Fine Surface Finish Research Articles

Experimental Investigation for the Multi-objective Optimization of Machining Parameters on AISI D2 Steel Using Particle Swarm Optimization Coupled with Artificial Neural Network

High Carbon High Chromium (or AISI D2) Steels, owing to the fine surface finish they produce upon grinding, find lot of applications in die casting. Machining parameters affect the surface finish significantly during the grinding operation. In this context, this work puts an effort to arrive at the optimum machining parameters relating to fine surface finish with minimum cutting force. The material removal caused by the abrasive grinding wheel makes the process a very complex and nonlinear machining operation. In many situations, traditional optimization techniques fail to provide realistic optimum conditions because of the associated complexity. In order to overcome this issue, particle swarm optimization (PSO) coupled with artificial neural network (ANN) is applied in this research work for parameter optimization with the objective of achieving minimum surface roughness and cutting force. The machining parameters selected for the investigation were table speed, cross feed and depth of cut and the responses were surface roughness and cutting force. ANNs, inspired from biological neural networks, are well capable of providing patterns, which are too complex in behavior. The ANN model developed was used as the fitness function for PSO to complete the optimization. Optimization was also carried out using conventional response surface methodology-genetic algorithm (RSM-GA) approach in which regression equation developed with RSM was considered as the fitness function for GA. Confirmatory experiments were conducted and the comparison showed that PSO coupled with ANN is a reliable tool for complex optimization problems.

Magnetorheological finishing of UHMWPE acetabular cup surface and its performance analysis

ABSTRACT Ultra-high molecular weight polyethylene (UHMWPE) is a highly used polymer in the medical field due to its properties such as good mechanical strength, high hardness, good chemical resistance, and excellent biocompatibility. UHMWPE is used for the manufacturing of acetabular cups in hip-joint implantation. For enhancing the life span and functionality of hip implants, the uniform fine surface finish of the acetabular cup is essential. This is because the non-uniform finish can cause wear and friction during different movements of implants which may lead to osteolysis. In the present work, the UHMWPE acetabular cup surface gets fine finished using the hemispherical tool tip-based magnetorheological (MR) finishing process. To study the efficacy of the tool, magnetostatic finite element analysis is used for analyzing the magnetic field. After the experimentation on 1140 mm2 surface area of the UHMWPE acetabular cup, the surface improvement obtained is 66.67% in 100 minutes of the finishing cycle. For the study of surface morphology, circularity, and microhardness on the finished UHMWPE acetabular cup surface, the scanning electron microscopy, co-ordinate measuring machine, and microhardness tester machine are used. Results show that the present process is suitable for the uniform fine finishing of the UHMWPE acetabular cup with improved surface characteristics.

Modelling and monitoring of abrasive finishing processes using artificial intelligence techniques: A review

Abstract Abrasive finishing processes such as grinding, lapping or disc polishing are one of the most practical means for processing materials to manufacture products with fine surface finish, surface quality and dimensional accuracy. However, they are one of the most difficult and least-understood processes for two main reasons. Firstly, the abrasive grains present in the tool surface are randomly oriented. Secondly, they undergo complex interactions in the machining zone. Given the advances in sensor technologies, the finishing processes can now be sensorized, and the vast amount of data produced can be exploited to model and monitor the processes using Artificial Intelligence techniques. Data-driven models have turned into a hot focus in engineering with the rise of machine learning and deep learning algorithms, which have greatly spread all through the academic community. The scope of this paper is mainly to review the application of Artificial Intelligence as well as supporting sensing and signal processing techniques in modelling and monitoring on different types of abrasive processes in metal finishing. The paper gives a detailed background on the key mechanisms and defects in the different abrasive finishing process and lists the suitable sensing techniques for their monitoring. The paper reports that most of the Artificial Intelligence algorithms available are not fully exploited for monitoring and modelling in abrasive finishing and emphasizes on bridging this gap. The probable research tendency on data-driven monitoring and modelling for abrasive finishing is also forecasted.

The influence of the process parameters of drag finishing on the surface topography of aluminium samples

Tribofinishing techniques are superfinishing processes that enable surface roughness improvement due to the mechanical action of abrasive media. A wide variety of kinematics can be employed and these abrasive media can have various trajectories and speeds when impacting the treated surface (normal, oblique, tangential, etc.). This work focuses on the drag finishing process, and in particular on the effect of spherical abrasive media impacting normally the surface of an aluminium part (6061T6). It investigates first the influence of the initial surface roughness and the diameter of spherical media when a lubricant is used. Secondly, it analyses the effect of a chemical accelerator surrounding abrasive media and the surface. An original experimental set-up was designed to observe the evolution of various surface roughness parameters and to identify local physical and chemical mechanisms. The results show that the final surface finishing greatly depends on the size of the abrasive media, and that a chemical additive can accelerate the material removal rate and improve the roughness when compared to a lubricant.

Enhancement in microstructural and mechanical performance of AA7075 aluminum alloy via severe shot peening and ultrasonic nanocrystal surface modification

In this experimental study, AA7075 aluminum alloy was subjected to pure severe shot peening (SSP), pure ultrasonic nanocrystalline surface modification (UNSM) and the combination of these two treatments. The treated specimens were analyzed with detailed microstructure analysis, micro-hardness, surface roughness, XRD investigations and wear-friction tests. The results demonstrated that UNSM exhibited fine surface finish and provided minimum surface roughness with the Ra value of 0.8 µm. Moreover, UNSM played an important role in the reduction of Ra as a secondary treatment. Electron back scatter diffraction (EBSD) analysis, full width at half maximum (FWHM) evaluations and compressive residual stress (CRS) measurements showed that the deformed layer structure was converted into a nanocrystallized and compressively stressed zone via SSP and UNSM. The hardness on the topmost layer was effectively enhanced by UNSM + SSP and SSP + UNSM processes. The wear and friction performance were particularly improved by two-stage operations of UNSM + SSP and SSP + UNSM. The performance was also compatible with the hardness, residual stress and nanocrystallization investigations.

Research Regarding the Improving of the Machining Parameters in the Field of Grinding Process

Grinding is one of the most important machining processes that confer the final size and surface finish for the workpiece. The paper presents a theoretical study regarding the manner in which the quantity of heat that results during grinding process is transmitted to the technological elements. The study reveals as well the influence of thermal deformations on the dimensional accuracy of the workpiece. Experimental data regarding the influence of cutting speed on the temperature in the machining zone for different cutting processes are distinguished.

Study on the Influence of Metallic Powder in Near-Dry Electric Discharge Machining

Near-dry electrical discharge machining (ND-EDM) is an eco-friendly process. In this study, an approach has been made to make the machining process more efficient than ND-EDM with the addition of metallic powder with the dielectric medium to machine EN-31 die steel. Powdermixed near-dry EDM (PMND-EDM) has several advantages over the ND-EDM or conventional electrical discharge machining (EDM) process, such as a higher material removal rate (MRR), fine surface finish (Ra), sharp cutting edge, lesser recast layer, and lower deposition of debris. The output response variables are MRR, Ra, residual stress (RS) and micro-hardness (MH) of the machined surfaces. Further study of the workpiece was performed, and a comparative study was conducted between ND-EDM and PMND-EDM. In this proposed method of machining, the MRR, Ra, and MH increased by 17.85 %, 16.36 %, and 62.69 % while RS was reduced by 56.09 %.

Polydopamine-Lysophosphatidate-Functionalised Titanium: A Novel Hybrid Surface Finish for Bone Regenerative Applications.

Aseptic loosening of total joint replacements (TJRs) continues to be the main cause of implant failures. The socioeconomic impact of surgical revisions is hugely significant; in the United Kingdom alone, it is estimated that £135m is spent annually on revision arthroplasties. Enhancing the longevity of titanium implants will help reduce the incidence and overall cost of failed devices. In realising the development of a superior titanium (Ti) technology, we took inspiration from the growing interest in reactive polydopamine thin films for biomaterial surface functionalisations. Adopting a “one-pot” approach, we exposed medical-grade titanium to a mildly alkaline solution of dopamine hydrochloride (DHC) supplemented with (3S)1-fluoro-3-hydroxy-4-(oleoyloxy)butyl-1-phosphonate (FHBP), a phosphatase-resistant analogue of lysophosphatidic acid (LPA). Importantly, LPA and selected LPA analogues like FHBP synergistically cooperate with calcitriol to promote human osteoblast formation and maturation. Herein, we provide evidence that simply immersing Ti in aqueous solutions of DHC-FHBP afforded a surface that was superior to FHBP-Ti at enhancing osteoblast maturation. The facile step we have taken to modify Ti and the biological performance of the final surface finish are appealing properties that may attract the attention of implant manufacturers in the future.

Development and Rheological Characterisation of Abrasive Flow Finishing Medium for Finishing Macro to Micro Features

Technological advancement demands the manufacturing of components with a fine surface finish at a minimal cost. This scenario acts as the driving force for the research communities to develop economic finishing processes. Abrasive flow finishing (AFF) is one of the advanced finishing processes employed for finishing, deburring, radiusing and recast layer removal from the workpiece surfaces. AFF process uses a finishing medium that acts as a deformable tool during the finishing process. It is the rheological properties of the medium that profoundly influences the end surface finish obtained on the workpiece after the AFF process. In the current work, an attempt is made to develop an economic AFF medium by using viscoelastic polymers i.e., soft styrene and soft silicone polymer. Detailed static and dynamic characterisation of the medium is carried out. Later, to study the finishing performance of the developed medium, AFF experiments are performed for the finishing of macro and micro feature components. The experimental study showed that the nano surface finish could be achieved by varying the viscosity of the developed medium. Developed medium achieved 89.06 per cent improvement in surface roughness during finishing of tubes (macro feature component), while 92.13 per cent and 88.11 per cent surface roughness improvement is achieved during finishing of microslots and microholes (micro feature component), respectively.

Development of a facile fluorophosphonate-functionalised titanium surface for potential orthopaedic applications

sBackgroundAseptic loosening of total joint replacements (TJRs) continues to be the main cause of implant failures. The socioeconomic impact of surgical revisions is hugely significant; in the United Kingdom alone, it is estimated that £137 m is spent annually on revision arthroplasties. Enhancing the longevity of titanium implants will help reduce the incidence and overall cost of failed devices.MethodsIn realising the development of a superior titanium technology, we exploited the natural affinity of titanium for phosphonic acids and developed a facile means of coating the metal with (3S)1-fluoro-3-hydroxy-4-(oleoyloxy)butyl-1-phosphonate (FHBP), a phosphatase-resistant analogue of lysophosphatidic acid (LPA). Importantly LPA and selected LPA analogues like FHBP synergistically cooperate with calcitriol to promote human osteoblast formation and maturation.ResultsHerein, we provide evidence that simply immersing titanium in aqueous solutions of FHBP afforded a surface that was superior to unmodified metal at enhancing osteoblast maturation. Importantly, FHBP-functionalised titanium remained stable to 2 years of ambient storage, resisted ∼35 kGy of gamma irradiation and survived implantation into a bone substitute (Sawbone™) and irrigation.ConclusionThe facile step we have taken to modify titanium and the robustness of the final surface finish are appealing properties that are likely to attract the attention of implant manufacturers in the future.The translational potential of this articleWe have generated a functionalised titanium (Ti) surface by simply immersing Ti in aqueous solutions of a bioactive lipid. As a facile procedure it will have greater appeal to implant manufacturers compared to onerous and costly developmental processes.

Experimental analysis of magnetorheological finishing of blind hole surfaces using permanent magnet designed tools

Permanent mould dies are used for various plastic injection moulding products. Most of the mould cavity is blind and henceforth difficult to finish. In this study, a novel magnetorheological fluid-based finishing process using permanent magnet tools has been developed for nano-finishing of cylindrical blind hole surfaces. Tools to finish the internal and flat-bottomed surfaces of the cylindrical blind hole are developed. The finishing performance of both tools is evaluated for finishing ferromagnetic material used in dies. The material of the die is P20 tool steel having 41 HRC hardness. Response surface methodology using a central composite design technique has been utilized for the plan of experiments and analysis of significant process parameters on the percentage change in surface roughness using newly developed tools. During finishing the internal cylindrical blind hole surface, the process parameters like rotational speed, reciprocation speed and abrasive mesh size are found to be significant. However, during flat-bottomed surface finishing of cylindrical blind hole workpiece, rotational speed, abrasive mesh size and abrasives volume percentage are found to process significant parameters. Experimentation at optimized parameters results in the final surface finish of 83 nm on internal cylindrical surface and 93 nm on the flat-bottomed surface of cylindrical blind hole workpiece.

Densification, mechanical behaviors, and machining characteristics of 316L stainless steel in hybrid additive/subtractive manufacturing

Directed energy deposition (DED) is capable of manufacturing high-density and complex metal components, whereas traditional machining methods are limited in these regards. Nevertheless, the fabrication of parts with DED that have accurate dimensions and geometries as well as acceptable surface states is a concern, as these factors are inferior to those of traditionally machined components. Therefore, the application of parts fabricated with DED is restricted. Thus, the hybrid additive/subtractive manufacturing (HASM) method has been exploited to comprehensively utilize the advantages of both. In this paper, the HASM method was used to fabricate bulk parts with four different scanning strategies (alternating the orientation of subsequent layers by 0°, 45°, and 90° and island scanning are referred to as an X-scan, a Rot-scan, an XY-scan, and an Island-scan, respectively) followed by subtractive milling to gain a smooth surface with a determined thickness for the next scanning and deposition period until the parts were completely finished. The influence of the scanning strategy on the densification level and mechanical behavior of the specimens fabricated with HASM was studied. The results show that the specimens fabricated with the 7 × 7 mm2 island scan with short scan vector lengths showed a higher densification than the specimens fabricated using long scan vector lengths (the three methods mentioned above). Finally, to obtain a fine surface finish, the influence of the feed per tooth (fz) on the surface quality of a 316L stainless steel during the milling process that occurs during the HASM process was also investigated. The result shows a fz of 0.25 mm yielding the minimum surface roughness value among the samples observed herein, which implies that the surface quality was better than that of the other studied conditions.

A study in turning of AISI D2 steel with textured and non-textured coated carbide tool at the flank face

Surface texturing of a cutting tool is a new technique which can enhance the cutting performance during machining. In the present work micro-EDM is applied to produce texture at the tool flank face. Two types of texture, i.e. groove and dot are made at the flank face of a coated carbide tool for machining AISI D2 steel. For comparison purpose, machining is performed using non-textured tool also. Cutting speed, feed and depth of cut are selected as the cutting parameters, each having two levels. The cutting force and feed force are considered as main performance parameters beside surface roughness and flank wear. From the experimental study, it is noticed that textured tool gives low values of cutting and feed forces during machining as compared to a non-textured tool. In comparison to groove-texturing tool, dot-texturing tool generates less cutting and feed forces. Both the texturing tool gives fine surface finish and less flank wears in comparison to non-textured tool.

Analyzing Process Parameters for Finishing of Small Holes Using Magnetically Assisted Abrasive Flow Machining Process

The necessity of fine surface finish on the interior surfaces with no imperfections is a significant thought in various manufacturing components like hydraulic chambers, bearings etc. This analysis presents one of the non-traditional technique of finishing i.e., magnetically assisted abrasive flow machining for finishing the interior surfaces of small holes of aluminum tubes with mechanically alloyed cum sintered magnetic abrasives. These abrasives have been developed in a ball mill i.e., attritor. The central composite design was proposed to perform the experiments to discuss the effects of process parameters like extrusion pressure, magnetic flux density, and no. of processing cycles on percent improvement in surface finish, and a mathematical model of these parameters was established. It was concluded that surface finish is improved up to 72.7% (Ra 0.22 µm) which is in close conformity with optimized value of 72.3% at optimum conditions. Scanning electron microscopy has been carried out to understand the surface texture of the machined surfaces.

Tribological studies of high surface finish ceramic coatings for low friction and adhesive wear resistant applications

Adhesive wear is a significant material loss mechanism that leads to wide scale surface degradation of functional components especially in engineering industries like wind turbine roller bearings. This paper deals with improving the tribological properties of surfaces where adhesive wear is prominent. Adhesive wear is a common problem in gears, bearings, cutting tools, fittings, valves and earth moving equipment. For instance in a planetary gear arrangement, worn out debris from gears cause adhesive wear on the surface of roller bearings. Ceramic coatings are significant for protecting components and to improve the performance of surfaces subjected to adhesive wear over longer periods. Most of the ceramic coatings have high surface roughness owing to which they contribute to further adhesive wear of fine surfaces. In this paper, focus is on studying the performance of ion plated titanium nitride (TiN) and titanium carbide (TiC) PVD coatings against adhesive wear on EN 31 steel (substrate). Surfaces of samples coated with TiN, TiC and uncoated substrate of EN 31 steel are comparatively studied for adhesive wear behavior using wear tests as per ASTM standards. EN 31 steel is composed of 95% Fe, 0.9–1.1% C, 0.35% Mn, and 0.2% Si. Surface morphology and compositional analysis is inferred from Electron Microscopy (SEM and EDS) and surface roughness is estimated using 3-D confocal microscopy and surface profile measurement. The bond strength of coating is analysed from nanoscratch test; the coefficient of friction, material removal rate and hardness of surface is obtained from nano indentation Test. On experimental investigation, it is found that TiN and TiC ceramic coatings have excellent wear resistance, a low coefficient of friction and fine surface finish which are suitable for adhesive wear resistant applications.

Nanoscale Depth Profiling of Residual Stresses Due to Fine Surface Finishing

AbstractMechanical polishing is commonly used for both surface finishing and metallographic sample preparation for a broad range of materials. However, polishing causes local deformation and induces residual stress, which has an important effect on many surface phenomena. Until recently, it has not been possible to quantify the nanoscale depth variation of polishing‐induced plastic deformation (eigenstrain) and the associated residual stress. In this study, the magnitude and depth of polishing‐induced residual stress are evaluated directly by focused ion beam milling and digital image correlation using the micro‐ring‐core geometry method. Depth‐resolved residual stress profiles are obtained with sub‐micrometer resolution at the surface of a titanium alloy sample that is subjected to various polishing steps. It is found that electrochemical polishing and polishing with colloidal silica do not induce any significant residual stress. However, polishing with diamond slurry leads to the formation of compressive residual stresses of up to 300 MPa, which extend deeper into the material when larger diamond particles are used. This study paves the way for further research on polishing and its effect on surface properties.

A comparative study of PSO, GSA and SCA in parameters optimization of surface grinding process

The selection of parameters in grinding process remains as a crucial role to guarantee that the machined product quality is at the minimum production cost and maximum production rate. Therefore, it is required to utilize more advance and effective optimization methods to obtain the optimum parameters and resulting an improvement on the grinding performance. In this paper, three optimization algorithms which are particle swarm optimization (PSO), gravitational search, and Sine Cosine algorithms are employed to optimize the grinding process parameters that may either reduce the cost, increase the productivity or obtain the finest surface finish and resulting a higher grinding process performance. The efficiency of the three algorithms are evaluated and comparedwith previous results obtained by other optimization methods on similar studies.The experimental results showed that PSO algorithm achieves better optimization performance in the aspect of convergence rate and accuracy of best solution.Whereas in the comparison of results of previous researchers, the obtained result of PSO proves that it is efficient in solving the complicated mathematical model of surface grinding process with different conditions.

Enhancement of material removal rate in magnetic field-assisted micro electric discharge machining of Aluminium Matrix Composites

Micro-electrical discharge machining (Micro-EDM) is a micro-machining process in which miniaturised and precision parts/components are manufactured with good dimensional accuracy and fine surface finish. The present work investigates the effect of magnetic field-assisted Micro-EDM of Aluminium Matrix Composites with a Tungsten electrode using the Response Surface Methodology (RSM). Experiments are conducted based on RSM based central composite design. The process parameters considered for this study are voltage, capacitance and feed rate. The material removal rate (MRR) is considered as the output process parameter. The response surface-based mathematical model is developed for MRR. The model is statistically significant and all the three machining parameters and interaction effects are also significant on the MRR. Experimental investigation shows that the addition of magnetic field in Micro-EDM increases the MRR. Finally the predicted values and experimental values are validated by confirmation experiments.

Polystyrene-supported dendritic mesoporous silica hybrid core/shell particles: controlled synthesis and their pore size-dependent polishing behavior

This work described a straightforward synthetic route to fabricating polymer/silica hybrid particles with controllable architectures and their advantages as abrasives. The poly(vinylpyrrolidone)-modified and divinyl benzene cross-linked polystyrene (PS) cores were synthesized via a developed soap-free emulsion polymerization, and the outer dendritic-like mesoporous silica (D-mSiO2) shells were coated onto the cores using an oil–water biphase approach combined with a selective removal of hexadecyltrimethylammonium bromide templates. The resulting core/shell PS/D-mSiO2 samples were characterized by SEM, TEM, XRD, FTIR, and nitrogen adsorption/desorption, offering comprehensive information on the composition, structure, morphology, pore size, shell thickness, and surface area. The pore size of D-mSiO2 can be controlled within the range of 3–9 nm by varying the upper oil phases, which serve as swelling agents to enlarge the mesochannels. The PS/D-mSiO2 particles can be used as novel polishing abrasives and present superior surface quality (0.16 ± 0.02 and 0.26 ± 0.03 nm of root-mean-square roughness) compared to the commercial solid SiO2 ones (0.54 ± 0.05 nm). Moreover, the PS/D-mSiO2 hybrids with an enlarged pore size result in an inferior structural stability, which is important for final surface finish and removal rate. The presented results provide not only a strategy for preparing PS/D-mSiO2 core/shell particles with tunable pore sizes, but also a regulation that can be applied to prepare other core/shell hybrids with dendritic-like mesosilica shells.

Experimental biocompatibility investigations of Ti–6Al–7Nb alloy in micromilling operation in terms of corrosion behavior and surface characteristics study

Titanium (Ti)-based alloy is extensively used in the biomedical field due to its properties that promote osseointegration. The present work deals with an experimental study on the effect of microcutting of Ti–6Al–7Nb on corrosion resistance and surface characteristics for enhanced biocompatibility. Experiments were carried out by using Taguchi L9 orthogonal array with process variables include cutting speed (vc), feed per tooth (fz), and depth of cut (ap). Microslot of size 700 µm for a length of 10 mm was made using high-speed micromachining station under wet condition. Surface morphology study was carried out using a scanning electron microscope and the inference was made. It is inferred that lower vc of 31.4 m/min and higher ap condition of 200 μm yield more microparticle adhesion and burr formation. At higher vc, minimum defects were found which results in fine surface finish. Potentiostat setup was used for corrosion resistance measurement, and corresponding Icorr values were obtained from potentiodynamic polarization curve. Icorr values are found as minimum at higher vc and lower ap conditions. Changes in surface characteristics are analyzed after corrosion study. It is observed that at higher vc and lower ap conditions, Ti–6Al–7Nb alloy exhibits higher corrosion resistance under in vitro condition that can promote osseointegration.