Machined Surface Roughness Research Articles

Abrasive aqua jet machining of NiTiV ternary smart alloy

ABSTRACT Nickel–titanium shape memory alloys (SMAs) are popular due to their usefulness and functional characteristics. The binary NiTi SMA was alloyed with vanadium to improve memory retention properties. In this study, the abrasive aqua jet machining method was adopted to machine the Ni50Ti48V2 ternary SMA to minimize the kerf taper angle (KTA), surface roughness (Ra) of machined Ni50Ti48V2 surface, and enhance the material removal rate (MRR). RSM-BBD optimization using the input variables such as abrasive flow rate (AFR), water jet pressure (PWJ), nozzle traverse speed (VTS), and standoff distance (SFD) predicted that PWJ and SFD highly contributed to MRR, Ra, and KTA responses. Small variation in variation after optimized AWJM conditions, and XRD analysis confirmed no phase changes after AWJM.

Machine tool operating vibration prediction based on multi‐sensor fusion and LSTM neural network

AbstractThis study proposes a machine tool vibration prediction method based on multi‐sensor fusion and a long short‐term memory (LSTM) network. Machine tool vibration significantly impacts machining quality, surface roughness, dimensional accuracy, and tool wear. By combining deep learning with industrial applications, this method achieves high‐precision vibration prediction through multi‐sensor data fusion. Data is input into the LSTM model to predict the next moment's vibration. Experimental results demonstrate strong prediction capability for periodic vibrations and machining‐specific vibration errors, effectively enhancing machining accuracy.

Fundamental study on dielectric oil viscosity for high-performance wire EDM

Dielectric oil has been recently used in wire electrical discharge machining (wire EDM) for achieving high-precision machining. However, the influence of dielectric oil properties on wire EDM characteristics has not been clarified sufficiently. This study fundamentally investigated the influence of dielectric oil viscosity on wire EDM characteristics. In this study, three types of dielectric oil differing only in viscosity were prepared and examined. Linear cutting experiment results showed that the removal rate and the machined surface roughness increase with dielectric oil viscosity. Then, the influence of viscosity on crater removal volume was investigated to discuss the cause of the change in removal rate, and it was found that crater removal volume increases with the viscosity. Furthermore, CFD (computational fluid dynamics) analysis results and discharge observation results showed that the debris exclusion becomes worse in higher viscosity oil, and the discharge concentration occurs frequently, resulting in the deterioration in machined surface roughness. Next, the difference in machining accuracy with dielectric oil viscosity was investigated. It was found that the corner shape accuracy deteriorates with the increase of viscosity while the machined surface waviness and straightness improve slightly. Structural analysis results showed that wire deflection increases with viscosity, resulting in the deterioration in corner shape accuracy. On the other hand, high-speed observation of wire vibration was carried out, and it was found that the wire vibration decreases in the case of higher viscosity, which leads to the improvement in machined surface waviness and straightness.

Pulse dynamic regulation of electrochemical discharge milling by utilizing the slotted tube electrode

Electrochemical discharge machining (ECDM) has a splendid application potential for machining difficult-to-cut materials. It is a challenge to limit and control the discharge energy and area of DC power supply in ECDM. Owing to the uncertainty and randomness of the position and range of the single discharge, the unpredictable discharges deteriorate the surface quality of the workpiece, alter the size of the inter-electrode gap (IEG), and influence the distribution of the multi-physical fields. Therefore, to regulate the machining state and energy, the ideology of pulse dynamic machining is introduced, and a method of pulse dynamic ECDM utilizing the slotted electrodes is proposed. With the tool electrode rotating, the tube electrode transforms the pure electrochemical machining (pure-ECM) stage and the electrochemical discharge machining (ECDM) stage periodically through the slots at the bottom of it. The machining current waveform, surface roughness and sidewall taper of machined grooves, material removal rate (MRR), and relative tool wear rate (RTWR) are investigated. Additionally, the discharge types of the ECDM are explicitly defined and statistically classified. The experimental results show that the pulse dynamic regulation of hybrid machining using the slotted electrodes is beneficial to regularize the machining current waveform and optimize the machining quality.

Influences of size effect and workpiece temperature during cryogenic micro milling of soft viscoelastic polymer: an experimental assessment

Application of tool-based micromachining in soft polymer has been limited due to high adhesion and low elastic modulus of this material at room temperature. This study aims to evaluate the machinability of a typical viscoelastic soft polymer and understand the effect of material and process parameters on machining performances. In this study, a micro-milling process using cryogenic-assisted cooling is proposed and the importance of temperature control toward glass transition zone was particularly addressed. To identify insight of machinability in micro domain, this article also determines minimum uncut chip thickness (MUCT) and size effects by considering the variations of cutting force and surface integrity with the ratio of h/re (uncut chip thickness (h) to cutting edge radius (re)). The experimental results reveal that consideration of size effect during micromilling of soft viscoelastic polymer helps in reduction of machined surface roughness (Sa) value. Based on the cutting force pattern, it is evaluated that higher machining stability can be achieved during cryogenic machining by reduction of specific cutting force value. Moreover, temperature range around glass transition zone yields more promising experimental outcomes, outperforming other cooling zones.

Influence of TiAlN coating thickness in dry machining of AISI 1045 steel using Finite Element simulation and experiments

High performance cutting can be accomplished using coated tools with optimal coating thickness. Therefore, Finite Element (FE) simulation and experimental investigation are employed to study the influence of thickness of TiAlN coating in the range of 1 to 4 μm during face milling of AISI 1045 steel under dry condition. FE simulation is successful in effectively investigating the influence of coating thickness in machining performance in terms of cutting forces, Von Mises stress, tool tip temperature and crater wear of uncoated as well as coated milling inserts. Simulation results have predicted cutting forces and temperature with maximum errors of 9.21 % and 12.20 %, respectively. FE simulation further demonstrates 2.100 and 1.602 μm as the depths of crater for 1 and 3 μm thick TiAlN coated inserts, respectively, which are also validated by the experiments. The experimental results demonstrate that 3 μm thick coated tool is superior in mitigating cutting forces, particularly under higher cutting speed (150 m/min), bringing down tool tip temperature (6.67 %) and machined surface roughness (18.18 %) as compared to 1 μm thick TiAlN coated milling insert. The results obtained from the current research work clearly indicate that the effect of coating thickness can be effectively investigated using the FE simulation before finalising the optimal coating thickness for the coating depositions and machining experiments.

In Vitro Comparison of Titanium Disc Surface Roughness and Bacterial Colonization After Ultrasonic Instrumentation With Three Different Tips.

During implant maintenance, preserving a smooth surface on the machined transmucosal abutment is critical to reduce biofilm attachment and colonization. The present study compared the surface roughness and bacterial colonization of machined titanium surfaces after instrumentation with various materials. Forty-four machined grade 23 titanium discs were instrumented with a round polyether ether ketone (PEEK) tip, a plastic curette tip, or a pure titanium curette tip with piezoelectric devices. Before and after instrumentation, the surface roughness (Ra and Rz) values were analyzed with a profilometer and scanning electron microscopy (SEM). Streptococcus sanguinis was cultured and incubated for 24 hours on the instrumented discs, and colony-forming units per milliliter were obtained for each group. Samples instrumented with the metal ultrasonic tip significantly increased surface roughness compared with the other groups. This resulted in greater colonization by S. sanguinis than surfaces instrumented with PEEK tips or the negative control. Samples instrumented with PEEK and plastic tips did not exhibit any statistically significant increase in surface roughness, and SEM analysis revealed a significantly rougher surface of discs instrumented with metal compared with discs instrumented with plastic or PEEK tips despite the possibility of debris from tip dissolution. Our results suggest that instrumentation with metal ultrasonic tips with piezoelectric devices significantly increased machined titanium's surface roughness and elicited higher biofilm formation in vitro. Meanwhile, instrumentation of machined titanium with PEEK or plastic ultrasonic tips did not affect the surface roughness or bacterial adhesion.

Experimental Research on Pollution-Free Alcohol Cutting Fluid in Scratching of Single-Crystal Copper Material

Cutting fluid can improve the heat dissipation and lubrication in the cutting process and thus increase the machining quality. In this work, a pollution-free alcohol solution was proposed as the cutting fluid in an ultra-precision cutting process to explore green cutting fluids. The scratching experiments were conducted with the alcohol cutting fluid to study its effect on the cutting process. It is found that the use of an alcohol cutting fluid, on average, reduces the tangential and normal force about 27–53%, but exhibits few effects on the friction coefficient in the cutting process. Compared to dry cutting, the alcohol cutting fluid reduces the exposed shear slip steps on the outside surface of the chip, which implies the decreased chip deformation degree of workpiece material in the cutting process. The alcohol cutting fluid can reduce microburrs and decrease the machined surface roughness Ra from 21 nm to 9.9 nm in the ultra-precision turning application on single-crystal copper material.

Investigation on the performance of spark plasma sintered ultrafine WC-Co cemented carbide end mills during high-speed precision milling of Ti-6Al-4V alloy

In this study, ultrafine WC-Co and WC-(Ti,W)C-Co cemented carbide end mills were fabricated via spark plasma sintering. The performance of those tools in the high-speed precision machining of Ti-6Al-4V alloy was investigated, focusing on the analysis of tool wear mechanisms, cutting performance, and machined surface roughness. The results reveal that adhesive wear emerges as the predominant wear mechanism influencing the performance of both tools. The addition of (Ti,W) C leads to high workpiece element enrichment on the flank face of the tool, increasing subsequently severe adhesive wear. WC-(Ti,W)C-Co displays a greater propensity for crack propagation and material chipping, culminating in premature tool failure with the formation of significant wear craters and cutting edge breakage. Conversely, WC-Co exhibits comparatively milder wear patterns and a reduced incidence of cutting edge chipping due to its inherent resistance to adhesive wear. Additionally, the comparison of the developed ultrafine cemented carbide tools with similar commercial tools demonstrates that WC-Co has superior cutting performance in terms of tool life, 1.5–1.8 times longer than the commercial tools. These findings provide guidance for optimizing machining strategies and developing advanced tool materials for high-speed milling titanium alloy.

Finite element analysis and experimental study on the cutting mechanism of SiCp/Al composite in laser ultrasonic elliptic vibration turning

SiCp/Al composites have excellent material properties and are increasingly being used in the aerospace, military, and electronic packaging industries. However, the inhomogeneity and non-conductivity of conventional turning (CT) results in poor material surface quality and high cutting forces, which seriously hinder the application of particlereinforced metal matrix composites. The thermal softening property of laser-assisted turning (LAT) and the intermittent cutting property of two-dimensional (2D) ultrasonic elliptical vibratory turning (UEVT) offer unique advantages in improving material surface quality. Therefore, a novel laser ultrasonic elliptical vibratory turning (LUEVT) machining technique is proposed to improve the machining of SiCp/Al composites with two different volume fractions. The effect of highfrequency intermittent machining on material processing was further investigated by adjusting the pulsed laser power. Finite element modelling was used to predict the machining state, surface roughness, and chip morphology between the workpiece and the PCD tool. The effects of varying the machining parameters during the experiment on the two composites were analysed. The results showed that the LUEVT of 25 % and 45 % SiCp/Al composites were reduced by 39.3 % and 30.7 % respectively compared to the CT cutting forces. The experiments verified the consistency of the surface roughness and chip morphology with the finite element simulation results. The stability of the cutting force during the cutting process is also improved, as the material removal process mainly takes the form of small particle fragmentation and matrix encapsulation.

Study on the cutting performance of AlTiN/AlTiSiN composite coating tool in deep-hole pull boring tool of GH4169

As one kind of difficult-to-cut material, when deep-hole machining Nickel-based superalloy GH4169, there are server adhesive wear, poor tool wear resistance and multiple surface defects, which limits its improvement of processing efficiency and processing quality. The comparative studies on the tool wear mechanism and the workpiece surface morphology characteristic are carried out during deep-hole pull boring GH4169 with AlCrN and AlTiN/ AlTiSiN composite coating tool. The results show that the flank and rake wear is mainly adhesive wear and abrasive wear, accompanied by coating shedding, micro-tipping, built-up edge and burn blackening. Compared with AlCrN, the AlTiN/ AlTiSiN composite coating tool has better wear resistance and slight adhesive wear. With the increase of feeding speed and boring depth, it is more likely to produce the built-up edges on the rake face and occur the vibration wrinkles on the flank face. But there is the smaller scale of the narrow wear groove mark on the minor flank face at a higher feed speed. Feed groove marks, material adhesion, rolling traces and the surface defects such as pits and micro-hole are the main features of the machined inner surface. Within the range of boring deepth 50 mm∼1060 mm, the machined surface roughness basically fluctuates between 1.130 µm and 1.940 µm which is smaller at the initial cutting edge. The higher the feed speed, the larger scale of the residual feed marks, and the rougher the machined surface of inner hole.

Effect of relative phase of loose tie rods on nonlinear dynamic behavior of rod-fastening rotor-bearing-seal system

Loosening of multiple tie rods in a circumferential rod-fastening rotor caused by thermal deformation and centrifugal loads is very common in engineering. The relative position of loose tie rods in the circumferential direction will also have an important impact on rotor dynamics. The relevant research has not been done yet. In this paper, a contact model of the rough machined surface is firstly established by combining the probability functions describing rough surfaces and fractal contact theory of asperities, then the contact stiffness model between disks is established based on the contact model. Finally, the dynamic model of the circumferential rod-fastening rotor-bearing-seal system is established and solved. The effect of relative phase of loose tie rods on the nonlinear dynamic characteristics of rod-fastening rotor-bearing-sealing system is studied. It can be concluded that relative phase of the loose tie rod has an important influence on the frequency, bifurcation, and periodic motion of the rotor system. At lower speed, the anisotropy of contact stiffness caused by loose tie rods has little effect on the rotor trajectory, while the generalized bending moment has a greater influence on dynamics of the system. At higher speed, the anisotropy of contact stiffness has a great influence on the axis rail of the rod-fastening rotor.

Predictive modeling of MRR, TWR, and SR in spark-EDM of Al-4.5Cu–SiC using ANN and GEP

In this study, Al-4.5Cu alloy was reinforced with varying weight percentages of SiC particles (2%, 4%, 6%, and 8%) to create metal matrix composites via the stir casting method. The formation of intermetallic compounds was confirmed through energy dispersive spectroscopy and x-ray diffraction analysis. This article compares the performance of Artificial Neural Network (ANN) and Gene Expression Programming (GEP) models in predicting the Metal Removal Rate (MRR), tool wear rate, and surface roughness in the die-sinking electro-discharge machining (EDM) process of the ex-situ developed Al-4.5%Cu–SiC composites. The study considers three machine parameters—pulse on time (TON), pulse off time (TOFF), and current (I)—along with the weight fraction of SiC particles as input variables for the models. Both ANN and GEP models demonstrated high predictive accuracy for the EDM performance metrics, with correlation coefficients (R) ranging from 0.973 68 to 0.980 65 for the ANN model and 0.980 11 to 0.982 59 for the GEP model. Notably, the GEP model exhibited superior predictive capability, as evidenced by its higher correlation coefficients and lower root mean square error, indicating greater effectiveness in predicting the EDM process outcomes than the ANN model.

Application of Abrasive Water Jet Cutting on Rubber Wood Plastic Composites

Wood-plastic composites (WPCs) possess a diverse arrange of advantageous characteristics resulting from the combination of wood and plastic. These include a prolonged lifespan, cost-effectiveness, and environmental friendliness. However, the net shape can only be roughly achieved by the extrusion method used to make WPCs. WPCs require additional machining to comply with the dimensional accuracy and assembly conditions. As a result, more research into the cutting process of this composite is needed. In this work, abrasive water jet cutting was used to cut WPCs manufactured from rubber wood flour and polypropylene (PP). The emphasis was on two distinctive architectures of 1-layered and 3-layered WPCs with a thickness of 10 mm. The effects of cutting factors including water pressure, traverse speed, and abrasive mass flow rate were taken into account. The study employed a full factorial analysis to investigate the correlation between cutting parameters and cutting performance, including kerf characteristics and machined surface roughness. The abrasive and water pressure in the experiment had a significant effect in cutting both materials. In some cutting conditions, without an abrasive, non-through cutting happens, particular for the 3-layered WPC structures, that are particularly strong. An increase in water pressure decreased machining surface roughness and kerf width. The cutting parameters of 350 MPa water pressure, 30 mm/s traverse speed, and 6.67 g/s abrasive flow rate were suggested for both the 1-layered and 3-layered WPCs structures. This procedure was considered suitable for post-cutting without requiring for surface finishing.

Effects of TiAlN Coating Thickness on Machined Surface Roughness, Surface Residual Stresses, and Fatigue Life in Turning Inconel 718

The surface roughness and surface residual stresses are affected by the coating thickness of physical vapor deposition (PVD) TiAlN tools, which could alter the service performance of machined components. However, the relationships among the tool coating thickness, the machined surface roughness, the surface residual stress, and the fatigue life are still not sufficiently illustrated. In this research, PVD TiAlN coatings with several thicknesses of 1.6 μm, 2 μm, 2.5 μm, and 3 μm were deposited on carbide tools. Turning experiments using Inconel 718 were conducted with uncoated and various TiAlN tools under flood cooling conditions. The surface roughness could be improved with the selection of thin PVD TiAlN coating thicknesses of 1.6 μm and 2 μm compared to that of uncoated tools. The tensile residual stresses at the machined surface in the directions of cutting speed and feed rate linearly decreased by 148.67% and exponentially decreased by 92.24% when the TiAlN coating thickness was increased from 0 μm to 3 μm. The values of the low-cycle fatigue life of machined Inconel 718 linearly increased by 15.60% with the increase in TiAlN coating thickness from 0 μm to 3 μm, which was mainly due to the improvement of surface residual stresses. The results could provide guidance for the selection of suitable TiAlN coating thicknesses for wet machining Inconel 718 based on the part service conditions.

The Analytical and Experimental Analysis of the Machined Surface Roughness in High-Feed Tangential Turning

A main topic in mass production of machine parts is how to increase the productivity to produce more parts in a given time while maintaining the prescribed surface quality on the machined surfaces. Novel machining procedures have been introduced to achieve this goal; however, the further development of already established and wide-spread procedures can offer simply accessible solutions. Tangential turning is a rediscovered variant of the traditional turning procedure, where a specially designed cutting tool ensures chip removal with a feed tangential to the workpiece. This process results in low surface roughness even at higher feed rates. In this paper, the achievable surface roughness is analyzed by analytical and experimental steps. In the mathematical analysis, the theoretical surface roughness is determined using the constructive geometric modelling method. The worked-out equations are validated in cutting experiments on 42CrMo4 grade steel workpieces. The theoretical and experimental analyses show that the strictly prescribed surface roughness can be achieved with high feed rates by the application of tangential turning.

Study of stress-assisted nano-cutting mechanism of gallium arsenide

The high-performance manufacturing of hard-brittle materials by single-point diamond turning (SPDT) is a very active and challenging research area. The stress-assisted nano-cutting is a promising method for improving the machinability of hard-brittle materials. However, the simulation results in the existing stress-assisted nano-cutting model would contradict the actual condition due to the pre-stress being released before tool entry into the workpiece. A modified stress-assisted nano-cutting model with a virtual boundary between the workpiece and tool is proposed for the first time in this paper to investigate the nano-cutting process of GaAs material under different external stresses. The emergence of an atomic flow vortex during stress-assisted nano-cutting significantly enhances the quality of the machined surface, leading to a substantial reduction in both machined surface roughness (34.4 %) and subsurface damage (56.2 %), compared to the normal nano-cutting. By evaluating surface roughness, subsurface damage depth, morphological accuracy, cutting force, and removal efficiency, a pre-strain of 0.06 is determined to be the optimal pre-strain for stress-assisted nano-cutting. Moreover, the selection of optimal pre-strain remains unaffected by variations in the nano-cutting depth. TEM results demonstrate that the nano-cutting mechanism elucidated by the MD analysis accurately reflects the genuine deformation of the GaAs material.

Experimental and numerical study on micro ball-end milling of pin fin-interconnected reentrant microchannels

Pin fin-interconnected reentrant microchannels (PFIRM) of microchannel heat sink cooling systems provide a promising solution for efficient heat dissipation of high heat flux devices. They feature interconnected Ω-shaped reentrant configurations in cross-section, with large circular cavities at the bottom and diamond pin fins at the top. In this paper, a micro ball-end milling process was proposed to fabricate PFIRM. The burr formation process and deformation mechanisms during the micromilling process of PFIRM were investigated with experiments and finite element (FE) simulations. Results revealed that the burrs were mainly formed under the vertex of diamond pin fins on both up-milling and down-milling sides. The burrs on the up-milling side were pushed by the tool neck to the left side of feed direction, whereas the burrs on the down-milling side were thrusted by the flank face to the right side of feed direction. Besides, two unique types of chips, i.e., swallowtail-shaped chips and half swallowtail-shaped chips, were found to be formed during the micro ball-end milling process. Moreover, the effects of spindle speed and feed rate on the machining accuracy and surface roughness of PFIRM were also explored. The machining accuracy and surface roughness firstly increased and then decreased with increasing spindle speed. As the feed rate increased, the machining accuracy decreased in general, and the surface roughness firstly decreased and then increased. The present study suggested that the spindle speed of 15000 r/min and feed rate of 20 mm/min was optimal to improve the surface quality and machining accuracy.

Tribology-driven strategies for tool wear reduction and surface integrity enhancement in cryogenic CO2-cooled milling of laser metal deposited Ti64 alloy

Additive manufacturing (AM) is chosen for its ability to streamline production processes and design freedom. This reduces material waste, enables rapid prototyping, and facilitates intricate geometries, ultimately offering cost-effective and customizable solutions for manufacturing complex components in diverse industries. Overlapping melting trajectories result in a low-quality surface (Ra=∼13.34 µm) in the laser metal deposition (LMD) of the Ti64 alloy. Therefore, post-processing is often essential for AMed parts for engineering applications. Milling trials were conducted on AMed specimens under four environmental conditions: dry, flood, minimum quantity lubrication (MQL), and cryogenic medium. The machinability was evaluated in terms of the cutting temperature, machined surface roughness, tool wear, chip morphology, and microhardness. The flank wear under cryogenic CO2 condition is 52.78–54.29 % lower than dry condition, 33.86–36.24 % lower than flood cutting, and 23.64–26.86 % lower than MQL. The outcomes show that cryogenic cooling augments the tool life and the surface integrity of milling LMD parts. Moreover, the hardness under cryogenic CO2 was higher, indicating dimensional stability and maintenance of shape integrity under applied loads.

Minimization of residual stress, surface roughness and tool wear in Electro Discharge Machining of inconel 625

Electro Discharge Machining (EDM) is a well-known non-traditional machining technique which is widely used to make die castings and turbine blades out of difficult-to-cut materials like Inconel 625. The machined part's surface quality and dimensional accuracy are affected by the EDM electrode's wear. Moreover, surface roughness and residual stress augmentation of EDM-machined components can reduce the workpiece's lifespan by decreasing the fatigue life of machined parts. To enhance the precision and durability of EDM machined components, residual stress, tool wear, and surface roughness should be evaluated and minimized. The majority of published research works for the assessment and optimization of EDM machining parameters are based on experimental works which are limited to testing, workpiece materials, and machining conditions. In order to improve the quality of machined surfaces and reduce tool wear and residual stress during Inconel 625 EDM processes, a virtual machining approach has been developed in the research work. To predict the cutting temperature during EDM operations, the modified Johnson Cook model of Inconel alloys is used. The finite element approach is then used to calculate the generated residual stress during the EDM process. The proposed virtual machining approach is also applied in order to predict the surface roughness of EDM machined parts. To minimize the residual stress, tool wear, and surface roughness during EDM operations of Inconel 625, the machining parameters of gap voltage, peak current, pulse-off time, and pulse-on time are optimized using the Taguchi optimization approach. Experiments and simulations are then conducted to verify the developed virtual machining system in the study. So, using the optimal machining parameters, the residual stress, surface roughness of machined items and wear of EDM electrode are minimized by 24.5 %, 25.4 %, and 25.4 % respectively. Thus, the quality and reliability of components made using EDM processes may be enhanced by the suggested virtual machining system.