Improved Surface Roughness Research Articles

A Study on the Machinability and Environmental Effects of Milling AISI 5140 Steel in Sustainable Cutting Environments

AISI 5140 steel is an alloy frequently used in the manufacturing and automotive industries. This steel alloy is shaped using different manufacturing methods and cooling is required during this process. This research study included the milling of AISI 5140 steel utilizing various cutting settings and cooling/lubrication procedures. For this purpose, two cutting speeds (75–100 m/min), two feed rates (0.075–0.100 mm/rev), and four cooling media (dry, MQL, flood, nanofluid) were used. Then, 5% Mo nanoparticles were added to the nanofluid cutting fluid. Machinability and power consumption analyses were carried out using the input parameters selected in light of the manufacturer’s recommendations and studies in the literature. The effects of sustainable cutting fluids and their parameters on machinability and power consumption were investigated through experiments. This study concluded that the use of nanofluid led to improvements in surface roughness, flank wear, and power consumption characteristics. It was determined that the flood environment is the most effective in reducing the cutting temperature. As a result, it is predicted that nanofluid cutting fluids can be used during machining.

On surface texture evolution in abrasive flow machining

ABSTRACT Abrasive Flow Machining (AFM) is highly effective for precise surface control and finishing. The process’s material removal mechanism significantly impacts surface quality, especially in complex parts. However, little research addresses how initial micro-surface textures affect AFM outcomes. This study prepared four types of initial surface profiles and machined them using various abrasive media particle sizes. The rheology of the abrasive media was analyzed, with a custom guide restricting the fluid domain to create gradient flow changes. Both experimental and simulated one-way and two-way AFM processes were conducted. Results demonstrated that the material removal efficiency improved according to an enhanced version of Preston’s equation for flat surfaces. Initial surface textures exerted more influence on material removal than anticipated. All abrasive media sizes yielded uniform surface quality, with surface roughness improvements exceeding 80%. Larger initial surface textures experienced greater material removal. Chemical element analysis confirmed the AFM process is contamination-free.

EXPERIMENTAL INVESTIGATION ON ONE-WAY ABRASIVE FLOW MACHINING ON HOT WORK STEEL

Abrasive flow machining (AFM) is a process where a semi-solid abrasive-laden media is forced to flow through the internal passages of a workpiece under pressure. In high-resolution work, increased accuracy and faster smooth surface polishing work with the developed motorized AFM prototype. This research presents the effect of the clearance of specimen tools for surface roughness (Ra) of SKD 61 (AISI H13) hot work steel related to AFM. This research experimented with half-spherical specimens. AFM experiments are performed to identify the improved surface roughness when applied to the polishing specimens. Specimens were prepared by being turned, hardened, and polished with sandpaper from number P180 to P1200 and measured with an original value of Ra compared with the final value of Ra at the end of the process. The experimental prototype uses a unidirectional motor drive system different from previously developed machines. The process parameters are as follows: a pressure (p) of 1, 2, and 3 bar, cycle time (t) of 10, 15, and 20 min., an abrasive particle size (Al2O3) of 5.0 μm in Silicon Oil (50 % concentration by weight), hardness of specimens 45±2 HRC, etc. The experimental results show that under these conditions, the average surface roughness of specimens was decreased from an original value of Ra 0.057 to 0.042 μm. The greatest response surface (RSM) was obtained at a pressure of 3 bar and a time of 20 minutes. The result allows for better precision control and further development in industrial applications.

Digital etching of AlGaN/GaN heterostructures with GaN cap using inductively coupled oxygen plasma process combined with wet chemical treatment

In this work, AlGaN with a GaN cap has been etched in a cyclical process with ICP-RIE O2 plasma oxidation and wet etching in dilute HCl. The oxygen plasma ICP-RIE etching of the AlGaN at an ICP plasma power of 200 W and radio frequency bias power of 100 W led to an etch depth of ∼1.5 nm per digital cycle with increased surface roughness. The AlGaN remained unaffected by the wet etching process alone without any ICP-RIE O2 plasma oxidation, maintaining a surface roughness similar to that of the substrate. AlGaN was etched to a depth of ∼12 nm after six cycles of digital etching with an etch rate of 1.9–2.1 nm/cycle showing an improved surface roughness. The XPS analysis at each stage of the etching process reveals that the O2 plasma oxidation initially oxidizes the GaN cap and the AlGaN layer and is later effectively removed by the HCl solution. The digital etching method has proven effective in controlling etch depth and surface roughness, which are needed to fabricate AlGaN high electron mobility transistors.

Expanding manufacturability of sheet-based triply periodic minimal surfaces by electron beam powder bed fusion in Wafer theme

Porous biomaterials based on triply periodic minimal surfaces (TPMS) are intensely studied and discussed in the literature. Manufacturing of these structures with a complex geometry became possible using additive manufacturing methods, having their own specifics and challenges. Previously, we demonstrated that sheet-based gyroids, one of TPMS structures, manufactured by electron beam powder bed fusion in Melt and Wafer themes could possess identical mechanical properties (quasi-elastic gradient). In the current research sheet-based gyroids were produced using Wafer Theme with five different settings, including electron beam current and scan speed variation with MultiBeam turned on and off, in attempt to obtain thin walls without losing mechanical performance. Mechanical tests revealed that the specimens manufactured with higher beam line energy on average show better mechanical properties. The specimens produced with MultiBeam showed slightly lower mechanical properties, and do not demonstrate significant improvement in the TPMS surface roughness. According to SEM studies, the average wall thickness was about 0.4 mm for specimens with high line energy, and 0.3 mm for low line energy. Through-hole defects on the horizontal surfaces, noticed and discussed by us previously, have larger average area of the hole and more irregular shape for increased beam line energy. TPMS surface morphology of the specimens produced with higher beam energy and no MultiBeam was on average more even. According to EBSD, α/α` martensite with laths oriented in a Widmanstätten basket-weave pattern was observed with no β phase in the resulting material. No significant differences in microstructure between specimens produced with different beam energy was detected. FEA modeling revealed the impact of the wall thickness, through holes size and orientation on quasi-elastic gradient of a gyroid. It was demonstrated that, through holes with small size located on the horizontal surfaces (layer plane) have only a minor impact on the mechanical properties of the samples if they are not extremely abundant.

The Study of Patterns and Mechanisms of Continuous Laser Ablation of Carbon Steel Rust Layers in Multi-Medium Environments

A new multi-scenario, low-cost, high-efficiency, medium-assisted continuous laser cleaning of corrosion layers was developed. By comparing the roughness and cleaning depth of rust layers cleaned under conditions of liquid-assisted, solid-assisted, and mixed solid–liquid-assisted laser cleaning, simultaneously establishing a three-dimensional finite element model to study the variations during the cleaning process, and conducting a comparative analysis of the results of both, the cleaning mechanism is elucidated. The experimental results indicate that under conditions of water-assisted cleaning, the depth of rust layer increases initially and then decreases with varying water layer heights. The maximum cleaning depth is achieved at a water layer height of 0.1 mm, while the optimal surface roughness occurs at a water layer height of 0.2 mm, indicating a change in cleaning mechanism. The cleaning pattern with SiO2 activator assistance follows a similar trend to a water medium, reaching maximum cleaning depth at 0.1 mm height, with a slight improvement in surface roughness compared to water-assisted cleaning. Finally, solid–liquid mixing can achieve cleaning completion and improve surface roughness under conditions where water-assisted cleaning alone fails to reach a clean state. Therefore, the active agent can be used for laser cleaning to promote the cleaning process, and solid–liquid mixing to assist the laser cleaning can be a theoretical guide for the field of laser cleaning.

Investigation of scanning strategies on performance of nanosecond and picosecond laser volume ablation of bronze

Understanding of laser volume ablation performance in different scanning strategies is indispensable for practical applications. This study investigates the influence of different laser scanning parameters on the performance of volume ablation of bronze material. The results reveal significant differences between the selected pulse durations of 16 ns (ns) and 12 picoseconds (ps), despite both using an identical maximum average power of 40 W. In both cases, increasing the scanning area resulted in a proportional increase in ablation depth. Compared to the ns-laser, the ps-laser exhibited significantly lower ablation depths, approximately 35 % to 40 % less, with consistent performance across different scanning directions. Surface topography analysis showed that scanning direction played a crucial role in determining the final surface quality, with a nearly 50 % improvement observed with the mixed scanning strategy. With the ps-laser, expanding the scanning area led to reduced surface roughness, primarily due to pure ablation and minimal surface re-melting. Further strategies, such as interlace and halftone were also explored. Adjusting the line delay time was also considered, with longer delays potentially resulting in deeper ablation and slightly improved surface roughness. The study also investigated the pitting phenomenon, which was found to be intensified around contour edges. Notably, pitting was more pronounced in ns ablation during the initial scanning layers, while in ps ablation, pitting distribution intensified with an increase in scanning layers and ablation depth.

Scaling up laser polishing using a polygon scanner

AbstractSurface roughness has a significant influence on the performance and appearance of components. By combining a boost laser with ultrafast beam deflection using a polygon scanner, very high processing speeds can be achieved. A 65 % improvement in surface roughness has been achieved on stainless steel, with Sa < 0.1 μm, while the gloss has increased from 130 to 366 GU. As a result, the previously matt surface became reflective, improving the appearance of the material. A real area rate of 156 cm2/s was achieved, comparable with industrial process times.

Zinc oxide bridges the nanofillers to enhance the wear resistance and stability of triboelectric nanogenerators

Triboelectric nanogenerators (TENGs) have received widespread attention as a means of harvesting mechanical energy from the environment and converting it into electricity. As people continue to explore the field of infinite sensors, traditional TENGs have faced persistent challenges in practical application, mainly due to the poor abrasion resistance and stability of the existing polymers commonly used. Herein, the polyphenylene sulfide (PPS) was melt blended with liquid crystal polymer (LCP) to be used as matrix, and the interfacial bonding strength between the matrix and filler was improved by zinc oxide (ZnO) grafted carbon nanotubes/graphene oxide (CNTs/GO). Under friction conditions of 100 N load and 0.5 m/s, the friction coefficient and wear rate of resultant nanocomposites were significantly reduced to 0.2 and 2.09 × 10-5 mm3/N, respectively. The abrasion resistant TENG (AR-TENG) was fabricated based on 0.3ZnO/CNTs/GO/LCP/PPS exhibited outstanding electrical output performance, which was attributed to the high dielectric constant of 5.3, improved surface roughness and interfacial contact area of composites. Consequently, this study reported a novel approach to tailor AR-TENG into a highly abrasion resistant and stable sensor. This customization enabled the AR-TENG to operate reliably in harsh environments (high temperatures and humidity), thereby expanding its potential applications.

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

Abstract Surface roughness is a critical indicator to evaluate the quality of 4H-SiC grinding surfaces. 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, we proposed a new analytical model for predicting surface roughness in 4H-SiC wafer rotational grinding, 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 analyze the distribution of the failure mode (ductile or brittle) on the surface of a material when the depth at which the material is cut instead follows a random distribution known as the Rayleigh distribution. To validate the accuracy of the established 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 this model and the traditional model. The findings demonstrate that the calculated data obtained from the proposed model exhibit better agreement with the measured data. This research addresses the need for an improved surface roughness model in 4H-SiC wafer rotational grinding.

Surface Topography in Cutting-Speed-Direction Ultrasonic-Assisted Turning.

Ultrasonic vibration has been employed to assist in turning, introducing intermittent machining to reduce average cutting force, minimize tool wear, and enhance machining efficiency, thereby improving surface roughness. However, achieving intermittent cutting necessitates specific conditions, with a cutting speed or feed rate falling below the critical speed associated with the ultrasonic vibration parameters. This study presents a theoretical model for surface formation in cutting-speed-direction ultrasonic-assisted turning (CUAT), covering both continuous and intermittent machining regimes. Experimental validation was conducted on C45 carbon steel and 201 stainless steel to demonstrate the applicability of the theoretical model across different materials. Digital microscope analysis revealed 3D topography consistency with the theoretical formula. Surface roughness evaluations were performed for both CUAT and CT (conventional turning) methods. The results indicated a significant reduction in roughness Ra for C45 steel samples machined with CUAT, up to 80% compared to CT at a cutting speed of 20 m/min, while only exhibiting slight fluctuations when turning 201 stainless steel. Detailed analysis and explanation of these phenomena are presented herein.

Improving and Predicting the Surface Roughness and the Machining Accuracy in Ultrasonic Vibration-Assisted Milling

AbstractThe present research work amis to develop a controlled vibratory system for improving the performance of slotting process based on the vibration-assisted milling technique. In addition, the establishment of a statistical model for predicting the process efficiency was a key aim target.In the current investigation, an ultrasonic vibratory device was designed to provide vibration oscillations in the cutting feed direction to the 7075 aluminum alloy workpiece side at 34.7 kHz frequency and 10 μm amplitude. A LabView code has been developed to control the input vibration parameters. A full factorial design of experiments with 4 factors and 2 levels was conducted. An in-depth statistical analysis is then implemented to study the effect of machining and vibration parameters on the process performance. Then, a statistical model for predicting the process response in terms of cutting force, surface roughness, and machining accuracy has been established.Some experiments showed a significant reduction in cutting force up to 50% in the feed direction. Additionally, an improvement in workpiece surface roughness was recorded. Regarding the machined surface accuracy, introducing ultrasonic vibrations significantly reduces the produced slot width error compared to Conventional Milling (CM).The developed statistical model shows a very well agreement with the experimental results. Therefore, the developed VAM technique is suitable for manufacturing parts that require high geometrical and dimensional accuracy.

Study on the Mechanism of Improving Surface Roughness of Gray Cast Iron Machining by Wiper Inserts

Study on the Mechanism of Improving Surface Roughness of Gray Cast Iron Machining by Wiper Inserts

Comparing Bio-Ester and Mineral-Oil Emulsions on Tool Wear and Surface Integrity in Finish Turning a Ni-Based Superalloy

The paper compares the performance of two bio-ester and two mineral-oil emulsion metalworking fluids (MWFs) in finish turning an Inconel 718 alloy bar with a high hardness (HB 397 – 418). In this study, a coolant with a lean concentrate diluted at 6.5% to create an emulsion with stabilised water hardness was used to prepare each MWF. The finish-turning method used a small tool nose radius (0.4 mm) and small depth of cut (0.25 mm) to turn down 52.2 mm diameter bars in multiple passes to reach a maximum tool flank wear of 200 µm. In each MWF turning test, the tool flank wear, cutting forces, and surface roughness were measured against cut time. Chips from each MWF turning test were also collected at the same cut time instances. The surface and subsurface integrity on a workpiece obtained from each MWF turning test were compared by using a new unworn tool. Overall, for the machining parameters studied, the findings suggest the bio-esters were capable of equivalent machining performance as the mineral-oil emulsions, apart from one bio-ester that displayed improved surface roughness. Common to all MWF turning tests was a change in the chip form at low flank wear, which is discussed. Further findings discussed include the sensitivity of the concentration of the MWF diluted in the emulsion and the effect of the workpiece hardness within the batch used, with useful recommendations to improve the finish-turning method for the assessment of MWFs.

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.

Effect of electropolishing on ultrasonic cavitation in hybrid post-processing of additively manufactured metal surfaces

This investigation centered on fundamental understanding of a hybrid post-processing method that synergistically combines electrochemical polishing and ultrasonic cavitation to improve the surface roughness and mechanical properties of additively manufactured parts efficiently and simultaneously in a single step. High-speed imaging was utilized to understand the effect of the DC bias applied during electropolishing on the cavitation generated at various ultrasonic amplitudes. This was aimed at validating the hypothesis that the hybrid process is characterized by more bubbles than with ultrasonic excitation alone, and, in the presence of the DC bias, the bubbles are transported from the cathode to the anode (workpiece) where their impacts cause surface hardening. High-speed imaging confirmed a higher bubble count in the hybrid process than in the cavitation-only process at different ultrasonic amplitudes. Microhardness measurements confirmed that the hybrid process yielded higher microhardness compared to cavitation peening alone, while microhardness in electrochemical polishing showed only incremental changes. This observation was also corroborated by the grain size measurements, with the hybrid process exhibiting more grain refinement than cavitation-only or electropolishing-only post-processing modes. Surface topography analysis revealed minimal improvement in surface roughness due to cavitation-only, emphasizing the importance of the hybrid process in enhancing both surface roughness and the mechanical properties. Scanning electron microscope (SEM) images showed randomly distributed micro-dimples on the surface produced by the hybrid process at the highest ultrasonic amplitude, attributed to the increased number of cavitation bubbles. This research provides fundamental insights into why the hybrid process excels in simultaneously reducing surface roughness and achieving superior surface microhardness.

Characterization of novel natural cellulose fiber from Ficus macrocarpa bark for lightweight structural composite application and its effect on chemical treatment

This study investigates Ficus Macrocarpa tree bark fibers (FMB) as a sustainable alternative reinforcement for polymer composites. The Industrial Revolution marked the evolution of polymer composites with synthetic material reinforcement, leading to environmental concerns. Natural fibers have recently gained prominence as efficient alternatives for polymer composites. Despite numerous natural fibers being considered, ensuring a sustainable raw material source remains crucial. In this study, fibers were extracted from FMB and subjected to alkali treatment to evaluate their impact on physical, chemical, and thermal properties. Initially, the extracted fibers measured 253.80 ± 15 μm in diameter, reduced to 223.27 ± 12 μm post-alkali treatment. Chemical analysis showed an increase in cellulose content to 59.7 wt%, a 23.34 % improvement over untreated fibers (48.4 wt%). The crystalline index for untreated and treated fibers measured 80.20 % and 84.75 %, respectively, with no noticeable changes in the cellulose phase. Additionally, the crystalline size increased to 3.21 nm. Thermogravimetric analysis demonstrated enhanced stability of treated fibers up to 378.87 °C, while the kinetic activation energy remained constant at 64.76 kJ/mol for both the treated and the untreated fibers. The alkali treatment further improved surface roughness to 39.26, confirmed by scanning electron microscopic images. These findings highlight the potential of cellulose fibers from Ficus Macrocarpa bark as a sustainable and environmentally friendly replacement for synthetic fibers in polymer composites. The enhanced physical properties and excellent thermal stability make them a promising choice for eco-conscious materials.

Protective effect of various toothpastes and mouthwashes against erosive and abrasive challenge on eroded dentin: an in vitro study

The study aimed to compare various toothpastes and mouthwashes on permanent tooth dentin after erosive and abrasive challenges. 130 sound premolars dentin were randomly submitted to an initial erosive challenge and a cycle of erosive and abrasive challenges for five days. The five experimental groups (n = 26) were: (1) Control group (artificial saliva), (2) Elmex erosion protection toothpaste and mouthwash, (3) Vitis anticaries biorepair toothpaste and mouthwash, (4) Oral B Pro-expert toothpaste and Oral B Fluorinse mouthwash, and (5) MI Paste ONE toothpaste and Caphosol mouthwash. Microhardness, surface roughness values, and the topographical characteristics of the dentin surface were assessed. The highest percentage of recovered dentin microhardness (%RDMH) value was observed in groups 2 and 4, followed by groups 5 and 3, respectively. The %RDMH values in groups 2 and 4 did not demonstrate a significant difference (p = 0.855). The highest percentage of improvement in surface roughness was recorded in groups 2 and 4, with no significant differences (p = 0.989). The atomic force microscopy (AFM) findings were consistent with the surface roughness data. The best recovery of dentin microhardness and roughness were measured with the Elmex and Oral B toothpaste and mouthwash, followed by MI Paste ONE toothpaste and Caphosol mouthwash and Vitis anticaries biorepair toothpaste and mouthwash.

On the Post‐Processing of Complex Additive Manufactured Metallic Parts: A Review

Additive manufacturing (AM) is gaining more attention due to its capability to produce customized and complex geometries. However, one significant drawback of AM is the rough surface finish of the as‐built parts, necessitating post‐processing for achieving the desired surface quality that meets application requirements. Post‐processing of complex geometries, such as parts with internal holes, lattice structures, and free‐form surfaces, poses unique challenges compared to other components. This review classifies various post‐processing methods employed for complex AM parts, presenting the experimental conditions for each treatment alongside the resulting improvement in surface roughness as a success criterion. The post‐processing methods are categorized into four groups: electrochemical polishing (ECP), chemical polishing (CP), mechanical polishing, and hybrid methods. Notably, mechanical methods exhibit the highest roughness improvement at 69.9%, followed by ECP (59.9%), hybrid methods (47.4%), and CP (49.5%). Nevertheless, mechanical post‐processing techniques are less frequently utilized for lattice parts, making chemical or electrochemical methods more promising alternatives. In summary, all four categories of post‐processing methods can improve the internal surfaces quality of AM holes. While mechanical methods offer the most substantial roughness improvement overall, chemical and electrochemical methods show particular potential for addressing the challenges associated with complex geometries.

Experimental study of pool boiling performance of Fe3O4 ferromagnetic nanofluid on a copper surface

Nanofluids significantly enhance the critical heat flux of boiling heat transfer. This paper experimentally investigates the pool boiling performance and the influence mechanism of Fe3O4 nanofluids. Compared with deionized water, the 0.001 vol% nanofluid increases a maximum enhancement in critical heat flux by 47.90%. During nanofluid boiling, Fe3O4 nanoparticles are deposited on the surfaces. The nanoparticle deposition surfaces are physically characterized to explain the influence mechanism of Fe3O4 nanoparticles on boiling heat transfer. Nanoparticle deposition modifies the surface micro-morphology, which increases roughness and improves wettability. The changes are essential factors for the enhancement of the critical heat flux. This paper further analyses the boiling results of deionized water on the nanoparticle deposition surfaces. Compared with a polished surface, the critical heat flux and heat transfer coefficient of the nanoparticle deposition surface show maximum increases of 52.39% and 56.19%. Due to the similar enhancement of critical heat flux using the Fe3O4 nanofluid and the nanoparticle deposition surface, it is found that the increased critical heat flux of the nanofluids is attributed to the improvement of surface wettability and roughness by nanoparticle deposition. This study analyzes the mechanism of Fe3O4 nanofluid for enhancing pool boiling heat transfer from the perspective of modifying boiling surface characteristics by nanoparticle deposition, especially in wettability and roughness, which advances the understanding of enhanced boiling heat transfer by nanofluids.