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Surface roughness is one of the key surface integrity factors affecting the strength and fatigue life of components. Stress concentrations occur due to the randomness of the surface profiles. The presence of a dominant valley, a complex geometry and interacting effects exasperate the severity of the stress concentrations. To estimate the theoretical stress concentration factor (SCF) at the valley, the notch root radius should be estimated carefully. We propose an effective method for estimating the root radius of the deepest valley using numerical derivative techniques. The surface roughness of a carefully sanded Alumec 89 block was measured using SJ-400 tester. The 1-D roughness data was used first to evaluate the root radius of the deepest valleys and then, estimate the SCF using analytical and computational methods. We used 2-D finite element (FE) models under uniaxial tension for the computational analyses. The validity of our method is based on determining the SCF using different theoretical methods and comparing the results to the FE calculations. The theoeritical estimations are made using the Neuber, Inglis and Arola-Ramulu approaches, whereas COMSOL Multiphysics is used for the FE analyses. Comparing the theoeritical methods with the FE calculations, the Arola-Ramulu approach was better, with a maximum of error. The minimum deviations can be explained by the model containing parameters such as , and which are inherent to the roughness profile of the material.

The objective of the presented work is to improve the machining parameters of fibre reinforced polymer (FRP) using Taguchi's robust design technique. A large number of variables impact the quality of the completed component throughout the machining process. The quality of machined FRP components is greatly influenced by the surface roughness. Manufacturers can make sure that the finished product fulfils the necessary quality requirements and is cost-effective by optimizing machining settings to achieve the specified surface roughness. Optimizing machining parameters for achieving the desired surface roughness can help reduce production costs by minimizing waste, improving tool life, and reducing the need for post-processing operations. To optimize the process, Three levels of each parameter were chosen for investigation for each such adjustable process parameter. Machining was performed on a CNC milling machine using a carbide end mill. Experiments were conducted utilising Taguchi's technique to generate an experiment design (L9 orthogonal array). Analysis of variance was used to determine the impact of each parameter (ANOVA). The recommended control factor values for the best possible surface finish of FRP are 1.64 m, 400 rpm spindle/cutting velocity, 1.5 mm depth of cut and 0.3 millimetre/revolution feed rate. Surface roughness was shown to be most impacted by cutting speed, followed by feed rate and depth of cut. To determine the relationship between process parameters and quality attributes, regression analysis and response surface methodology was used.

In this investigation on Viscoelastic magnetic abrasive finishing process, a deep learning model is applied to predict the change in surface roughness. A dedicated experimental setup along with the abrasive media was prepared to carry out the finishing process. Experiments were performed on mild steel to inspect the effect of several parameters such as finishing time, magnetic flux density, abrasive mesh number, magnetic tool rotational speed, feed, ultrasonic amplitude on the surface roughness. The paper aims to provide a cost-effective as well as time-effective predictive method to depict the change in surface roughness.

The selection of parameters affects the surface roughness in the additive manufacturing process. This study aims to determine the optimal combination of input parameters for predicting and minimising the surface roughness of samples produced by Fused Deposition Modelling on a 3D printer using a cascade-forward neural network (CFNN) and genetic algorithm. Box–Behnken Design with four independent printing parameters at three levels is used, and 25 parts are fabricated with a 3D printer. Roughness tests are performed on the fabricated parts. Models generated by the hybrid algorithm achieve the best results for predicting and optimising surface roughness in 3D-printed parts. The surface roughness prediction accuracy of the trained CFNN with optimised parameters is more accurate compared to previous random test results.

Highly filled conductive polymer composites (CPCs) are widely used in applications such as bipolar plate materials for polymer electrolyte membrane fuel cells and redox flow batteries, electromagnetic interference shielding and sensors due to their useful electrical properties. A common method for determining through-plane electrical conductivities $\left(\sigma_{\rm tp} \right)$ of such highly filled CPCs applies a conductive carbon paper between electrodes and sample with application of external pressure to improve electrical contact. We show the pressure-dependence of the measured $\sigma_{\rm tp}$ can be eliminated by using a liquid metal such as the gallium-indium eutectic alloy (EGaIn) as contact material. Results indicate that EGaIn reduces contact resistances and cause three to five times larger $\sigma_{\rm tp}$ compared to measurements with carbon paper contacts and pressures up to 20 bar.

Powder-based (inkjet) three-dimensional printing (3DP) technology presents great promise in the construction industry. The capacity to build complex geometries is one of the most appealing features...

Objective: The aim was to evaluate the effect of activated bleaching agents on the nanoceramic composite resins based on microhardness and surface roughness measurements. Methods: Opalescence Boost (Ultradent Products, USA) and Whiteness HP Blue Calcium (FGM Dental Products, Brazil) bleaching agents and a nanoceramic composite resin Ceram.X® SphereTEC™ One (DENTSPLY, Germany) were used in the study. Fifty composite samples in disc form (8x2mm) were prepared. The samples were polished with discs (Sof-Lex, 3M Dental Products, St.Paul, USA) and incubated in the dark in distilled water. Samples were divided into 5 main groups (n=10). Control group (C), Opalescence Boost/ without light (OB), Opalescence Boost/ with light (OBL), Whiteness HP Blue/ without light (WB), and Whiteness HP Blue/ with light (WBL). Surface roughness (Ra) and Vickers microhardness (VHN) measurements were conducted after the bleaching process. Statistical analyses were performed using the Kruskal Wallis – H test and the Mann Whitney – U test; a p value of < 0.05 was considered statistically significant. Result: The VHN was significantly different among groups in terms of the application of bleaching agents and light (p = 0.008). The Ra was not significantly different among groups with respect to the application of bleaching agents or lighting conditions (p = 0.144). Conclusion: Within the conditions of this study, after bleaching procedure the microhardness values of the nanoceramic composite increased, however bleaching did not show any effect on surface roughness.

PURPOSE To investigate the discoloration and surface properties of four CAD/CAM composite resins provoked by a variety of food solutions and cigarette smoke. MATERIALS AND METHODS A total of 74 specimens (N = 370) were prepared per material (Brilliant Crios [Coltene], CeraSmart [GC], Lava Ultimate [3M Espe], Shofu Block HC [Shofu], and SonicFill 2 [Kerr]). Discoloration (ΔE) was investigated with a spectrophotometer. Measurements were taken before immersion in the storage media for 2 weeks (carrot juice, curry, cigarette smoke, red wine, energy drink, and distilled water), immediately after immersion, and after manual polishing of the specimens following immersion. The mean surface roughness (Ra) was measured using a profilometer. Qualitative surface observation was performed with scanning electron microscopy (SEM). Data were analyzed using Kolmogorov-Smirnov, Mann-Whitney U, and one-way analysis of variance with Tukey post hoc tests. RESULTS The highest influence on ΔE after immersion was observed by the storage medium (ηP. = 0.878, P < .001), followed by the interaction between storage medium and material (ηP. = 0.770, P < .001) and the material (ηP. = 0.306, P < .001). For ΔE after polishing, the highest influence was indicated by the interaction of material and medium (ηP. = 0.554, P < .001), followed by the medium (ηP. = 0.244, P < .001) and the material (ηP. = 0.196, P < .001). Immersion in carrot juice led to the highest color change (ΔE: 8.0 to 10.4), whereas the lowest values were recorded in distilled water (ΔE: 2.0 to 2.4). Carrot juice and the energy drink provoked the highest Ra values (0.120 to 0.355 μm). SEM pictures indicated a loss of the organic matrix after manual polishing. CONCLUSION The different materials reacted dissimilarly in the various storage media in terms of discoloration. Surface roughness increased after immersion and polishing. Neither discoloration nor surface roughness could be reset to default by manual polishing.

The interfacial energy γWe perform static and advancing contact-line experiments with aqueous and organic liquids on different hydrophilic surfaces (Al, Cu, Si) with varying Wenzel roughnesses in the range 1-2. These parameters are combined with the liquid's known surface tension to determine FF

Additive manufacturing (AM), also known as three-dimensional (3D) printing, of polymer-based materials is growing as a time-efficient, economical, and environmentally sustainable technique for prototype development in load-bearing applications. This work investigates the defects arising from the processing in material extrusion-based AM of polymers and their impact on the part performance. The influence of raster angle orientation and printing speed on tribological characteristics, microstructure, and surface finish of acrylonitrile butadiene styrene (ABS) fabricated in a heated build chamber was studied. Comprehensive analysis with fractography and tomography revealed the formation, distribution, and locations of internal voids, while surface defects were studied with the topography analysis of as-printed surfaces. Surface roughness and tribological results show that printing speed can be optimally increased with a minimal impact on interlayer bonding and part performance. Increased printing speed allowed up to 58% effective reduction in printing time obtaining comparable mechanical properties at varying process parameters. 3D printed ABS exhibited dry sliding friction coefficients in the range of 0.18–0.23, whilst the maximum specific wear rate was 6.2 × 10−5 mm3/Nm. Higher surface roughness and increased printing speed exhibited delayed running-in during dry sliding, while insignificant influence was observed for steady-state friction and wear behaviors. The findings indicate that improved surface finish and reduced internal defects can be achieved with a controlled build environment allowing for higher printing speed. The observations in this study are evidence that 3D printing can be adapted for the sustainable manufacturing of polymeric components for tribological applications. Validerad;2023;Nivå 2;2023-03-21 (joosat);Licens fulltext: CC BY License

The aim of this investigation was to evaluate the ability to predict the roughened surface area of soft polymeric materials using the machine learning method. Random forest and extremely random forest machine learning methods have been applied to predict roughened monolithic butadiene styrene rubber surface area based on the grain diameter of the abrasive paper. It was found that there is a very strong negative correlation between surface roughness and abrasive grain diameter (the Pearson correlation coefficient is equal to - 0.83 and the Spearman correlation coefficient is equal to - 0.91). The statistics of Shapiro-Wilk criteria confirmed that independently of the diameter of abrasive grain, the lengths of rubber surface profiles are normally distributed. It was determined that random forest and extremely random forest algorithms are suitable tools for predicting rubber surface area in dependence on abrasive grain diameter. The forest structure in which results obtained best coincidence with the observed (R2 = 0.95): for the random forest model the number of trees is equal to 20, the leaf size is equal to 4, at the subset of the feature (abrasive paper grain diameter) equal to 1. In the case of an extremely random forest, the number of trees is equal to 350, the size of the subset of the features is equal to 1, and the leaf size is 2. The experimental and generated results agree well. The relative approximation error does not exceed 0.079 %.

This paper presents an optimization of process parameters of turning operation using multi-response optimization Grey Relational Analysis (GRA) method instead of single response optimization. These parameters were optimized based on a three level two factor factorial design with three center points was used for the experimental design with Grey Relational Analysis. The machining parameters such as cutting speed, feed rate, and depth of cut were chosen for experimentation. The performance characteristics chosen for this study are material removal rate (MRR), tool life, and surface roughness. Experiments were conducted using coated carbide tool (KC5010) as the tool and martensitic stainless steel (AISI 420) as the workpiece. Experimental results have been improved through this approach.

The surface created by machining significantly affects the service life and functional reliability of the component. As part of this study, four different chip machining technologies were evaluated on the surface texture of the polymer material Ertacetal C. The samples were processed by turning, milling, grinding and polishing technologies, 5 samples for each technology. Within the given technology, different cutting conditions were chosen to compare the effect of cutting conditions on the resulting surface roughness. The machined surfaces were comprehensively evaluated on the basis of 16 profile and surface roughness parameters due to the practical use of the tested material. Surface texture measurements were performed on a Talysurf CCI Lite device. A non-contact method using a coherence correlation interferometer was used for the measurement. The obtained data were evaluated using TalyMap Platinum software. Graphical documentation of the machined surfaces was made using an Olympus DSX500 optodigital metallographic microscope., Univerzita Tomáše Bati ve Zlíně, Department of Mechanical Engineering, University of Defence in Brno [SV20-216]; Project for the Development of the Organization "DZRO VAROPS"; Tomas Bata University in Zlin [VaV-IP-RO/2022/01]

Electric discharge machining (EDM) routehas capability of machining hard materials. Even intricate shapes can be machined by this process. Traditional machining routes develop machining issues like tool wear and pitiable surface finish. It can be overcome by the EDM process. The objective of this work is to prepare AA6351-10wt%Al2O3-5wt%Gr composites through stir casting process. The manufactured composites were machined via EDM route and their machining characteristics material removal rate (MRR) and surface roughness (SR) were studied via Taguchi process. The results display that for MRR current is the major influencing parameter and for SR voltage is the foremostpersuading parameter.

The goal of this experiment is to investigate the effect of laser engraving parameters on Al 6063 aluminum alloy specimens using a fiber laser engraving equipment. The experimental design makes use of Taguchi's L16 orthogonal array. Surface roughness and engraving depth are the responses which are to be optimum for machining process parameters such as fill spacing, power, frequency, and scan speed. Using regression analysis, the mathematical models for individual responses were created. Grey relational analysis coupled with the Taguchi technique has been presented for simultaneous response optimization. The optimal setting parameters for multiple performance characteristics is fill spacing at level-3, power at level-4, frequency at level-2 and scan speed at level-4 i.e., FS3-P4-F2-SS4. To determine the significance of the models, the Analysis of Variance (ANOVA) approach is used. Finally, in the confirmation test, it is observed that the grey relational grade is improved from the initial process parameter combination.

Selective laser melting (SLM), an additive manufacturing technology, is expected to replace the traditional lost-wax casting process used in producing removable partial denture (RPD) frameworks. However, studies comparing the accuracy of RPD frameworks and the effects of process parameters are lacking.The purpose of this in vitro study was to optimize SLM process parameters and use a quantitative analysis method to improve the accuracy of 3D-printed RPD frameworks.The orientation and support structure of Kennedy Class II RPDs were designed in various ways by using 2 different software programs, CAMbridge and Magics. The optimum melt-pool parameters, including laser power, scan speed, hatch distance, and layer thickness, were determined empirically before manufacturing 12 RPD frameworks with 4 different process designs by using SLM (n=3). The accuracy of the RPD frameworks was determined by 3D scanning and comparing the 3D scan data with the original standard tessellation language (STL) RPD design with the best-fit algorithm of the Geomagic software program.Optimum melt-pool parameters were found with the function of density, surface roughness, and productivity (P=180 W, v=1200 mm/s, h=60 μm, t=30 μm). RPD frameworks fabricated by the optimized process parameters (167 ±105 μm) showed significantly better (P.05) mean ±standard deviation accuracy than the 3 other groups of RPD frameworks manufactured by using the nonoptimized process parameters (180 ±121 μm to 222 ±136 μm). The best accuracy was found with the transverse orientation and interconnected support structure.With the optimized design of process parameters, clinically acceptable RPD frameworks were produced. The accuracy of RPD frameworks fabricated by using SLM varied according to the design of the process parameters, indicating that SLM technology can replace the traditional lost-wax casting process.

The tool and die applications are preferred the unconventional machining processes as they are popular in machining the difficult to cut type complex contour/ profile. The complex profile machined on hard material. Some special materials like Stainless Steel 12X18H10T withstand its inherent properties even it exposes at higher temperature. This investigation aims to expand its application by investigating its machinability in Electro Chemical machining process for surface finish. The process parameters like gap between work material and tool, discharge current, concentration of electrolyte and applied voltage at three levels. The Taguchi approach is used for optimizing the process parameters and confirmation runs also conducted for developing the mathematical modelling. For optimizing number of experiment the Taguchi L9 is utilized for this investigation.

Titanium alloy is difficult to machining in the conventional machining process. Hybrid production technology for abrasive water jet machining (AWJM) allows the machining of all engineering applications. This paper explores the optimization of the process variables of Titanium alloy AWJM (Ti- 6Al- 2Sn- 4Zr- 2Mo). The AWJM process parameters such as water jet strength, traverse speed, and standoff distance were studied against the material removal rate, surface roughness, kerf angle. The contribution of this parameter to responses has been calculated by variance analysis. For material removal rate, surface roughness, kerf angle, regression models were obtained.

This paper deals about the optimization and modelling of Wire cut Electric Discharge Machining factors such as pulse OFF-Time (Toff), gap voltage (Vg) and pulse ON-Time (Ton) during machining nano- silicon carbide (nSiC) and nano-zirconium oxide/zirconia (nZrO2) reinforced in Al6061 aluminium alloy matrix. Nanomaterial is synthesis in the planetary high energy ball milling and the hybrid aluminium metal matrix composite (HAMMC) was fabricated by using the stir casting technique. For performing machinability studies on the cast composite. To design the experiments, Response Surface Methodology (RSM) based central composite design (CCD) with face-centred approach is implemented. To optimize input conditions, kerf width and surface roughness were analysed. To determine the suitability of the developed model, Analysis of Variance (ANOVA) is applied and to model the process factors regression analysis is carried out. It is observed from the results that, kerf width decreases when Toff increases and increases with increase in Ton and Vg. A decreasing trend of surface roughness is observed with increasing trend of Vg and surface roughness increase with increase in Ton increases.

Nowadays, the additive manufacturing process had significant attention due to its great advantages that are being used for developing products and producing prototypes. This technology overcomes the various drawbacks of existing techniques and it becomes the most efficient approach. In the industrial sector, this technology is most important for individual designing products and extended with different functions. The performance of additively manufactured parts, on the other hand, is largely influenced by their surface integrity and dimensional accuracy. The surface integrity is an important issue because the additively manufactured products are affected by staircase effects resulting from layer-by-layer manufacturing. The rapid prototyping contains multiple methods such as VAT Photopolymerization and Poor surface quality is caused by the staircase effect in all additive manufacturing processes so therefore, the various post-processing efforts and controlling different process parameters of additive manufacturing are necessary on the produced component for improving surface quality and reducing surface roughness. To focus on improving the finish of an additively manufactured part's surface, there are numerous methods presented. This research described the various existing approaches of surface finishing with various efficacies such as reduction of surface roughness value, mechanical strength, and dimensional accuracy. Current post-processing methods for improving the surface characteristics of additively manufactured parts are discussed, with a classification based on the processes' mechanisms.

Machining of titanium alloys such as Ti-6Al-4 V can be very intimidating due to their low thermal conductivity leading to elevated cutting temperatures at the chip-tool interface (ICT). In this regard, the self-lubrication effect of coatings like TiSiVN represented by topography, oxidation, and diffusion at the chip-tool interface are crucial. Thus, the present work investigates the latter three mechanisms during dry machining of Ti-6Al-4 V titanium alloy with uncoated and TiSiVN coated Al2O3/SiC whiskers-reinforced ceramic cutting tools. The results reveal that the adhesion height (AH) and O% increases with cutting temperature, showing the dominant influence of cutting temperature on material adhesion and oxidation levels at the ICT. AH increases with increased cutting speed for both coated tools, indicating that the crater depth increment was not so severe for the coated tools. However, a drastic upward surge of crater depth for uncoated and TiSiN coated tools at 125 m/min cutting speed makes the crater edge near the ICT act as a chip breaker and facilitates the chip's bending away from the tool face causing reduction in chip bend angles (BA). Additionally, the TiSiVN coating accounts to a reduction of approximately 23% in AH and 18% in Ti%, and 37% lower oxygen levels at the highest cutting speed when compared to the uncoated tool primarily due to lower cutting temperatures and self-lubricating behavior. The work is supported by Maria Zambrano grants and funded by: MCIN/AEI/10.13039/501100011033 and “FSE invierte en tu futuro”, and Basque Government university group IT1573-22, High performance machining, and MiCINN PDC2021–121792-I00 “New tooling production oriented to manufacture high value-added components of turbomachinery” (Haute Couture Taylor Made). The authors are also grateful to Grant PID2019-109340RB-I00 funded by MCIN/AEI/10.13039/5 The authors thank SGIker (UPV/EHU/ERDF, EU) for technical and human support provided. Also, Filipe Fernandes acknowledges the MCTool21 - ref. "POCI-01–0247- FEDER-045940" and CEMMPRE – ref. “UIDB/00285/2020″ projects, sponsored by FEDER funds through the COMPETE program – Operational Program on Competitiveness Factors – and by national funds through FCT – Foundation for Science and Technology.

U ovom radu analiziran je utjecaj parametara postupka elektrolitičkog-plazma poliranja na stanje površine ispitnih uzorka izrađenih od titanijeve legure, koja se koristi za proizvodnju dentalnih protetskih nadomjestaka. U teorijskom dijelu rada, nakon uvoda, obuhvaćen je povijesni pregled dentalnih protetskih nadomjestaka. Također, detaljno su opisane različite vrste dentalnih protetskih nadomjestaka, istaknuti su zahtjevi vezani uz njihova svojstva, pružen je pregled postupaka obrade njihovih površina te su navedene vrste metalnih materijala koji se koriste u izradi dentalne protetike. U eksperimentalnom dijelu rada, najprije je opisan proces izrade ispitnih uzoraka koji su potom podvrgnuti postupku elektrolitičkog-plazma poliranja uz primjenu različitih parametara postupka. Nakon provedbe postupka, na ispitnim uzorcima izmjerene su vrijednosti parametra hrapavosti površine Ra, a površine uzoraka analizirane su pomoću digitalnog mikroskopa. This paper examines the influence of various parameters of plasma electrolytic polishing on the surface properties of titanium alloy used in manufacure of dental prostheses. In the theoretical part of the paper, a historical overview of dental prostheses is given after the introduction. Also, described in detail are different types of dental prostheses, their property requirements, as well as the types of surface treatment and metal materials used in their manufacture. In the experimental part of the paper, the process of manufacturing test specimens is first described. The test specimens were then subjected to plasma electrolytic polishing using various parameters of the process. Lastly, the values of the surface roughness parameter Ra were measured on the test specimens and their surfaces were analysed using a digital microscope.

Rotational abrasive finishing (RAF) is a new nano-finishing technique in which the finishing forces are applied to the workpiece by the opposite rotations of a stirring-blades and the workpiece. The RAF process allows for finishing the inner and outer surfaces of workpieces, particularly complex ones with axial symmetry. The present study aims to propose a new theoretical model to obtain deeper insights into the material removal mechanism, surface roughness prediction, and forces in RAF process. Since the abrasive-workpiece interaction is random and complex in nature in the RAF, some initial assumptions were considered. To validate the repeatability of the experimental results, the experiments were designed based on the Response surface method (RSM). To validate the new proposed theoretical model, a number of influential parameters were investigated. It was found that the stirring-blade speed (S), working gap (W), and abrasive grain size (A) had significant effects on Ra. The minimum surface roughness (Ra) was obtained to be 46.87 nm at a rotational speed of 600 rpm, a working gap of 1 mm, and grain size of 18 µm. The experimental results were relatively in good agreement with the theoretical results so that the maximum error was about 24%. This can be assumed that the most important explanation for the difference between the theoretical and experimental results can be attributed to the initial theoretical assumptions. Objectius de Desenvolupament Sostenible::9 - Indústria, Innovació i Infraestructura

Son yıllara kadar sürücünün görüşünü kolaylaştırmak ve araç görünürlüğünü sağlamak amacıyla kullanılan otomotiv aydınlatma sistemleri, günümüzde gelişen teknolojinin yardımıyla, stil odaklı çalışmalara dönüşmüştür. Estetik görünüme verilen önemin artması; ışık tüpleri gibi istenilen alana uyarlanabilen, farklı şekil ve geometrilerde uygulanabilen ve araç stilini yansıtan optik aydınlatma sistemlerinin ön plana çıkmasına neden olmuştur. Bu çalışmada, farklı şekil ve geometrilerin etkisini incelemek amacıyla 3 farklı mekanik yapıda ışık tüpü optik tasarımı ve aydınlatma yüzeyi homojenite analizleri gerçekleştirilmiştir. Optik tasarımlar ve simülasyonlar özel bilgisayar yazılımları kullanılarak yürütülmüştür. Işık tüplerinin malzemesi PMMA olarak belirlenmiş ve her bir geometri için farklı ışık çıktısına sahip ışık kaynakları seçilmiştir. Yapılan simülasyonlar ışığında, en uygun optik tasarım parametreleri sabitlenmiş ve ışık tüplerinin uluslararası standartlarda belirtilen ışık değerlerini sağlayarak, hedeflenen yüzey homojenliğine sahip olduğu doğrulanmıştır. Optik tasarımları tamamlanan ve arzu edilen sonuçları veren ışık tüplerinin prototipleri üretilmiştir. Üretilen prototipler üzerinden fotometri testleri ve yüzey homojenliği analizleri yapılarak tasarım çıktıları ile prototip sonuçları karşılaştırılmıştır. Elde edilen sonuçlar ışığında, tasarım ile prototip sonuçları arasında genel olarak % 80’ in üzerinde uyum olduğu tespit edilmiştir. Farklı büyüklüklerdeki yüzey pürüzlülüklerinin ışık dağılımı, ışık değerleri ve yüzey aydınlanması üzerine etkilerini incelemek amacıyla, 6 farklı büyüklükte yüzey pürüzlülüğü numunesinin davranışı incelenmiştir. Elde edilen veriler değerlendirildiğinde, yüzey pürüzlülüğü uygulanmamış ışık tüpünde en dar yayınım açısı ve en yüksek ışık şiddeti görülürken, yüzey pürüzlülüğü arttıkça ışık dağılımının FWHM değerinin daha geniş açılara yayıldığı gözlenmiştir. Yüzey pürüzlülüğünün artması prizmatik yüzeylerin TIR özelliğinin kaybolmasına, dolayısıyla daha çok saçılmaya neden olmuştur ve sonuç olarak sistemin yaydığı ışık şiddeti azalmıştır. Until recent years automotive lighting systems were used to facilitate the driver's vision and provide vehicle visibility, today with the help of developing technology they have turned into style-oriented works. Increasing emphasis on aesthetic appearance; optical lighting systems such as light guides, that can be adapted to the desired area, can be applied in different shapes and geometries and that reflect the vehicle style, have become more attractive. In this study, optical design and illumination surface homogeneity analyzes of light guides were carried out in 3 different mechanical structures in order to examine the effect of different shapes and geometries. Optical designs and simulations were carried out using a special computer software. The material of the light guides was determined as PMMA and for each geometry light sources were selected with different light output. Optimum optical design parameters were determined and according to the simulation results, it was verified that the light guides are fullfilling the light values that specified in international standards by providing good level of surface homogeneity. After the determination of optimum optical parameters and reaching the desired results in simulation enviroment, light guide prototypes were produced. Photometry tests and surface homogeneity analyzes were made on the prototypes and the design outputs and prototype results were compared. It is observed that there is a general agreement of over 80 % between the design and prototype results. In order to examine the effects of different surface roughness on light distribution, the behavior of 6 different surface roughness samples was investigated. It was observed that the narrowest diffusion angle and the highest light intensity were observed in the light guide without surface roughness, while the FWHM value of the light distribution spread over wider angles as the surface roughness increased. The increase in the surface roughness caused the loss of the TIR of the prismatic surfaces, thus more scattering, and as a result, the light intensity emitted by the system is decreased. T.C. Bilim, Sanayi ve Teknoloji Bakanlığı Teknoloji Bakanlığı ve Odelo Otomotiv Aydınlatma Sistemleri A.Ş.

Machining titanium alloy (Ti6Al4V) used in orthopedic implants via conventional metal cutting processes is challenging due to excessive cutting forces, low surface integrity, and tool wear. To overcome these difficulties and ensure high-quality products, various industries employ wire electrical discharge machining (WEDM) for precise machining of intricate shapes in titanium alloy. The objective is to make WEDM machining parameters as efficient as possible for machining the biocompatible alloy Ti6Al4Vusing Box–Behnken design (BBD) and nondominated sorting genetic algorithm II (NSGA II). A quadratic mathematical model is created to represent the productivity and the quality factor (MRR and surface roughness) in terms of varying input parameters, such as pulse active (Ton) time, pulse inactive (Toff) time, peak amplitude (A) current, and applied servo (V) voltage. The established regression models and related prediction plots provide a reliable approach for predicting how the process variables affect the two responses, namely, MRR and SR. The effects of four process variables on both the responses were examined, and the findings revealed that the pulse duration and voltage have a major influence on the rate at which material is removed (MRR), whereas the pulse duration influences quality (SR). The tradeoff between MRR and SR, when significant process factors are included, emphasizes the need for a reliable multi-objective optimization method. The intelligent metaheuristic optimization method named nondominated sorting genetic algorithm II (NSGA II) was utilized to provide pareto optimum solutions in order to achieve high material removal rate (MRR) and low surface roughness (SR).

In the injection molding process, weld line regions occur when a molten polymer flow front is first separated and then rejoined. The position, length, and angle of weld lines are dependent on the gate location, injection speed, injection pressure, mold temperature, and, especially, the direction and degree of the polymer melt velocity in the mold-filling process. However, the wall surface velocity of the thermoset melt in the mold-filling process is not zero, which is not found for thermoplastic injection molding. The main reason leading to this difference is the slip phenomenon in the filling phase between the thermoset melt and the wall surface, which is directly affected by the filler content. In this study, commercial thermoset phenolic injection molding compounds with different amounts of filler were employed to investigate not only the mechanism of weld line formation and development behind an obstacle in the injection molding process but also the flow disturbance of the thermoset melt in the spiral flow part. In addition, the effect of the wall slip phenomenon on the flow disturbance characterization and the mechanism of weld lines of selected thermoset materials was carefully considered in this research. Furthermore, the generated material data sheet with the optimal developed reactive viscosity and curing kinetics model was imported into a commercial injection molding tool to predict the weld line formation as well as the mold-filling behavior of selected thermoset injection molding compounds, such as the flow length, cavity pressure profile, temperature distribution, and viscosity variation. The results obtained in this paper provide important academic knowledge about the flow disturbance behavior as well as its influence on the mechanism of weld line formation in the process of thermoset injection molding. Furthermore, the simulated results were compared with the experimental results, which helps provide an overview of the ability of computer simulation in the field of the reactive injection molding process.

The curing characteristics of photopolymer resin determine the relationship between the vat polymerization (VP) process parameters and the layer thickness, geometric accuracy, and surface quality of the 3D printed specimen. Dispersing filler material into the photopolymer resin changes its curing characteristics because the filler scatters and absorbs light, which modifies the curing reaction. However, the ability to cure photopolymer resin with high filler volume fraction is important to 3D print material specimens for specific engineering applications, e.g. structural polymer composite materials, electrical and thermal conductive materials, and ceramic materials for biological and high-temperature environments. We methodically measure the curing characteristics of diacrylate/epoxy photopolymer resin with dispersed glass microspheres. The experiments show that the curing depth, degree-of-cure, and surface roughness depend on both the light exposure dose and the filler fraction. We determine that the degree-of-cure increases with increasing filler fraction for constant exposure dose, and approaches 90% with increasing exposure dose, independent of the filler fraction. The geometric accuracy of the 3D printed specimens decreases with increasing exposure dose and with increasing filler volume fraction due to so-called profile broadening. Finally, we show that the average surface roughness of the 3D printed specimens decreases with increasing exposure dose and filler fraction. This work has implications for VP of photopolymer resins with high filler fraction. Master of Science Photopolymer resin is a gel-like liquid material that hardens (cures) into solid after absorbing light energy, and such a material is often used in the field of additive manufacturing (3D printing) to create complex geometry. Certain types of filler materials, such as metal powder or carbon fiber, can be added into the photopolymer resin to tailor the material properties, and thus, affects the curing behavior of photopolymer resin mixed with these filler materials. We conducted an experiment to understand how adding glass microspheres to a consumer grade photopolymer resin affects the process of creating 3D objects. This is important in the context of 3D printing engineered composite materials that derive their function from the organization and orientation of filler material in a matrix. To do this, we created many samples in the shape of a "VT" logo using the composite resin we made and measured their thickness (curing depth), degree-of-cure, surface roughness, and geometric accuracy, as a function of the amount of light energy being exposed to the resin (exposure dose) and the amount of the glass filler being added into the resin (filler fraction). We observed that when we increased the amount of light exposure, it resulted specimens that are thicker and more in degree of cure. Adding the glass filler to the liquid had mixed effects on the hardening process, because glass can scatter light and change how light travels within the resin. As a result, the printed objects became less accurate in shape and have smoother surface with increasing exposure dose and filler fraction, because more light is scattered off the designed curing profile and unintentionally cured the surrounding resin.

Selective laser sintering (SLS) is a well-established technology that is used for additive manufacturing. Significant efforts have been made to improve SLS by optimizing the powder deposition, laser beam parameters, and temperature settings. The purpose is to ensure homogeneous sintering and prevent geometric and appearance inaccuracies in the manufactured objects. We evaluated the differences in the surface roughness and grain size of curved objects manufactured by using upcoming SLS technology that features two CO laser sources. Our analysis was carried out on polyamide 11 (PA11), which is a sustainable biobased polymer that has been gaining popularity due to its high-performance properties: its low melting point, high viscosity, and excellent mechanical properties. By using a Taguchi experimental design and analysis of variance (ANOVA), we examined the influence on the surface roughness and grain size of the build setup, the presence of thin walls, and the position of the sample on the powder bed. We found significant differences in some surface roughness and grain size measurements when these parameters were changed.

In this paper, we develop fabrication technology and study aluminum films intended for superconducting quantum nanoelectronics using AFM, SEM, XRD, HRXRR. Two-temperature-step quasiepitaxial growth of Al on (111) Si substrate provides a preferentially (111)-oriented Al polycrystalline film and reduces outgrowth bumps, peak-to-peak roughness from 70 to 10 nm, and texture coefficient from 3.5 to 1.7, while increasing hardness from 5.4 to 16 GPa. Future progress in superconducting current density, stray capacitance, relaxation time, and noise requires a reduction in structural defect density and surface imperfections, which can be achieved by improving film quality using such quasiepitaxial growth techniques.

Aim: To evaluate the effects of two air-polishing powders, during orthodontic treatment, on the surface roughness of sound and demineralised enamel. Materials and methods: Forty-two caries-free human molars were collected, and the enamel surfaces were flattened and polished. Teeth were assigned to two groups (n = 21 each), a sound- and a demineralised-enamel group (subjected to pH-cycling over 2 weeks to create artificially induced white spot-like lesions). Within each group, teeth were further assigned to three groups (n = 7 each), air polished with either sodium bicarbonate, erythritol, or a negative control (water). Each sample was treated for 5 and 150 s. The average surface roughness (Ra) for each sample was measured using white-light-sensor profilometry. Results: On sound enamel, the Ra was roughly 0.17 ± 0.07 μm. After 150 s of air polishing, the Ra increased with erythritol (by 0.28 μm), and even more so with bicarbonate treatment (by 0.68 μm) (p < 0.01). On demineralised enamel, the Ra was roughly 0.79 ± 0.56 μm. The Ra increased after 5 s of air-polishing treatment similarly with erythritol and bicarbonate powders (by 1.03 μm and 1.04 μm, respectively) (p = 0.025), and even more after 150 s (by 2.48 μm and 2.49 μm, respectively) (p < 0.001). Conclusions: On white spot lesions, one should be aware that enamel surface roughness will increase with both erythritol and bicarbonate air-polishing powders, especially with longer exposure times.

Introduction: The purpose was to investigate the surface roughness and the color changes of nanohybrid and microhybrid resin composites subjected to calcium active whitening toothpastes with different RDA values through a novel Press-on Force-Guided (PFG) Brushing Simulator. Material and Methods: Twenty-eight disc-shape samples (10x2mm) of a nanohybrid (Herculite, Kerr) and a microhybrid (Z250, 3M) composites were prepared and randomly divided into 4 subgroups (n=7). The samples were polymerized with a LED-curing unit with an irradiance of 1000 mW/cm2 (Valo Cordless, Ultradent). Finishing and polishing procedures were performed with 2 fine grits of Sof-Lex Discs (3M). Samples were stored in distilled water at 37°C for 24 hours. Composite samples were brushed with a medium-bristle toothbrush (ROCS Pro 5940, ROCS) using the PFG brushing simulator (Marmara University, Turkey) for 60.000 strokes (correspondence to 6 years clinically) in a slurry containing toothpaste with 120 RDA (Ca Active Whitening, ROCS) and 70 RDA (Electro Whitening, ROCS) under 300-320g load (200 strokes/min). In particular, surface roughness (Ra) and color change (ΔE) were investigated utilizing profilometer (MarSurf PS 10, Mahr) and spectrophotometer (Easy-Shade-5, VITA). Analysis of variance was used for repeated measurements; Bonferroni test was used for pairwise comparisons. The level of significance was set at p0.05) except Herculite group brushed with Electro whitening (p=0.05) which showed the most roughness change (36.99%). There is a significant difference between Herculite (1.163±0.701) and Z250 (0.400±0.154) in Ra values after electro-whitening brushing (p=0.002). No significant color change was observed in any group, regardless of composite or tooth-paste type (p>0.05). ΔE values of Herculite (1.007±0.463; 1.100±0.452) and Z250 (1.558±0.618; 1.196±0.835) brushed with Ca Active Whitening and Electro Whitening toothpastes were less than 1.8 respectively. Conclusion: Tooth brushing with Ca active whitening toothpastes (different RDA values) affected differently on the surface roughness of Herculite and Z250 due to their filler and resin composition, but there is no effect on color. Keywords: brushing simulator, resin composite, whitening toothpaste, surface roughness, color change

Aim: Air powder polishing (APP) can cause roughness on composite surfaces, and consequently the color change that occurs over time affects the aesthetic negatively. Here, we aim to investigate the effect of repolishing on the roughness and discoloration of resin composites after APP to avoid its negative effects for the first time. Methodology: A total of 39 composite discs were randomly allocated into three groups: Group I: Control (n = 13), Group II: Air Powder Polished (n = 13), and Group III: Air Powder Polished + Re-polished (n = 13). Color and surface roughness of the discs were measured before and after immersion in coffee for 1 week. Color was measured using a colorimeter (CR-400, Konica Minolta), and roughness was measured using a surface roughness analyzer (SJ-400, Mitutoyo, Japan). Results: All specimens in the groups, except those in Group III, showed significant changes in roughness, and all materials showed significant color changes after immersion in the coffee relative to the baseline. There was no statistically significant difference between the groups in terms of roughness and color. Conclusion: In this study, we showed that repolishing after APP does not significantly improve the color stability and roughness of the composite restorations. How to cite this article: Altaş N, Sağır K, Aydınoğlu A, Gözetici Çil B, Keleşoğlu E, Sağır K, Hazar Yoruç AB. Effect of repolishing on the surface roughness and color stability of air-abraded resin composites. Int Dent Res 2022;12(3):137-42. https://doi.org/10.5577/intdentres.2022.vol12.no3.5 Linguistic Revision: The English in this manuscript has been checked by at least two professional editors, both native speakers of English.

Background: Despite the development of many denture base material like chrome-cobalt, fluid and plastic material but the heat cure polymethylmethacrylate considered as the most widely used denture base material. The aims of this study to evaluate and compare the impact strength and surface roughness of heat cured denture base resin after immersing in coca-cola drink for two and four weeks. Methods: A total number of 40 samples were prepared, 30 samples for impact strength test and 10 samples for surface roughness test. The samples were divided into three group; A (control), B (2 weeks immersed in coca cola drink), and C (4 weeks immersed in coca cola drink). Result: Data analyzed by using SPSS software with ANOVA test indicated a non significant differences between the different tested groups, however the samples that were immersed in coca cola drink for 4 weeks revealed non dramatic increase in surface roughness, while the samples that were immersed for 2 weeks showed a non dramatic decrease in the impact strength. Conclusions: The coca cola drink non significantly caused dropping in the tested properties in comparison to the control group.

This paper introduces optimization of machining parameters for high-pressure abrasive water jet cutting of Hardox 500 steel utilizing desirability function analysis (DFA). The tests were carried out according to the orthogonal matrix (Taguchi) L9. The control parameters of the process such as pressure, abrasive flow rate, and traverse speed was optimized under multi-response conditions namely cutting depth and surface roughness. The optimal set of control parameters was established on the basis of the composite desirability value obtained from desirability function analysis and the significance of these parameters was determined by analysis of variance (ANOVA). The effects show that optimal sets for high cutting depth and small surface roughness is high pressure, middle abrasive flow rate, and small traverse speed. A confirmation test was also leaded to validate the test results. Results of the research have shown that machining efficiency at keeping good level quality of cut surface can be improved this approach.

The present work explored the use of the selective laser melting (SLM) technique to develop a Zr-based bulk metallic glass (BMG) and investigate the influence of the process parameters on obtaining different levels of surface roughness. Moreover, the potential of the additively manufactured BMG Zr59.3Cu28.8Al10.4Nb1.5 (trade name AMLOY-ZR01) as an implant material was studied by evaluating the osteoblastic cell response to the alloy and its stability under simulated biological environments. The materials were characterized in terms of degree of crystallinity, surface roughness, and morphology, followed by a systematic investigation of the response of the MC3T3-E1 preosteoblastic cell line to the as-printed samples. The materials supported cell proliferation and differentiation of the preosteoblastic cells, with results comparable to the reference material Ti-6Al-4V. The surface microroughness and surface morphology (porous or groove-type laser tracks) investigated in this study did not have a significant effect on modulating the cell response. Ion release experiments showed a large increase in ion release under inflammatory conditions as compared to regular physiological conditions, which could be attributed to the increased local corrosion under inflammatory conditions. The findings in this work showed that the surface roughness of the additively manufactured BMG AMLOY-ZR01 can be tailored by controlling the laser power applied during the SLM process. The favorable cell response to the as-printed AMLOY-ZR01 represents of a significant advancement of the investigation of additively manufactured BMGs for orthopedic applications, while the results of the ion release study highlights the effect that inflammatory conditions could have on the degradation of the alloy.

Roughness, defined as unevenness of material surfaces, plays an important role in determining how engineering components or natural objects interact with other bodies and their environment. The emergence of fractal roughness on natural and engineered surfaces across a range of length scales suggests the existence of common processes and mechanisms for nucleation and evolution of roughness. In this article, we review recent advances in understanding the origins of roughness and topography evolution on natural and engineered surfaces and their connection with subsurface deformation mechanisms. Directions for future research toward understanding the origins of roughness on solid surfaces are discussed.

Nickel-based alloy has been widely used due to its outstanding mechanical properties. However, Nickel-based alloy is a typical difficult-to-machine material, which is a great constrain for its application in the manufacturing field. To improve the surface quality of the ground workpiece, a new high-shear and low-pressure grinding wheel, with high ratio of tangential grinding force to normal grinding force, was fabricated for the grinding of selective laser melting (SLM) manufactured Inconel718 alloy. The principle of high-shear and low-pressure grinding process was introduced in detail, which was quite different from the conventional grinding process. The fabrication process of the new grinding wheel was illustrated. A serial of experiments with different processing parameters were carried out to investigate the grinding performance of the developed grinding wheel via analyzing surface roughness and surface morphology of the ground workpiece. The optimal processing parameters of high-shear and low-pressure grinding were obtained. The surface roughness of ground workpiece was reduced to 0.232 μm from the initial value of 0.490 μm under the optimal grinding conditions. It was found that the initial scratches on the ground workpiece were almost completely removed after the observations with the metalloscopy and the field-emission scanning electron microscopy (FE-SEM). The capability of the newly developed high-shear and low-pressure grinding wheel was validated.

Statement of problem Whether procedures performed before the cementation of computer-aided design and computer-aided manufacturing (CAD-CAM) glass-ceramic restorations, including milling, fitting adjustment, and hydrofluoric acid etching introduce defects on the ceramic surface that affect the mechanical and surface properties is unclear. Purpose A systematic review and meta-analysis were conducted to assess the effect of milling, fitting adjustments, and hydrofluoric acid etching (HF) on the flexural strength and roughness (Ra) of CAD-CAM glass-ceramics. Material and methods Literature searches were performed up to June 2020 in the PubMed/MEDLINE, Web of Science, and Scopus databases, with no publication year or language limits. The focused question was “Do milling, fitting adjustments, and hydrofluoric acid etching affect the flexural strength and roughness of CAD-CAM glass-ceramics?” For the meta-analysis, flexural strength and Ra data on milling, fitting adjustment, and HF etching versus control (polishing) were analyzed globally. A subgroup analysis assessed the effect of etching parameters (HF concentration and time) on the flexural strength and roughness of CAD-CAM glass-ceramics with different microstructures. Comparisons were performed with random-effect models at 5% significance. Results Fourteen studies from 2764 potentially relevant records were included in the qualitative syntheses, and 12 in the meta-analysis. Milling and fitting adjustments increased roughness and reduced the flexural strength of CAD-CAM glass-ceramics. The effect of HF etching was dependent on the glass-ceramic microstructure, HF concentration, and etching time. For feldspathic- and leucite-reinforced ceramics, HF 5% applied for between 30 and 120 seconds increased roughness without affecting flexural strength. For lithium disilicate glass-ceramics, HF concentrations greater than 4.9% used for 20 seconds or more reduced the strength without affecting the surface roughness. Conclusions The flexural strength of CAD-CAM glass-ceramic is reduced by grinding procedures such as milling and fitting adjustment. Ceramic microstructure, HF concentration, and etching time determined the effect of hydrofluoric acid etching on the flexural strength and surface roughness of glass-ceramic materials.

In this study, Mg–6.0Zn–3.0Sn–0.5Mn (ZTM630) magnesium alloy was pre-activated by colloidal Ti, oxalic acid, and phosphoric acid, and a phosphate conversion coating (PCC) was prepared on the alloy surface. The morphology and corrosion resistance of the prepared PCCs were investigated. Surface morphology studies showed that the phosphate crystals that formed the coating were the smallest for the sample pre-activated by phosphoric acid. The coating on the colloidal Ti and the phosphoric acid samples had the largest and the smallest thickness and surface roughness, respectively. The reason for the discrepancy was analyzed by comparing the surface morphologies of alloy samples immediately after the pre-activation treatment and various phosphating treatments. X-ray diffraction analysis revealed that all three PCCs contained the same compounds. The corrosion resistance time from the copper sulfate drop test and the electrochemical data from the potentiodynamic polarization curves showed that the coating pre-activated by phosphoric acid had the best corrosion resistance. Finally, the 1500 h neutral salt spray corrosion test confirmed that the phosphating treated magnesium alloy, which was pre-activated by phosphoric acid, exhibited excellent corrosion resistance and behavior.

Statement of problem The development of polymethyl methacrylate (PMMA) computer-aided design and computer-aided manufacturing (CAD-CAM) resin blocks with reported improved mechanical properties has simplified complete denture production. However, whether the objective of improved mechanical properties has been achieved compared with conventional heat-polymerized PMMA is not yet clear. Purpose The purpose of this systematic review and meta-analysis was to evaluate the mechanical properties of denture base resins manufactured by conventional heat-polymerization and by CAD-CAM in terms of flexural strength, flexural modulus, and surface roughness. Material and methods Electronic databases (PubMed/MEDLINE, Scopus, Web of Science) were independently searched by 2 researchers for relevant studies published up to November 2020. The population, intervention, comparison, and outcome (PICO) question was, “Does the conventionally manufactured, heat-polymerized PMMA resin, as a denture base, demonstrate the same mechanical properties as the CAD-CAM resin block?” In addition, a meta-analysis was based on the inverse variance method. Flexural strength, flexural modulus, and surface roughness were analyzed through the continuous outcome evaluated by mean difference and standard deviation, with 95% confidence intervals. To evaluated heterogeneity, the I2 value (≤25%=low, ≥50%=moderate and ≥75%=high) and the P value were considered. P Results Thirteen in vitro studies were included in the analysis. A total of 507 specimens were evaluated, 222 conventional and 285 CAD-CAM. In terms of flexural strength, the data showed no significant difference when conventional heat-polymerized PMMA was compared with CAD-CAM PMMA resins (P=.06; mean difference=18.28; 95% confidence interval:-0.42 to 36.97). In terms of flexural modulus, there was a significant difference for the CAD-CAM PMMA group (P=.01; mean difference=589.22; 95% confidence interval: 117.95 to 1060.48). In terms of surface roughness, a significant difference was observed between the groups (P=.02; mean difference=-0.53; 95% confidence interval: -0.97 to -0.09) with the conventional heat-polymerized PMMA resin having higher surface roughness values. Conclusions The mechanical properties of CAD-CAM PMMA resins were generally improved when compared with heat-polymerized polymethyl methacrylate resin.

This work aims to investigate and assess the beneficial function and feasibility of nanofluids in minimum quantity lubrication (MQL) assisted machining. The goal is to develop newly generated CNT based nano hybrid cutting fluid and demonstrate its effect on surface roughness of Al alloy. Moreover, the fabricated nano hybrid cutting fluid will eventually reduce cutting fluid consumptions and maintain an eco-friendly environment. Three conditions were used to perform the machining process such as dry condition, conventional oil and Al_2O_3/CNT nanoparticle with EVO oil as base fluid. The lowest surface roughness achieved for nanofluid and the maximum surface roughness for the dry condition. In terms of looking for optimum parametric combination, Artificial Neural Network (ANN) and Response Surface Methodology (RSM) have been used. The ANN technique has proved its efficiency since its correlation coefficients, mean prediction errors (MPEs), and root mean square errors (RMSEs) are small compared to the RSM approach.

The processing of wood-based panels such as plywood, particleboard and fiberboard, which are widely used in the furniture industry, with CNC (Computer Numerical Control) milling machines has been increasing recently. Even though CNC milling machines have many advantages for furniture producers, it is difficult to set process parameters to obtain the desired surface quality of the material. Therefore, it is necessary to determine the most suitable of these parameters for the surface quality of each wood-based panel. This study aimed to determine the effects of processing parameters on the surface quality of plywood, particleboard and medium density fiberboard (MDF) panels processed in CNC milling machines. Furthermore, the average surface roughness values of these panels were compared after CNC processing. Three spindle rotational frequencies (10.000, 14.000 and 18.000 rpm), three feed rates (5, 7, and 9 m/min) and two cutting tool diameters (2 and 5 mm) were selected as CNC processing parameters. To determine the surface quality of wood-based panels, the surface roughness measurements were performed according to DIN 4768 standard and three surface roughness parameters (Ra, Rmax and Rz) were determined. According to the results of this study, it can be concluded that the surface roughness values of wood-based panels decreased with increasing spindle rotational frequency and feed rate, while they increased with increasing cutting tool diameter. Among the wood-based panels used in this study, the lowest average roughness values were obtained for plywood samples., Za obradu ploča na bazi drva kao što su furnirske ploče, iverice i vlaknatice, koje imaju široku primjenu u industriji namještaja, u posljednje se vrijeme sve češće primjenjuju CNC (Computer Numerical Control) glodalice. Iako CNC glodalice imaju mnoge prednosti za proizvođače namještaja, teško je odrediti parametre procesa za postizanje željene kvalitete površine obrađivanog materijala. Stoga je potrebno odrediti najprikladnije parametre obrade za svaku vrstu ploče na bazi drva. Cilj ovog istraživanja bio je utvrditi utjecaj parametara obrade CNC glodalicama na kvalitetu površine furnirske ploče, iverice i ploče vlaknatice srednje gustoće (MDF ploče). Nadalje, uspoređene su srednje vrijednosti hrapavosti površine tih ploča nakon CNC obrade. Kao parametri CNC obrade odabrane su tri frekvencije vrtnje vretena (10 000, 14 000 i 18 000 okr./min), tri posmične brzine (5, 7 i 9 m/min) te dva promjera reznog alata (2 i 5 mm). Za određivanje kvalitete površine ploča na bazi drva provedena su mjerenja hrapavosti površine prema normi DIN 4768, a hrapavost je iskazana trima parametrima hrapavosti površine (Ra, Rmax i Rz). Prema rezultatima ovog istraživanja može se zaključiti da su se vrijednosti hrapavosti površine ploča na bazi drva smanjivale s povećanjem frekvencije vrtnje vretena i posmične brzine, dok su se povećavale s povećanjem promjera reznog alata. Među pločama na bazi drva na kojima je provedeno ovo istraživanje najniže srednje vrijednosti hrapavosti dobivene su za uzorke furnirske ploče.

In order to investigate the influence of liquid viscosity and surface roughness of the substrate on the improvement of wettability by ultrasonic vibration, a liquid droplet was put on a Langevin type vibrator, and ultrasonic vibration was applied to observe the change of the droplet shape. The droplets were deformed by the application of ultrasonic vibration, and the contact angle between solid and liquid was reduced, so that the wettability was improved. It was considered that the ultrasonic radiation pressure acting inside the droplet had an effect on the deformation of the droplet, and the value of the radiation pressure was estimated based on Laplace's equation. It was confirmed that when the viscosity of the liquid was high, the change in the shape of the droplet was prevented by an increase in the shear stress for deformation. Regarding the surface roughness, it was found that the pinning effect made it difficult to reduce the contact angle. When the ultrasonic vibration was stopped, the shape of the droplet recovered to some extent before the ultrasonic vibration, but did not completely return to the original shape.

The amalgamation of metallic alloys and fiber-reinforced composites has helped Fiber Metal Laminates (FMLs) like Carbon fiber reinforced aluminum laminates (CARALL) and Glass laminate aluminum reinforced epoxy (GLARE) overcome the limitations of standalone metals and composites. As a result, they have found increasing applications in the aircraft and defense industries. Moreover, the inhomogeneous nature and poor machinability of the materials make hole drilling a challenging task. Therefore, to enhance drilling performance, the paper reports a systematic analysis on the effect of spindle speed and axial feed on key performance measures, including thrust force, machining temperature, surface roughness, hole size, burr size, and chip morphology. Experimental outcomes indicate a significant reduction in the thrust force while utilizing higher spindle speed (4000 rev/min) and lower axial feed (0.1 mm/rev), while the surface finish improved under high feed conditions (0.4 mm/rev). The analysis revealed that machining temperature increased with the employment of higher spindle speed and lower axial feed. Higher spindle speeds and axial feeds are desirable from the perspective of hole accuracy as they help produce holes within H9 diameter tolerance. Burr size was verified to be larger at the hole exit compared to hole entry, with the size of the burr increasing with an increase in spindle speed and axial feed. The results show that the axial feed was the significant variable affecting chip size followed by spindle speed. Higher axial feed (0.4 mm/rev) and spindle speed (4000 rev/min) helped improve the chip breakability, thus helping in better chip evacuation.

Current study renders its focus on the investigation of functionally graded Yttria Stabilized Zirconia (YSZ) and alumina (Al2O3) thermal barrier coatings (TBC) deposited on EN steel substrates used in gun barrel through atmospheric plasma spray (APS) process. A bond coat and the top coats was made with two distinct compositions using YSZ-Al2O3 in 75:25 and 50:50 weight ratio through APS process with two carrier gas concentrations of 3 and 4 standard cubic feet per hour (scfh). Coatings were characterized with thermal testing, X-ray Diffraction (XRD) and Field Emission Scanning Electron Microscope examination (FESEM). Surface roughness test, wear and scratch test of the uncoated and coated steel specimens was also measured. YSZ-Al2O3 coated EN36C steel possessed greater insulation performance under a carrier gas flow rate of 3 scfh compared to all other specimens. EN36C steel coated with YSZ-Al2O3 in the ratio of 75:25 has better wear and scratch resistance indicating lesser deformation compared to other materials.

Refereed/Peer-reviewed Titanium and its alloys are frequently the biomaterial of choice for dental implant applications. Although titanium dental implants have been utilized for decades, there are yet unresolved issues pertaining to implant failure. Dental implant failure can arise either through wear and fatigue of the implant itself or peri-implant disease and subsequent host inflammation. In the present report, we provide a comprehensive review of titanium and its alloys in the context of dental implant material, and how surface properties influence the rate of bacterial colonization and peri-implant disease. Details are provided on the various periodontal pathogens implicated in peri-implantitis, their adhesive behavior, and how this relationship is governed by the implant surface properties. Issues of osteointegration and immunomodulation are also discussed in relation to titanium dental implants. Some impediments in the commercial translation for a novel titanium-based dental implant from “bench to bedside” are discussed. Numerous in vitro studies on novel materials, processing techniques, and methodologies performed on dental implants have been highlighted. The present report review that comprehensively compares the in vitro, in vivo, and clinical studies of titanium and its alloys for dental implants.

To explore the evolution mechanism of multistage machining processes and torsional fatigue behaviour based on strain energy for the first time and provide process optimization of axis parts of low-alloy medium-carbon steel for service performance, four multistage machining processes were applied to the 45CrNiMoVA steel, including the rough turning process (RT), RT + the finish turning process (FRT), FRT+ the grinding process (GFRT) and RT+ the finish turning process on dry cutting condition (FRT0). The result showed that the FRT process’s average low-cycle torsional fatigue life increased by 50% when it evolved from the RT process. The lower surface roughness of Ra 1.3 μm caused the total strain energy to increase by 163.8 Pa mm/mm instead of the unchanged strain energy density, and the crack feature evolved from some specific bulges to flat shear plane characteristics. When the GFRT process evolved from the FRT process, its average fatigue life increased by 1.45 times, compared with the RT process. Plastic strain amplitude decreased by 21%, and the strain energy density decreased by 4% due to more considerable compressive residual stress (-249 MPa). Plastic deformation layer depth had a consistent tendency with surface roughness. In this paper, surface integrity evolutions on cyclic characteristics and fatigue behaviour have also been explained. A fatigue life prediction model based on the energy method for machined surface integrity is proposed.

Ti6Al4V is widely applied in the integral cascades of aero engines. As an effective machining method, electrochemical trepanning (ECTr) has unique advantages in processing surface parts made of hard-to-cut materials. In ECTr, the state of the flow field has a significant effect on processing stability and machining quality. To improve the uniformity of the flow field when ECTr is applied to Ti6Al4V, two different flow modes are designed, namely full-profile electrolyte supply (FPES) and edges electrolyte supply (EES). Different from the traditional forward flow mode, the flow directions of the electrolyte in the proposed modes are controlled by inlet channels. Simulations show that the flow field under EES is more uniform than that under FPES. To further enhance the uniformity of the flow field, the structure of EES is optimized by modifying the insulating sleeve. In the optimized configuration, the longitudinal distance between the center of the inlet hole and the center of the blade is 6.0 mm, the lateral distance between the centers of the inlet holes on both sides is 16.5 mm, the length to which the electrolyte enters the machining area is 1.5 mm, and the height of the insulating sleeve is 13.5 mm. A series of ECTr experiments are performed under the two flow modes. Compared with EES, the blade machined by FPES is less accurate and has poorer surface quality, with a surface roughness (Ra) of 3.346 μm. Under the optimized EES, the machining quality is effectively enhanced, with the surface quality improved from Ra = 2.621 μm to Ra = 1.815 μm, thus confirming the efficacy of the proposed methods.