Material Ratio Curve Research Articles

Surface Roughness Evaluation of AZ31B Magnesium Alloy After Rough Milling Using Tools with Different Geometries

This paper presents the experimental results of a study investigating the impact of machining parameters on 3D surface roughness after rough, dry milling. The following 3D roughness parameters were analysed: Sa (arithmetic mean height), Sq (root mean square height), Sz (maximum height), Sku (kurtosis), Ssk (skewness), Sp (maximum peak height), and Sv (maximum pit height). Roughness measurements were made on the end face of the specimens. Additionally, 3D surface topography maps and Abbot-Firestone material ratio curves were generated. Carbide end mills with variable rake and helix angles were used in the study. Experiments were conducted on AZ31B magnesium alloy specimens using a contact-type profilometer. The machining process was conducted using the parameters of so-called high-speed machining. Three variable technological parameters were analysed: cutting speed vc, feed per tooth fz, and axial depth of cut ap. The results showed that the surface roughness of the rough-milled specimens depended to a great extent on the tool geometry and applied machining parameters. Feed per tooth was found to have the greatest impact on surface roughness parameters. Lower values of the analysed surface roughness parameters (and therefore higher surface quality) were obtained (in most cases) for the tools with a rake angle γ of 5° and a helix angle λs of 50°. The results provided both theoretical and practical knowledge about the achievable surface roughness after rough milling using tools with different tool blade geometry. It was shown that rough milling is an effective and efficient type of machining for the AZ31B alloy.

Preliminary Study On the Function-Defining 3D Surface Roughness Parameters in Tangential Turning

The function-defining three-dimensional (3D) surface roughness parameters (which describe an aspect of the surface quality based on areal topography measurements) are studied on tangentially turned surfaces with different technological parameters in this paper. The 23 factorial design is applied in the planning of experiments. Two levels of depth of cut, cutting speed and feed were chosen for the comprehensive analysis of the tangential turning process. The values of Core Roughness, Reduced Peak Height, Reduced Valley Depth, Skewness and Kurtosis are measured by the application of a 3D areal roughness measurement machine. Equations were determined for the calculation of the studied parameters according to the factorial design method. The results were evaluated in two steps: first the functional parameters derived from the Areal Material Ratio curve were analyzed, then the Skewness and Kurtosis of the assessed area were studied. It is found that a two-fold increase in the cutting speed decreases the Core Roughness Depth, Reduced Peak Height, and Reduced Valley Depth 2-4-fold. The increasing feed rate lowers the presence of inordinately extremes, resulting in a smoother surface. In the point of view of Skewness and Kurtosis, lower cutting speeds and higher feeds are more favorable.

Generating synthetic as-built additive manufacturing surface topography using progressive growing generative adversarial networks

Numerically generating synthetic surface topography that closely resembles the features and characteristics of experimental surface topography measurements reduces the need to perform these intricate and costly measurements. However, existing algorithms to numerically generated surface topography are not well-suited to create the specific characteristics and geometric features of as-built surfaces that result from laser powder bed fusion (LPBF), such as partially melted metal particles, porosity, laser scan lines, and balling. Thus, we present a method to generate synthetic as-built LPBF surface topography maps using a progressively growing generative adversarial network. We qualitatively and quantitatively demonstrate good agreement between synthetic and experimental as-built LPBF surface topography maps using areal and deterministic surface topography parameters, radially averaged power spectral density, and material ratio curves. The ability to accurately generate synthetic as-built LPBF surface topography maps reduces the experimental burden of performing a large number of surface topography measurements. Furthermore, it facilitates combining experimental measurements with synthetic surface topography maps to create large data-sets that facilitate, e.g. relating as-built surface topography to LPBF process parameters, or implementing digital surface twins to monitor complex end-use LPBF parts, amongst other applications.

Metrological relations between the spray atomization parameters of a cutting fluid and formation of a surface topography and cutting force

Aerosol formation parameters are very important, as they are responsible for the ability of spray-forming droplets to penetrate the area to which they are applied. Research into modifying these parameters can therefore provide a solution for increasing the effectiveness of cooling and lubrication of the cutting zone during machining. This is particularly important for hard-to-cut materials such as titanium alloys, the machining of which requires the selection of effective cooling/lubricating methods to reduce tool wear or improve the machined surface quality. Previous research indicates that any modification in the air or oil flow rates – which form aerosols during cutting in minimized quantity lubrication (MQL) technique – contribute to an increase or decrease in the penetration of droplets into the cutting zone. It can consequently has a significant impact on machining results. This paper presents results on the effect of volumetric air flow rate P and cutting fluid mass flow rate E during the MQL cutting method on the machined surface topography after turning of Ti6Al4V alloy and the values of the cutting force. On the basis of conducted computational fluid dynamics (CFD) simulation studies, it was shown that the droplet size is more influenced by the change in volumetric air flow rate than cutting fluid mass flow rate and also that as the value of P increases, the droplet diameters decrease and the spray angle increases, which promotes the penetration of the cutting zone. As a result of the analysis of selected 3D surface roughness parameters, as well as contour maps, isometric views and material ratio curves, it was shown that the most favorable machined surface topography is being formed during MQL turning method with a volumetric air flow rate above 20 l/min. Whereby, with conditions of P = 30 l/min and E = 1.182 g/min, the machined surface topography is characterized by a uniform distribution of irregularity peaks and valleys, compared to the MQL turning with other tested values of aerosol formation parameters.

Evaluating Some Functional Properties of Surfaces with Partially Regular Microreliefs Formed by Ball-Burnishing

In the present work, functional properties of three different types of regular microreliefs, formed by ball burnishing process on flat surfaces are evaluated. For their estimation, heights and material ratio curve’s criteria were used, according to the international standard ISO 21920-2:2021. The influence of the regular relief’s type and ball burnishing process parameters on the surface functional properties were investigated using full factors experimental design. Based on the obtained results, statistical models were derived that describe the dependencies between the topography characteristics and the regular reliefs’ types and regime parameters of the ball burnishing process. Based on the obtained results, several conclusions have been formulated about the applicability of these standardized methods and criteria for evaluating the functional characteristics of the different types of regular reliefs at the end of the work.

Influence of Contour Scan Variation on Surface, Bulk and Mechanical Properties of LPBF-Processed AlSi7Mg0.6.

Metal additive manufacturing technologies have great potential for future use in load-bearing aerospace applications, requiring a deeper understanding of mechanical performance and influencing factors. The objective of this study was to investigate the influence of contour scan variation on surface quality, tensile and fatigue strength for laser powder bed fusion samples made of AlSi7Mg0.6 material and to create high-quality as-built surfaces. The samples were produced with identical bulk and different contour scan parameters to accommodate the investigation of the impact of as-built surface texture on mechanical properties. The bulk quality was evaluated by density measurements according to Archimedes' principle and tensile testing. The surfaces were investigated using the optical fringe projection method, and surface quality was assessed by the areal surface texture parameters Sa (arithmetic mean height) and Sk (core height, derived from material ratio curve). Fatigue life was tested at different load levels, and the endurance limit was estimated based on a logarithmic-linear relation between number of cycles and stress. All samples were found to have a relative density of more than 99%. Surface conditions distinctive in Sa and Sk were successfully created. The resulting mean values of the ultimate tensile strength σult are between 375 and 405 MPa for 7 different surface conditions. It was confirmed that the influence of contour scan variation on bulk quality is insignificant for the assessed samples. Regarding fatigue, one as-built condition was found to perform as well as surface post-processed parts and better than the as-cast material (compared to literature values). The fatigue strength at the endurance limit for 106 cycles is between 45 and 84 MPa for the three considered surface conditions.

Application of artificial neural networks (ANN) and gray relational analysis (GRA) to modeling and optimization of the material ratio curve parameters when turning hard steel

Application of artificial neural networks (ANN) and gray relational analysis (GRA) to modeling and optimization of the material ratio curve parameters when turning hard steel

Surface integrity of SLM manufactured meso-size gears in laser shock peening without coating

The present work aimed to improve the surface integrity of the selective laser melting manufacturing (SLM) manufactured 10 mm sized meso gears using the unconventional Laser Peening without Coating (LPwC) technique. To accomplish LPwC on meso gears low energy in the range of 200 mJ to 1000 mJ at 10 Hz were applied underwater in the gear root and fillet gap generating significant surface compressive residual stresses (from +73 MPa to −298 MPa). Besides the surface, residual stresses, average surface roughness (Ra), arithmetical mean height (Sa) and parameters of the material ratio curve were also considered as a part of the study. Notable improvement was achieved in Sa, as it improved over 50 % while considerable improvement in Ra and the material ratio curve parameters has also been observed. Scanning electron microscopy confirmed that the void and porosity seen in the unpeened gears were filled. The electron backscatter diffraction analysis confirms the grain refinement in LPwC region up to 100 μm depth. It was observed that multifold dislocation occurs within the grain, and dislocation generates sub-grain. The sub-grain formation substantially inhibits further nucleation and crack propagation owing to an increase in grain boundary density. Such improvement justifies the set objectives, and the outcome of this research will pave a foundation to improve the overall performance of the micro/meso parts using the LPwC process.

Acceleration of surface roughness evaluation using RANSAC and least squares method for Running-in wear process analysis of plateau surface

ISO 21920–2 defines an analysis method and the roughness parameters needed for evaluating the roughness of plateau structure surfaces. The roughness parameters are calculated by fitting straight lines to a material ratio curve. The analysis method by ISO 21920–2 cannot calculate the roughness parameters of surfaces with insufficient plateau structure. In previous studies, analysis methods that enable the calculation of roughness parameters for surfaces with insufficient plateau structure were proposed. However, these analysis methods have the problem that the algorithms do not achieve both automation and speed-up of the plateau surface analysis. Therefore, in order to solve this problem, we propose a new method called “Straight Lines Fitting using RANSAC and Least Squares Method (RLF method)”. RLF method enables the automatic and more than 100 times faster calculation of roughness parameters for surfaces with insufficient plateau structure. RLF method is expected to contribute to improvements in productivity at production sites.

Correlation between morphology parameters and skid resistance of asphalt pavement

Abstract Pavement skid resistance is critical for contributing to traffic safety. In this study, two pavement specimens were fabricated using different aggregate gradations and binder contents. Compaction efforts were made to ensure the same porosity of the two specimens. Some parameters related to the surface morphology were measured using the sand patching method and a 3D laser. The parameters include mean texture depth (MTD), interface roughness (Ra), skewness (Rsk), kurtosis (Rku), fractal dimension (D) and parameters related to material ratio curve. Relationships between these parameters and skid resistance were quantitatively developed. Skid resistance increased along with the increase of MTD, Raand D. From the surface A to surface B, MTDincreased from 0.23 to 1.10 mm, Ra increased from 0.93 to 1.80 mm, Dincreased from 2.25 to 2.43 and the British Pendulum Number increased from 80 to 97 accordingly. The comprehensive analysis could assist scholars and practitioners to facilitate the understanding of tyre-pavement interaction and further assist pavement design.

Surface texture analysis of different focal knee resurfacing implants after 6 and 12 months in vivo in a goat model.

The clinical success of osteochondral implants depends significantly on their surface properties. In vivo, an implant may roughen over time which can decrease its performance. The present study investigates whether changes in the surface texture of metal and two types of polycarbonate urethane (PCU) focal knee resurfacing implants (FKRIs) occurred after 6 and 12 months of in vivo articulation with native goat cartilage. PCU implants which differed in stem stiffness were compared to investigate whether the stem fixating the implant in the bone influences surface topography. Using optical profilometry, 19 surface texture parameters were evaluated, including spatial distribution and functional parameters obtained from the material ratio curve. For metal implants, wear during in vivo articulation occurred mainly via material removal, as shown by the significant decrease of the core-valley transition from 91.5% in unused implants to 90% and 89.6% after 6 and 12 months, respectively. Conversely, for PCU implants, the wear mechanism consisted in either filling of the valleys or flattening of the surface by dulling of sharp peaks. This was illustrated in the change in roughness skewness from negative to positive values over 12 months of in vivo articulation. Implants with a softer stem experienced the most deformation, shown by the largest change in material ratio curve parameters. We therefore showed, using a detailed surface profilometry analysis, that the surface texture of metal and two different PCU FKRIs changes in a different way after articulation against cartilage, revealing distinct wear mechanisms of different implant materials.

Effect of Process Parameters on the Surface Microgeometry of a Ti6Al4V Alloy Manufactured by Laser Powder Bed Fusion: 3D vs. 2D Characterization

The influence of the main process parameters, laser power, point distance and time exposure, on the surface microgeometry of Ti6Al4V specimens produced by a pulsed powder bed fusion process was investigated. A 3D characterization was carried out and collected data were elaborated to reconstruct the surface and to determine both the 3D and the 2D material ratio curves along different directions. The 3D material ratio curve gives a slightly lower material ratio of peak zone Mr1 and higher material ratio of valley zone Mr2, reduced peak height Rpk and reduced valley height Rvk than the 2D curves. Roughness is greater in the 3D analysis than in the 2D one, skewness is the same and kurtosis increases from <3 in 2D to >3 in 3D. Roughness and skewness increase on increasing point distance and decreasing time exposure and laser power. Within the investigated ranges (27.3–71.2 J/mm3), an increase in energy density reduces the surface roughness while skewness and kurtosis are not significantly affected. The results indicate that a 3D approach allows better characterization of the surface microgeometry than a 2D one.

Investigation on pulsed electrolytically polished AlSi10Mg alloy processed via selective laser melting technique

Currently, the surface integrity-related issues of additively manufactured parts are limiting the potential high-end applications. The present work investigates the effectiveness of the pulsed-electropolishing technique to improve the surface integrity of aluminium alloys fabricated using the selective laser melting (SLM) technique. Due to its low density, high corrosion resistance, the aluminium alloys considerably enhance the performance of lightweight critical parts for different industrial applications. In this study, selective laser melted AlSi10Mg samples were subjected to microstructural examinations using optical microscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy and X-ray diffraction technique. The microhardness and tensile properties were determined using a microhardness tester and a universal testing machine, respectively. The pulsed-electropolishing process was employed for the surface finishing of the SLM-processed AlSi10Mg samples. The effect of current density on the electropolishing of selective laser melted AlSi10Mg alloy were also investigated. The microstructures of printed samples revealed a density of greater than 99.9% and weld beads along the build direction (longitudinal) and laser scan paths perpendicular to the build direction (transverse). The microhardness, yield and tensile strength properties were similar in both as-printed conditions. The pulsed electropolishing results showed a beneficial effect of higher current density values, resulting in decreased surface roughness of the SLM-processed AlSi10Mg samples. Compared to as-printed conditions, a significant decrease in surface roughness of about ∼73.35% under optimized electropolishing conditions was noted. The material ratio curve shows that the surface topography becomes more uniform with increased current density and has lesser surface undulations for as-printed samples. The 2D line profilogram and 3D surface topography of electropolished SLM-processed samples reveal the surface finish quality characteristics. The material ratio curve aids as an effective method to assess and qualify the surface topography of electropolished samples.

Electropolishing of Inconel 718 manufactured by laser powder bed fusion: Effect of heat treatment on hardness, 3D surface topography and material ratio curve

In the present study, the laser powder bed fusion (LPBF) technique was used to produce Inconel 718 parts as a fabrication route. The LPBF processed samples microstructure, and surface characteristics were analyzed in both the as-printed and heat-treated conditions. The surface irregularities in the as-printed Inconel 718 was minimized using the pulsed electropolishing technique. The weld bead along the build direction and laser scan path to the build direction was observed. The electropolished results showed that increasing the current density and polishing time decreases the areal surface roughness of the as-printed sample (~64%) and heat-treated sample (~54%). The material ratio curve shows an increase in current density and electropolishing time; the surface topography becomes more uniform and lesser surface undulations for the as-printed samples and less uniform in the case of heat-treated samples. It was attributed to the interplay between microstructural constituent phases and electropolishing process parameters. The material ratio curve serves as an effective method to assess and qualify the surface characteristics of the electropolished LPBF processed samples. Furthermore, the 2D line profilogram and 3D surface topography benefit better understanding the surface finish quality characteristics of electropolished LPBF processed samples.

Nondestructive investigations of expansion gap concrete roughness

This paper presents the results of non-destructive investigations of concrete roughness in expansion gaps in reinforced concrete structures. The goal of this paper is to contribute to surface roughness measurement techniques. Concrete specimens with differently prepared surfaces: 1) not rubbed down, 2) manually cleaned and 3) mechanically cleaned were examined. The spatial geometric structure of the specimen surfaces was investigated using a scanning optical profilometer. Surface geometry, profile and roughness were measured. Then surface features were analysed and presented in the form of histograms, Abbott-Firestone material ratio curves and surface micro asperity profiles. Moreover, area-related surface topography parameters, i.e. height, frequency and hybrid parameters as well as functions and associated parameters, were determined. Then morphometric measurements, geometric profile and roughness measurements as well as analyses of the surface undulations and the spatial locations of the parameters were carried out. The results obtained for the mechanically prepared surfaces were found to be the best. The results were compared and conclusions important for building practice were drawn.

Material ratio curve of 3D surface topography of additively manufactured parts: an attempt to characterise open surface pores

Surface topography of additively manufactured components often contains 3D features, e.g. particles, open surface pores. X-ray computed topography can capture these features, allowing measurement data to be used for 3D surface texture characterisation. On the basis of the newly developed 3D surface texture parameters, this paper investigates material ratio curves of the surfaces produced by additive manufacturing processes, i.e. selective laser melting and high speed sintering. The material ratio curves of these surfaces vary in their shapes, depending on the specific process and associated process parameters, as well as surface orientations. Re-entrant topography features can result in recess shapes on the material ratio curve at the surface heights where these features locate. This unique characteristic makes the material ratio curve an effective analysis tool to differentiate various AM surface topographies, allowing surface texture to be linked with process control and functional assessment. Furthermore, (valley void volume) is identified as a useful volume parameter to characterise the open surface pores of AM surfaces. The material ratio for the determination of is discussed with the consideration of three options to address the open surface pores. The secant scanning approach proposed by ISO 13565-2 and the manual set ratio at the first sharp drop of the material ratio curve were found to be able to achieve reasonable results for the AM open surface pore characterisation.

Evaluation of Surface Topography after Face Turning of CoCr Alloys Fabricated by Casting and Selective Laser Melting.

The machinability of hard-to-cut CoCr alloys manufactured by Selective Laser Melting (SLM) technology is not yet sufficiently studied. Therefore, this work focuses on evaluation of surface texture formation during face turning of CoCr alloy. As part of the research, two specimen types were subject to comparison: made with the application of conventional casting and manufactured by additive manufacturing—SLM. A number of analytical and experimental methods were employed to describe the specimen composition and morphology, as: X-Ray Diffraction Analysis (XRD), optical metallurgical microscopy, confocal optical microscopy, and Vickers hardness HV0.1 measurements. In the next stage, the measurements of surface topographies formed during turning in a range of variable cutting speeds and feeds were carried out. Ultimately the multi-factor MANOVA (Multivariate Analysis of Variance) illustrating the influence of manufacturing technology, cutting speed, and feed ratio on selected surface parameters of samples was made. It has been demonstrated that during face turning with feeds up to 0.15 mm/rev, the similar values of surface roughness height and material ratio curve parameters were reached for both tested CoCr alloys. However, in a range of higher feed values, the surface quality of CoCr samples fabricated by SLM was lower than that reached for CoCr after casting process.

Forecast of the fatigue crack initiation site of commercially pure Titanium miniature specimens with local surface topography data

Surfaces of technical components rarely appear in perfectly smooth condition. During fatigue loading, stress concentrations at surface asperities cause localized plastic deformation that can lead to crack initiation. Therefore, we have established a computer-aided method based on material ratio curves to investigate the possibility to predict the crack initiation site in fatigue tests by using detailed information on the local surface topography.The present study shows the results of investigations on the mutual influence of the average grain size and the surface condition on the fatigue behavior of commercially pure Titanium (cp-Ti) miniature specimens. Three cp-Ti states were investigated: two types of coarse-grained cp-Ti Grade 2 with 35 µm and with 100 µm average grain size and one ultrafine-grained cp-Ti Grade 4 state with less than 2.5 µm average grain size. Confocal microscopy provided the surface topography data of all specimens and data post-processing was applied to the topography in order to locate critical areas where crack initiation may preferentially occur. These areas were compared with the actual crack initiation areas in fatigue test. Finally, scanning electron microscopy (SEM) images of the fracture surfaces were studied to analyze fatigue crack initiation site and crack path of the three microstructural states.

Effects of Surface Roughness Parameters on Tribological Performance for Micro-textured Eutectic Aluminum–Silicon Alloy

Abstract Micro-textured samples with different depths exhibit various contact surface morphology parameters including Sa, Sq, Ssk, and Sku, and material ratio curves. In this paper, the relationship between micro-textures and roughness parameters was investigated. The effect mechanism of micro-textures on the friction and wear through the height and functional roughness parameters was elucidated. Micro-textured samples presented more negative Ssk, higher Sku, and larger Svk with the increasing dimple depth. The pin-on-disc reciprocating tribological test results indicated that the more negative Ssk, higher Sku, and larger Svk presented lower friction coefficient under the constant Sa and Sq. The wear topographies for the flat and micro-textured specimens with various dimple depths were examined by laser scanning confocal microscope. X-ray photoelectron spectroscopy was employed to describe the formation of absorbed film and tribofilm on the worn surface of flat and micro-textured samples. It was confirmed that more negative Ssk, higher Sku, and material ratio curves with their relative parameters (smaller value of Spk, Sk, Smr1, and larger value of Svk) could be used for predicting the tribological performance of micro-textured samples.

Impact of Processing Parameters on Surface Roughness and Strain Hardening of Two-Phase Stainless Steel

Abstract Products used in the construction of machines and shipbuilding as well as petrochemical industry, such as shafts, bars, pipes and the like from two-phase stainless steel are currently very popular. It is required that they meet certain quality criteria. They must be characterized by suitable properties of the surface layer to meet the requirements of potential buyers. In the article impact of processing parameters on the degree of relative strain hardening and index of surface roughness reduction were presented. The burnishing process was carried out for two-phase stainless steel. Burnishing process of the shafts neck was performed using burnisher roller. The experimental research were obtained in the surface layer increase in hardness and the material ratio curve a convex shaped, which, taking into account the load capacity of the surface will be directly affected by its resistance to wear and corrosion. The experimental research by application of the burnishing process was made in the Laboratory of Production Engineering. After the studies it was found that the hardness of the surface layer and the roughness of the shaft necks an important influenced by technological parameters of processing (burnishing speed, feed rate and depth of burnishing). The objective of applying burnishing process may be, for example, the need to increase surface smoothness and dimensional accuracy of part.