape defects induced by the micro-machining of glassy polymers such as polycarbonate. An experimental approach is proposed in this study using an instrumented orthogonal cutting configuration. Diamond inserts have been considered as a cutting tool and have been subjected to different levels of accelerated wear. The worn tools were first characterized to identify the wear mechanisms that occurred on the active cutting zone and were then used to perform orthogonal cutting experiments on polycarbonate. Micro-cutting depth values (3–20 µm) were considered to respect the micro-machining configuration. Chip morphology, cutting forces, and machined surfaces’ topography have been acquired to analyze and assess the effectively removed material depth regarding the theoretical cutting depth for each worn tool. Results show that the increase of the cutting edge radius is the main wear mechanism that occurred in the diamond inserts. This tool wear evolution was found to be the most influential factor on the induced shape defect by increasing the elastic deformation of polycarbonate rather than its shear when using micro-cutting depths, which induces a spring-back of polycarbonate after cutting.