Arithmetic Roughness Research Articles

Surface roughness assessment of zinc oxide nanostructures formed on biomedical steel

This investigation explores the effect of hydrothermal time on the topographical characteristics of zinc oxide nanostructures-based coating formed on AISI 316L steel. First, a Zn adhesion layer was deposited and later a ZnO film. Next, the ZnO nanostructures were grown by the hydrothermal method at a temperature of 90 °C for 60 and 120 minutes. Elemental analysis was conducted at the surface and its topographic characteristics were assessed by atomic force microscopy. After images acquisition of the surface of the samples, arithmetic roughness (Ra), root mean square roughness (Rq), kurtosis (Rk) and skewness (Rsk) were determined. The arithmetic roughness Ra varied from ~26 nm to ~41 nm when hydrothermal time increased from 60 to 120 min, whereas Rq increased from ~35 nm to ~53 nm. Regarding the kurtosis and skewness parameters, when varying the hydrothermal time, a decrease in their values was found.

A Sustainable Approach-based Optimization of Internal Diamond Burnishing Operation

The related works of the diamond burnishing processes focused on improvements in surface quality. The study aims to optimize burnishing factors, including the spraying distance of the nozzle (S), the inlet pressure of the cold air (I), and the quantity of the liquid CO2 (L) of the cool and cryogenic-assisted diamond burnishing operation for minimizing energy consumed (EC) and arithmetical mean surface height roughness (Sa). Burnishing responses are modeled based on the radial basis function network and full factorial data. The entropy method, improved grey wolf optimizer, non-dominated sorting genetic algorithm II, and technique for order of preference by similarity to ideal solution were implemented to calculate the weights, produce solutions, and select the best outcome. As a result, the optimal data of the S, I, and L were 15.0 mm, 3.0 bar, and 11.0 L/min, respectively. The Sa and EC were reduced by 20.4% and 3.8%, respectively, at the optimality. The optimized outcomes could be employed to improve energy efficiency and machining quality for the internal diamond burnishing process. The optimizing technique could be used to solve complicated issues for different burnishing operations. The cool and cryogenic-assisted diamond burnishing process could be utilized for machining different internal holes.

Aerodynamic and acoustic evaluation of a cylinder covered by stretched grooved fabric near critical Reynolds numbers

This study investigates aerodynamic drag and acoustic noise generated from a circular cylinder by wrapping longitudinally grooved fabrics. The fabrics are stretched to different levels to explore their potential for flow and acoustic control near critical Reynolds numbers. To analyze the fabrics' surface characteristics, 3D scanning and several microscopic techniques were employed. The parallel-mounted load cells and an array of microphones were used to measure the drag and noise at Reynolds numbers, based on cylinder diameter, ranging from \num{3.3e4} to \num{1.1e5} in an anechoic wind tunnel. Additionally, hotwire anemometry was used to examine the wake structures in the vicinity of the cylinder. The surface scanning results revealed that stretching the fabric transversely to twice its original size reduced the groove depth by approximately $54\%$ and increased the width by around $25\%$, resulting in an overall reduction of the arithmetic surface roughness $S_a$ by $18.6\%$. Based on the wind tunnel data, it was observed that a grooved fabric with higher stretch, and thus lower surface roughness exhibited a minimum drag coefficient at a higher Reynolds number, along with reduced acoustic tonal noise levels.

On the Optimization of Roughness and Corrosion Resistance of Laser Beam Powder Bed Fusion Fabricated Ti–6Al–4V Parts—An Electrochemical Approach

Laser beam powder bed fusion is emerging as a technology for fabricating components made of advanced alloys, such as Ti–6Al–4V. However, it suffers from rough as‐built (AB) surfaces, necessitating postprocessing for desired quality and performance. Electrochemical methods such as electrochemical polishing (ECP) and anodization (AN) are promising postprocessing methods; ECP can effectively smoothen surfaces irrespective of their complexity and hardness, while AN enhances the material's corrosion resistance. However, literature lacks research that discusses combined ECP and AN treatment on surface texture evaluation and corrosion behavior. This work presents a detailed study on the effects of different processing factor levels using a Taguchi design of experiment (DOE) approach and discusses the underlying process mechanisms. The optimized treatment conditions to achieve highest roughness improvement and best corrosion resistance are discussed and the most influential postprocessing factors are revealed and ranked. The treatment that achieved smooth surfaces and high corrosion resistance is ECP at 20 V and 15 °C for 20 min, followed by AN at 15 V for 5 min. This treatment achieves a 72% roughness improvement, providing an arithmetic areal surface roughness of 2.63 μm and a corrosion current density of 0.09 μA cm−2, which is almost similar to the AB part.

Hybrid Fabrication of Zirconia Parts with Smooth Surface Texture and Tight Tolerances

The conventional manufacturing chain for technical ceramics is too expensive for the production of small series or unique parts with complex designs. Hybrid machines that combine additive and subtractive processes can be an interesting solution to overcome this technology lock-in. However, despite the great interest in hybrid machines for metallic parts, there is a lack of data in the literature when it comes to ceramics. The purpose of this paper is to contribute to closing this gap. It is the first to evaluate the achievable geometrical tolerances according to ISO 2768-2 as well as the surface textures of composite zirconia parts shaped sequentially by pellet additive manufacturing (PAM, from ceramic injection molding feedstock) and finish milling. The green parts were then debinded and sintered to analyze the influence of these steps. Compared to the initial green parts, the sintered parts exhibited shiny and smooth surfaces with sharp edges. Flatness, parallelism and perpendicularity all achieved an H (fine) class, while the surface textures were significantly improved, resulting in arithmetic roughness (Ra) below 1.6 µm.

Theoretical and experimental investigations on conformal polishing of microstructured surfaces

Microstructured surfaces play a pivotal role in various fields, notably in lighting, diffuser devices, and imaging systems. The performance of these components is intricately related to the accuracy of their shapes and the quality of their surfaces. Although current precision machining technologies are capable of achieving conformal shapes, the post-machining surface quality often remains uncertain. To appropriately address this challenge, this paper introduces a novel conformal polishing methodology, specifically designed to enhance the surface quality of microstructured surfaces while maintaining their shape accuracy. As part of the investigations, specialized tools, namely the damping tool and profiling damping tool, are methodically developed for polishing rectangular and cylindrical surfaces. A shape evolution model is established based on the simulation of individual microstructures, incorporating the concept of finite-slip on the microstructured surface. The findings reveal that principal stresses and velocities experience abrupt variations at the convex and concave corners of rectangular surfaces as well as at the ends of cylindrical surfaces. The numerically predicted surface shape errors after polishing demonstrate reasonably good agreement with experimental results such that their discrepancies are less than 1 μm. Additionally, this method is able to successfully eradicate pre-machining imperfections such as residual tool marks and burrs on the microstructured surfaces. The arithmetic roughness (Ra) of the rectangular surface is measured to be an impressively low 0.4 nm, whereas the cylindrical surface exhibits Ra = 6.2 nm. These results clearly emphasize the effectiveness of the conformal polishing method in achieving high-quality surface finishes.

Effect of Cutting Conditions on Surface Integrity when Robotic Drilling of Aluminum 6082-GFRP Stacks

Six-axis robots are increasingly employed in manufacturing due to their excellent volume on cost ratio and extensive reach, facilitating the machining of large components, including those made of composites. However, this enhanced volume on cost ratio often compromises rigidity. This study investigates the effect of cutting conditions on surface integrity and robotic drilling forces when machining Aluminum 6082-GFRP stacks using 6 mm solid carbide drills and a 6-axis Sta¨ubli TX200 robot. Two distinct drill geometries are assessed in various drilling sequences. Feed rate emerges as a pivotal parameter affecting drilling forces and hole quality. Comprehensive testing encompasses a range of feed rates and drilling strategies in both individual materials and stack sequences. The analysis includes cutting forces and hole quality, considering surface integrity and standard quality indicators such as delamination, arithmetic roughness, and burr height. The research seeks to propose optimal cutting conditions, specifically feed rate and cutting speed, essential for advanced industrial applications. These conditions ensure hole quality and surface integrity, which is particularly important for riveting processes and ensuring effective sealing.

Multiscale Modeling of a Chain Comprising Selective Laser Melting and Post-Machining toward Nanoscale Surface Finish.

The generation of rough surfaces is an inherent drawback of selective laser melted (SLM) material that makes post-treatment operation a mandatory process to enhance its surface condition and service performance. However, planning an appropriate and optimized chain to attain the best surface finish needs an integrated simulation framework that includes physics of both additive manufacturing and post-processing. In the present work, an attempt is made to model the alternation of surface roughness which is produced by SLM and post-processed by milling and sequential surface burnishing. The framework includes a series of closed-form analytical solutions of all three processes embedded in a sequence where the output of the preceding operation is input of the sequential one. The results indicated that there is close agreement between the measured and predicted values of arithmetic surface roughness for both SLM material and the post-processed ones. It was also found that a nanoscale surface finish is obtained by finishing milling and single pass rolling at a static force of 1500 N. In addition, the results of the simulation showed that elimination of the milling process in the chain resulted in a six-times-longer production time that requires three times bigger rolling force compared to a chain with an included milling operation.

Optimization of laser beam parameters during processing of ASA 3D-printed plates

AbstractNew developments in manufacturing processes impose the need for experimental studies concerning the determination of beneficial process-related parameter settings and optimization of objectives related to quality and efficiency. This work aims to improve cutting geometry, surface texture, and arithmetic surface roughness average in the case of post-processing of filament material extrusion 3D-printed acrylonitrile styrene acrylate (ASA) thin plates by a low-power CO2 laser cutting apparatus. This material was selected owing to its unique properties for thin-walled customized constructions. Three parameters, namely focal distance, plate thickness, and cutting speed, were examined with reference to the Box-Behnken design of experiments (BBD) and regression modeling. Four responses were considered: mean kerf width, Wm (mm); down width, Wd (mm); upper width, Wu (mm); and average surface roughness Ra (μm) of cut surfaces. Different regression models were tested for their efficiency in terms of predicting the objectives with an emphasis on full quadratic regression. The results showed that a focal distance of 6.5 mm and 16 mm/s speed optimizes all quality metrics for the three plate thicknesses. The regression models achieved adequate correlation among independent process-related parameters and optimization objectives, proving that they can be used to improve the laser cutting process and support practical applications.

PARAMETER SCREENING IN LONGITUDINAL TURNING OF C45E STEEL FOR SURFACE ROUGHNESS ANALYSIS

Parameter screening refers to the identification of the most important controllable factors with respect to a given performance characteristic of a given system/process. In this study, PlackettBurman design was applied in order to identify the factors that significantly affect surface roughness in longitudinal turning of C45E steel. The experiment involved realization of geometric PlackettBurman design with eight trials and two replicates. Six turning controllable factors were considered in the design matrix (depth of cut, feed rate, cutting speed, insert nose radius, minor cutting edge angle and cooling/lubrication condition) and were varied at two levels. Analysis of the obtained results has shown that factors differently affect surface roughness and that their influences are in accordance with known theoretical knowledge. It was also observed that three factors have statistically significant impact on the machining quality, i.e., arithmetic surface roughness. These results can be considered as the first step for further experimental investigation of significant factors and their possible interactions effects

Effect of roughness, contact pressure and lubrication on the onset of galling of the 6082 aluminium alloy in cold forming, a numerical approach

The effect of surface roughness, contact pressure and lubrication on the onset of galling of aluminum 6082-T6 is studied with a pin-on-plate tribometer. The design of experiments involves pins with mean arithmetic roughness Ra equaled to 0.2, 0.35 and 0.6 μm, normal loads ranging from 5 to 600 N, and 4 different lubrications: without lubricant, with MoS2 dry lubricant, with pure mineral oil and with a highly chlorinated paraffin oil. Tests are performed at room temperature and are repeated three times. Experimental results show the great sensitivity of the onset of galling to the roughness and the beneficial effect of dry and liquid lubricants. The occurrence of galling is study by optical micrographs, by the analyses of the coefficient of friction, and by the use of finite element simulations. It comes that the variation of the coefficient of friction is not self-sufficient to detect the onset of galling. The finite element computations involves Wilson’s lubrication model and Xue’s damage model. Galling is assumed when finite elements near the contact area reach the critical damage Dc. This numerical approach leads to a good prediction of the onset of galling for the tests performed under constant normal load. For tests performed with increasing normal loads and various lubricants, the numerical prediction overestimate the sliding length before galling occurs.

Adsorption behavior of serum proteins on anodized titanium is driven by surface nanomorphology.

Protein adsorption behavior can play a critical role in defining the outcome of a material by affecting the subsequent in vivo response to it. To date, the effect of surface properties on protein adsorption behavior has been mainly focused on surface chemistry, but research on the effect of nanoscale surface topography remains limited. In this study, the adsorption behavior of human serum albumin, immunoglobulin G, and fibrinogen in terms of the adsorbed amount and conformational changes were investigated on bare and anodized titanium (Ti) samples (40 and 60 V applied voltages). While the surface chemistry, RMS surface roughness, and arithmetic surface roughness of the anodized samples were similar, they had distinctly different nanomorphologies identified by atomic force microscopy and scanning electron microscopy, and the surface statistical parameters, surface skewness Ssk and kurtosis Sku. The Feret pore size distribution was more uniform on the 60 V sample, and surface nanostructures were more symmetrical with higher peaks and deeper pores. On the other hand, the 40 V sample surface presented a nonuniform pore size distribution and asymmetrical surface nanostructures with lower peaks and shallower pores. The amount of surface-adsorbed protein increased on the sample surfaces in the order of Ti < 40 V < 60 V with the predominant factor affecting the amount of surface-adsorbed protein being the increased surface area attained by pore formation. The secondary structure of all adsorbed proteins deviated from that of their native counterparts. While comparing the secondary structure components of proteins on anodized surfaces, it was observed that all three proteins retained more of their secondary structure composition on the surface with more uniform and symmetrical nanofeatures than the surface having asymmetrical nanostructures. Our results suggest that the nanomorphology of the peaks and outer walls of the nanotubes can significantly influence the conformation of adsorbed serum proteins, even for surfaces having similar roughness values.

Exploring wide-parametric range for tool electrode selection based on surface characterization and machining rate employing powder-mixed electric discharge machining process for Ti6Al4V ELI

The titanium alloy Ti6Al4V ELI (grade 23) is widely used in biomedical industry because of its engineering attributes. However, it requires surface modifications and has processing challenges because it is difficult to machine nature. Therefore, powder-mixed electric discharge machining process is commonly applied to simultaneously machine the material and carry out surface treatment. The performance of the process is limited by both low cutting efficiency and the formation of a rough surface. In this regard, the current study evaluates SiC powder-mixed electric discharge machining of Ti6Al4V ELI using a range of tool materials such as copper, brass, graphite, and aluminum along with a comprehensive list of process parameters. The surface roughness parameters involving arithmetic roughness, the average peak-to-valley distance, and the highest peak-to-deepest valley distance along with material removal rate are comprehensively studied. Taguchi design of experiments L16 orthogonal array is used to study the process performance with parametric effect analysis, parametric significance analysis, and surface morphological analysis with a scanning electron microscope. Furthermore, the experimental results are optimized against a multi-response optimization matrix using grey relational analysis approach. An optimal compromise between surface attributes and cutting efficiency is identified by Al electrode, pulse current of 14 A, pulse on time of 75 µs, pulse off time of 75 µs, and negative polarity parametric conditions.

Advanced morphological characterization of DC sputtered copper thin films

In this paper, Cu thin films were successfully deposited on glass substrates using DC magnetron sputtering at varying deposition times. The deposition time was varied as 5, 9, 11 and 17[Formula: see text]min. The obtained Cu thin films were analyzed for morphology and topography using atomic force microscopy (AFM). The size of the surface structures/grains was seen to evolve with deposition time. The conventional/statistical, fractal and multifractal analyses were carried out on AFM images using existing imaging algorithms. The arithmetic roughness and interface width parameters were seen to evolve with the sputtering time. The autocorrelation and height–height correlation functions revealed that the surfaces of all the Cu thin films exhibited self-affine character, but were not mounded properties. The fractal dimensions computed using box counting and power spectral density functions revealed that larger dimensions were associated with larger surface features. The lacunarity coefficients were too small indicating that the surfaces were generally deficient in porosity and other defects. The multifractal analyses revealed that spatial roughness does not exhibit linear relationship with the deposition time. The study reveals that surface evolution and nanoscale behavior is significantly influenced by the deposition time although a linear relationship is not established.

Determination of key factors affecting biofilm formation on the aged Poly(ethylene terephthalate) during anaerobic digestion

Biofilm formation on plastic surface is a growing concern because it can alter the plastic surface properties and exacerbate the ecological risk. Identifying key factors that affecting biofilm formation is critical for effective pollution control. In this study, the poly (ethylene terephthalate) (PET) was aged in water and air conditions with UV irradiation, then incubated in the digestate of food waste anaerobic digestion to allow biofilm formation. Surface analysis techniques, including scanning electron microscopy (SEM), atomic force microscopy (AFM), and Fourier-transform infrared spectroscopy with attenuated total reflection (FTIR-ATR), were utilized to investigated the changes in the topography, roughness, hydrophily, and functional groups change of the PET surface during the aging process. Confocal laser scanning microscopy (CLSM) was used to determine the distribution of microorganisms on the PET surface after incubation in the digestate. This study focused on understanding the interactions between the PET surface and biofilm to identify critical surface factors that affect biofilm formation. Results showed that the four months aging process decreased the contact angle of the PET surface from 96.92° to 76.08° and 68.97° in water and air conditions, respectively, corresponding to an increase of 44% and 70% in the surface energy. Additionally, aging in air conditions led to a rougher surface compared to water conditions. The arithmetic roughness average (Ra) of the PET-Water was 11.0 nm, comparable to that of the pristine PET, while the value of PET-Air was much higher (43.9 nm). The results further indicated that biofilm formation during anaerobic digestion was more sensitive to roughness than hydrophily. The PET surface aged in air conditions provided a more suitable environment for microbial reproduction, leading to the aggradation of living cells.

Integrating experimental modeling techniques with the Pareto search algorithm for multiobjective optimization in the WEDM of Inconel 718

Inconel 718 is a superalloy with a high nickel content that is widely used in applications requiring solid mechanical behavior and resistance to oxidation and corrosion at high temperatures. This alloy has numerous applications in manufacturing steam turbine and jet aircraft interiors, aviation sector manifolds, and rotary spindles. It can be classified as a difficult-to-cut material unsuitable for traditional machining. The purpose of this paper is to develop prediction models for a wire electrical discharge machining (WEDM) process using response surface methodology (RSM), artificial neural networks (ANN), and adaptive neuro-fuzzy inference systems (ANFIS) and to determine which model is better at making accurate predictions. Pulse_ontime, pulse_offtime, servo voltage, flushing pressure, and wire feed were considered the main factors affecting volumetric material removal rate (VMRR) and arithmetic surface roughness (Ra), which were evaluated as WEDM performance characteristics. I-optimal design made with a computer algorithm was employed to develop experimental models. The results reveal that the wire feed and pulse_ontime were the most vital factors influencing VMRR, respectively, and the most significant factor influencing Ra is the pulse_ontime. The total percentage error of the three models demonstrated that the ANN and ANFIS models are more reliable and accurate than the RSM mathematical model. Finally, multiobjective optimization using the Pareto search algorithm was used to optimize mathematical, ANN, and ANFIS models to determine the optimum WEDM process parameters for machining Inconel 718 superalloy.

Circular Production, Designing, and Mechanical Testing of Polypropylene-Based Reinforced Composite Materials: Statistical Analysis for Potential Automotive and Nuclear Applications.

The circularity of polymer waste is an emerging field of research in Europe. In the present research, the thermal, surface, mechanical, and tribological properties of polypropylene (PP)-based composite produced by injection molding were studied. The pure PP matrix was reinforced with 10, 30, and 40% wt. of pure cotton, synthetic polyester, and polyethylene terephthalate post-consumer fibers using a combination of direct extrusion and injection molding techniques. Results indicate that PP-PCPESF-10% wt. exhibits the highest value of tensile strength (29 MPa). However, the values of tensile and flexural strain were lowered with an increase in fiber content due to the presence of micro-defects. Similarly, the values of modulus of elasticity, flexural modulus, flexural strength, and impact energy were enhanced due to an increase in the amount of fiber. The PP-PCCF-40% wt. shows the highest values of flexural constant (2780 MPa) and strength (57 MPa). Additionally, the increase in fiber loadings is directly proportional to the creation of micro-defects, surface roughness, abrasive wear, coefficient of friction, and erosive wear. The lowest average absolute arithmetic surface roughness value (Ra) of PP and PP-PCCF, 10% wt., were 0.19 µm and 0.28 µm. The lowest abrasive wear value of 3.09 × 10-6 mm3/Nm was found for pure PP. The erosive wear value (35 mm3/kg) of PP-PCCF 40% wt. composite material was 2 to 17 times higher than all other composite materials. Finally, the single-step analysis of variance predicts reasonable results in terms of the p-values of each composite material for commercial applications.

Large magnetostriction in γʹ-Fe4N single-crystal thin film

An Fe4N(110) single-crystal film of 50 nm thickness with γʹ phase is prepared through hetero-epitaxial growth on an MgO(110) single-crystal substrate at 400 °C by reactive sputtering. The out-of-plane and in-plane lattice constants agree with those of bulk within small differences less than 0.2% and the orientation dispersions are about 1.2°. The degree of N site ordering in Fe4N structure is estimated to be 0.995. The arithmetical mean surface roughness is as small as 0.3 nm. These data show that a high-quality Fe4N single-crystal film is successfully formed. The Fe4N film shows in-plane magnetic anisotropy with the easy magnetization direction parallel to [001] and with the hard direction parallel to [1_11], which is reflecting the positive magnetocrystalline anisotropy, K1. A large negative λ100 value of –40 × 10–6 and a fairly-large positive λ111 value of +150 × 10–6 are observed. The present study has shown that γʹ-Fe4N compound is one of the strong candidates for rare-metal-free magnetostrictive materials.

On the Biotribological Surfaces of Dental Implants: Investigation in the Framework of Osseointegration

In the last decades, the use of dental implants has been growing exponentially, but some clinical issues such as inflammations, infections or mechanical complications like fractures or implant loosening, are still open, leading to a failure and implants' revision surgery. Many researchers state that one of the main reasons is certainly due to a not complete or stable implant osseointegration respect the surrounding bone. As stated in literature the formation and the growth of the bone in contact with the implant is strictly correlated with the micro topography of the implant contact surfaces, because of the biotribological, biological and chemical interactions occurring on the surface. To date, however, only arithmetical roughness is reported in the most part of investigations as a valid surfaces' topographical parameter which could be correlated with osseointegration. Moreover, a consolidated and standardized procedure for dental implant surface measurements is not established. Hence, the aim of this investigation was to propose an advanced methodology for analyzing dental implant surfaces based on optical measurements and accurate data processing, and to discuss the results obtained on a real implant, in the framework of osseointegration and biotribological contact literature findings. With reference to a commercial dental implant, the topography was accurately achieved by an optical confocal and interferometric apparatus and then post processed to obtain all the quantities necessary for the contact surface accurate description discussing the role of the topographical quantities on the influence of bone/implant contact/osseointegration phenomena. Height, spatial, hybrid and functional parameters were presented for both waviness and roughness profiles providing significant discrepancies in most of the roughness values. On the other hand, the additional specific investigations such as surface isotropy or particle analysis may yield the basis for a novel protocol of surfaces topographical characterization procedure in dentistry.

Electric Discharge Machining of Ti6Al4V ELI in Biomedical Industry: Parametric Analysis of Surface Functionalization and Tribological Characterization.

The superior engineering properties and excellent biocompatibility of titanium alloy (Ti6Al4V) stimulate applications in biomedical industries. Electric discharge machining, a widely used process in advanced applications, is an attractive option that simultaneously offers machining and surface modification. In this study, a comprehensive list of roughening levels of process variables such as pulse current, pulse ON time, pulse OFF time, and polarity, along with four tool electrodes of graphite, copper, brass, and aluminum are evaluated (against two experimentation phases) using a SiC powder-mixed dielectric. The process is modeled using the adaptive neural fuzzy inference system (ANFIS) to produce surfaces with relatively low roughness. A thorough parametric, microscopical, and tribological analysis campaign is established to explore the physical science of the process. For the case of the surface generated through aluminum, a minimum friction force of ~25 N is observed compared with the other surfaces. The analysis of variance shows that the electrode material (32.65%) is found to be significant for the material removal rate, and the pulse ON time (32.15%) is found to be significant for arithmetic roughness. The increase in pulse current to 14 A shows that the roughness increased to ~4.6 µm with a 33% rise using the aluminum electrode. The increase in pulse ON time from 50 µs to 125 µs using the graphite tool resulted in a rise in roughness from ~4.5 µm to ~5.3 µm, showing a 17% rise.