Minimum Surface Roughness Research Articles

Analysis of Surface Roughness, Cutting Force and Cutting Fluid Consumption in Turning Operation with and Without Use of Cutting Fluid Optimizer

In the present work, cutting fluid consumption, surface roughness, component of forces and tool temperature were analyzed with and without online regulation cutting fluid. Cutting Fluid Optimizer (CFO) is a device that automatically regulates the supply of cutting fluid based on the temperature of the tool tip generated during the machining. Taguchi orthogonal L9 is employed for design of experiments using MINITAB-21. Every experiment was conducted on mild steel work material with use of a tungsten carbide tool insert on the conventional lathe. The best parameter is determined via grey relational analysis. Optimal condition of regulation of coolant with the Cutting Fluid Optimizer (CFO) and non-regulation of coolant with the cutting fluid optimizer are compared. Minimum surface roughness, machining forces, tool–work piece temperature was recorded in case of non-regulation of cutting fluid with the CFO at the cost of the consuming large amount cutting fluid. However, regulation of cutting fluid with the CFO was able to reduce coolant consumption by 15.3% but significantly resulting 3.3 % increase in component of forces, surface roughness and tool-work piece temperature.

Multi-Objective Optimization of the Inconel 718 Turning Parameters Using MARCOS–Based Taguchi S/N ratio

Nickel-based alloys, such as Inconel 718, are widely used in space technology, rocket engines, nuclear reactors, petrochemicals, submarines, power plants, and other applications. It is classified as a challenging material to process due to its strong mechanical properties, low thermal conductivity, and other characteristics. The main objective of this work is to determine the optimal cutting parameters for turning Inconel 718 using a coated carbide tool, with the aim of reducing cutting tool vibration, minimizing surface roughness, and maximizing material removal rate. This is achieved by employing the Measurement of Alternatives and Ranking according to Compromise Solution technique (MARCOS) coupled with Taguchi's signal-to-noise ratio. The results have demonstrated that the configuration of the cutting parameters for achieving the aforementioned objectives is as follows: r = 0.8 mm, Vc = 70 mm/min, f = 0.08 mm/rev, and ap = 0.3 mm.

OPTIMIZATION OF MACHINING PARAMETERS ON THE SURFACE ROUGHNESS OF ALUMINUM IN CNC TURNING PROCESS USING TAGUCHI METHOD

In this research, Taguchi method is employed by focusing on spindle speed, feed rate, and depth of cut to optimize the CNC turning parameters for aluminum alloy 6063. The main goal of this study is to improve the surface roughness of the material. A L9 orthogonal array is used for experimentation, and the results are subsequently analyzed using ANOVA (Analysis of Variance). A spindle speed of 1300 rpm, a feed rate of 0.5 m/min, and a depth of cut of 1.5 mm are the optimal conditions to achieve the minimum average surface roughness (Ra). The main effect plot of the signal-to-noise (S/N) ratio provides significant evidence supporting the primary research goal. Furthermore, the ANOVA table reveals that spindle speed contributes 59.71%, feed rate contributes 29.80%, while depth of cut only contributes minimally at 0.72%. Based on the research findings, spindle speed and feed rate can be adjusted to control surface roughness. Both factors are highly significant in influencing the surface roughness of the material. The prediction equation from the linear regression analysis is Ra = 1.745 – 0.001024 spindle speed + 0.3000 feed rate – 0.0233 depth of cut. A coefficient of determination or R-squared value of 0.9115 indicates that the independent variables can explain 91.15% of the variation in the dependent variable. The experimental and predicted surface roughness (Ra) values have a predicted error percentage of 2.26%.

Morphological and Electrical Characterization of AlGaN/GaN Heterostructures Modified By Atomic Layer Etching

Modern microelectronic components for high-power and high-frequency applications based on III-V compound semiconductors offer high break down voltage (GaN: 5 MV/cm and AlN: 15 MV/cm) at low specific on-resistance. However, it requires reliability and reproducibility of the production processes. Going to higher frequencies (5 GHz and beyond) and more integration in consumer electronics, smaller structure sizes are needed. This is going along with increasing demands on the manufacturing processes like dry etching. The main goal is to reach smaller and high controllable etching rates, going down to single atomic layers, low damage, and minimized surface roughness. Atomic layer etching (ALE) represents a key technology in order to achieve such requirements.An ALE process consists of two independent steps forming a repeatable cycle with a specific etching amount per cycle (EPC). First a surface modification is done by a chemical precursor i.e., adsorbing or oxidizing the surface. The second step is the removal of the modified layer, either physically by low energy non-reactive ion bombardment (Plasma Enhanced ALE [PEALE]) or chemically by a reactive species (Thermal ALE). The two steps are separated by an inert gas purge. This purging grants the removal of the chemistry after the first step, preventing further chemical reaction and transporting the chemical products out of the chamber after the second step.In this study, a PEALE conducted on different tools is used, for gate and contact recess study in a AlGaN/GaN heterostructure to form high electron mobility transistors (HEMT) with reduced ohmic contact resistance and threshold voltages. The results show a reduction of ohmic contact resistance at reduced forming temperatures and a linear dependence of the threshold voltage on gate recess depth. In order to determine the etching rate and roughness, atomic force microscopy (AFM) measurements were performed.The PEALE module is either integrated into a cluster tool consisting of atomic layer deposition (ALD) and chemical vapor deposition (CVD) or done in a combined ALD/ALE chamber. This opens the possibility of etching and depositing in-situ, reducing contamination and degradation of the substrate material.By this means, metal insulator semiconductor (MIS)-HEMTS with a recessed gate are studied. The monitoring of the individual processes is achieved by test structures like transfer length method structures (TLM) and metal oxide semiconductor (MOS), which showed the improved electric performance of these devices and may indicate unwanted interface issues, respectively. Additional, pre- and post-treatments could improve the interfaces further. The results will be presented and discussed in terms of ALE process development and optimization.This work was financially supported within the ALEStar project by the government of the Free-state of Saxony and the European Regional Development Fund under grant no. SAB 100402929.

Precision machining performance and mechanism of Ni/Ni3Al alloy under cryogenic temperature

Nickel-based superalloys are extensively used in extreme environments due to their excellent mechanical properties, which are attributed to the large volume fraction of the γ' phase. However, the manufacturing process of these alloys is still challenging and can be improved by cryogenic machining. Despite numerous experimental studies on this topic, experimental methods are not sufficient to analyze the ultra-precision machining of Ni-based alloys at low temperatures. There is a lack of mechanistic understanding of the low-temperature nano-cutting process of Ni-based alloys. Thus, we performed a simulation analysis of cryogenic nano-cutting on a Ni/Ni3Al alloy using molecular dynamics (MD). We investigated the stability of cutting forces and microstructural evolution of this two-phase single-crystal alloy. We found that appropriate low temperatures can significantly improve the cutting performance of Ni/Ni3Al two-phase single-crystal alloy. Specifically, we found that the stability of cutting at 123 K is the best for workpiece A, while the cutting stability at 173 K is the best for workpiece B. Additionally, we calculated the machined surface roughness and precision. The minimum surface roughness is observed at 123 K in workpiece A, followed by 223 K. In workpiece B, the minimum roughness is observed at 223 K, while the roughness at 123 K is considerably higher compared to other temperature levels. This study outlines a reference method for determining the optimal temperature during the material removal process. This approach is significant as it helps in understanding the micro-removal mechanism of Ni-based alloys better.

Effect of phosphate post-treatment on corrosion behavior of cerium-based conversion coated Mg-4.0Y-4.0Zn-0.5Zr-0.2Ca (wt.%) alloys

The present study aims to investigate the effect of cerium-based conversion coating and phosphate post-treatment on the corrosion behavior of Mg-4.0Y-4.0Zn-0.5Zr-0.2Ca (wt.%) alloy (WZ44) in chlorinated solution. In this regard, as-cast and forged WZ44 alloy was subjected to cerium salt bath treatment at ambient followed by NaH2PO4 solution at 85 °C. The morphological evolution and chemical composition of the composite coating were examined using field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX), two and three-dimensional surface topography, and X-ray photoelectron spectroscopy (XPS) reveal the formation of complex phase mixture of CeO2, Ce2O3, CePO4, Mg(OH)2, and unknown hydrated compounds. The as-prepared cerium conversion coating possesses nodular CeO2 precipitates with abundant mud-cracks features originating due to hydrogen evolution and film dehydration-induced tensile stress. However, phosphate treatment develops a relatively smoother and compact coating with minimum surface roughness and conversion of nodular CeO2 precipitates into CePO4, albeit with few fine cracks. The tape adhesion and scratch test disclose that coating delamination predominant in cerium conversion coated specimens was reduced drastically by phosphate treatment with ∼16–23 % improvement in scratch hardness. Corrosion in terms of mass loss and potentiodynamic polarization (PDP) highlights that phosphate treatment improves the corrosion rate by ∼25–65 % compared to blank. Electrochemical impedance spectroscopy (EIS) demonstrates that coating (Rcoat) and polarization resistance (RP) at the film-metal interface was substantially increased to ∼953 Ω cm2 and ∼729 Ω cm2 for phosphate-treated specimens with a progressive increase in semicircular capacitive loop diameter indicating surface passivation. Overall, a duplex coating strategy with cerium salt bath followed by phosphate treatment can essentially develop a compact double-layer that effectively minimizes severe corrosion of WZ44 alloy in a 0.1 M NaCl electrolyte.

Additive Manufacturing of Side-Coupled Cavity Linac Structures from Pure Copper: A First Concept

Compared to conventional manufacturing, additive manufacturing (AM) of radio frequency (RF) cavities has the potential to reduce manufacturing costs and complexity and to enable higher performance. This work evaluates whether normal conducting side-coupled linac structures (SCCL), used worldwide for a wide range of applications, can benefit from AM. A unit cell geometry (SC) optimized for 75 MeV protons was developed. Downskins with small downskin angles α were avoided to enable manufacturing by laser powder bed fusion without support structures. SCs with different α were printed and post-processed by Hirtisation (R) (an electrochemical process) to minimize surface roughness. The required accuracy for 3 GHz SCCL (medical linacs) is achieved only for α>45∘. After a material removal of 140 µm due to Hirtisation (R), a quality factor Q0 of 6650 was achieved. This corresponds to 75% of the Q0 simulated by CST®. A 3 GHz SCCL concept consisting of 31 SCs was designed. The effective shunt impedance ZT2 simulated by CST corresponds to 60.13MΩm and is comparable to the ZT2 of SCCL in use. The reduction in ZT2 expected after Hirtisation (R) can be justified in practice by up to 70% lower manufacturing costs. However, future studies will be conducted to further increase Q0.

Fabrication of Vitrified Bond Diamond Grinding Wheel via LCD Photopolymerization

In this paper, a liquid crystal display (LCD) photopolymerization method is proposed, and a vitrified bond diamond grinding wheel is successfully prepared. A high-performance vitrified bond was obtained by melting SiO2-B2O3-Al2O3-Na2O ceramic raw materials and used for grinding wheel preparation. LCD photopolymerization technology is characterized by high precision in shaping, fast processing speed, and superior quality, making it a promising technology for fabricating vitrified bond diamond grinding wheels. The preparation of vitrified bond slurry with high solid content and low viscosity was extensively investigated to meet the fabrication requirements. The effects of dispersant, the particle size of the vitrified bond, and solid content on the viscosity of the slurry were systematically analyzed. The vitrified bond slurry with solid content up to 65 wt.% (approximately 45.5 vol.%) was successfully prepared and met the requirements for printing. Furthermore, we explored the optimal formulation of the grinding wheel, debinding and sintering conditions, sintering temperature, grit-to-bond ratio, and the evaluation of the grinding performance of the wheel on hard and brittle materials, such as silicon carbide ceramic. Vitrified bond and abrasive slurry systems with a solid content of 65 wt.% (approximately 42.8 vol.%) were prepared. The results show that the vitrified bond diamond grinding wheel exhibits optimal comprehensive performance, with a sintering temperature of 680 °C and a grit-to-bond ratio of 4:6. The minimum surface roughness of the workpiece after grinding was 1.767 μm, the material removal rate was 5.08 mg/s, the grinding ratio was 9.78, and the friction coefficient was stabilized at about 0.5 during grinding. This paper guides the manufacturing of vitrified bond diamond grinding wheels via LCD photopolymerization.

Моделирование рабочих характеристик и мультикритериальная оптимизация при токарной обработке нержавеющей стали AISI 304 (12Х18Н10Т) резцами с износостойким покрытием и с износостойким покрытием, подвергнутым микропескоструйной обработке

Introduction. High-speed machining of stainless steel has long been a focus of research. Due to characteristics such as low thermal conductivity and work hardening, AISI 304 is considered to be a difficult material to cut. Machinability indicators provide important information about the efficiency and effectiveness of the machining process, enabling manufacturers to optimize their operations for increased productivity and precision. The purpose of the work. Coated carbide tools are most often used for machining AISI 304 stainless steel. Few studies, meanwhile, have examined the effects of pre-and post-treated coated carbide tools when turning these alloys at high speeds. In addition, only a small number of studies have simultaneously optimized the cutting parameters while employing pre-and post-treated tools. The methods of investigation. The present work comparatively evaluates the performance of coated and coated-microblasted tools during the turning of AISI 304 stainless steel. The tools were PVD-AlTiN coated, PVD-AlTiN coated with microblasting as a post-treatment (coated-microblasted), and MTCVD-TiCN/Al2O3 coated (MTCVD). The experimental-based mathematical models were developed to predict and optimize the turning performance. Results and Discussion. In this study, it is found that PVD-AlTiN coated tools have the lowest cutting forces and surface roughness, followed by PVD-AlTiN coated-microblasted and MTCVD-TiCN/Al2O3 coated tools. However, there is no significant difference observed in these responses for coated and coated-microblasted tools. It is found that the cutting forces increased with feed and depth of cut while decreasing with cutting speed. However, this effect is significant for MTCVD-coated tools. On the other hand, higher tool life is observed with MTCVD-TiCN/Al2O3 coated tools, followed by PVD AlTiN coated-microblasted and PVD-AlTiN coated tools. Tool life was largely affected by cutting speed. However, PVD-AlTiN coated tools exhibited this effect more noticeably. The models, with correlation coefficients found above 0.9, can be utilized to predict responses in turning AISI 304 stainless steel. The optimization study revealed that turning AISI 304 stainless steel with MTCVD-TiCN/Al2O3 coated tools incurs lower cutting forces of 18–27 N, produces a minimum surface roughness of 0.3–0.44 μm, and has a better tool life of 36–51 min compared to PVD-AlTiN coated (C) and PVD-AlTiN coated-microblasted (CMB) tools.

The dynamics of glassy behavior in SrRu1-xFexO3 heterostructure

We report the magnetic interactions in SrRu1-xFexO3 epitaxial thin films. All the films showed a single-phase and good step-terrace structure with minimal surface roughness. The X-ray photoelectron spectra of Fe and Ru revealed that both transition metal elements exist in the films as Fe3+ and Ru4+. With Fe doping, the itinerant ferromagnetic behavior and ferromagnetic transition temperature gradually decreased, but the coercivity field increased. The magnetic interplay between Fe3+-O-Fe3+ is coined as antiferromagnetic. There was another interaction between Ru4+-O-Fe3+ which is best described as ferromagnetic. Furthermore, the magnetic frustration in our films caused by the doped Fe resulted in dynamic glassy behavior. On the other hand, the epitaxial strain from the imminent SrTiO3 substrate along with change in oxygen vacancy might have strong evidence for the spin-glass nature in our thin films.

Stir Cast AA 6351/Graphene/TiB2/Rice Husk Ash composite: Fabrication and assessment of mechanical properties

Single composites are replaced by hybrid composites because of their highly efficient properties and easy processing ability. In this research work, the stir casting process has been used for the fabrication of an Aluminium 6351 metal matrix composite. The TiB2, Graphene and Rice Husk Ash (RHA) have been used as reinforcements. The various mechanical (hardness, impact, flexural, tensile) and surface (SEM, EDS, XRD) characterization have been carried out. The different samples with varying compositions of Graphene (0.0, 0.5, 1.0 and 1.5 wt.-%), the constant composition of Titanium boride (10 wt.-%) and Rice Husk Ash (2.0 wt.-%) have been fabricated. The maximum values of hardness and energy absorbed were 78.8 HV0.3 and 6 Joule respectively and minimum surface roughness of 0.308 µm have been obtained by doping 1.5 wt.-% Graphene in AA6351. Whereas, the maximum value of flexural and tensile strength was 418.73 and 154.81 MPa for AA6351 having 0.5 wt.-% of Graphene as reinforcement. Moreover, the presence of TiB2, Graphene, and RHA showed their uniform distribution in fabricated composites using surface characterization (such as SEM, EDS and XRD).

Multi-objective Optimization of Milling Parameters for Carbon Fiber Reinforced Polymer Based on MOEA / D

In order to study the optimal milling parameters of carbon fiber reinforced polymer, this paper takes carbon fiber composite unidirectional plate as the research object, and the effects of cutting parameters on cutting forces and surfaces roughness were analyzed by high-speed cutting experiments. Experimental tests have validated the effectiveness of high speed cutting in reducing cutting forces, improving cutting efficiency, and improving machined surface quality. With the minimum surface roughness and maximum material removal rate as optimization goals, and the spindle speed, feed speed, and radial feed as design variables, the MOEA/D algorithm is used for multi objective optimization on, and to give the optimal solution set of carbon fiber composite milling.

EXPERIMENTAL ANALYSIS OF WIRE-EDM ON SUB-COOLED LOW-CARBON TOOL STEEL USING HYBRID MARCOS METHOD AND HONEY BADGER ALGORITHM

AISI P20 tool steel is commonly used for engineering of die holders, rails, plastic molds, wear strips, bolsters, shafts, and backers. When normally heated and sub-cooled, it experiences metallurgical modifications. Because the essential aspect of the “wire-electro discharge machine (WEDM)” is product finishing, this research examines the parametric responses when machining parent metal and sub-cooled metal (AISI P20). Thus, it is always necessary to choose a proper parametric arrangement for reaching maximum material removal rate (MRR), cutting speed with minimum surface roughness (SR), and kerf width. The effects of pulse on time, wire speed, discharge current, wire tension, and flushing pressure on individual machining reactions are also discussed in this study. An orthogonal array was created using Taguchi’s mixed experimental approach. The measurement alternatives and ranking according to compromise solution (MARCOS) method, the Honey Badger Algorithm, and the Taguchi-MARCOS method are engaged to obtain the important machining constraints and the optimal parametric settings for each response. When compared to the parent material, sub-cooled material has a greater cutting speed, SR, kerf breadth, and MRR. Here, cutting speed, MRR, and fitness were maximized along with minimization of SR and kerf width using the Honey Badger Algorithm as compared to both the MARCOS and Taguchi-MARCOS methods. According to ANOVA, for both parent and sub-cooled material, discharge current was the most significant and influential factor. The sub-cooled material’s machined surface contains smaller deposits and more spherical globules than the parent material, which has bigger melted deposits.

Role of laser power and scan speed combination on the surface quality of additive manufactured nickel-based superalloy

In laser-based powder bed fusion (L-PBF), the volumetric energy density (VED) controlled by laser power (LP) and scan speed (SS) significantly affects the desired surface quality. Any variations in the LP and SS on the VED notably affect the surface quality due to changes in laser powder interactions. Therefore, the present study concentrated on the effect of various combinations of LP and SS, i.e. low LP (160 W) with high SS (1250 mm/s), high LP (320 W) with low SS (410 mm/s), low LP (160 W) with low SS (550 mm/s) and high LP (320 W) with high SS (1100 mm/s). The wide range of varying VEDs was chosen between 29 and 177 J/mm3. The results showed the VED range between 66 and 90 J/mm3 exhibited minimum surface roughness parameters of 0.51 < Ra < 0.52 µm, 0.63 < Rq < 0.64 µm, and 2.53 < Rz < 2.79 µm. The specific impact of LP and SS combination between 160 and 320 W with 400–1250 mm/s by maintaining a constant VED of 66 J/mm3 was also investigated. At a constant VED of 66 J/mm3, the combination of 280 W and 960 mm/s shows minimum roughness parameters of Ra = 0.527 µm, Rq = 0.645 µm, and Rz = 2.446 µm. The results showed that the combination of low LP with low SS, high LP with high SS, low LP with high SS, and high LP with low SS, increases surface roughness.

Investigation of the performance of integrated intelligent models to predict the roughness of Ti6Al4V end-milled surface with uncoated cutting tool

Abstract Titanium alloys are broadly used in the medical and aerospace sectors. However, they are categorized within the hard-to-machine alloys ascribed to their higher chemical reactivity and lower thermal conductivity. This aim of this research was to study the impact of the dry-end-milling process with an uncoated tool on the produced surface roughness of Ti6Al4V alloy. This research aims to study the impact of the dry-end milling process with an uncoated tool on the produced surface roughness of Ti6Al4V alloy. Also, it seeks to develop a new hybrid neural model based on the training back propagation neural network (BPNN) with swarm optimization-gravitation search hybrid algorithms (PSO-GSA). Full-factorial design of the experiment with L27 orthogonal array was applied, and three end-milling parameters (cutting speed, feed rate, and axial depth of cut) with three levels were selected (50, 77.5, and 105 m/min; 0.1, 0.15, and 0.2 mm/tooth; and 1, 1.5, and 2 mm) and investigated to show their influence on the obtained surface roughness. The results revealed that the surface roughness is significantly affected by the feed rate followed by the axial depth. A 0.49 µm was produced as a minimum surface roughness at the optimized parameters of 105 m/min, 0.1 mm/tooth, and 1 mm. On the other hand, a neural network having a single hidden layer with 1–20 hidden neurons, 3 input neurons, and 1 output neuron was trained with both PSO and PSO–GSA algorithms. The hybrid BPNN–PSO–GSA model showed its superiority over the BPNN–PSO model in terms of the minimum mean square error (MSE) that was calculated during the testing stage. The best BPNN–PSO–GSA hybrid model was the 3–18–1 structure, which reached the best testing MSE of 3.8 × 10−11 against 2.42 × 10−5 of the 3–8–1 BPNN–PSO hybrid model.

Cu, Ni and Ag ions assisted preparation of nonpolar preferential oriented ZnO films with controlled morphology and optical properties

ZnO nanodevices have been widely used in practice, but one-dimensional ZnO grown in a polar preferred orientation is still partially localized. In this work, copper nitrate, nickel nitrate and silver nitrate were assisted with zinc acetate and hexamethylenetetetramine for the synthesis of ZnO films by conventional chemical bath deposition method. All samples were characterised by X-ray diffraction, field emission scanning electron microscopy, atomic force microscopy, photoluminescence, and UV–visible spectrophotometer. The results show that non-polar (110), (100) and coexisting preferred orientation ZnO films were controllably prepared by controlling the type and concentration of nitrate. On this basis, the growth process and mechanism of ZnO films with different nonpolar preferred orientations were characterized. It was also found that the ZnO films with 5 % Cu(NO3)2·3 H2O had the minimum surface roughness. The PL spectra confirmed the type and number of defects were also related to the preferred orientations. In addition, the non-polar (110) preferred orientation ZnO films had the highest optical transmittance of 82.26 %. This work enriches the method of preparing ZnO films with various nonpolar preferred orientations and provides new ideas for the design of ZnO-based transparent nanodevices.

Investigations on hardness and surface roughness of 3D printed ABS-ZrO2 composite structures for post processing applications

The present research aims to develop composite materials made from acrylonitrile butadiene styrene (ABS) as the matrix with Zirconia (ZrO2) as the filler material. ABS-ZrO2 composite test samples were fabricated using a fused filament fabrication (FFF) based 3D Printer, using Taguchi’s L9 orthogonal array (OA). The ABS-ZrO2 composite 3D printed samples were supported by shore D hardness and surface roughness tests, which revealed that 230˚C barrel temperature, 100% infill, and octet infill pattern are the best set of FFF parameters for obtaining maximum Shore D hardness of 80.50 Shore D. This set of process parameters provide the good conditions for 3D Printing of ABS-ZrO2 composite, and it may be used as potential material for post-processing applications, whereas 240˚C barrel temperature, 60 % infill percentage, and linear infill pattern are best conditions for minimum surface roughness.

Evaluation of process parameter of friction stir processing of AA2024-T351 Alloy using RSM and GRA

A fundamental method for changing the characteristics of metals through localised severe plastic deformation is friction stir processing (FSP), which is both straightforward and efficient. Because of its high strength-to-mass ratio and resilience to fatigue, aluminium alloy 2024 is commonly utilised. The experiments were designed utilising the Box–Behnken method and the process parameters’ chosen range values. In this research, the impact of FSP process variables on the tensile, surface roughness, and hardness properties of AA2024 will be examined. These parameters include tool rotation speed, welding speed, and axial load. The base sample tensile strength, surface roughness and microhardness values were 325 MPa, 0.5125 μm, and 120 HV. The optimised sample’s maximum tensile strength, minimum surface roughness, and maximum microhardness values were 420 MPa, 0.4 μm, and 144 HV. The grey relational analysis (GRA) determines the ideal combination of process parameter values for the best values in all responses. XRD was used to assess residual stress, dislocation density and micro-strain. The optimal process parameters have been obtained at a rotational speed of 1000 rpm, traverse speed of 45 mm/min, and axial load of 10.25 kN.

Research on the machining mechanism of AISI 304 ultrasonic vibration assisted grinding

Compared with conventional grinding (CG), ultrasonic vibration assisted grinding (UVAG) has more prospects and competitiveness in processing AISI 304. Due to the change of strength of materials, when the vibration is superimposed on the workpiece, the mechanism of ultrasonic assisted machining is different from that of tool ultrasonic assisted machining. Therefore, this article proposes a workpiece vibration grinding device suitable for UVAG to study the corresponding grinding mechanism. The vibration characteristics of workpiece ultrasonic generator were discussed based on finite element simulation and the vibration situation of the device was tested with instruments to verify the accuracy of the simulation. Meanwhile, the machining mechanism of workpiece ultrasonic vibration was studied through grinding comparative experiments. The experiment showed that the displacement curve of the output end of the ultrasonic vibration of AISI 304 with time could be approximated to a sine wave and there was no other clutter. As the amplitude percentage of the ultrasonic generator increased, the output amplitude of the transducer showed an increasing trend. The ultrasonic amplitude and the amplitude percentage of ultrasonic generator approximately follow a linear relationship. The grinding force decreased with the increase of spindle speed and amplitude, and increased with the increase of feed rate and grinding depth. Compared with conventional grinding force, the grinding force of tangential ultrasonic vibration assisted grinding (TUVAG) decreased by about 29 %, while the grinding force of radial ultrasonic vibration assisted grinding (RUVAG) decreased by about 28 %. Under the action of ultrasound, the workpiece obtained better surface morphology. Under processing conditions of vw = 25 mm/min, ap = 0.01 mm, n = 2000r/min, A = 8 μm, f = 20000 Hz, the minimum surface roughness Ra of TUVAG is 0.51, followed by RUVAG with Ra = 1.02, while the surface roughness Ra of CG is the worst at 1.56 due to grinding burns.

Influence of surface polishing on the degradation behavior of biodegradable Magnesium alloy

Mechanical polishing can significantly improve the surface integrity of Mg alloys to reduce the corrosion rate (CR) by minimizing the galvanic corrosion sites. In this study, an emery-polishing attachment on a lathe machine has been used for surface polishing of as-turned cylindrical ZM21 Mg alloy. Using Taguchi’s L9 orthogonal array, three process variables with three levels were investigated and optimized for minimum surface roughness (Ra and Rz values) of Mg-alloy samples. The minimum surface roughness values of Ra; 195 nm and Rz; 1481 nm were obtained corresponding to emery paper (EP) grade; 2000, rotational speed; 250 rpm, and polishing time; 2 min. An in-vitro immersion study was conducted in simulated body fluid (SBF) for up to 28 days to investigate the degradation behavior of as-turned and as-polished Mg alloy samples. In-vitro study showed that the as-turned samples (surface roughness; Ra: 640 nm, Rz: 4640 nm) had a higher degradation rate (CR: 3.9 mm year−1 after 28 days) with a higher volume of H2 evolution rate, whereas the polished sample with the minimum surface roughness (Ra: 195 nm, Rz: 1481 nm) exhibited lower weight loss, H2 release rate, degradation rate (CR: 0.95 mm year−1 after 28 days) and minimum loss of mechanical strength. Based on the present study, polishing is recommended as a secondary operation after machining of Mg alloy to reduce the corrosion rate for biodegradable implant applications.