Surface Roughness Research Articles

Chemical treatment in 3D dental model production for clear aligners via additive manufacturing: a comprehensive evaluation

Purpose Stereolithography (SLA) additive manufacturing (AM) technique has enabled the production of inconspicuous and aesthetically pleasing orthodontics that are also hygienic. However, the staircase effect poses a challenge to the application of invisible orthodontics in the dental industry. The purpose of this study is to implement chemical postprocessing technique by using isopropyl alcohol as a solvent to overcome this challenge. Design/methodology/approach Fifteen experiments were conducted using a D-optimal design to investigate the effect of different concentrations and postprocessing times on the surface roughness, material removal rate (MRR), hardness and cost of SLA dental parts required for creating a clear customized aligner, and a container was constructed for chemical treatment of these parts made from photocurable resin. Findings The study revealed that the chemical postprocessing technique can significantly improve the surface roughness of dental SLA parts, but improper selection of concentration and time can lead to poor surface roughness. The optimal surface roughness was achieved with a concentration of 90 and a time of 37.5. Moreover, the dental part with the lowest concentration and time (60% and 15 min, respectively) had the lowest MRR and the highest hardness. The part with the highest concentration and time required the greatest budget allocation. Finally, the results of the multiobjective optimization analysis aligned with the experimental data. Originality/value This paper sheds light on a previously underestimated aspect, which is the pivotal role of chemical postprocessing in mitigating the adverse impact of stair case effect. This nuanced perspective contributes to the broader discourse on AM methodologies, establishing a novel pathway for advancing the capabilities of SLA in dental application.

Enhancing the interfacial bond performance of engineered cementitious composites and concrete

This study aims to investigate the influence of different surface treatments, including smooth interface, rough interface, anchor bolt connection, and epoxy bonding agent, on the shear resistance of Engineered Cementitious Composites (ECC)-concrete interface through bi-surface shear testing. The experimental results show that the interfacial shear strength between ECC and concrete is significantly enhanced by the implementation of the three interface treatment methods, as opposed to the smooth interface. Among these methods, the anchor bolt connection exhibits the greatest improvement in interfacial bonding performance. Notably, cohesive failure is observed in the anchor bolt connection method, while the other three methods result in adhesive failure, with only the anchor bolt connection method displaying ductile failure behavior. Following a comprehensive review of relevant studies and the outcomes of this experiment, three distinct interface bonding mechanisms were identified and the forces contributing to the bond were analyzed. Results indicated that the interfacial bond strength is notably influenced by the surface roughness. These research findings substantiate the viability of utilizing the anchor bolt connection method, particularly in applications where ductility requirements in the repair layer are essential for structural integrity.

Clinical and radiographic performance of late placed and early loaded dental implants with a conditioned hydrophilic surface in posterior mandible sites: A prospective case series with an 8.5- to 9.5-year follow-up.

To assess the clinical outcomes by means of implant and prosthetic survival of late placed and early loaded implants with a hydrophilic, moderately rough surface for partially edentulous patients after a follow-up of 8.5 to 9.5 years. A prospective case series study involving 15 patients with single, late placed and early loaded implants in the posterior mandible was performed. Clinical and radiographical parameters, including biological and technical complications and patient satisfaction, were assessed. From an initial sample of 15 patients, 12 were included. A total of 16 implants were observed. After a mean follow-up of 9 years and 7 months (SD ± 3.8 months), implant success and survival rate were 100%. The prosthetic survival rate was 100%, and the prosthetic success rate was 93.8% since a major chipping was observed. No biological complications were observed, and the mean modified plaque index was 0.03 (SD ± 0.09) with a mean probing pocket depth of 2.95 mm (SD ± 0.09). A mean marginal bone level (MBL) of 0.04 mm (SD ± 0.88) and a mean VAS of 9.42 (SD ± 0.90) for patient satisfaction were recorded. Late placed and early loaded implants with a moderately rough endosseal surface are a reliable option for rehabilitating partially edentulous patients. An implant survival rate of 100% and a prosthodontic success rate of 93.8% were observed. Patient satisfaction scores were high and peri-implant hard and soft tissues remained healthy. The study findings should be carefully interpreted because of the small sample.

Comparative Evaluation of Action of Risa and Sodium Hypochlorite on the Surface Roughness of Heat Treated Single Files, Hyflex EDM and One Curve- An Atomic Force Microscopic Study

Comparative Evaluation of Action of Risa and Sodium Hypochlorite on the Surface Roughness of Heat Treated Single Files, Hyflex EDM and One Curve- An Atomic Force Microscopic Study

Antibacterial Activity and Mechanism of Action of Osthole against Listeria monocytogenes.

The purpose of this study was to investigate the antibacterial activity and mechanism of action of osthole against Listeria monocytogenes. The antibacterial activity of osthole was evaluated by determining the minimum inhibitory concentration (MIC) and growth curve. Cell morphology, membrane permeability, membrane integrity, bacterial physiology, and metabolism were explored using different methods to elucidate the mechanism of action of osthole. It was shown that the MIC of osthole against L. monocytogenes was 62.5 μg/mL and it inhibited the growth of L. monocytogenes effectively in a concentration-dependent manner. Scanning electron microscopy (SEM) images demonstrated morphology changes of L. monocytogenes, including rough surface, cell shrinkage, and rupture. It was found that extracellular conductivity and macromolecule content were increased significantly in the presence of osthole, indicating the disruption of cell membrane integrity and permeability. Laser confocal microscopy results supported the conclusion that osthole caused severe damage to the cell membrane. It was also noticed that osthole depleted intracellular adenosine triphosphate (ATP), inhibited Na+-K+-ATPase and Ca2+-Mg2+-ATPase activity, and promoted the accumulation of intracellular reactive oxygen species (ROS), leading to cell death. This study suggests that osthole is a promising antibacterial agent candidate against L. monocytogenes, and it shows potential in the prevention and control of foodborne pathogens.

Influence of Nanoparticles in Lubricant on Sliding Contact of Atomic Rough Surfaces—A Molecular Dynamics Study

Influence of Nanoparticles in Lubricant on Sliding Contact of Atomic Rough Surfaces—A Molecular Dynamics Study

Effect of rotation frequency of polishing discs on the surface roughness of resin composite material.

The aim of this study was to evaluate the effect of rotation frequency (rpm) of different polishing discs on the surface roughness of a nanohybrid resin composite material. 126 specimens were prepared in metal molds of 10 mm diameter and 2 mm depth using a nanohybrid resin composite material. The prepared specimens were kept in distilled water for 24 hours. Polishing treatments at 5k, 10k, 15k, and 20k rpm were applied to the nanohybrid resin composite material by grouping different brand polishing discs: Sof-Lex Contouring and Polishing Discs (3M Espe, USA) (3M Group), Optidisc (Kerr Corporation, USA) (Kerr Group), Super-Snap Rainbow Technique Kit (Shofu Dental, Japan) (Shofu Group), Finishing Disc (Bisco Dental, USA) (Bisco Group). The surface roughness was evaluated at three different points by atomic force microscopy for all specimens and scanning electron microscopy was used for visual assessment. Data were evaluated by Two Way ANOVA and Tukey's HSD Test. The mean surface roughness (Ra, μm) of all prepared samples showed significant differences (α = 0.05). According to Two-Way ANOVA, there is a statistically significant relationship between the rpm values and the discs. The 3M group showed the highest roughness value at all rpm speeds. Shofu group at 15k, 20k rpm, Bisco group at 10k, 15k, 20k rpm, the Kerr group at 15k, 20k rpm showed the lowest roughness value and had roughness close to the surfaces finished with a mylar strip. The smoothest surfaces were obtained at 15k rpm, even though polishing discs from different brands were used. It was also observed that 5k and 20k rpm polishing speeds can increase the surface roughness of the nanohybrid resin composite material.

Prediction of Surface Roughness Components in Turning with Single Point Tool—Measurement of Tool Edge Contour and Prediction of its Position During Cutting—

Surface roughness is affected by the tool geometry, feed rate, overcutting by built-up edge, and tool vibration in the depth of the cut direction. However, dividing the roughness value into each component is difficult. Therefore, a new prediction method for the position of the tool contour on the roughness curve is proposed to divide the measured roughness value into components. This proposed method consists of two processes. In one, the roughness curve is divided into the roughness curve formed during each revolution of the work material regardless of the clarity of the feed marks. The other is the process that predicts the vertical position of the tool contour. If the vertical position of the tool contour can be predicted, the vibration and overcutting components of roughness can also be predicted. In this study, the transition of roughness components such as the theoretical roughness, vibration width, and overcutting is studied with the increase in the cutting distance in the turning of chromium molybdenum steel, JIS SCM435. When supplying a 10% emulsion mist, the measured Rz is smaller than that of the dry condition. In both the dry and mist supply conditions, the measured Rz increases from the beginning of cutting then decreases and then increases again with the increase in the cutting distance. The largest component of the total roughness in both the dry and mist supply conditions is the theoretical roughness Rth. The ratio ranges between 50.3% and 78.7%. Regardless of the cutting conditions, the vibration width in the depth of the cut direction is relatively constant. The overcutting slightly increases after the start of cutting, then decreases when the maximum contact length exceeds approximately 0.1 mm. The proposed method verifies the ratio of the surface roughness components and is an effective method for improving the surface roughness.

Restoration Temperature Control through Glass Transition Temperature Modulation of Shape Memory Polymer for Thermally Switchable Adhesive.

Shape memory polymers (SMPs) undergo changes between arbitrary shapes and programmed shapes upon exposure to specific stimulus, allowing them to restore their original shape. All kinds of external stimuli have a threshold to change the shape of the SMP. Especially, for the thermal type SMP, the critical temperature for shape restoration is typically near the glass transition temperature (Tg). In this study, the controllability of the restoration temperature is analyzed by adjusting the Tg of the polymer using Norland Optical Adhesive 63, which can be cured with UV irradiation. By varying the ambient temperature from 20 to 120°C during UV exposure, Tg changes ranging from 35.84 to 50.50°C are obtained, with corresponding changes in restoration temperature. As a practical application, a thermal-activated SMP dry adhesive is developed with programmable Tg and switchable adhesion. The fabricated SMP dry adhesive exhibited strong adhesion to substrates with various surface roughness. Additionally, the shape memory effect allowed for easy detachment through shape recovery, and different adhesive performances at different temperatures are achieved by programming various Tg values. Moreover, the simple manufacturing process of the SMP dry adhesive is confirmed to be suitable for continuous fabrication processes based on roll-to-roll methods.

Improving Machined Accuracy Under a Constant Feed Speed Vector at the End-Milling Point by Estimating Machining Force in Tool Approach

A five-axis machining center (5MC) is capable of synchronous control, which makes it a feasible tool for quickly and accurately machining complicated three-dimensional surfaces, such as propellers and hypoid gears. Recently, the necessity of improving both the machined shape accuracy and the machined surface roughness of free-form surfaces is growing. Therefore, in our previous study, we aimed to maintain the feed speed vector at the end-milling point by controlling two linear axes and a rotary axis of the 5MC to improve the quality of the machined surface. Additionally, we developed a method for maintaining the feed speed vector at the end-milling point by controlling the three axes of the 5MC to reduce the shape error of the machined workpieces (referred to as the shape error herein), considering the approach path of the tool determined via calculation. However, a high machining force at the start of the workpiece cutting was observed and the factor contributing to this phenomenon was not determined, although this phenomenon leads to a shape error to a certain degree according to the machining condition. In this study, the main objective is to suggest a method to reduce the machining force at the start of the workpiece cutting and shape error. Hence, we develop a theoretical method to estimate the machining force by using an instantaneous cutting force model, which considers the synchronized motion of two linear axes and a rotary axis of the 5MC. Subsequently, we determine the most suitable approach path of the tool considering the prediction of the machining force. The results of this study indicate that the machining force can be estimated by applying an instantaneous cutting force using the feed per tooth and machining angle, and that both a high machining force at the start of the workpiece cutting and shape error reduction can be realized by using the proposed approach path of the tool.

Special Issue on Advanced Metal Cutting Technologies

Cutting technologies are utilized in many industrial sectors, such as automobile, aircraft, and medical-device manufacturing as well as dies and molds. Thus, the requirements for higher geometric accuracy, better surface integrity, and longer component service lifetimes have substantially increased. In addition, maintaining high machining efficiency while simultaneously reducing power consumption and CO2 emissions during machining is important for sustainable development. This special issue features 11 papers on the most recent advances in cutting technologies for metals and composite materials. - Reverse finishing characteristics of drilling surfaces - Machining error simulation for end milling - Visualization of cutting phenomena using a single-crystal diamond tool - Milling of TiB2 particle-reinforced high-modulus steel - Electrodischarge-assisted turning of carbon fiber-reinforced polymers - Suppression of chatter vibration during double-insert turning - Prediction of surface roughness components during turning - Microtome blades for high-precision tissue sectioning - Boiling of coolant near the cutting edge in high-speed machining - Residual stress during drilling of aluminum alloy - Effect of strain hardening on burr control during drilling This issue provides an understanding of recent developments in cutting technologies, aiming to inspire further research in this field. We deeply appreciate the careful work of all the authors and thank the reviewers for their diligent efforts.

Influence of Reverse Finishing on Characteristics of Drilling Surface

Aluminum alloys are often used in automobile and aircraft parts that require higher dimensional accuracy and durability. Drilling is often used in the machining process of these products and accounts for about 60% of the machining performed on these products. Deterioration of finishing surface accuracy in drilling causes problems such as decreased tool life due to wear and increased cost due to the introduction of the finishing process. The objective of this study is to evaluate the finished surface characteristics in the drilling of aluminum alloys using reverse finishing, with a focus on the cutting direction of finishing, with respect to the roughing direction. The torque and thrust force are smaller in reverse finishing than in forward finishing. The reduction effects of cutting force in reverse finishing were more significant when the finishing depth of cut was smaller in relation to the roughing-affected layer. Under conditions where the finishing depth was equal to or greater than the roughing-affected layer, it was possible to reduce cutting forces and improve surface roughness while obtaining compressive residual stresses equivalent to forward finishing.

The effect of high values of relative surface roughness on heat transfer and pressure drop characteristics in the laminar, transitional, quasi-turbulent and turbulent flow regimes

AbstractThis study investigated the effect of large values of relative surface roughness on the heat transfer and pressure drop characteristics using simultaneously measured heat transfer and pressure drop data. Experiments were conducted using a horizontal circular tube with a base inner diameter of 5 mm and length of 4 m. One smooth and two rough tubes, with relative roughnesses of 0.04 and 0.11, were tested at different constant heat fluxes between Reynolds numbers of 100 and 8 500. Water was used as the test fluid and the Prandtl number varied between 3 and 7. Contrary to the trend in the Moody Chart, a significant increase in laminar friction factors with increasing surface roughness was observed. Both the friction factors and Nusselt numbers as functions of Reynolds number showed a clear upward and leftward shift with increasing surface roughness across the different flow regimes. Furthermore, the boundaries between the flow regimes were the same for the pressure drop and heat transfer results. The width of the transitional flow regime was narrower for rough tubes and had a differing trend. The quasi-turbulent and turbulent flow regimes occurred at lower Reynolds numbers for increasing roughness. When investigating the relationship between heat transfer and pressure drop, it was found that an increase in surface roughness favoured heat transfer in the quasi-turbulent flow regime. This is useful for rough tubes as the quasi-turbulent flow regime onsets early with regards to the Reynolds number in tubes with large roughnesses.

Effect of hydrogen embrittlement on mechanical characteristics of DLC-coating for hydrogen valves of FCEVs

Diamond-like carbon (DLC) coating is a surface coating technology with excellent hydrogen permeation resistance and wear resistance. However, it is difficult to completely prevent hydrogen permeation, and when hydrogen penetrates into the coating layer, the DLC coating is adversely affected. Therefore, we investigated the effect of hydrogen embrittlement on the adhesion strength and wear resistance of the DLC coating layer. As the results of the research, the surface roughness of the DLC coating was increased by a maximum of 3.8 times with hydrogen charging, and the delamination ratio of the DLC coating reached about 58%. In addition, the Lc3, which refers to the adhesion strength corresponding to the complete delamination of the DLC coating, was decreased by a maximum of 2.0 N due to hydrogen permeation. In addition, the wear resistance decreased due to hydrogen permeation, and the exposed width of the substrate due to wear increased by more than 4 times. It was also determined that hydrogen blistering or hydrogen-induced cracking occurred at the interface between the DLC coating and the chromium buffer layer due to hydrogen permeation, which decreased the durability of the DLC coating.

Surface Roughness Model of Ground 4H-SiC Considering Ductile and Brittle Removal

Abstract Surface roughness is a critical indicator to evaluate the quality of ground surfaces for 4H-SiC. Determining surface roughness experimentally is a time-consuming and laborious process, and developing a reliable model for predicting surface roughness is a key challenge in 4H-SiC grinding. However, the existing models for surface roughness in wafer rotational grinding fail to yield reasonable results because they do not adequately consider the processing parameters and material characteristics. In this study, a new analytical model for surface roughness in 4H-SiC wafer rotational grinding is proposed, which comprehensively incorporates the grinding conditions and material characteristics of brittle substrate. This model derives and calculates the material's elastic recovery coefficient based on contact mechanics and elastic contact theory. Subsequently, we modified the grain depth-of-cut model by incorporating elastic recovery coefficient. Additionally, we considered the co-existing of machining-induced ductility and brittleness of the substrate surface under random grain depth-of-cut distribution that conforms to the Rayleigh distribution. To validate the accuracy of the proposed model, a series of grinding experiments are conducted using various grain depth-of-cut to produce 4H-SiC wafers with different surface roughness values. These results are then compared with those predicted by both the proposed model and the existing models. The findings demonstrate that the predictions obtained from the proposed model exhibit better agreement with the experimental results. This research addresses the need for an improved surface roughness model in 4H-SiC wafer rotational grinding.

Surface roughness estimation using vibration characteristics extracted by variational mode decomposition in turning

Abstract This study presents an approach that combines variational mode decomposition (VMD) and relevance vector machine (RVM) as a prediction technique for surface roughness during turning. The method helps machinists detect irregularities during machining, such as looseness in machine parts or tool wear. The study uses work hardened EN8 steel and extracts vibration signal features into five modes. PSO optimized RVM prediction models are developed using these modes with and without combining cutting parameters. The most sensitive mode is selected for accurate surface roughness prediction. The results show that the first mode of decomposition when combined with cutting parameters provides the least mean square error of 0.1095. Surface roughness was found to be primarily influenced inversly by cutting speed and directly by feed rate respectively. The signal with high surface roughness value has high amplitude noise scattered over the large frequency range. The first decomposed mode of vibration signal increases noise with a large amplitude as surface roughness increases. The approach can be integrated into a microcontroller to regulate machine settings based on vibration data.

The effect of surface roughness on the performance of 3D printed surface plasmon resonance sensors for refractive index measurements

AbstractIn this study, a polymer-based surface plasmon resonance (SPR) sensor for refractive index measurements was designed and manufactured via inkjet 3D printing; then, it was optically characterized. Next, it was investigated how the surface finish of the 3D printed optical waveguide affects the sensor performance, i.e., its sensitivity. More in detail, it was studied how the surface roughness changes with the placement of the 3D printed items on the building platform. To achieve this purpose, a Phase I distribution-free quality monitoring analysis of the selected manufacturing process was implemented for a small pilot production run. The aim was to check the stability of surface roughness versus the placement of the 3D printed parts on the building platform. The 3D printed sensor’s surface roughness was assessed through a profilometry study. In particular, the surface roughness was determined for the core of the optical waveguide used to excite the SPR phenomena. Furthermore, the SPR sensors were optically characterized to find the existing relationship between their sensitivity and the considered quality of surface finish. In particular, by varying the surface roughness of the used waveguide, the light scattering in the waveguide changes, and the SPR sensitivity changes too, similarly to the light-diffusing fibers covered by gold nanofilms where the guided light is scattered through a plurality of voids distributed in the core. The procedure followed to investigate the sensor roughness, and establishing their performance enabled the optimal operative range for their application in practice to be identified. Finally, a better knowledge of the 3D printing manufacturing process has been achieved to improve quality of surface finish.

Microphysical characterization of boundary layer ice particles: results from a 3-year measurement campaign in interior Alaska

Abstract A three-winter study has been conducted to better understand the relationship between atmospheric conditions and ice fog or diamond dust microphysics. Measurements were conducted east of downtown Fairbanks in the Interior Alaska during non-precipitating conditions. Atmospheric conditions were measured with several weather stations around the Fairbanks region and two Meteorological Temperature Profiler instruments (ATTEX MTP-5HE and MTP-5PE). Near surface ice particle microphysical observations were conducted with the Particle Phase Discriminator (PPD-2K) instrument which measures particles from 8 to 112 μm (sphere-equivalent). Panoramic camera images were captured and saved every ten minutes throughout the campaign for visual assessment of atmospheric conditions. Machine Learning was used to classify both cloud particle microphysical characteristics from the PPD-2K data as well as to categorize boundary layer conditions using the panoramic camera images. For panoramic camera images, data were categorized as: cloudy, clear, fog, snowing, and a nearby powerplant plume was characterized. For the PPD-2K Machine Learning study the scattering pattern images were used to identify: rough surface, pristine, sublimating, and spherical particles. Three additional categories were used to identify indeterminant or saturated images. These categories as well as categories derived from weather station data (e.g., temperature ranges) are used to quantify ice microphysical properties under different conditions. For the complete microphysical dataset, pristine plates or columns accounted for 15.5%, 16.3% appeared to be sublimating particles and 43.4% were complex particles with either rough surfaces or multiple branches. Although the temperature was as warm as −20°C during measurements, only 1.3% of particles were classified as liquid.

An eco-friendly and facile method for oil–water separation using the bio-Zn oxide-based superhydrophobic membrane

ABSTRACT This manuscript presents a novel approach for developing an environmentally friendly and effective oil–water separation membrane. Achieving a superhydrophobic (SH) coating on textile fabric (TF) involved a two-step process. Initially, the surface roughness was enhanced by applying bio-zinc oxide (ZnO) nanoparticles obtained from Thymbra spicata L. Subsequently, the roughened surface was modified with stearic acid, a material known for its low surface energy. The bio-ZnO nanoparticles exhibit a circular morphology with an average size of 21 nm. The coating demonstrated remarkable mechanical stability, maintaining SH properties even after an abrasion length of 300 mm. Chemical stability studies revealed that the prepared membrane retained SH properties within a pH range of 5–11, which ensures robust performance. Absorption capacity measurements showcased different capacities for n-hexane (Hex), corn oil (C.O), and silicone oil (S.O), with consistent performance over 10 absorption–desorption cycles. High oil–water separation efficiencies were achieved for hexane, C.O, and S.O, emphasizing the coating's versatility. Flux rate measurements demonstrated that oil passed through the membrane efficiently, with the highest flux observed for Hex. The prepared SH membrane has superior mechanical and chemical stability and high separation efficiencies, which positions it as a promising candidate for diverse industrial applications.

Nanopowder-mixed EDM on biodegradable Mg alloy AZ31B for improved surface characteristics and biocompatibility

Powder-mixed electrical discharge machining (PM-EDM) was conducted on biodegradable magnesium (Mg) alloys for biomedical applications. The Mg alloy AZ31B has shown outstanding mechanical properties, similar to human bone, and is lightweight. Efforts were made to enhance the EDM capabilities by a PM-EDM process using nanopowder mixed in the dielectric medium and copper tool electrode amid the machining of Mg alloy AZ31B, followed by investigating surface modification by minimum machining time, morphology, chemistry, topography and wettability of the surfaces. The surface produced by nano PM-EDM operation exhibits minimal cracks and craters, an acceptable range of recast layer thickness (2.4 − 2.7μm), satisfactory corrosion resistance and surface roughness (Ra = 2.87μm) as well as suitable hydrophobic behaviour (CA122q) and bioactivity with Ringer’s solution, suggesting an improvement in the degradation rate. Thus, PM-EDM-induced surface modification suggests the suitability of Mg alloy AZ31B as a biodegradable implant in adults and children.