Search Results (20)

Skin-pass cold rolling is a crucial step in sheet metal production, modifying the sheet surface topography, ensuring thickness uniformity, and enhancing tribological performance. A key factor in this process is the surface texturing of work rolls, which, when transferred to the rolled sheet, directly affects lubrication distribution and formability in subsequent stamping operations. Properly textured sheets promote lubricant retention, reducing friction and wear, while roll wear can compromise texture transfer, leading to defects in the final product. This review presents a holistic view of surface texturing from the roll topography to the final product. First, it explores different texturing methods for work rolls, analyzing their efficiency, durability, and impact on texture transfer. Then, alternative texturing techniques and coatings are discussed as strategies to mitigate roll wear. By assessing the relationship between roll texturing and sheet drawability, this study provides insights to improve industrial processes, enhance product quality, and promote more sustainable manufacturing solutions. Full article

The effect of extreme water repellency, called the lotus effect, is caused by the formation of a Cassie–Baxter state in which only a small portion of the wetting liquid droplet is in contact with the surface. The rest of the bottom of the droplet is in contact with air pockets. Instrumental methods are often used to determine the textural features that cause this effect—scanning electron and atomic force microscopies, profilometry, etc. However, this result provides only an accurate texture model, not the actual information about the part of the surface that is wetted by the liquid. Here, we show a practical method for estimating the surface fraction of texture that has contact with liquid in a Cassie–Baxter wetting state. The method is performed using a set of ethanol–water mixtures to determine the contact angle of the textured and chemically equivalent flat surfaces of AlSI 304 steel, 7500 aluminum, and siloxane elastomer. We showed that the system of Cassie–Baxter equations can be solved graphically by the wetting diagrams introduced in this paper, returning a value for the texture surface fraction in contact with a liquid. We anticipate that the demonstrated method will be useful for a direct evaluation of the ability of textures to repel liquids, particularly superhydrophobic and superoleophobic materials, slippery liquid-infused porous surfaces, etc. Full article

This paper explores the impact of various milling strategies, including up-milling, down-milling, and hybrid approaches, on the surface roughness of AISI P20 mold steel. The study is methodically divided into three stages to comprehensively understand the effects of these strategies. The first stage involves milling single slots with varying cutting parameters to establish baseline effects. The second stage examines the effects of consistent milling strategies (up-up and down-down) on surface quality. The third stage probes into hybrid strategies (up-down and down-up) to assess their effectiveness. Central to this investigation is not only the type of milling strategy but also how cutting speed and feed rate influence the resultant surface roughness. Our findings indicate that up-milling generally leads to a 22% increase in surface roughness compared to down-milling. This trend is visually verified by surface texture analyses. When comparing consistent strategies, up-up milling tends to produce rougher surfaces than down-down milling by approximately 25%, characterized by distinctive scratches and feed mark overlays. Remarkably, while the hybrid milling strategies do not exhibit significant differences in surface roughness, variations in cutting speed and feed rate play a crucial role. Specifically, at lower speeds, hybrid milling achieves smoother surfaces than the identical double milling mode, while at a cutting speed of 100 m/min, the double mode demonstrates a notable decrease in roughness. Additionally, this study introduces a color mapping simulation for machined pockets, validated by experimental results, to predict surface roughness based on the strategic history of milling, thereby offering valuable insights for optimizing milling processes. Full article

The formation of a dense fibrous capsule around the foreign body and its contracture is the most common complication of biomaterial implantation. The aim of our research is to find out how the surface of the implant influences the inflammatory and fibrotic reactions in the surrounding tissues. We made three types of implants with a remote surface topography formed of polylactide granules with different diameters: large (100–200 µm), medium (56–100 µm) and small (1–56 µm). We placed these implants in skin pockets in the ears of six chinchilla rabbits. We explanted the implants on the 7th, 14th, 30th and 60th days and performed optical coherence tomography, and histological, immunohistochemical and morphometric studies. We examined 72 samples and compared the composition of immune cell infiltration, vascularization, the thickness of the peri-implant tissues, the severity of fibrotic processes and α-SMA expression in myofibroblasts. We analyzed the scattering coefficient of tissue layers on OCT scans. We found that implants made from large granules induced a milder inflammatory process and slower formation of a connective tissue capsule around the foreign body. Our results prove the importance of assessing the surface texture in order to avoid the formation of capsular contracture after implantation. Full article

Seizure during ironing negatively affects the quality of parts and die life. To prevent seizures, lubrication has to be improved. In this study, laser-textured dies with lubricant pockets were utilized to improve seizure resistance in the ironing of aluminum alloy sheets and stainless steel cups. The effects of array patterns of micro-pockets, such as grid and crossing array patterns with circular pockets, as well as a grooved array patterns on seizure resistance, were experimentally examined by strip ironing. The sheet and die materials were the A1050-O aluminum alloy and JIS SKD11 tool steel, respectively. Moreover, the underlying physics of the lubricant flow influencing the load-carrying capacity were investigated using three-dimensional computational fluid dynamics simulations. The optimum array patterns of the micro-pockets were then utilized on a tungsten carbide-cobalt (WC-Co) die surface for ironing SUS430 stainless steel cylindrical cups. The strip ironing results showed that the grid array pattern was successful in ironing sheets with a high ironing ratio. The grid array pattern increased the load-carrying capacity of the lubricant more than the crossing pattern, as demonstrated by the simulations, thereby improving the ironing limit. The subsequent ironing of stainless steel cups revealed that when using a textured die with a grid array pattern and lubricant without the extreme pressure additive in comparison to an untextured die, the ironing limit increased by 6% and the average ironing load decreased by 35%. The seizure resistance was improved because the pockets on the surface structured by laser surface texturing improved the load-carrying capacity during ironing. Full article

This study reports the possibility of obtaining sugar-free WPI-based macarons with erythritol addition. The whey protein isolate (WPI) solution (20%, w/v) was whipped, and erythritol was added to the foam at concentrations of 20, 40, and 60 g, with 125 g of almond flour. The rheological properties (τ, G′, G″, and tan (δ)) and stability of the macaron batters before baking were evaluated. In order to produce the macarons, the batters were solidified at 147 °C for 12 min. The textural and surface properties (roughness and color), as well as the microstructures and water activities, were determined for the macarons. It was feasible to produce macarons over the entire range of the tested erythritol content. Even the smallest amount of erythritol (20 g) facilitated the preservation of the macaron structure. The medium erythritol concentration (40 g) improved the stability of the batters and their rheology and was the most effective for air pocket stabilization during baking; however, its largest addition (60 g) resulted in an increase in the final macaron volume. The increased erythritol addition improved mechanical properties and shelf life, producing a smoothing effect on the macaron surfaces and having a significant effect on their color co-ordinates. Full article

Characterization of surface topography, roughly divided into measurement and data analysis, can be valuable in the process of validation of the tribological performance of machined parts. Surface topography, especially the roughness, can respond straightly to the machining process and, in some cases, is defined as a fingerprint of the manufacturing. When considering the high precision of surface topography studies, the definition of both S-surface and L-surface can drive many errors that influence the analysis of the accuracy of the manufacturing process. Even if precise measuring equipment (device and method) is provided but received data are processed erroneously, the precision is still lost. From that matter, the precise definition of the S-L surface can be valuable in the roughness evaluation allowing a reduction in the rejection of properly made parts. In this paper, it was proposed how to select an appropriate procedure for the removal of the L- and S- components from the raw measured data. Various types of surface topographies were considered, e.g., plateau-honed (some with burnished oil pockets), turned, milled, ground, laser-textured, ceramic, composite, and, generally, isotropic. They were measured with different (stylus and optical) methods, respectively, and parameters from the ISO 25178 standard were also taken into consideration. It was found that commonly used and available commercial software methods can be valuable and especially helpful in the precise definition of the S-L surface; respectively, its usage requires an appropriate response (knowledge) from the users. Full article

Surface friction in metal forming processes can be reduced by creating lubricant reservoirs at the interface between surfaces in contact, and a laser texturing process can be employed to produce the micro-dimples that act as the reservoirs on the surfaces. However, the role of the laser texturing parameters in the friction reduction of tool steel surfaces has still received very little attention. Therefore, this study aims to reduce the friction of the AISI D2 tool steel surface on which a nanosecond pulse laser was applied to create an array of micro-lubricant pockets for trapping lubricant. The effects of laser power, irradiation duration, and spacing distance between pockets on the pocket diameter, size of the heat-affected zone, surface friction, and wettability were investigated in this work. The average laser power in the range from 5 to 10 W and laser irradiation duration of 0.02 to 0.10 s were applied. The results showed that the increase in laser power and irradiation duration enlarged the pocket diameter and heat-affected zone. The largest pocket diameter of 40 µm was achievable by using 10 W laser power together with 0.10 s irradiation time. The pin-on-disc method was employed to determine the friction coefficient of the tool steel, where JIS SPFC 980Y advanced high-strength steel was used as a disc. The friction coefficient of laser-textured with different spacing distances of 150, 200, and 250 µm versus untextured surfaces was compared and found to vary depending on the applied normal load. The laser-textured surface having a pocket spacing distance of 150 µm and pocket density of 5.6%, offered the lowest friction coefficient of 0.097 on average for all tested loads, whereas the average friction coefficient of the untextured surface was 0.117. In addition, the wettability of textured surfaces was insignificantly changed compared to that of untextured ones, so the micro-lubricant pockets did not cause oleophobicity affecting the performance of lubrication. Well-defined micro-pockets using the most appropriate laser parameters, i.e., 10 W laser power with 0.10 s irradiation duration and 150 µm spacing distance, successfully reduced the sliding friction of contacting couples between the laser-textured tool steel and advanced high-strength steel surfaces. The low surface friction induced by the laser-fabricated micro-lubricant pockets has been feasible for the forming tool and die applications where the energy consumed in their operations can be minimized. Full article

The most common long-term complication of silicone breast implants (SMI) remains capsular fibrosis. The etiology of this exaggerated implant encapsulation is multifactorial but primarily induced by the host response towards the foreign material silicone. Identified risk factors include specific implant topographies. Of note, breast implant-associated anaplastic large cell lymphoma (BIA-ALCL) has only been observed in response to textured surface implants. We hypothesize that reduction of SMI surface roughness causes less host response and, hence, better cosmetic outcomes with fewer complications for the patient. A total of 7 patients received the routinely used CPX^®4 breast expander (~60 µM Ra) and the novel SmoothSilk^® (~4 µM Ra), fixed prepectoral with a titanized mesh pocket and randomized to the left or right breast after bilateral prophylactic NSME (nipple-sparing mastectomy). We aimed to compare the postoperative outcome regarding capsule thickness, seroma formation, rippling, implant dislocation as well as comfortability and practicability. Our analysis shows that surface roughness is an influential parameter in controlling fibrotic implant encapsulation. Compared intra-individually for the first time in patients, our data confirm an improved biocompatibility with minor capsule formation around SmoothSilk^® implants with an average shell roughness of 4 µM and in addition an amplification of host response by titanized implant pockets. Full article

Surface topography in general is not easy to characterize due to a great number of different features that appear on it. It is still more challenging for machined textured surfaces that are of high functional significance for tribological purposes. For practical reasons, there is a need to describe such surfaces using only a small number of parameters. Which of them represent surface details the best is still an open issue. To find out which parameters can be the most suitable in that case, three groups of machined textured surfaces were prepared. They were plateau-honed cylinder surfaces made of gray cast iron, steel, and bronze surfaces with isolated dimples and steel surfaces after abrasive blasting followed by lapping. All of them were measured by means of a white light interferometer. Different parameters and relationships were evaluated and based on them correlation and regression analyses were used. The basic description contained statistically independent parameters that can be used in production control, while the wider description in scientific research. In general, parameters of random surfaces were more intercorrelated than those of surfaces with isolated dimples. As was found for the basic description of random two-process surfaces, five parameters were enough while description of textured surfaces with isolated oil pockets needed six. In wider, scientific description, regardless the surface type seven parameters contained the necessary information about the surface. It was also proved that a pair of parameters, the emptiness coefficient Sp/Sz and Sq/Sa, can describe the shape of the ordinate distribution of machined textured surfaces better than, for example, skewness Ssk and kurtosis Sku, commonly used for that purpose. Full article

Studies of surface topography including processes of measurement and data analysis have an influence on the description of machined parts with their tribological performance. Usually, surface roughness is analysed when a scale-limited (S-L) surface, excluding short (S-) and length (L-) components from the raw measured data, is defined. Errors in the precise definition of the S-L surface can cause the false estimation of detail properties, especially its tribological performance. Errors can arise when the surface contains some burnished details such as oil pockets, dimples, scratches, or, generally, deep or wide features. The validation of proposed methods for S-L surface definition can also affect the accuracy of the ISO 25178 surface topography parameter calculation. It was found that the application of commonly used procedures, available in commercial software (e.g., least-square fitted cylinder element or polynomial planes, regular or robust Gaussian regression, spline, median or fast Fourier transform filters) can be suitable for precise S-L surface definition. However, some additional analyses, based on power spectral densities, autocorrelation function, texture direction graphs, or spectral characterisation, are strongly required. The effect of the definition of the S-L surface on the values of the ISO 25178 parameters was also comprehensively studied. Some proposals of guidance on how to define an appropriate S-L surface with, respectively, an objective evaluation of surface roughness parameters, were also presented. Full article

The effect of cylinder liners on engine performance is substantial. Typically, the cylinder surfaces were plateau honed. However, recently additional dimples or grooves were created on them. This work discusses the tribological impacts of textured cylinder liner surfaces based on a review of the literature. The results of the experimental research obtained using test rigs and fired engines were critically reviewed. In addition, the results of the modeling are shown. Circular oil pockets and grooves perpendicular to the sliding direction of piston rings of small depths were typically used. Surface texturing of the cylinder liners governs lubrication between the cylinder liner and the piston ring by an increase in oil film thickness near the reversal points leading to reductions in friction force and wear and in the fired engine to a decrease in fuel consumption and to an increase in power or torque. The correct texturing pattern ensures a decrease in the oil consumption, blow-by, and emissions of the internal combustion engine compared to plateau-honed surfaces. Considerations of future challenges are also addressed. The volume of lubricant reservoir in surface topography, called oil capacity, should be a substantial parameter characterizing textured surfaces. Full article

The article discusses the effect of milling strategies on surface quality and geometric deviations during pocket milling when the perpendicular position of the tool is used. For experimental research, an aluminum alloy, AlCu4Mg, was used. For the production, a three-axis milling machine was used, and consequently, the geometric deviations and roughness parameters of the machined surface were evaluated. Also, the surface texture from each strategy was compared. For the production strategy, the constant Z, circular pocket, constant stepover pocket auto border, and spiral strategies were used. The geometric characteristic evaluation showed the influence of the ball end mill used in the machining process. Constant Z strategy achieved the lowest shape deviations. In the spiral strategy, it was possible to observe an effect of plowing, where the cutting tool crushed the material at the tool center. There was a minimal effect on the surface texture in the circular pocket and constant stepover pocket auto border strategies. Using the constant Z strategy, a non-oriented surface texture was obtained. 3D maps of the extracted residual scallop height for each strategy were observed when examining the surface texture. The roughness parameters Ra and Rz for the circular pocket and constant stepover pocket auto border strategies were the lowest. Full article

Surface texturing can improve lubrication and entrap wear debris but increases the effective roughness of the surfaces, which can induce higher contact pressures. On the one hand, this can be detrimental, but on the other hand, the increase in contact pressure could be used to activate the formation of a ZDDP tribofilm from fully-formulated lubricants. This work investigates the synergistic effect between surface texturing via Maskless Electrochemical Texturing (MECT) and ZDDP additive. The surface texture consisted of an array of annular pockets manufactured on a gray cast iron cylinder liner. These textured surfaces were evaluated by scanning electron microscope (SEM) and energy-dispersive X-ray spectroscopy (EDX). The results indicated that surface texturing via MECT changes the chemical composition of the surfaces, by inducing a preferential dissolution of the metal matrix. Consequently, it exposed the carbon present in the material. The tribological performance was evaluated by a ring-on-cylinder-liner tribometer in reciprocating sliding under boundary lubrication conditions using both a base oil and a commercial formulated oil containing ZDDP additive. For comparison, a commercially honed liner was also tested. After the tribological tests, the surfaces were evaluated by white light interferometry and SEM/EDX. Although the textured surfaces showed higher friction, they induced more ZDDP-tribofilm formation than conventional cylinder liner finish. Full article

Various methods, based on both surface frequency and direction, can be alternatively proposed to reduce the influence of high-frequency measurement and data analysis errors. Various types of details were studied, e.g., cylinder liners after the plateau-honing process, plateau-honed cylinder liners with additionally burnished oil pockets (dimples), turned, ground, milled or laser-textured. They were measured with stylus or non-contact (optic) techniques. It was suggested to support various frequency-based methods, e.g., Frequency Spectrum, Power Spectral Densities or Autocorrelation Function, with direction techniques to provide reduction of errors in both detection and extraction of high-frequency measurement errors. Results can be especially valuable for regular studies when frequency-based measurement errors are difficult to be identified. Full article