Mean Roughness Ra Research Articles

Hot embossed micropatterned slippery Al 5083 alloys in stagnant and laminar saltwater

Slippery AA 5083 alloy surfaces were fabricated by using ground (mean roughness-Ra = 45±2 µm), polished (Ra = 9±3 µm) and hot embossed micro-patterned specimens, and coating them with silicone oils of varying viscosities (1000−100000 cSt). The surface energy of aluminium alloy (AA) 5083 was estimated to be 850±210 mJ·m−2 using Schultz model. The ground/polished specimens were coated with 12±1 µm and 24±0.3 µm thick oil. They showcased slippery character, wherein apparent water static contact angles (SCAs) of 94±1° to 104±1°, slide-off angles (SAs) of 4±0° to 21±2° and contact angle hysteresis (CAH) of <10° were observed. Also, CAH and SAs revealed an increasing trend with an increase in the oil viscosity, irrespective of the coating thickness or the substrate roughness. In addition, the water droplets bounced-off the oil coated (24 µm thick) surfaces up to Weber no. (We) of 3.91. Furthermore, micro-patterned specimens were fabricated by hot embossing at 300 °C, 17+1 MPa, 5 min and comprise of hexagonally arranged pillars and holes with 6.5−7.1 µm diameter and 9.5−13.6 µm pitch. A key finding is that micro-pillars offered the highest tolerance to shear drainage of oil under saltwater (3.5 wt% NaCl) for up to 7 days, in both stagnant and flowing laminar (Reynolds no.‐Re =247) conditions, as compared to micro-holes and unpatterned surfaces. Interestingly, the slippery properties of oil coated unpatterned AA5083 have retained after 7 days of submersion, showing SCAs ≥ 97±3° and SAs ≤ 14°, despite the negative spreading coefficient of oil on AA5083 under water. Such slippery durable micro-pillared and micro-holed AA5083 surfaces could be highly beneficial for mitigating biological corrosion of ship hulls in marine environments.

"Fabrication of cutting inserts with chromium-molybdenum steel for turning operations using material extrusion technology"

In this study, cutting inserts for turning were produced using metal 3D printing's material extrusion technology. The primary focus was on optimizing cutting parameters. An experimental plan was devised involving rounds of cutting tests based on a design of experiments and analysis of variance. Inserts were manufactured by printing bound metal powder filament, a combination of chromium-molybdenum tool steel with a polymeric binder. After printing, green parts underwent debinding to eliminate the binder, eventually resulting in full metal parts via sintering. These inserts underwent machining tests on aluminum-copper EN AW-2030 alloy specimens. Results indicated that the inserts could function within cutting speeds (Vc) ranging from 40 to 260 m/min, feed rates (f) from 0.05 to 0.25 mm/r, and radial pass depths (ap) from 0.1 to 2.4 mm. Optimal technological conditions were determined as Vc = 160–200 m/min, f = 0.20–0.25 mm/r, and ap = 1.2 mm. Analysis revealed that cutting speed was less significant than feed rate or depth of cut on tool wear. Feed rate minimized wear within the 0.15–0.25 mm/r range, while pass depth proved most influential on wear, with optimal values between 0.8 and 1.2 mm. Surface finish, assessed through mean roughness Ra, showed high dependence on pass depth, improving for low ap values and relatively high Vc values. These findings demonstrate that inserts fabricated via material extrusion can operate within a technological range like commercial inserts, presenting an advanced approach for customizing design and manufacturing while surpassing conventional insert limitations.

Comparative Study of Flank Cams Manufactured by WEDM and Milling Processes

Cam-follower mechanisms are usually employed in different machines, like combustion engines, sewing machines, machine tools, etc. In the present paper, the option to manufacture cams utilizing wire electrical discharge machining (WEDM) has been considered. For this, surface roughness and shape error of cam profiles manufactured by the processes of milling and wire electrical discharge machining (WEDM) are presented. The methodology used covers different stages: design, prototyping, manufacturing, and measurement of the cams. As a reference, a cam-follower mechanism from a motorcycle internal combustion engine has been used. A reverse engineering process has been performed to determine the geometrical parameters of the mechanism, which are used for the synthesis of the profile of the cam and its subsequent design. The manufacturing process of the cams has been assisted by CAD-CAM (Computer Assisted Drawing-Computer Assisted Manufacturing) software. Using fused filament fabrication (FFF), a physical prototype of the cam has been manufactured, in order to validate the goodness of the design. Finally, the roughness and shape parameters have been measured on the contour surface of the cams. The arithmetical mean roughness Ra value of the milled cam was 0.269 μm, below the requirement of 0.4 μm, and shape error was 18 μm, below 50 μm. Shape error of the WEDM cam of 48 μm meets the requirements for cams. However, the Ra value of 1.212 μm, exceeded the limit. For this reason, a finish operation is recommended in this case. Some advantages of WEDM cams over milled cams are that different conductive materials can be employed, more complex shapes can be obtained, and that, in rough operations, the amount of material to be removed in subsequent operations is considerably reduced.

Role of Surface Roughness in the Interlayer Boundary Formation during Manufacturing of Clad Metal Composites

In the present research work, the role of surface roughness in the interlayer boundary formation during manufacturing of clad metal composites was analyzed. Process of interlayer boundary formation was described through mathematical and computer simulation. The importance of taking into account not only arithmetical mean roughness Raor ten-point mean roughness Rz, but also Rz/S ratio (where S – mean spacing of adjacent peaks) is shown, because this relation affects the length of actual contact between dissimilar materials. As the result of mathematical and computer simulation, dependence of the length of actual contact between dissimilar materials on Rz/S ratio and semi-angle of the ridge vertex was obtained.

Experimental study on CNC engraving parameters of Afghan white jade

The CNC machining of nephrite is increasingly used in the jade engraving industry. As the most important standard for quality evaluation, surface roughness is influenced by cutting parameters. In this paper, taking the Buddha head as the machining object, the influence of cutting parameters on the surface quality of was studied by SYIL S7 CNC milling machine. The grooving experiment was carried out at spindle speed of 24,000 rpm, then the CAXA manufacturing engineer and JDpiant software were comparatively applied in machining. Furtherly, the influence of the spindle speed on the roughness was investigated. The research results were summarized as follows: (1) No edge breakage appeared when feed speed lower than 300 mm/min with the maximum depth of cut of 0.1 mm. In this case, when the jade is machined with the spindle speed range of 16,000–24,000 rpm, the mean roughness Ra was in the range of 1,496.111–891.842 nm. (2) JDpiant software is more suitable for CNC jade engraving than CAXA manufacturing engineer. (3) In roughing stage, only the high-speed grinding contdition is satisfied, the integrity of side profile could be guaranteed. The higher spindle speed was conducive to achieve the fine surface quality. (4) The tungsten steel cutter in finish machining stage shows better grinding ability than diamond cutter used in rough machining stage. In order to formulate an economic spindle speed, the finishing surface roughness should be considered in conjunction with the requirement of polishing.

Control of hydrophobic and hydrophilic characteristics of metallic materials using shot blasting

In this study, changes in surface texture and surface wettability caused by shot blasting were analysed quantitatively by measuring the contact angle. Shot blasting was performed on stainless steel (AISI 304). Six types of particles with different shapes and mechanical properties were used, and the processing pressure and time were varied. It was observed that the shape and mechanical properties of the particles affected the surface wettability more than the processing pressure and time. In particular, the wettability improved when using polygonal particles than on an untreated surface, and it decreased slightly when using spherical particles. A correlation was observed between arithmetic mean roughness (Ra) and wettability. In other words, a parameter describing the height direction in the surface roughness can be used as a guideline to control wettability. In addition, we performed theoretical calculations based on Wenzel's theory and compared the theoretical and the measured values. The increase of the surface roughness by the shot blasting was found to have little influence on the wettability in the Wenzel theory method. A correlation between the arithmetic mean roughness Ra and the wettability was observed. However, a comparison with Wenzel's theory showed that there are other parameters that affect the wettability rather than the roughness.

Influence of the Thickness of Gadolinium Layers on the Magnetic Properties and Magnetization Reversal Processes in Low-Dimensional Co/Gd/Co Systems

Structural and magnetic characteristics and behavior of thin-film Co/Gd/Co systems obtained by ion plasma sputtering in a magnetic field are reported. X-ray studies showed that cobalt layers in all investigated samples have a nanocrystalline structure. The mean roughness Ra of the surface of the samples does not exceed 0.5 nm and is independent of the Gd layer thickness. The shape of hysteresis loops observed for the Co/Gd/Co system depends of the thickness of the Gd layer, tGd. The dependence of the saturation field HS on tGd has an oscillatory character. This fact is explained by interaction of the Co layers through the intermediate Gd layer.

How does the surface treatment change the cytocompatibility of implants made by selective laser melting?

ABSTRACTIntroduction: The study investigates the potential for producing medical components via Selective Laser Melting technology (SLM). The material tested consisted of the biocompatible titanium alloy Ti6Al4V. The research involved the testing of laboratory specimens produced using SLM technology both in vitro and for surface roughness. The aim of the research was to clarify whether SLM technology affects the cytocompatibility of implants and, thus, whether SLM implants provide suitable candidates for medical use following zero or minimum post-fabrication treatment.Areas covered: The specimens were tested with an osteoblast cell line and, subsequently, two post-treatment processes were compared: non-treated (as-fabricated) and glass-blasted. Interactions with MG-63 cells were evaluated by means of metabolic MTT assay and microscope techniques (scanning electron microscopy, fluorescence microscopy). Surface roughness was observed on both the non-treated and glass-blasted SLM specimens.Expert Commentary: The research concluded that the glass-blasting of SLM Ti6Al4V significantly reduces surface roughness. The arithmetic mean roughness Ra was calculated at 3.4 µm for the glass-blasted and 13.3 µm for the non-treated surfaces. However, the results of in vitro testing revealed that the non-treated surface was better suited to cell growth.

NANOSCALE CHARACTERIZATION OF CR, CU, AL AND NI METALLIC MAGNETRON NANOFILM MULTILAYERS ON SITALL

Results of nanoscale study (by atomic force microscopy and X−ray diffraction) of single−, two− and three−layered Cr, Cu, Al and Ni metallic nanofilms formed on a ceramic sital substrate on MVU TM−Magna T magnetron equipment (NIITM, Zelenograd) have been reported. The growth rates and the structure of the nanofilms were determined while varying of power/current ratio from 200/0.7 to 800/2 Wt/A and magnetron sputtering time from 30 to 360s at an operating pressure of 0.5 Pa Ar. The criterion for optimization quality based on the minimum roughness was as follows: Ra = min{Rai} and/or Rq → min{Rqi} (i is the number of varies modes used). The mean roughness Ra and RRMS = Rq have been determined from the scan of the vertical profile (resolution 20 pm) of the atomic force microscopic image. We found that the nanofilm–forming nanocluster structure size for the modes when Ra and Rq were the smallest had a close–to–Gaussian grain size distribution. The film growth rates have been determined based on the atomic force images of the nanofilm structure in the form of either a single step or steps obtained at different time intervals. The mode and parameters of magnetron sputtering and the composition of the Cr, Cu, Al and Ni targets affect the size of clusters which form the surface of the metallic nanofilms. X−ray phase and structural analyses have been carried out in order to determine the texture and the change in the distances between the lattice planes. The correctness of the optimization criterion correlating the nanolayer deposition parameters and their quality has been corroborated by the coincidence of the magnetron sputtering modes which provided for the lowest roughness and the smallest average size of the X−ray coherence region as using the Debye− Scherrer equation.

Sand-blasting treatment as a way to improve the adhesion strength of hydroxyapatite coating on titanium implant

In the current study, the effect of corundum particle sizes (50 and 250–320 μm) used for sand–blasting on the structure, roughness, wettability, mechanical properties, and adhesion of radio frequency magnetron hydroxyapatite coating deposited on treated titanium substrate is studied. Morphology analysis revealed that pretreatment uniformly deforms the surface and induces the formation of pits, which size depends linearly on the grit size. The deposited coatings (Ca/P was in a range of 1.75-1.79) are homogeneous and repeat the relief of the substrate (mean roughness Ra is 1.9±0.1 (250–320 μm) and 0.8±0.1 μm (50 μm)). Texture coefficient calculations revealed the predominant (002) growth texture of hydroxyapatite coatings. The resistance of the coating to plastic deformation and the surface hardening were significantly higher for coatings formed on sand blasted with particle size of 50 μm. Scratch test have shown the significant improvement of wear resistance and lower friction coefficient of coatings for smoother samples. Dynamic contact angle measurements revealed the hydrophilic properties of the hydroxyapatite coating. Thus, sand–blasting of titanium with corundum powder having the size of 50 μm prior to the deposition of RF magnetron coating is recommended for the medical applications intended to improve the bonding between the substrate and coating.

Multi Objective Optimisation for High Speed End Milling Using Simulated Annealing Algorithm

Machining at high cutting speeds produces higher temperatures in the cutting zone. These temperatures affect the surface quality and flank wear progress. Therefore, determining the optimum cutting levels to achieve the minimum surface roughness and flank wear is an important for it is economical and mechanical issues. This paper presents the optimization of machining parameters in end milling processes by using the simulated annealing algorithm (SAA) as one of the unconventional methods in optimization. The minimum arithmetic mean roughness (Ra) and minimum flank wear length were the objectives. The mathematical models have been developed, in terms of cutting speed, feed rate, and axial depth of cut by using Response surface Methodology (RSM). This paper presents the optimum cutting parameters: cutting speed, feed rate and depth of cut to achieve the minimum values of surface roughness and minimum flank wear length. The results show that the cutting speed in the range of 200 m/min, feed rate of 0.05 mm/tooth and depth of cut of 0.1mm gave the minimum arithmetic mean roughness (Ra) for 164 and minimum flank wear for 0.0379 in the boundary design of the experiment after 8000 iteration.

Study of the Effects of Sand Blasting on Soda Lime Glass Erosion

In Saharian regions, the erosion of glass by sand particles during sandstorms is a regular phenomenon. The progressive loss of matter on surface affects both the optical transmission and the mechanical strength. In the present work, we examine the effects of sand blasting on the erosion of soda lime glass intended for vehicles windshields manufacture. We used a sand coming from Algerian Sahara (Ouargla) which is characterized by a mostly rounded shape. All sand blasting erosion tests were simulated in laboratory. The erosive wear of soda lime glass is evaluated at different impingement angles (30, 45, 60 and 90°, with sand masses varying from 10 to 300 g and three different velocities (16, 20 and 24 m/s). The results obtained show that the erosion rate (Er), the mean roughness (Ra) and the mass loss (∆m) reach their maximum at 90° (flow normal to the surface). After exposure to a sand mass of 300 g at normal incidence, the glass surface becomes totally blurred. The ∆m of the glass is 54 mg and the Ra reaches about 3.57µm and the optical transmission (To) is affected proportionally to the sand mass used (mP). It decreases from 91.5% down to 12 % when the mass reaches 300 g. The morphologies of eroded surface were examined by the scanning electronic microscopy. From these observations, we noticed that the erosion mechanism is often of a brittle kind characterized by the formation of radial and lateral cracks that develop into chippings.

A Study Comparative of Cu and Cu-Zn Electrode during Electrical Discharge Machining on Martensitic Stainless Steel AISI 410

The objective of this research is to study comparisons of Cu and CuZn electrodes, during Electrical Discharge Machining (EDM) of martensitic stainless AISI 410. The workpiece material was a rectangular plate, measuring 30x50x5 mm. The conditions of the EDM process were 3.0mm depth and 2.0 mm diameter, with variables of parameter being: currents, on/off-times and open circuit voltages of spark. Evaluation of the electrical discharge was conducted using Material Removal Rate (MRR), Electrode Wear Ratios (EWR) and Arithmetical Mean Roughness (Ra), respectively. The results found that CuZn electrode materials provide higher MRR and EWR than electrode materials of Cu. Also, when considering the melting of white layer, initial melts found that the white layer surface material is also good for the integrity of the state park, and it was additionally also found that when the current level increases, then that will rise accordingly.

Impact of the Parameters of Laser-Vibration Treatment on the Roughness of Aluminium Melts

This paper presents the preliminary, experimental results of laser-vibration treatment to increase the roughness of aluminium melts in compliance with EN AW-6060 (AlMgSi0.5). Using this method, metal objects are melted with a mobile laser beam while being vibrated. The effects of laser beam scanning velocity on the shapes of aluminium melts were studied at the set laser power and vibration frequency. The studied parameter was the mean roughness Ra. The value of Raparameter grew significantly. The studies were undertaken to employ this technology for the purpose of intensifying the exchange of heat in aluminium heating panels.

Study of electrical discharge machining parameters for mould steel AISI P20

This research paper aims to study the effect of parameters in Electrical Discharge Machining (EDM) process of mould steel AISI P20 when adjusted the parameter’s on-time, off-time, polarity electrode, and discharge current. The effects on the processing will be measured by investigating the Material Removal Rate (MRR), the Electrode Wear Ratio (EWR) and the surface quality from arithmetical mean roughness (Ra). The material used in the experiment is copper electrode on EDM of AISI P20 steel products. From the experiment it is found that the on-time and discharge current are affected to material removal rate, electrode wear ratio and the arithmetical mean roughness. When off-time decrease, material removal rate will be stimulated to increase but the off-time has only little effect to EWR and Ra.With regard to the polarity electrode, it is found that positive polarity electrodehas higher MRR and lower EWR than the negative polarity electrode, while the negative polarity electrode has better effect on surface quality than the positive when measured by Ra but there will be micro-cracking on the surface. The experiment shows that the best processing capability is at 100 μs on-time, 2 μs off-time, 14 A discharge current and positive polarity electrode, in which the MRR in experiment was 15.63 mm3/min and the EWR is 0.52 percent.

Fractal Dimension and Maximum Roughness Applied as Sculpture Descriptor for Tektites

X-ray computed tomography (three-dimensional μ-CT) as a non-destructive method is applied to a geological investigation. This technique is applied to the analysis of twelve tektites which provides detailed images of them in three dimensions. The visualisations of the CT extract the information for the evaluation of the surface profile by fractal dimension and statistical tools. The statistic roughness parameters, the maximum roughness Rt and the mean roughness Ra, are calculated through roughness profiles. The fractal dimension D describes complexity by one number and was estimated by the applied mix of the box-counting and ‘Minkowski sausage’ method. These methods were applied to describe the surfaces of tektites. The evaluation methods of geometry statistics resulted in different Rt, Ra and D data concerning their strewn fields. We suggest that the applied methods are appropriate as sculpture descriptors for tektites.

フォトリソグラフィ−陽極酸化−化学エッチングによるアルミニウム圧延板の装飾的表面加工

Surface patterning is an important technology for improving product design. This paper describes the fabrication of three-dimensional microstructures on aluminum plates using photolithography, anodization, and chemical etching. Photoresist patterns were prepared on an aluminum plate using a standard photolithography technique. The aluminum plate was anodized in sulfuric acid at a controlled concentration and bath voltage. During anodization, an anodic oxide film was formed on the photoresist/aluminum plate interface and in an open region. The oxide film formation was sensitive to both sulfuric acid concentration and bath voltage. The aluminum plate was expanded by anodization. The volume expansion factor (calculated as the ratio of the oxide film thickness to the thickness of the consumed aluminum) was 1.44-1.69.The oxide film was removed by chemical etching in phosphoric acid. Thereby, the aluminum surface was exposed, and convex shapes were formed. The surface roughness of the plate after chemical etching was comparable to its value before fabrication. The mean roughness Ra was <20 nm. Quadrangular pyramids, cones, and hexagonal pyramids were fabricated successfully on the aluminum plate by changing the photoresist mask pattern. Anodization and chemical etching conditions were controlled for accurate shape control of the three-dimensional metallic microstructures.

Biocompatible, Smooth, Plasma-Treated Nickel–Titanium Surface – An Adequate Platform for Cell Growth

High nickel content is believed to reduce the number of biomedical applications of nickel-titanium alloy due to the reported toxicity of nickel. The reduction in nickel release and minimized exposure of the cell to nickel can optimize the biocompatibility of the alloy and increase its use in the application where its shape memory effects and pseudoelasticity are particularly useful, e.g., spinal implants. Many treatments have been tried to improve the biocompatibility of Ni-Ti, and results suggest that a native, smooth surface could provide sufficient tolerance, biologically. We hypothesized that the native surface of nickel-titanium supports cell differentiation and insures good biocompatibility. Three types of surface modifications were investigated: thermal oxidation, alkali treatment, and plasma sputtering, and compared with smooth, ground surface. Thermal oxidation caused a drop in surface nickel content, while negligible chemistry changes were observed for plasma-modified samples when compared with control ground samples. In contrast, alkali treatment caused significant increase in surface nickel concentration and accelerated nickel release. Nickel release was also accelerated in thermally oxidized samples at 600 °C, while in other samples it remained at low level. Both thermal oxidation and alkali treatment increased the roughness of the surface, but mean roughness R(a) was significantly greater for the alkali-treated ones. Ground and plasma-modified samples had 'smooth' surfaces with R(a)=4 nm. Deformability tests showed that the adhesion of the surface layers on samples oxidized at 600 °C and alkali treatment samples was not sufficient; the layer delaminated upon deformation. It was observed that the cell cytoskeletons on the samples with a high nickel content or release were less developed, suggesting some negative effects of nickel on cell growth. These effects were observed primarily during initial cell contact with the surface. The most favorable cell responses were observed for ground and plasma-sputtered surfaces. These studies indicated that smooth, plasma-modified surfaces provide sufficient properties for cells to grow.

Experimental Characteristics of Aluminum Alloys in Dry End Milling

This paper describes the cutting characteristics of aluminum alloys in dry end milling experimentally. The tested materials are A1050, A2017, A2024, A5025 and A7075. The cutter is a flat end mill of Co-cemented High Speed Steel with the diameter of 20 mm. Through the experimental results of side milling, the following three aspects have been found out. Firstly, as to the machining error, A1050 showed smaller machining error than 15 μm in the cutting speed rage from 62.8 m/min to 251.3 m/min. Other Aluminum alloys showed greater values. Secondly, as to the cutting force, those of aluminum alloys except A2017 were generally proportional to their material hardness. The cutting forces of A1050 and A5052 were constant over the whole range of cutting speed. Thirdly, as to the machined surface roughness, A7075 showed the smallest surface roughness among the all materials with its arithmetical mean roughness Ra under 0. 2 µm and with its maximum height of profile Rz under 1 μm. The machined surface roughness of A2017 varied widely. Through the visual inspection of machined surface, A2017 and A2024 showed picked surface as generated by a built-up edge. This document explains and demonstrates how to prepare your camera-ready manuscript for Trans Tech Publications. The best is to read these instructions and follow the outline of this text. The text area for your manuscript must be 17 cm wide and 25 cm high (6.7 and 9.8 inches, resp.). Do not place any text outside this area. Use good quality, white paper of approximately 21 x 29 cm or 8 x 11 inches (please do not change the document setting from A4 to letter). Your manuscript will be reduced by approximately 20% by the publisher. Please keep this in mind when designing your figures and tables etc.

Interaction of water with glass at very high temperature under dynamic condition and the properties of the obtained glass surface

A conventional soda–lime–silicate glass-melt was treated with water vapor during the course of cooling from 1300 to 600 °C in less than a minute. The water vapor was generated spontaneously from a wet porous carbon substrate beneath the glass-melt. Within the treated glass surface, sodium was found to be depleted more and deeper than calcium. The morphology of the treated surface was found to be very smooth and homogeneous without defects (mean roughness Ra=0.26 nm ), unlike the water treatment at lower temperatures where the glass surface suffers from corrosion. As a consequence of the lower alkali concentration and homogeneous morphology, water vapor-treated surface showed improved chemical stability. The results are considered to be brought about by the combined effects of the alkali ion depletion through ion-exchange with hydronium ion, hydration, followed by the repeated hydrolysis and reformation of SiOSi bond. These processes are believed to be accelerated significantly at high temperatures.