Advanced Machining Technology Research Articles

Study on cell wall deformation in ultrasonic cutting aluminum honeycomb by straight-blade knife

Aluminum honeycomb sandwich structure has been widely used in the aeronautic and astronautic fields. As the core part, aluminum honeycomb needs to be machined but defects are easily generated. Ultrasonic cutting is an advanced machining technology for honeycomb materials due to improved machining quality. However, ultrasonic cutting aluminum honeycomb by straight-blade knife is usually accompanied by cell wall deformation, which results in poor machining quality. To facilitate the industrial use of ultrasonic cutting aluminum honeycomb with a straight-blade knife, a finite element (FE) model was developed, and experimental studies had been performed. The effects of the blade-inclined angle and lead angle of the straight-blade knife were studied by analyzing the cutting force, the stress and deformation in the cutting zone. Results showed that the cell wall deformation was significantly suppressed when cutting with a corresponding blade-inclined angle and a lead angle. Meanwhile, effects of ultrasonic cutting parameters on the cell wall deformation were also studied, indicating that a well-machined cell wall could be obtained when cutting with large ultrasonic amplitude.

Performance evaluation in die-sinking EDM of polygonal micro cavities over EN-24 alloy steel using cylindrical electrode and polygon cycle approach

The integration of advanced Electrical Discharge Machining (EDM) technology, incorporating short and electronically pulsed discharges with precise circular electrode movements, has enabled the production of intricate 3D microstructures and cavities. This paper aims to investigate the machining performance of polygonal cavities—triangular, square, pentagon, and hexagon—fabricated on steel samples using a 400 µm cylindrical copper electrode within the polygon cycle approach of EDM. Experimental investigations were conducted to assess shape error, tool wear rate, recast layer formation, and elemental characterization. Various discharge patterns and side discharges were examined to understand their effects on spark gap uniformity, tool deflection, and discharge stability. The results revealed non-uniform spark gaps, tool deflection, and corner rounding due to varying discharge patterns and side discharges. Tool wear rate was found to be directly related to polygon complexity, with higher-order polygons leading to increased wear due to extended machining durations and heat accumulation. The maximum tool wear of 7.69 × 104 µm3/s occurred in case of hexagonal cavities while in case of triangular cavities, the tool wear rate was minimum having value of 5.77 × 104 µm3/s. Scanning Electron Microscopy (SEM) examinations showed the presence of recast layers and micro-cracks, particularly in cavities with higher shape complexities. Energy Dispersive X-ray Spectroscopy (EDS) analysis identified copper deposition, local material evaporation, and foreign element accumulation on the cavity surfaces. This study provides insights into the machining performance of polygonal cavities in EDM processes. The findings underscore the influence of discharge patterns, polygon complexity, and material interactions on tool wear, surface quality, and microstructure integrity. Understanding these factors can inform optimization strategies for EDM processes, leading to enhanced precision and efficiency in microstructure fabrication.

Prediction of pose- and position-dependent tool-tip dynamics in high-speed dry gear hobbing

High-speed dry gear hobbing is an advanced and efficient machining technology for automotive gears. Frequent changes in the hob mounting angle (tilt angle) and shifting position result in variations in the tool-tip frequency response function (FRF), which inevitably modify the hobbing stability boundary. To construct an accurate stability boundary for high-speed dry gear hobbing, the primary objective is to predict the tool-tip FRF related to different combinations of hob tilt angles and shifting positions, that is, pose- and position-dependent tool-tip FRF. This study proposes a novel tool-tip FRF prediction strategy that combines multi-output Gaussian Process regression (MOGPR) and Receptance Coupling Substructure Analysis (RCSA). First, the FRFs at the tips of the hob-mounting base were estimated through a series of impact tests under a limited combination of hob tilt angles and shifting positions, and the corresponding modal parameters were identified. The MOGPR model was then leveraged to reveal the mapping relationships between the modal parameters, hob tilt angles and shifting positions. Based on this, the hob-mounting base pose- and position-dependent FRFs can be obtained using the modal fitting technique. Subsequently, the pose-and position-dependent tool-tip FRFs were obtained by coupling the receptances of the hob-toolbar assembly with the fitted hob-mounting base FRFs through the RCSA. Finally, a series of impact tests were conducted to verify the effectiveness of the proposed method. The prediction of pose- and position-dependent tool-tip dynamics can provide a foundation for accurately modeling hobbing stability.

Prediction of the Modal Parameters of The Spindle System in High-speed Dry Hobbing Machine with Thermal Effects

High-speed dry hobbing is an advanced green machining technology for gears. However, thermal issues in the machine tools become serious under the high cutting speed and dry cutting conditions, which result in a nonlinear evolution of the machine tool dynamics, and finally affect the hobbing stability. In view of this, introducing the hob spindle system as the object, this paper intends to investigate the influence of time-varying temperatures on the modal parameters based on the modal tests. Then, a temperature-dependent modal parameters prediction model based on the multi-output Gaussian process regression (MOGPR) is proposed. The experimental results indicated that the modal parameters of the spindle system vary obviously with changing thermal states. The natural frequencies for the first and third modes increased with the temperature rise, while the variation of the natural frequency for the second mode was insignificant. The damping ratios for the first three modes showed a decreasing trend with the temperature rise. The constructed MOGPR model has the capability to effectively predict the modal parameters with the time-varying thermal effects, which can provide a support to build the temperature-dependent hobbing stability boundaries.

Plasma characteristics and material erosion mechanism in multi-channel wire electrical discharge machining

Multi-channel wire electrical discharge machining (MC-WEDM) is an advanced and high-efficiency machining technology, but its material erosion mechanism remains unclear. In this study, dual-channel wire electrical discharge machining was utilized as a case study to investigate the impact of the plunging current on both the plasma characteristics and material erosion under complex discharge conditions. Force analysis was conducted on the charged particles in the plasma, revealing that the plunging current can influence the trajectory of the plasma by modifying the self-magnetic field. The particle tracking method was employed to simulate the motion of electrons, revealing that in MC-WEDM, electrons exhibited a larger and more uniform distribution. The evolution of the plasma within a single-pulse discharge was observed using high-speed photography technology, and the discharge signals collected from different channels were analyzed. It was observed that the plasma in MC-WEDM experienced more intense back-and-forth sweeping on the workpiece surface, facilitating the ejection of molten metal from the molten pool. The oscillating plasma exhibits a larger processing area and a more uniform distribution of energy, resulting in the formation of larger and shallower discharge craters. Furthermore, the influence of the amplitude and time point of the plunging current on the volume and area of the discharge craters was summarized. Finally, MC-WEDM significantly reduced the occurrence of holes and micro-cracks and exhibited a thinner recast layer in the continuous discharge experiment.

Developments, challenges and future trends in advanced sustainable machining technologies for preparing array micro-holes.

The use of array micro-holes is becoming increasingly prevalent across a range of industries, including the aerospace, automotive, electronics, medical and chemical industries. The utilization of advanced sustainable machining technologies offers distinctive advantages and is pivotal for the sustainable manufacture of array micro-holes. This paper examines the sustainable machining techniques commonly employed in the production of array micro-holes, including electrical discharge machining, laser machining, electrochemical machining and composite machining technologies. The paper begins with an elaboration of the processing principles and characteristics of multiple non-traditional machining techniques. The performance indicators of the most commonly used processing technologies in industrial production are summarized from seven perspectives. Six significant avenues for the advancement of sustainable manufacturing technology for array micro-holes have been identified and categorized. This article provides a summary and evaluation of the previous relevant literature, with the aim of offering guidance for the development of array micro-hole processing technologies.

Improving the machined surface in electrochemical mill-grinding by particle tracking fluid simulation and experimental research

The hybrid machining method called electrochemical mill-grinding is an advanced machining technology, which can achieve high-quality processing of various difficult-to-cut materials. However, achieving rapid transportation and removal of processed products within a small machining gap is a key challenge, which directly affects the final machined surface quality. In this paper, the product transport under different flushing modes was studied through numerical simulation of the flow field. By using the particle tracking method, the time required for the removal of machining products from the machining gap was dynamically simulated. The analysis results indicated that the removal speed of machining products could be significantly improved when the flushing pressure was 0.8 MPa and the electrolyte jet angle was 30°. In addition, machining experiments were conducted. The machining experiment results showed that the machined surface had a metallic luster with clear edge contours. The grinding marks on the machined surface indicated the grinding effect. The continuous machining of complex patterns demonstrated the reliability of this hybrid machining process.

Research on Digital Manufacturing Technology of Key Components of Artificial Knee Joint

The surface of the artificial knee joint manufactured by 3D printing technology is rough. This study uses advanced multi-axis machining technology to study how to improve the manufacturing accuracy of the artificial knee joint surface, and uses five-axis machining CAM software to analyze the process of three-dimensional model of the artificial knee joint and to compile tool path, create a five-axis special post-processor, convert the tool path point file into the NC program for machine tool processing. In order to ensure the safety and efficiency of the processing procedure, a Mikron HEM-500U machine tool simulation platform was built in the VERICUT simulation system for simulation processing verification, and then the blank prototype obtained by 3D printing was processed in a five-axis machine tool to meet medical clinical use requirements.

A review on the drilling of CFRP/Ti stacks: Machining characteristics, damage mechanisms and suppression strategies at stack interface

Carbon fiber reinforced polymer (CFRP)/titanium alloy (Ti) stacks have promising application in aerospace field due to their excellent mechanical properties. During integrated drilling of CFRP/Ti stacks, the machining process at interface between CFRP and titanium alloy is very complicated. The interaction among CFRP, titanium alloy and cutting tool leads to poor processing quality, serious tool wear and other problems. In this paper, in order to deeply analyze the influence mechanism of interface area on the machining process, the research achievements and progress of drilling CFRP/Ti stacks are reviewed. Special attention is paid to the machining characteristics and CFRP damage mechanism at stack interface during drilling and helical milling of CFRP/Ti stacks. The cutting force characteristics, temperature characteristics and tool wear characteristics of interface machining are analyzed, and the damage mechanism and evaluation method are summarized. In order to solve the existing problems in drilling CFRP/Ti stacks, the suppression strategies of interface damage in recent years are discussed from four aspects: machining parameters, machining environment, tool structure and advanced machining technology. The research trend of laminated interface machining is prospected, which provides an important reference value for the realization of precision, high efficiency and low damage integrated drilling of CFRP/Ti stacks.

Investigations on the effect of dielectric medium and WEDM parameters on surface characteristics of Al 7068 (ordnance aluminium) alloy

The current experimental work focuses on determining the optimum machining parameter combination for machining AA7068 in wire electrical discharge machining (WEDM). WEDM is a promising advanced machining technology, capable of processing complex-shaped components, machining hard/heat treated materials, and cutting conductive ceramics that are complicated to machine using traditional methods. Taguchi’s L18 orthogonal array is adopted to conduct the experiments by considering dielectric medium, pulse on time, pulse off time, peak current, gap voltage, and wire feed as input factors. The output responses like surface roughness, material removal rate, micro hardness, recast layer, surface morphology of the machined surfaces and wire tool were considered for study. The ANOVA method was used to analyse the impact of individual processing parameters on material removal rate and surface roughness. Microhardness of the cut surface was studied using Vicker’s method. Besides, scanning electron microscopy (SEM) and Energy Dispersive X-Ray analysis are conducted to examine the surface characteristics and elemental composition of the machined working piece at various cutting parameters (EDX). TOPSIS method is chosen to identify the optimal parametric conditions. From the results, the optimum condition achieves surface roughness (3.684 μm) and material removal rate (5.106 mm3 min−1) respectively.

Review of field-assisted ultraprecision machining difficult-to-machine materials

<p indent="0mm">Field-assisted ultraprecision machining is an advanced manufacturing technology innovated from the traditional ultraprecision machining technologies by combining laser, ultrasonic vibration, and magnetism, among others. It achieves a nano- or subnanometer machining accuracy when manufacturing difficult-to-machine materials. This paper reviews the development of field-assisted techniques in ultraprecision machining, including turning, grinding, and milling. Considering the surface quality, machining efficiency, forces, tool wear, and other experimental results, field-assisted ultraprecision machining has obvious advantages compared to traditional ultraprecision machining. This review summarizes the present shortcomings and prospective challenges in field-assisted ultraprecision machining, which is beneficial to the development of the advanced hybrid multienergy field-assisted machining technology.

Assessment of cumulative energy demand, production cost, and CO2 emission from hybrid CryoMQL assisted machining

China’s manufacturing sector accounts for more than half of the country’s total energy demand, and specifically, metal processing is one of the manufacturing sectors that consume significant energy. However, reducing the electrical energy consumption of the machine tool, improving productivity, and ultimately increasing profit is a challenge while machining difficult-to-cut materials. To mitigate these challenges, advanced hybrid lubri-cooling machining is gaining attention in modern manufacturing. This paper aims to explore a holistic sustainability evaluation of advanced machining technologies specifically, the evaluation of a hybrid cryogenic-LN 2 and minimum quantity lubrication (MQL) – named ‘CryoMQL’. In Addition, a comparison of CryoMQL with flood machining of Ti–6Al–4V has been performed. The machining power, specific cutting energy , specific electrical energy consumption, Cumulative Energy Demand (CED), carbon emission per part, energy cost, and production cost are considered the key sustainable performance measures . The research findings have shown that the CryoMQL approach is sustainable only when employed at high cutting conditions. Also, sustainable production of LN 2 is inevitable to reduce the CED per part in CryoMQL assisted machining. In addition, the environmental cost considering Chinese manufactured products could be an effective way to reduce carbon emissions since it shares 10.9% of the total cost of the product. The present study is applicable to implement 3E (i.e., Energy, Environment, and Economy) concepts for the Chinese Manufacturing Industry. • External turning of Ti–6Al–4V alloy using Flood and CryoMQL conditions. • New empirical models for sustainable metrics are developed. • A holistic comparison between conventional and CryoMQL approach has been made. • During aggressive cutting, CryoMQL approach produced 27.8% lower-price products. • In present case, CryoMQL is sustainable economically but not environmentally.

Analysis of advanced transpedicular screw machining technologies

Abstract: The purpose is to improve the machining efficiency of titanium alloy transpedicular screws on highperformance machine-tools based on the selection of advanced technological approaches, and to analyze the current manufacturing technology of implants on CNC machines of the semi-automatic longitudinal turning lathe type. The efficiency is assessed using the following criteria: process performance determined by the machine time and the quality of implant processing (surface roughness, geometric accuracy, mechanical properties). It is found that semi -automatic longitudinal lathes equipped with a collet feed system and drive heads for thread whirling allow processing the implants of the transpedicular screw type in a single set-up with maximum efficiency. It is shown that the machining technology of transpedicular screws is largely determined by the features of their design. The type and shape of the thread have the greatest influence on the used cutting tool and cutting modes. The analysis of screw breakages revealed that the main failure reasons are design defects and poor machining quality of the threaded part. It is determined that the use of the thread whirling method makes it possible to obtain the thread in one cutting pass and, therefore, significantly increase the machining performance compared to the traditional technology without any loss of quality. Additional advantages of this method are the reduction in the number of tools used and follow-on finishing deburring operations. Based on the conducted analysis the manufacture of transpedicular titanium alloy screws is recommended to perform using advanced cutting tools, primarily thread whirling cutters ensuring 4 times increase in machining performance without any loss of the processed item quality and 2 times reduced surface roughness. In this case the temperature in the cutting zone decreases, which has a positive effect on processed product service life. The condition for the effective use of the cutters is equipping of the machine-tools involved in the technological process with special drive heads.

Comparative Analysis of Burrs in UD-CFRP Composites Using Advanced Hole Machining Technologies

Machining of carbon fibre reinforced polymer (CFRP) composites is challenging due to their inhomogeneous and anisotropic structure as well as the strong effect of the carbon fibres on wear. Burrs are critical machining-induced macro-geometrical defects in the case of the machining of CFRP composites, which may lead to assembly difficulties. Nowadays, although novel hole-machining technologies reduce the likelihood of burrs occurring, these technologies are often more costly and require longer machining times. The current experimental study focuses on the analysis of burrs induced by advanced hole machining technologies (helical milling, tilted helical milling and wobble milling) and comparison with a conventional one (conventional drilling).A total of 32 experiments were carried out in a VHTC 5-axis machining centre using uncoated solid carbide end mills. Furthermore, these technologies are compared and discussed based on the burrs experienced and average material removal rate (AMRR). Experimental results show that conventional drilling caused the lowest amount of burrs, followed by wobble milling, tilted helical milling and helical milling. Even though wobble milling is one of the most advantageous technologies in terms of burrs, the AMRR of conventional drilling is twenty times larger than that of wobble milling, therefore, the further development of wobble milling is recommended.

The First Four-Year Activity Report of the Advanced Machining Technology Group of Japan Aerospace Exploration Agency

The First Four-Year Activity Report of the Advanced Machining Technology Group of Japan Aerospace Exploration Agency

Abrasive water jet machining process parameters optimisation for machining of complex profiled component from Inconel 718 super alloys

The demands for machining complex profile from difficult to machine materials find wide applications in various industries, that has been triggered the neck for development of advanced machining technologies, specifically non-conventional processes and associated optimisation of machining parameter. Keeping in view the applications of Inconel-718 material for aerospace applications, it has been selected as the specimen material for machining complex profiled component on KMT steam line SL-V50 water jet five axes CNC abrasive water jet machine (AWJM) at the research organisation. In the present work AWJM process parameters are optimised by Taguchi-Grey relational method on dimensions, geometries and surface roughness of complex curved contours. Additionally, the Pareto analysis of variance (ANOVA) of Grey relational grade is also applied to find the most significant process parameter. Traverse speed is found to be the most significant process parameter for profile cutting in AWJM, also confirmation experiments were conducted to validate the results. The experiment was done for a specified profile for cross sectional thickness of 6.6 mm and 18 sets of experiments were conducted based on stark's L18 orthogonal array.

Investigation on the Tool Wear Suppression Mechanism in Non-Resonant Vibration-Assisted Micro Milling.

Excessive tool wear during hard and brittle material processing severely influences cutting performance. As one of the advanced machining technologies, vibration-assisted micro milling adds high-frequency small amplitude vibration on a micro milling tool or workpiece to improve cutting performance, especially for hard and brittle materials. In this paper, the tool wear suppression mechanism in non-resonant vibration-assisted micro milling is studied by using both finite element simulation and experiment methods. A finite element model of vibration-assisted micro milling using ABAQUS is developed based on the Johnson cook material and damage models. The tool-workpiece separation conditions are studied by considering the tool tip trajectories. The machining experiments are carried out on Ti-6Al-4V with a coated micro milling tool (fine-grain tungsten carbide substrate with ZrO2-BaCrO4 (ZB) coating) under different vibration frequencies (high, medium, and low) and cutting states (tool-workpiece separation or non-separation). The results show that tool wear can be reduced effectively in vibration-assisted micro milling due to different wear suppression mechanisms. The relationship between tool wear and cutting performance is studied, and the results indicate that besides tool wear reduction, better surface finish, lower burrs, and smaller chips can also be obtained as vibration assistance is added.

Optimization of scanning path under ion beam cleaning process based on thermal effect

Ion beam figuring (IBF) is an advanced machining technology for high precise optical component. For brittle materials with high thermal expansion coefficient such as KDP crystal, thermal effect is an intractable problem due to the accumulative heat introduced by incident ions on optical surface. Asymmetrical heating induces rapid changes of thermal stress and once the thermal stress exceeds the mechanical strength, the component may crack or break. In this paper, the number of scanning rows was factorized to various combinations with times of scanning and the number of moving rows. Temperature field and thermal stress of each combination were simulated using finite element analysis software ANSYS. Comparing with the results, the much better combination was found. With optimized scanning path, peak of thermal stress is lower than that of traditional scanning path. Especially, peak of tensile stress on X-distance and Y-distance were reduced obviously. At last, a law for optimization was established: when times of scanning and the number of scanning rows are equal or approximately equal, the thermal stress appears lower.

Micro patterning on curved surface with a fast tool servo system for micro milling process

Demand for generating functional micro patterns on a curved surface such as molds has increased in various industrial sectors. In order to meet the demand, it is important to develop advanced micro machining technology to generate curved form and fine patterns, simultaneously and efficiently. This paper presents a newly developed machining system equipped with a fast tool servo mechanism for milling process driven by a giant magnetostrictive actuator and evaluation of its basic machining performance. The results confirmed that the developed system has capability to position the end mill precisely during machining and to generate patterned curved surface.

Sustainability Assessment of Advanced Machining Technologies

Efficient cooling and lubrication techniques are required to obtain sustainable machining of difficult-to-cut materials, which are the pillars of aerospace, automotive, medical and nuclear industries. Cryogenic machining with the assistance of lubricated Liquid Carbon Dioxide (LCO2) is a novel approach for sustainable manufacturing without the use of harmful water-based metalworking fluids (MWFs). In case of unavoidable use of MWFs under high pressure, such as turning finishing processes of difficult-to-cut materials, the pulsating high pressure delivery of MWFs prolongs the tool life and enables the control over chip length to prevent surface damage of high value-added parts. In this paper, sustainability assessment of both advanced principles was carried out, considering overall costs and operational safety. Experimental tests were executed on difficult-to-cut materials in comparison to conventional flood lubrication. For both techniques, longer tool life compared to flood lubrication was observed additional cleaner production and higher part quality led to reduced long-term overall costs. These advanced machining technologies are also operation safe, proving to be a sustainable alternative to conventional machining.