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•Optimization of surface roughness, tool wear and MRR.•Investigations of tool wear mechanism in turning 40 HRC steel under MQL.•vc = 90 m/min, f = 0.2 mm/rev, ap = 1.5 mm optimized ...roughness and MRR.•vc = 60 m/min, f = 0.2 mm/rev, ap = 1.0 mm minimized tool flank wear.•Prominent tool wear mechanisms are adhesion, abrasion and BUE.
Minimum quantity lubrication (MQL) is adorned with improved machining performance and environmental sustainability. In this context, this paper presents the study of roughness parameters (Ra, Rq, Rz), tool wear parameters (VB, VS) and material removal rate (MRR) in MQL-assisted hard turning by using coated cemented carbide tool. As methodology, the Taguchi orthogonal array-based design of experiment and signal-to-noise ratio-based optimization have been utilized. Prior to this, the collected machining data have been tested to check the normal probability distribution. Furthermore, the analysis of variance determined the influences of cutting speed, feed rate and depth of cut on the aforementioned responses. In addition, different types of tool wear, prevailed in principal and auxiliary flank faces, have been identified. The quantitative analysis revealed that the cutting speed impacted the surface roughness; the depth of cut influenced the tool wear; the feed rate afflicted the material removal rate predominantly. Based on the imagery evidence the adhesion, abrasion, and built-up-edge were found as the governing wear mechanism.
The machining of low-rigidity components (e.g. thin-walled) with compliant tools presents accuracy challenges as both sides in contact are being deformed. The controlling method presented in this ...paper enables, for the first time, to obtain the desired and uniform material removal rate by controlling the nominal tool offset when two bodies (workpiece and tool) are compliant in grinding. A contact deformation model is proposed to predict the relation between the nominal and actual tool offsets. The function of nominal tool offsets and material removal rates is obtained based on the calibration tests. Spot grinding tests have been performed for the validation of the calculated material removal rates, normal grinding forces and spot sizes, presenting position-dependent characteristics. The controlling method has been tested for the case of continuous grinding the whole area of a circular aluminium thin wall. The surfaces ground under the time-variant tool offsets (proposed approach) reach the desired removal depth with an average error of ≤10% and achieve 11.2 μm–24.2 μm (P–V) accuracy in the elastic domain, compared with the error of 76.8%~113.7% and accuracy of 42.6 μm–50.1 μm (P–V) in the circumstance of constant tool offsets (conventional approach).
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•A theoretical contact model for the first time was proposed for grinding involving two compliant bodies.•The model reveals the position-variant characteristics of the relation between nominal and actual tool offsets.•This paper proposed a new control strategy by time-variant tool offset design to obtain a constant material removal rate.•The ground surfaces obtained from the proposed strategy reach the desired removal depth with an average error of ≤10%.
The material removal rate (MRR) plays a critical role in the chemical mechanical planarization (CMP) process in the semiconductor industry. Many physics-based and data-driven approaches have been ...proposed to-date to predict the MRR. Nevertheless, most of them neglect the underlying equipment structure containing essential interaction mechanisms among different components. To fill the gap, this paper proposes a novel hypergraph convolution network (HGCN) based approach for predicting MRR in the CMP process. The main contributions include: (1) a generic hypergraph model to represent the interrelationships of complex equipment; and (2) a temporal-based prediction approach to learn the complex data correlation and high-order representation based on the hypergraph. To validate the effectiveness of the proposed approach, a case study is conducted by comparing with other cutting-edge models, of which it outperforms in several metrics. It is envisioned that this research can also bring insightful knowledge to similar scenarios in the manufacturing process.
•Electrochemical dissolution models of TiAl 45XD in NaNO3 and NaCl are proposed.•The surface integrity of TiAl 45XD in NaNO3 is better than that in NaCl solution.•The polarization behavior of TiAl ...45XD is quite different in NaNO3 and NaCl.•The ηω-j curves show an unusual dissolution behavior of TiAl 45XD.•Corrosion morphology of TiAl 45XD in NaNO3 and NaCl are different.
Electrochemical machining is an effective method for the processing of Ti-45Al-2Mn-2Nb+0.8 vol% TiB2 XD (or TiAl 45XD) alloys due to the absence of tool wear and the high material removal rate. This study investigated the electrochemical dissolution behavior of TiAl 45XD in NaNO3 and NaCl solutions, explaining the unique phenomena during the dissolution. The polarization curves, open-circuit potentials and material removal rate (ηω-j curves) were measured. It is found that the lamellar colonies are fully exposed after the electrochemical polarization in NaCl solution and that only some insoluble TiB2 disperse on the specimen surface in NaNO3 solution. The ηω-j curves reveal an unusual dissolution behavior of TiAl 45XD. Dissolution experiments were then carried out at different current densities and corrosion times. The corroded specimens were examined and analyzed using a surface-finish measuring instrument, scanning electron microscope and energy-dispersive X-ray spectroscopy. The results indicate that the surface quality is higher in NaNO3 solution than in NaCl solution because the specimen surface suffers from the pitting and severe localized corrosion and then forms many micro-protrusions in NaCl solution. It is also found that the micro-protrusion plays an important role in the electrochemical dissolution behavior of TiAl 45XD. Finally, qualitative models for the electrochemical dissolution behavior of TiAl 45XD in NaNO3 and NaCl solutions were proposed.
•Influence of alumina content on fs-laser machining of zirconia-alumina composites was studied.•Significant influence of material composition on material removal behavior was demonstrated.•Single ...phase materials have larger laser ablation thresholds and smaller material removal rate than their composites.•A lower scan speed is preferred for single phase materials while a higher scan speed is beneficial for the composites.
Laser texturing of zirconia-alumina ceramics is a promising surface modification method for many applications, such as enhancing osseointegration of alumina toughened zirconia (ATZ) dental implants or improving friction behavior of zirconia toughened alumina (ZTA) hip replacement bearing components. The common problems in laser texturing of ATZ/ZTA ceramics are thermal cracking, low material removal rate (MRR), and laser-induced phase transformation (LIPT). Furthermore, the compositional variation of those ceramics will complicate these problems. In order to improve the manufacturing processability, ultrashort pulsed laser ablation behavior of ATZ/ZTA composites was investigated in this research. Single phase zirconia and alumina were found to have smaller MRRs than their composites, and this behavior was negatively correlated to the materials single-pulse laser ablation threshold. However, under multi-pulse laser irradiation, the ablation thresholds of all materials saturated to the same level, indicating that single phase materials were more sensitive to the incubation effect than their composites. This led to the MRRs of the single phase materials being reduced at larger scan speeds, while the MRRs of their composites remained independent of scan speed. It was also shown that single phase materials were less susceptible to thermal cracking than their composites under excessive heat accumulation. These results suggest that a lower scan speed is preferred for single phase materials in order to achieve a larger MRR, while a higher scan speed is beneficial for the composites for suppressing thermal cracking without compromising ablation efficiency. In addition, no LIPT was detected for zirconia dominated materials after laser ablation.
•Pulsating electrolyte flow, generated via a servo-valve in the electrolytic supply pipe, is introduced to improve the heat transfer and material removal rate in ECM.•A multi-physics model coupling ...of electric, heat, transport of diluted species and pulsating flow is established.•Both the simulations and experiments indicate that pulsating flow has a significant impact on ECM.
Electrochemical machining (ECM) is a promising and low-cost process for yielding various components of difficult-to-machine materials, and has been well established in diverse applications. Distributions of gas and temperature affect the electrolyte electrical conductivity and determine the machining accuracy in ECM. Attempts have been made to generate the pulsating flow via a servo-valve in the electrolytic supply pipe, which is introduced to improve the heat transfer, material removal rate and surface profile in ECM. A multi-physics model coupling of electric, heat, transport of diluted species and fluid flow is presented. Simulation results indicate that pulsating flow has a significant impact on the distributions of velocity, gas fraction, and temperature near the workpiece surface along the flow direction. Experiments are conducted to verify the feasibility of the proposed process and study the effects of pulsating flow on material removal rate. The experimental results agree well with the simulations. Using optimal pulsating parameters, the material removal rate and surface profile are enhanced.
With the advantages of electrochemical milling (ECM) and conventional milling (CM), mechano-electrochemical milling (MECM) is effective for shaping titanium alloys. However, previous research failed ...to clarify the mechanism for material removal in MECM, seriously limiting its further application. This work focuses on an in-depth investigation of the material removal mechanism in the MECM of TC4 titanium alloy. There are three material removal processes in MECM, and a model for each is established. To generalize the MECM material removal mechanism, the first (vff) and second (vsf) critical feed speeds are defined: when the feed speed is less than vff, the MECM material removal process is that of ECM; when the feed speed is between vff and vsf, the process is that of ECM→CM→ECM; when the feed speed exceeds vsf, the process is that of CM→ECM. The surface morphologies of solid products during MECM at different feed speeds are also consistent with the proposed MECM material removal mechanism. When the MECM material removal process is ECM→CM→ECM, the difference in material removal rate between MECM and pure ECM is the largest, showing the higher machining efficiency of MECM. Also established is a mathematical model for calculating the relative contributions of ECM and CM during MECM. In addition, compared to 304 stainless steel, the machined surface of TC4 titanium alloy is poor; this is due mainly to the strong self-passivation of titanium in NaNO3 solution, and this aspect must be improved in future work.
Subsurface damage (SSD) and surface roughness (SR) induced by the finishing process significantly influence the industrial and technological application of optical components. In this paper, a novel ...non-resonant vibration-assisted roll-type polishing (NVRP) was presented to process the silicon carbide (SiC) ceramic workpiece. The feasibility of the two-dimensional vibration-assisted processing device (2D-VPD) was verified, and the predicted value of SSD was modelled. Besides, the surface deformation and SSD during the polishing process of the SiC workpiece were discussed by numerical simulation. To experimentally verify the proposed polishing method, a set of contrast experiments were conducted on SiC samples to evaluate the effects of different processing conditions on SR and SSD quantitatively. The experimental results further demonstrated a good consistency with the theoretical values in terms of SSD depth, considering the rotational angle of the grain and polishing depth. Also, relatively lower subsurface/surface damages and good surface uniformity were achieved through combining non-resonant vibration-assisted technology and roll-type polishing system. Finally, the comparative experiment of the material removal rate (MRR) between NVRP and non-vibration roll-type polishing (NRP) is conducted.
Plasma-assisted polishing (PAP) was confirmed to be high-efficiency and high-quality when applied to single crystal diamond (SCD) substrates. The effects of polishing pressure applied to the SCD ...substrate and sliding speed between the polishing plate and SCD substrate in PAP were systematically investigated in this study. Higher polishing pressures or sliding speeds resulted in a higher material removal rate (MRR) of SCD substrate, and the highest MRR achieved 5.3 μm/h. In the case of PAP conducted at low polishing pressures such as 62.5, 81.3 kPa, scanning white light interferometer (SWLI) (84-μm square) and atomic force microscope (AFM) (5-μm square) measurements revealed an atomic-scale smooth surface without the surface texture depending on the crystal direction and the lowest Sq roughness of 0.3 nm (84-μm square) was achieved. Correspondingly, at low polishing pressure of 62.5 kPa, MRRs in PAP along the and directions were nearly identical, suggesting that isotropic removals occurred. In the case of PAP performed at high polishing pressures such as 143.8, 246.9, and 350.0 kPa, SWLI and AFM measurements revealed a rough surface with bands of grooves along direction. Correspondingly, at high polishing pressures of 246.9 and 350.0 kPa, MRRs in PAP along direction were ~11 and ~12 times faster than that in direction, respectively, suggesting that anisotropic removals occurred. Moreover, scanning transmission electron microscopy and angle-resolved X-ray photoelectron spectroscopy measurements confirmed that no damage or non-diamond layer was present on the PAP-processed SCD substrate. However, as the sliding speed varied, both SWLI and AFM measurements demonstrated that Sq roughness remained nearly constant with the same polishing pressure applied to the SCD substrate.
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•The higher polishing pressure or sliding speeds increased MRR of SCD substrate.•When the PAP was conducted at low polishing pressures such as 62.5 kPa, an atomic-scale smooth surface without the surface texture depending on the crystal direction generated.•When the PAP was conducted at high polishing pressures such as 350 kPa, a rough surface with bands of grooves along generated.•The influence of the sliding speed variation on Sq roughness of SCD substrate was negligible.•PAP was damage-free when applied to SCD substrate polishing.
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