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Purpose: To investigate the influence of finishing, polishing, and glazing on the roughness, flexural strength, and microstructure of lithium disilicate glass-ceramics. Materials and Methods: LD CAD/CAM blocks were cut into 96 discs (1.2 x 12 mm). After crystallization, a layer of glaze was applied to the discs' surfaces. The specimens were randomly divided into eight groupsn = 12) for different surface treatments (glaze [G], diamond abrasion [D], find diamond abrasion [F], and polishing [P]): G(glaze, control), GD, GDG, GDP, GF GFG, GFP, and GDFP. Mean roughness (Ra), mean square height (Rq), and maximum roughness (Rz) were measured. The biaxial flexural strength test was performed in a universal testing machine at 0.5 mm/minute. Microstructural analysis was performed using x-ray diffraction patterns (XRD). Differences on the roughness obtained in distinct groups was analyzed with Kruskal-Wallis and Bonferroni tests (α = .05). The flexural strength tests were compared with one-way ANOVA. Results: Glazed groups (G, GDG, and GFG) presented the lowest surface roughness, lower crystallinity, and higher flexural strength than the other groups. Although polishing and glaze presented similar surface roughness, polishing protocol decreased the flexural strength compared to the control group G. Conclusions: Clinically adjusted LD glass-ceramic restorations should be reglazed whenever possible to improve strength. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the effect of different finishing protocols on the wear behavior of lithium disilicate glass-ceramics (LD). Materials and Methods: Specimens were produced from LD prefabricated CAD/CAM blocks and divided into three groups according to the surface treatment (n = 8): control, polishing, and glaze. Ceramic specimens were subjected to wear testing using a dual-axis chewing simulator. A 49-N load was applied in the axial direction combined with a lateral movement (1-mm path) using an LD spherical piston for a total of 106 cycles. Qualitative analysis of the wear surface was performed using an optical microscope. Quantitative analysis of surface roughness and volume loss was performed using a confocal microscope and a 3D-image editing software, respectively. Surface roughness and volume loss data were analyzed using Friedman's nonparametric statistical test for repeated measures and the Student-Newman-Keuls test (a = .050). Results: There were statistical differences for surface roughness and volume loss of LD specimens in the different experimental conditions (P < .001). The control and polishing groups showed similar surface roughness and volume loss values for all testing times. The glaze group had greater wear volume after 103, 104, and 105 cycles. After 106 cycles, surface roughness and volume loss were similar in all groups. For the piston, surface roughness was similar over time and among groups. Conclusions: A distinct wear behavior was found for glazed glass-ceramic specimens compared to control and polished specimens. At the end of the simulation, the surface roughness and volume loss was similar for the groups. [ABSTRACT FROM AUTHOR]

Advances in Additive Manufacturing (AM) technologies have made it possible to reduce the design and prototyping costs to a minimum especially for a low-productivity material like titanium. Titanium alloys are commonly and widely used alloys in the aerospace and biomedical sector due to their advantageous material properties. This paper is an evaluation study of factors affecting the productivity characteristics of Laser Engineered Net Shaping (LENS) titanium alloy (Ti-6Al-4 V) using face milling. Some of the productivity challenges associated with titanium such as rapid tool wear, poor surface finish, and high-power consumption are explored in this paper. All materials processed using AM face the same critical problem that the manufactured part requires a post machining since AM produces relatively poor surface finish. Machining trials are conducted using the combinations of machining parameters such as spindle speed of 800 and 1600 rev/min; feed rate of 50 and 100 mm/min; and a constant depth of cut of 1 mm, respectively. Titanium being a poor thermal conductivity material, the effect of coolant was investigated using wet/dry machining. Data related to the productivity factors and material behavior under a milling trial was recorded and analyzed. The obtained data from the trials include productivity factors such as Metal Removal Rate (MRR), power consumed, and the surface finish for each plate/trial. The power consumed in dry milling was observed to be lower than that in wet milling which is contrary to the observations from conventional wet milling. The paper concludes the trends observed for LENS titanium are opposed to the trends in conventional machining such as increasing cutting speed will result in lower cutting force and power consumed. [ABSTRACT FROM AUTHOR]

3D printing technology proves itself to be effective in the field of medical industry due to processing potential of titanium alloys. Nonetheless it also has its drawbacks, the most severe being high roughness of printed elements’ area as well as the need to remove support structures created following the printing. Mechanical processing is commonly used for said parameters being enhanced. The completion of that process, however, takes a lot of time and prevents hard-to-reach elements from being reached. The task of this article is to provide a new method of firming the print’s surface and removing load-bearing structures. To achieve this, selective laser melting (SLM) technology will be used along with bathing prints in HF/HNO3 solution, all of which are supported by ultrasound. This process will enhance the material fatigue processing while reducing the postprocessing time and complexity. [ABSTRACT FROM AUTHOR]

The promising routes of metallic additive manufacturing favor the fabrication of refined functional components. Nonetheless, dealing with the Laser Powder Bed Fusion (L-PBF) parameters and costs for making the most of this technology is still an issue. The challenge gets bigger when considering less explored parameters, such as the process atmosphere and build location. So, this study aimed to address the main differences in microstructure, crystallography, mechanical properties, and surface finishing of maraging steel components manufactured under two different atmospheres (N2 and a mixture of 75%Ar-25%He atmospheres) and three build locations arranged along the gas flow direction. Based on experimental characterizations, the porosity fraction, microstructural constituents and metallurgical flaws, phase composition and martensite matrix crystallographic parameters, macrotexture, mechanical properties, roughness, and surface residual stress were investigated and compared for the different manufacturing conditions. The porosity fraction had the most expressive changes with the gas type and the build location, reaching a 53% overall reduction under N2 and a 112 to 302% rise for the front located sample compared to the others. The underlying mechanisms involved in the observed results, mainly related to process by-products behavior, were discussed. Broadly, the N2 atmosphere stands out over the analyzed properties. These findings underscore the role of atmospheric selection in the LPBF process, considering the overall quality and performance of the fabricated material and the possibility of cost reduction. [ABSTRACT FROM AUTHOR]

AbstractTitanium alloy can be found in numerous applications, such as chemical, aerospace, and energy industries, among other sectors, due to its excellent performance. Nevertheless, the possible uses of a variety of titanium-based alloys have been greatly restricted by their low hardness and inadequate resistance to wear. Therefore, in this research work, WC–Cu composite electrode assisted electrical discharge coating (EDC) is used for improving microhardness (MH) and surface integrity of Ti–6Al–4V alloy. By utilizing powder composite electrode, the conductivity of the electrode can be increased, which provides controlled electric spark, resulting in uniform deposition. In order to increase the rate of deposition, the terminal of the EDM has been changed as WC–Cu composite electrode as anode and workpiece as cathode. Response surface methodology is used for studying the variables including compacting pressure (MPa), discharge current (I), pulse on time (Ton). In addition, microstructure, elemental analysis and coating interface of deposited Ti–6Al–4V alloy are investigated through scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS). The surface roughness of 8.86 µm was achieved at 400 MPa, 6 A, and 40 µs. The maximum MH of 988 HV was obtained at 400 MPa, 10 A, and 80 µs. The MH of the deposited layer is around 2–3 times harder than base material. Moreover, a greater adhesion strength coated layer was ∼118 N, which permits the alloy to have improved wear resistance. It was concluded that using a high-pressure electrode with lower settings resulted in an improved surface finish, while higher settings led to increased MH. [ABSTRACT FROM AUTHOR]

Titanium and its alloys are widely utilized in the field of aerospace and medical devices, owing to their impressive high-temperature durability and excellent corrosion resistance. Many researchers have machined millimeter-scale features on titanium using electrochemical jet machining (EJM). However, achieving submillimetre scale features on titanium with high efficiency and surface integrity is still a hindrance. In this research, a small nozzle with a diameter of 200 μm has been proposed for EJM of pure titanium (TA2) with NaCl-ethylene glycol (EG) solution. This non-aqueous electrolyte is able to prevent the formation of oxide layers during the machining process. In the experimental part, the utilization of EJM in processing dimples and channels on TA2 has been examined. The direct current mode and the pulsed current mode have been compared in terms of dimensions, surface finish, and material removal localization. It is found that by utilizing suitable parameters, EJM with non-aqueous electrolyte is suitable to manufacture submillimetre structures on pure titanium with high precision and high surface quality. [ABSTRACT FROM AUTHOR]

The completed study investigated the creation of Martian regolith simulant composite parts using injection molding and additive manufacturing. Traditional manufacturing techniques such as injection molding are not feasible on the Martian surface therefore in-situ processes must be developed using additive manufacturing processes to prepare habitats prior to having a human presence on the surface. The goal of this study was to investigate the impacts of additive manufacturing on the material property values between parts made using traditional injection molding and additive manufacturing. Martian regolith simulant composite pellets were created by combining a Martian regolith simulant at 40 wt% loading with polypropylene via twin screw extrusion. This material was then used to create test specimens using injection molding and additive manufacturing. Samples underwent tensile, flexural, Izod impact, and immersion density tests according to ASTM International and standardized test instructions. Additive manufactured parts saw a nearly 40% reduction in tensile and flexural strength with more than double the tensile modulus when compared to injection molded parts. The flexural modulus for additive manufacturing was around 36% that of the injection molded part with a minor decrease in density of around 13%. The collected test results suggested that while there were differences in the material property values between the manufacturing processes, a more interesting foaming behavior of the extrudite was observed during the additive manufacturing process resulting in an extremely rough and pitted surface. This rough surface finish was a stark comparison to the smooth injection molded parts. This observed foaming behavior in the polymeric composite material during thermal processing prompted the theory that thermal releases from the Martian regolith simulant was the most likely cause of the observed differences. Pellet surface moisture tests, Martian regolith simulant thermogravimetric analyses, and literature reviews of thermal decomposition of the Martian regolith simulant constituents revealed that most likely olivine releases oxygen and hydrated silica releases water during the thermal processing of the Martian regolith simulant composite. During a closed mold process such as injection molding, these volatile gases are forced out of the part by the pressures of the molding process, but in an open to atmosphere process such as additive manufacturing these gases foam to the surface during cooling leaving the part with an inferior surface finish. [ABSTRACT FROM AUTHOR]

Simultaneous four‐axis machining involves a cutter that moves in all degrees of freedom during carving. This strategy provides higher‐quality surface finishing compared to positional machining. However, it has not been well‐studied in research. In this study, we propose the first end‐to‐end computational framework to optimize the toolpath for fabricating complex models using simultaneous four‐axis subtractive manufacturing. In our technique, we first slice the input 3D model into uniformly distributed 2D layers. For each slicing layer, we perform an accessibility analysis for each intersected contour within this layer. Then, we proceed with over‐segmentation and a bottom‐up connecting process to generate a minimal number of fabricable segments. Finally, we propose post‐processing techniques to further optimize the tool directionand the transfer path between segments. Physical experiments of nine models demonstrate our significant improvements in both fabrication quality and efficiency, compared to the positional strategy and two simultaneous tool paths generated by industry‐standard CAM systems. [ABSTRACT FROM AUTHOR]

Duplex stainless steels are composed of ferrite and austenite in equal volume fractions of these phases, which provides an excellent combination of mechanical properties and corrosion resistance, especially when compared with conventional stainless steel grades. When these steels are welded, there are significant changes in the austenite-to-ferrite ratio therefore in their final properties. Nowadays, the ferritoscope is the unique non-destructive technique used to quantify these two phases content in situ. This tester instrument is limited to the evaluation of large areas, is not suitable for the heat affected zone and is also very sensitive to the surface finish, being considered an intermediate precision technique. So, it is necessary to develop more reliable field techniques. In this research, thermoelectric power measurements and induced current techniques are proposed to evaluate the phase quantification in S32205 welds. According to the results, both techniques are reliable and highly sensitive to phase changes in the weld bead, heat affected zone and base metal. For the thermoelectric power technique, a probe with nickel tip should be used to obtain the highest sensitivity and for the induced current technique, a probe type-pencil with a central frequency of 6 MHz should be used. [ABSTRACT FROM AUTHOR]

This paper investigates the significant factors influencing the measurement uncertainty of 3D laser scanners, an essential tool in industrial contexts for swiftly and accurately analysing complex geometric objects. Through a designed experimental study, parameters such as object size, surface texture, scanner resolution, and ambient light intensity were systematically varied to assess their impact. The results demonstrate that nominal shaft diameter, ambient light intensity, surface finish of the shaft, scan resolution, and the interaction between surface finish and resolution significantly affect repeatability. An empirical model was developed to predict repeatability in shaft diameter measurements. Additionally, the exploration of developer coating revealed its pivotal role in minimising errors stemming from reflective surfaces, underscoring its importance in ensuring measurement reliability. The main contribution of the paper belongs to the knowledge and practice of 3D laser scanning by offering practical recommendations and guidelines. [ABSTRACT FROM AUTHOR]

Additively manufactured medical devices require proper surface finishing before their use to remove partially adhered particles and provide adequate surface roughness. The literature widely investigates regular lattice structures—mainly scaffolds with small pores to enhance osseointegration; however, only a few studies have addressed the impact of surface finishing on the dimensional deviation and the global and local mechanical responses of lattice samples. Therefore, the current research investigates the impact of biomedical surface finishing (i.e., corundum sandblasting and zirconia sandblasting) on Voronoi lattice structures produced by laser powder bed fusion (LPBF) with large pores and different thicknesses on the surface morphology and global and local mechanical behaviors. MicroCT and SEM are performed for the assessment of dimensional mismatch and surface evaluation. The mechanical properties are investigated with 2D digital image correlation (DIC) in quasi-static compression tests to estimate the impact of surface finishes on local maps of strain. In the quasi-static tests, both the global mechanical performances, as expected, and local 2D DIC strain maps were mainly affected by the strut thickness, and the impact of different surface finishings was irrelevant; on the contrary, different surface finishing processes led to differences in the dimensional deviation depending on the strut thickness. These results are relevant for designing lattice structures with thin struts that are integrated into medical prostheses that undergo AM. [ABSTRACT FROM AUTHOR]

Massively carbon-supersaturated (MCSed) tool steel dies were developed to make galling-free forging products from titanium bar feedstocks in dry conditions without lubricating oils. Two types of tool steel dies were used, SKD11 and ACD56, following the Japanese Industrial Standard (JIS). The plasma-immersion carburizing process was employed to induce massive carbon supersaturation in two kinds of tool steel dies at 673 K for 14.4 ks. A pure titanium bar was upset in a single stroke up to the reduction of thickness of 70% using the MCSed SKD11 die. Very few bulging displacements of the upset bar proved that μ = 0.05 on the contact surface of the MCSed SKD11 die to pure titanium work. Two continuous forging experiments were performed to demonstrate that an in situ lubrication mechanism played a role to prevent the contact surface from galling to titanium works in both laboratory- and industry-scaled forging processes. After precise microstructure analyses of the contact surface, the free-carbon film formed in situ acted as a lubricating tribofilm to reduce friction and adhesive wear in continuous forging processes. The MCSed ACD56 dies were also used to describe the galling-free forging behavior of manufacturing eyeglass frames and to evaluate the surface quality of the finished temples. The applied load was reduced by 30% when using the MCSed ACD56 dies. The average surface roughness of the forged product was also greatly reduced, from 4.12 μm to 0.99 μm, together with a reduction in roughness deviations. High qualification of forged products was preserved together with die life prolongation even in dry manufacturing conditions of the titanium and titanium alloys. [ABSTRACT FROM AUTHOR]

Metal additive manufacturing has significantly evolved since the 1990s, achieving a market valuation of USD 6.36 billion in 2022, with an anticipated compound annual growth rate of 24.2% from 2023 to 2030. While powder-bed-based methods like powder bed fusion and binder jetting dominate the market due to their high accuracy and resolution, they face challenges such as lengthy build times, excessive costs, and safety concerns. Non-powder-bed-based techniques, including direct energy deposition, material extrusion, and sheet lamination, offer advantages such as larger build sizes and lower energy consumption but also encounter issues like residual stress and poor surface finish. The existing reviews of non-powder-bed-based metal additive manufacturing are restricted to one technical branch or one specific material. This survey investigates and analyzes each non-powder-bed-based technique in terms of its manufacturing method, materials, product quality, and summary for easy understanding and comparison. Innovative designs and research status are included. [ABSTRACT FROM AUTHOR]

The machinability of various grades of austempered ductile iron (ADI) has been investigated by using the surface roughness and the resultant chip formation as criteria. Grade 1 ADI, Grade 2 ADI, and Grade 3 ADI were commercially produced, commercially heat treated and machined under controlled conditions using coated carbide inserts with coolant in the laboratory. The milling performance of the various grades was compared to that of AISI 4340, which has a similar hardness to Grade 2 ADI. Grade 100-70-03 ductile iron was used as a reference material in the drilling study. The results of this study show that the surface finish of ADI and the resultant chip formation give quick indications if proper cutting parameters were used during machining of ADI. [ABSTRACT FROM AUTHOR]

The high level of tensile stress and high roughness induced by cutting are the main causes of low surface integrity of Mg-Li alloy components. Their values depend on the evolution mechanism of the cutting metamorphic layer. This research was aimed to analyze and compare the microstructure evolution mechanisms of the metamorphic layer under dry and cryogenic milling and reveal their action mechanism on the surface integrity for the duplex LA103Z Mg-Li alloy based on the microstructure characterization and mechanical properties measurement experiments. It was revealed that the metamorphic layers under dry and cryogenic milling both consists of second phase particles accumulation layer and featureless layer with less visible grain boundaries. The compositions and degree of the phase transition and the texture evolution of the cutting metamorphic layer both change dramatically from dry to cryogenic milling. The deformation modes of dry milling is non-basal slip, and appears the dynamic recrystallization (DRX) related prismatic fiber texture {11 2 ¯ 0} <0001> in α-Mg phase and γ fiber {111} <112> in the β-Li phase. Whereas cryogenic milling is basal slip accompanied by prismatic slip, and appears a dynamic recovery (DRV) related α fiber {111} <110> in β-Li phase. Moreover, cryogenic milling exhibits a more pronounced phase transformation characteristics owing to the transient pressurization heating and extremely cold conditions. Compared with dry milling, cryogenic milling has significant advantages in improving surface hardness, reducing surface tensile stress and improving surface finish by increasing the hard phase, forming the strong basal texture, and strengthening the material physical parameters on the milled surface. In general, the cryogenic regulation method is found to be more suitable for machining high-quality Mg-Li alloy components. [ABSTRACT FROM AUTHOR]

Conventional metal (sand) casting requires solid patterns consisting of two halves (cope and drag) prepared to remove the pattern. The approach is simple but leads to numerous steps and mismatch errors. Also, sand, a porous material, is very sensitive to vibration and susceptible to cracks and breakage. This research presents a novel approach for investment metal casting, where a water-soluble material is used for pattern generation using material extrusion additive manufacturing (AM). As a proof of concept, a semi-complex non-prismatic geometry with various dimensional features is physically realized using this soluble pattern casting (SPC) technique. The pattern is designed and 3D printed out of a water-soluble acrylonitrile butadiene styrene (ABS) thermoplastic using an indigenously fabricated screw extrusion–based AM setup. A ceramic mould is created from plaster of Paris (PoP) around the soluble pattern, generating the mould cavity on further dissolution. A heated water bath with added turbulence via solid vibrations assisted the dissolution process. The final geometry is realized by firing the mould cavity followed by metal pouring. Various geometrical features and intricate details, such as layer lines, are satisfactorily replicated from the 3D-printed pattern to the final metal casting. The dimensional accuracy and surface finish are analysed along the process, starting from the printed pattern to the ceramic mould cavity and the final metal cast part. The presented method has applications in investment casting (IC) industries as it can help significantly reduce the lead time and provide excellent dimensional conformance and geometrical replication from the pattern to cast. [ABSTRACT FROM AUTHOR]

Hybrid manufacturing combines the simultaneous benefits of additive manufacturing (complex geometries, part consolidation, and mass customization) with the advantages of subtractive manufacturing (superior surface finish and enhanced dimensional accuracies) by integrating a suite of complementary traditional processes into a base platform of additive manufacturing. The use of hybrid technology has grown in recent years given its capabilities on repairing metallic structures, producing parts with conformal cooling features, and manufacturing functionally graded products. These kinds of capabilities are of great interest to the medical implant, energy, automotive, maritime, and aerospace industry sectors, among many other fields. This work investigated the mechanical properties of stainless steel (SS) 316L as a function of different tool paths strategies using an integrated 5-axis CNC hybrid Mazak system with a laser hot wire deposition system (LHWDS). This study includes the evaluation of different printing parameters and their impact on the quality of the printed bead as well as the incorporation of a structure–property material relationship based on the mechanical performance of the manufactured coupons. [ABSTRACT FROM AUTHOR]

The bidirectional composite vibratory finishing (BCVF), which is a novel high efficiency collaborative surface finishing technology of structure shape and surface integrity, is expected to solve the problem of poor machinability in grooves, slits, corners, and intricate profiles of the workpiece. The basic research was carried out to expand its engineering applications. Based on the discrete element method (DEM), the particle flow behavior and velocity distribution were analyzed, it is found that the particle temperature can explain the changes of the normal and tangential cumulative contact energy on the workpiece surface. In addition, the normal contact force on the container sidewall and the pressure distribution on the workpiece surface were measured under different process parameters. The comparison with the simulations reveals that DEM model accurately predicted the particle–wall normal contact force frequency content, and the dominant frequencies are the container driving frequency and its multiplication. Meanwhile, the pressure-sensitive film can intuitively demonstrate the integrated action behavior of particles, including normal impact, inclined impact, rolling, scratching, and ploughing. Moreover, the axial uniformity and machining efficiency were enhanced by the rise in the frequencies and amplitudes of both horizontal and vertical vibration. For the combined effect of vibration frequency and amplitude, it was verified that the dimensionless vibration velocity amplitude was linearly and positively correlated with the normal contact force and the tangential cumulative contact energy on the workpiece surface. As a result, the simulations using spherical particles can predict some critical properties in non-spherical processing, and provide reference for the popularization of the BCVF process. [ABSTRACT FROM AUTHOR]

The characteristics of additively manufactured parts (topological optimisation, freedom of design ...) present a challenge from a metrological point of view. In this respect, non-contact inspection is of great importance for the rapid verification of this type of parts. However, their particular characteristics (stair-effect, high roughness, surface finish) can contribute to measurement errors and deviations when using different optical inspection equipment. In relation to this, 3D scanning point-clouds filtering can improve the results by increasing precision during inspection. In particular, this paper evaluates the influence of applying filters to digitize additive manufactured metal parts, which are scanned using different optical inspection systems commonly used in industry (based on laser triangulation, conoscopic holography and structured light techniques). The main objective is to establish the most suitable inspection procedure depending on the inspection system used. According to the dimensional results achieved, it can be concluded that the filtering does not have significant influence, regardless of the used sensor. However, the geometrical results are strongly influenced by the point-cloud quality; consequently, it is recommended to apply filters for most of the evaluated optical systems. One of the main contributions of this study is the definition of the filtering process methodology prior to non-contact inspection, depending on both the used optical system and the part to be evaluated, in order to define the most suitable filtering parameter to achieve a precise optical inspection. • Effect of sigma filter on optical inspection of additively manufactured metal parts • Point cloud filtering does not influence dimensional results, only geometric ones • Different industrial optical sensors require filtering for accuracy geometric inspection • Applying 3σ/2σ filter allows to achieve geometric results similar to contact values • 1σ filter (more restrictive) distorts values, resulting in form error below reference [ABSTRACT FROM AUTHOR]

Due to the poor surface characteristics of additively manufactured parts, the necessity for post-process surface enhancement is crucial. Among the prevalent post-processing techniques, the acoustic cavitation-based surface finishing technique has recently emerged. Despite a considerable amount of focused research on the material removal mechanisms of this technique, less attention has been devoted to addressing its limitations associated with enhancing the process capability towards achieving a better surface finish. The driving force behind the acoustic cavitation technique is the bubble implosion through cavitation streaming, and the cessation of the acoustic cavitation streaming beyond a certain length is the main limitation. It has restrained the process capability towards finishing both external and internal surfaces. Hence, this research aims to unravel novel ways of employing the acoustic cavitation-generating parameters and achieving better-quality surface finishing of additively manufactured (AM) components. A study has been conducted on different AM materials, including Inconel 625 and aluminum alloy, by introducing various methods associated with acoustic amplitude, working mediums, temperature, and external vibration. The results reveal a significant reduction in average surface roughness for both materials. The topographical and morphological observations confirm the qualitative improvement on the surfaces. In addition, the conical bubble structures that frame the acoustic cavitation streaming are elucidated by implementing high-speed imaging techniques, and their enhancement at different parametric conditions is delineated. Henceforth, the findings suggest a notable insight into the potential of the employed approaches in enhancing the acoustic cavitation streaming for achieving a better surface finish of AM components. [Display omitted] • Surface finishing of AM components by enhanced acoustic cavitation. • Overcoming the limitations of acoustic cavitation for surface quality improvement. • Acoustic cavitation: factors affecting acoustic streaming and AM surface quality. • Thermal effect on bubble structures in free-field and confined acoustic cavitation. • A study on parametric investigation of acoustic cavitation: a different approach. [ABSTRACT FROM AUTHOR]

Titanium alloy is the most promising superalloy widely used in avionics systems, because of its high strength and great corrosion resistance. Machining efficiency of this alloy can be enhanced with modeling and optimization approaches. In the present work, modeling of response surface methodology is used for milling of Ti-6Al-4V using no-coolant (dry), minimum amount coolant (MAC), and use of liquid carbon dioxide as cryogen with spray of nitrogen gas besides minimum amount of biodegradable mixture (Hybrid). Cutting speed (v), feed rate (f), and depth of cut (d) are input parameters, whereas temperature, tool wear, surface finish, and material removal rate are responses. GA, JAYA, and Rao1, 2, and 3 algorithms were used to solve a multi-objective function (Z). For hybrid condition compared to no-coolant and MAC, 35 and 17% reduction in T, 32 and 21% reduction in Vf, 45 and 33% reduction in Ra, and 45 and 15% improvement in MRR, respectively, was observed. JAYA performed 91, 64, 62, and 57% better than GA, Rao-1, Rao-2, and Rao-3 algorithms, respectively, for MAC condition. It has been observed that JAYA algorithm is better at achieving steady state and requires less generations, whereas Rao algorithms run faster. From the computational tests, it is observed that the performance of the Rao algorithm is superior to the other optimization algorithms. In terms of execution time, Rao-1 performed 49, 74, and 42% better than Rao-3, whereas 60, 77, and 41% better when compared to Rao-2 for three milling conditions, respectively. [ABSTRACT FROM AUTHOR]

Ball burnishing has been an effective surface finishing process that generally requires pressing hardened steel rolls/balls, during feed motion, into the surface of the metallic workpiece. The purpose of this study is to examine the improvement of the burnished surface quality by optimizing several burnishing factors, including ball diameter (d), depth of penetration (p), number of passes (N) and type of lubricants (L) for improving surface quality of AISI 1010 steel plates. A second-order mathematical model is developed to predict the surface quality as functions of ball burnishing parameters. The optimal burnishing parameters were determined by conducting central rotatable design matrix experiments and predicting the response models for the surface roughness and hardness. The optimal burnishing conditions for the steel plates were found by using a ball diameter of 12 mm, a burnishing depth of 0.25 mm, a number of passes of 5 and 15W-40 (L3) for the type of lubricant. With these optimal parameters, the mean surface roughness is reduced from Ra = 2.48 to Ra = 0.37 µm, while Brinell hardness increases from 59 to 70.88 HRB. The results show that all lubricants used in this study had negligible effect on the surface hardness. [ABSTRACT FROM AUTHOR]

In the last decade, impressive development of nanofiller reinforced nanocomposite spotted to fulfil the demand of industries like automobile, aerospace, biomedical and many more due to splendid mechanical, electrical and thermal properties. Presented review article consist machinability of metal,ceramic and polymer nanocomposite and the effect of controllable parameters on the output parameters like surface finish,material removal rate,tool wear etc. The work presented here in the form a review of machining of nanocomposites will be useful for the researchers working in various allied domains related to the aforementioned domains. Due to the necessity to produce multifunctional products, reduce manufacturing and running costs, and boost operational efficiency, the miniaturization of machined features has become an essential demand in current industrial production.For good surface finish, dimensional accuracy and high productivity micro machining of nanocomposite is required. Due to their improved anisotropic, heterogeneous structure and improved mechanical properties the machining of nanocomposites is difficult with conventional and non-conventional machining. [ABSTRACT FROM AUTHOR]

Following sustainability in manufacturing, the machining chain can be optimized by either reducing the time and energy consumption of each operation or eliminating the unnecessary operations subjected to keeping the quality of the final product as consistent. However, the roadblock in designing an optimum machining chain is lack of prediction tool to interact between the included operations. In this paper, an integrated algorithm is developed to simulate the surface roughness generation and following modification caused by milling and burnishing, respectively. Predict the surface roughness generation by milling process and its alternation after burnishing. The algorithm works on the basis of clouds of points which were generated in the engagement region of tool and workpiece and their transformation from tool to workpiece coordinate systems. Moreover, some mechanical attributes of the process regarding effect of surface work hardening and elastic rebound were added to the algorithm to enhance the accuracy of simulation. To verify the results, a series of burnishing experiments with multi-roller rotary tool have been carried out on the surface of the finish-milled samples and the surface roughness change was taken into investigation. The obtained results showed that by applying the work hardening and springback effect to predictive algorithm the prediction accuracy of roughness at submicron level enhances up to 50%. It was also found that the most influential parameters influencing the surface roughness after milling-burnishing sequence are milled surface roughness, burnishing force and pass number. In addition, results showed that applying burnishing after rough machining consumes lots of energy to achieve nanoscale surface finish. Accordingly, the sequence of rough-milling, finish-milling and burnishing results in achieving sound surface finish within significantly shorter period of time and applied force. [ABSTRACT FROM AUTHOR]

This study delves into the comparative analysis of vibrational tumbling and electrolytic polishing, two distinct surface finishing techniques, on the surface roughness parameters of additively manufactured Inconel 718 alloy. Surface roughness significantly impacts the functionality of components, especially in aerospace and automotive applications where Inconel 718 superior mechanical properties are sought after. Vibrational tumbling relies on mechanical abrasion, while electrolytic polishing utilizes chemical processes, offering different pathways to attain smoother surfaces. Three samples were individually subjected to vibrational tumbling, electrolytic polishing and combination of both to determine its effects on surface roughness parameters Sa, Sq, Sp and Sv, evaluated via surface profilometry. Surface wettability was also determined for all the formed surfaces to evaluate the surface nature and functionality. The results indicated that the areal roughness parameter values ranged from Sa = 5.68 to 3.38 µm. The maximum surface height parameter varied from Sz = 53.36 to 32.44 µm, while the maximum valley height Sv ranged from 29.418 to 18.026 µm, and the maximum peak height Sp varied from 23.942 to 14.418 µm across all the printed samples. The findings showed a decrease of 32%, 12% and 42% for vibrational tumbling, electrolytic polishing and combination of both, respectively in the surface roughness values from as built samples. Further, the surface wettability results showed increase in the hydrophilic nature of the surface for each treated surface. The results furnish valuable insights into the efficacy of each method in enhancing surface quality, aiding in informed selection of the optimal surface finishing technique for additively manufactured Inconel 718 components. [ABSTRACT FROM AUTHOR]

The effects of vibratory peening (VP), shot peening (SP), and SP followed by vibratory finishing (SPVF) on the surface and fatigue properties of Ti‐6Al‐4 V were compared to conventional low‐stress grinding (LSG). VP processing produced seven times smoother surface finish than SP and 66% deeper compressive residual stresses (CRS) but with 12% lower magnitudes. SPVF produced optimal surface properties with a perfectly flat surface and CRS‐like SP. All three mechanical surface treatments generated similar fatigue life improvements (108–122%) over LSG when the cyclic stress was below the yield stress. Above the yield stress, most of the CRS relaxed during the first cycle in VP specimens, resulting in up to 97% fatigue life improvement over LSG. The CRS relaxed more gradually in SP specimens leading to larger (up to 239%) fatigue life improvement. This shows the need to amplify CRS magnitudes produced in VP to maximize fatigue life improvement. [ABSTRACT FROM AUTHOR]

The Ti–29Nb–13Ta–4.6Zr alloy (TNTZ) is a β-Ti alloy that has a potential for use in biomedical applications as an alternative to the less-compatible Ti64 alloys. Enhancing the strength and the surface finish of TNTZ is essential for biomedical applications. In this research, a combination of high-pressure torsion (HPT) and laser treatment was used to improve the TNTZ properties. The HPT-treated samples showed significantly enhanced mechanical properties when compared with the traditional solution-treated TNTZ. A laser surface treatment immediately forms a hydrophilic surface that transforms into a steady hydrophobic state after 14 days in air and the surface roughness increases with an increase in laser power and a slower scanning rate. The corrosion resistance of TNTZ improves significantly after laser treatment, with the corrosion current dropping from 1 × 10−8 to 1.2 × 10−9 A and the corrosion potential peak shifting to a more positive value from − 0.349 to − 0.158 V. The friction coefficient after laser treatment decreased from 0.134 to 0.093 and then further reduced to 0.082 after 14 days in air thereby suggesting an enhancement in the tribological properties. Overall, the results show that HPT processing combined with a post-HPT laser treatment is beneficial for enhancing the mechanical properties and the corrosion and wear performance of the TNTZ alloy. [ABSTRACT FROM AUTHOR]

The ultra-precision diamond cutting (UPDC) employs larger cutting parameters in half-finishing process to improve machining efficiency, which introduces microwavy profile to the unmachined surface of finishing process with microscale cutting parameters. The paper makes theoretical and experimental investigations on the microwavy profile effect on cutting process and surface generation in UPDC. The influence of microwavy profile on the surface being machined is considered in diamond cutting process by studying its effect on the instantaneous cutting depth, shear angle, stress, and effective rake angle to build dynamic force model. A new dynamic surface generation model is developed by adding the wavy profile effect and workpiece material properties. The simulated surface profiles in diamond single cutting of different workpiece materials meet well with the experimental ones under different wavy profile patterns. Further studies are conducted to build turning force model and surface profile prediction model for single point diamond turning (SPDT) by adding the diamond-turned microtopography effect on the instantaneous cutting depth. Diamond single cutting experiment and diamond turning experiment are conducted to verify the developed dynamic models, which indicates that the predicted results including cutting force and surface profiles agree well with the experimental results. [ABSTRACT FROM AUTHOR]

The SLS additive manufacturing industry enables the development of products for diverse applications with distinct properties due to its excellent surface finish and ability to create varied part geometries, but it consumes high-performance materials with high acquisition costs. An extensive quarrying of stone leads to the accumulation of mineral residues, posing environmental hazards by contaminating soil and water when disposed of in landfills. The primary objective of the study was to incorporate mineral waste into the SLS technique and investigate the influence of its addition, along with a silane-based chemical treatment, on the mechanical performance of polymer-mineral composites (PA12-slate). Additionally, the feasibility of producing a highly loaded printed prototype, employing 50 wt% of mineral waste, was examined. Samples of PA12, PA12 blended with 50 wt% slate waste, and slate waste treated with silane underwent fabrication via selective laser sintering (SLS) and subsequent mechanical characterization, including tensile, flexural, and compressive tests. Additionally, the samples underwent accelerated aging using a QUV weathering tester, followed by mechanical characterization. The geometric accuracy, stability, and processing feasibility of these formulations were evaluated through SLS-printed composite prototypes utilizing PA12_50Sla_Si. It was found that the addition of 50% of slate to the PA12 presented mechanical properties decreasing compared to the printed PA12 only. However, an increase was verified when using silane-induced mineral bonding. The incorporation of mineral agents and silane enhanced the resistance of PA12 to aging. However, after aging, both tensile and flexural strength decreased across all printed samples. Nonetheless, this study showcased the feasibility of producing complex PA12-slate waste specimens containing up to 50 wt% of mineral waste using the SLS printing technique. Therefore, SLS presents itself as a viable means of adding value to this mineral waste. [ABSTRACT FROM AUTHOR]

The selection of the right tool path trajectory and the corresponding machining parameters for end milling is a challenge in mold and die industries. Subsequently, the selection of appropriate tool path parameters can reduce overall machining time, improve the surface finish of the workpiece, extend tool life, reduce overall cost, and improve productivity. This work aims to establish the performance of end milling process parameters and the impact of trochoidal toolpath parameters on the surface finish of AISI D3 steel. It especially focuses on the effect of the tool tip nose radius deviation on the surface quality using precision measurement techniques. The experimental design was carried out in a systematic manner using a face-centered central composite design (FCCD) within the framework of response surface methodology (RSM). Twenty different experiment trials were conducted by changing the independent variables, such as cutting speed, feed rate, and trochoidal pitch distance. The main effects and the interactions of these parameters were determined using analysis of variance (ANOVA). The optimal conditions were identified using a multiple objective optimization method based on desirability function analysis (DFA). The developed empirical models showed statistical significance with the best process parameters, which include a feed rate of 0.05 m/tooth, a trochoidal pitch distance of 1.8 mm, and a cutting speed of 78 m/min. Further, as the trochoidal pitch distance increased, variations in the tool tip cutting edge were observed on the machined surface due to peeling off of the coating layer. The flaws on the tool tip, which alter the edge micro-geometry after machining, resulted in up to 33.83% variation in the initial nose radius. Deviations of 4.25% and 5.31% were noted between actual and predicted values of surface roughness and the nose radius, respectively. [ABSTRACT FROM AUTHOR]

The present research aims to improve the surface quality of laser powder bed fusion (LPBF) built cobalt chrome alloy (CoCr) by pulse laser remelting. The laser power, overlap percentage, and spot diameter are varied to determine the best parameters for laser polishing. The microhardness and microstructural changes associated with pulse laser remelting are described. Surface morphology and surface roughness parameters are reported for various laser remelting parameters. Among the three different spot diameters, 1, 2, and 3 mm, the maximum (> 50%) reduction in surface roughness was obtained for 2 mm with 1J laser energy and 50% X and 20% Y as well as 20% X and 50% Y overlaps. A DoE- and RSM-based approach has been utilized for parametric optimization of the surface roughness. The squared laser power is identified as a critical parameter by ANOVA. A Pareto chart confirms the significance of squared laser power across spot diameters. Optimization suggests that a 2-mm spot diameter works best with specific parameters to produce a better surface finish. However, the nanosecond order laser pulses have a limitation on the depth of surface modification without severe ablation and thereby on the reduction in the surface roughness. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

This study concentrates on the utility of the newly formulated machining fluid used for turning AISI 4340 steel under the near dry machining method. The preparation of the novel machining fluid involves a blending of vegetable oils and conventional lubricant in a 50:50 ratio. Three distinct compositions were investigated within this work. The biodegradability tests confirms that the novel lubricantaligns with the ethos of "Green Machining." The study's focal points include an analysis of the following crucial metrics – machining force, machining temperature, and surface finish. From the analysis, the best-formulated blend was identified. To evaluate its performance, the variance analysis on the dataset (ANOVA) and Weighted Entropy decision-making method that ranks the best option along with alternatives was executed. Further, the optimal process parameters were determined using Dragon Fly Algorithm (DFO) and Particle Swarm Algorithm (PSO) to enhance the efficacy and quality of machining. [ABSTRACT FROM AUTHOR]

This study focused on optimizing the process of CNC machining to enhance productivity and product quality of surface finish Ra via the process parameters of the cutting speed (vc), feed rate (vf), and cutting depth (doc). Experimentation was performed on workpieces of AA-6061 to investigate the response Ra through variation of the process parameters to analyze their best fit using RSM with 2³ full factorial designs L-8 of DOE. The analysis of variance (ANOVA) was then used to find the major contributors among them that were responsible for the Ra. Based on the result, better Ra was obtained at 0.103 µm using the best fit of vf (150 mm/min), vc (220 m/min), and doc (0.1 mm). ANOVA shows vf contributed better Ra followed by vc and doc respectively. In addition, the level of Ra's was analyzed through contour plots represented by different colours. It continued to analyze the effect of the process parameters via the main effects plot, Pareto chart, and the contour plot in the predictive desirability model, which indicated that the plots and chart confirmed the vf had more influence compared to others. The study confirmed that the low-level parameters provided better Ra to be used for polishing. [ABSTRACT FROM AUTHOR]

By combining sacrificial nanoimprint lithography (SNIL) and transfer printing, sacrificial nanotransfer (SNT) lithography can create metalized polymer surfaces that enable lightweight conductive surface composites. SNT begins with a metal mold made from a high surface finish metal possessing high resistance to intermetallic alloying. A thin metallic transfer layer is then electroplated onto the mold by selecting a material unlikely to alloy with the surface. The selected nanomaterial, zinc oxide (ZnO), is grown on the top layer of the plated metallic transfer layer via a seedless hydrothermal approach used to synthesize high‐quality ZnO nanowire arrays. A resin material or laminate is cured in contact with the ZnO nanostructures, such that the ZnO nanorods are embedded onto the top layer of the resin. The embedded nanomaterials provide a larger surface area than the weak transfer layer‐mold interface. As a result, when the final component is removed from the mold, the metallic multilayer is transferred with it. The final metalized polymeric surface resembles the same surface finish as the starting mold, with an exposed metal layer and a durable interface. In this study, the importance of nanomaterial morphology and the selection of metal layers are explored to obtain high‐quality final transfers. [ABSTRACT FROM AUTHOR]

Fused Deposition Modeling (FDM) is an extrusion type additive manufacturing (AM) method in which a molten polymer is selectively extruded in layer-by-layer manner. Although there are several other AM techniques, FDM is a suitable method to produce fabric structures as it is capable of processing polymers and is widely used in various engineering applications. This article summarizes the current research works in characterization of FDM parts, advancements in materials used in FDM and latest works related to making fabric samples using FDM. The results show that the mechanical properties and surface quality are compromised in FDM parts. Strength and flexibility with better surface finishing are essential parameters in fabric structures. There are mainly two techniques that are explored by researchers to enhance the quality of the parts. The first is optimizing process parameters and the second is improving material quality. FDM process parameters like extrusion temperature, layer height, print speed and built orientation can significantly influence the quality of the parts. Optimizing these parameters can significantly enhance the strength of the fabric produced. Moreover, a great amount of impetus is given to improve material by reinforcing it and making polymer blends with specific qualities. There has been studies related to the development of fabric structures and deposition of polymers on fabrics with FDM. It is concluded that the major concern with such structures is strength and processability. To address these issues, optimizing process parameters and developing new filaments for exclusively making fabrics can be the future work in this area. [ABSTRACT FROM AUTHOR]

Metal-based additive manufacturing (AM) displayed a revolutionary influence in the world of engineering and opened the doors to new opportunities for individuals as well as for industries. The design flexibility and high mechanical performance make this process more widespread and popular. Furthermore, the usage of minimal material with less wastage and the lowering of tooling expenses stands out as noteworthy benefits of the AM process. Nonetheless, an inherent limitation of AM printed materials includes issues related to the unique microstructure of AM parts, such as varying material densities, anisotropic properties and residual stresses. These factors can lead to unpredictable tool wear, poor surface finish and dimensional inaccuracies during machining operations. Additionally, the presence of hard inclusions or defects within the printed material can further exacerbate tool wear and increase machining difficulty. As a result, machining processes are often required to obtain the desired surface quality of the component. This study undertook a comprehensive and systematic review of the machinability of metal additive manufactured (AMed) components, contrasting them with wrought materials based on their response parameters. It investigated the turning, milling and drilling performances of AMed components, examining factors such as cutting forces, tool morphology, chip formation, hole quality, surface integrity, tool wear and temperature. This analysis encompassed diverse cutting conditions, building orientations and machining environments including flood, MQL, cryogenic cooling as well as AM parameters and post-heat treatments. Furthermore, this study places a significant emphasis on the sustainable attributes of the cutting fluids utilized in the machining of AM parts, alongside the overall sustainability of the manufactured components. It aims to pinpoint pivotal research findings and constraints while proposing avenues for future research endeavors. The main goal of this review is to furnish a comprehensive resource that consolidates knowledge regarding the surface quality and machinability of AMed metallic objects. Furthermore, it offers suggestions on machining strategies and insights into challenges and potentials related to machining AM parts. Additionally, it provides recommendations to enhance their machinability. Finally, the article introduces potential directions for future research to advance the field and enhance the efficacy of the AMed part. [ABSTRACT FROM AUTHOR]

The development of wire electrochemical spark machining setup is always challenging in the form of industrial viable for machining advanced engineering materials such as polymer nanocomposites, quartz, glass, ceramics, etc. Because of some drawbacks associated with it, like irregularity in kerf width, poor surface finish, no spark formed at high wire velocity, wire breaking at high voltage, etc. In the present work, a newly developed hybrid machining process that is reversible motion-wire electrochemical spark machining (RM-WECSM) has been developed for curve profile cutting, especially on non-conducting workpieces such as aluminum oxide epoxy nanocomposite of 3.5 mm thickness. The effect of NaOH concentration, applied voltage, reversible wire velocity, pulse on-and-off time, on material removal rate and average surface roughness have been studied using a one-parameter-at-a-time approach. Sparking occurred from the electrolyte surface to 10 mm above the electrolyte surface to cut the workpiece. The spark length is equal to the workpiece thickness. A continuous, stable spark has been formed at a high reversible wire velocity (19.8 m/min). Simultaneously, self-electrolyte flow has been generated, due to which melted materials have been washed out of the cut-surface and provided the smooth (1.987 µm) cut-surface of the workpiece. The maximum MRR is found as 1.63 mg/min. Thermal cracks, heat-affected zones and recast layers were not found on the curve cut-surface, and it was analyzed by a field emission scanning electron microscope. [ABSTRACT FROM AUTHOR]

Tool vibration is a key factor that affects surface finish, generates noise, and reduces the tool life during conventional boring because of the excessive overhanging length of the tool holder. The interaction between the dynamics of the machine tool and the boring process led to progressive vibration. The creation of appropriate mechanisms in reducing tool vibration will help manufacturing industries to become more productive. In this research, in order to control vibration in the overhanging boring bar, a passive vibration control method was employed. Constrained layer dampers consist of boring bar, substrate, and elastic materials and it is used to minimize tool vibration produced during boring operation. The investigation utilized computational analysis through the ANSYS Workbench platform, employing key parameters such as the overhanging length of the tool holder (100, 150, and 200 mm), substrate material (aluminum, brass, and copper), and elastic material (Nitrile rubber, Natural rubber, and polyurethane). A comprehensive series of 27-run boring experiments were conducted to assess the impact of the constrained layer damper on tool vibration and cutting properties. The results of the study revealed remarkable improvements in various performance metrics. The constrained layer damper demonstrated an impressive 98% reduction in tool vibration, signifying its efficacy in dampening vibrational forces during the boring operation. Furthermore, a substantial 83% decrease in surface roughness was observed, indicating enhanced machining precision and surface finish. The constrained layer damper also exhibited a noteworthy 97.5% reduction in tool wear, highlighting its ability to significantly prolong tool life under challenging machining conditions. [ABSTRACT FROM AUTHOR]

Sn-10Bi low-bismuth-content solder alloy provides a potential alternative to the currently used Sn-Ag-Cu series due to its lower cost, excellent ductility, and strengthening resulting from the Bi solid solution and precipitation. This study primarily investigates the interfacial evolution and shear strength characteristics of Sn-10Bi joints on a Ni/Au surface finish during the as-soldered and subsequent isothermal aging processes. To improve the joint performance, a 0.2 or 0.5 wt.% dopant of Zn was incorporated into Sn-10Bi solder. The findings demonstrated that a 0.2 or 0.5 wt.% Zn dopant altered the composition of the intermetallic compound (IMC) formed at the interface between the solder and Ni/Au surface finish from Ni3Sn4 to Ni3(Sn, Zn)4. The occurrence of this transformation is attributed to the diffusion of Zn atoms into the Ni3Sn4 lattice, resulting in the substitution of a portion of the Sn atoms by Zn atoms, thereby forming the Ni3(Sn, Zn)4 IMC during the soldering process, which was also verified by calculations based on first principles. Furthermore, a 0.2 or 0.5 wt.% Zn dopant in Sn-10Bi significantly inhibited the Ni3(Sn, Zn)4 growth after both the soldering and thermal aging processes. Zn addition can enhance the shear strength of solder joints irrespective of the as-soldered or aging condition. The fracture mode was determined by the aging durations—with the brittle mode occurring for as-soldered joints, the ductile mode occurring for aged joints after 10 days, and again the brittle mode for joints after 40 days of aging. [ABSTRACT FROM AUTHOR]

Due to their high hardness at elevated temperatures and chemical stability, alumina-based ceramic cutting tools have been successfully applied in the machining of ferrous materials, especially quenched and tempered steels. Their low fracture toughness, however, makes it difficult to finish them by grinding, as cracks and defects can occur. In addition, its application in machining processes demands appropriate edge preparation to avoid tool failure. Within this context, the paper aims to demonstrate the applicability of an experimental Al2O3 + MgO ceramic cutting insert in hard turning. For this, grinding tests were performed to determine the most appropriate conditions to improve its surface and edge quality. The effects of cutting and feed speeds, grinding wheel bonding material, and abrasive grain size were investigated. Moreover, different cutting-edge geometries were prepared in this tool material and tested in turning a hardened AISI 4140 steel (50 HRC) to determine their performance regarding tool life and workpiece roughness. The results demonstrated that a finer grinding wheel (D15) combined with high cutting (60 m/s) and feed (10 mm/min) speeds leads to the lowest surface roughness and edge chipping. In addition, both symmetric (Κ = 1) and asymmetric (Κ = 2) edge roundings led to higher tool lives in hard turning in comparison to a single chamfered tool, as they contributed to better load distribution in the cutting region. The paper provides information for the manufacture and application of alumina-based ceramic cutting inserts in the metalworking industry, as it disseminates good manufacturing practices and recommendations for appropriate cutting-edge geometry. [ABSTRACT FROM AUTHOR]

Wire arc directed energy deposition (Wire Arc DED) has become a popular metal additive manufacturing technique for its capability to print large metal parts at a high deposition rate while being economically efficient. However, the Wire Arc DED process exhibits geometric inaccuracies resulting from the variability in the bead geometry and demonstrates heterogeneity in microstructure and mechanical properties. This study investigates the use of tailored periodic machining interventions during the Wire Arc DED process to address these shortcomings. The as-built geometry and surface finish, microstructure, and microhardness of multilayer wall structures produced with and without machining interventions carried out at different temperatures are compared. The machining interventions are found to reduce the uncertainty in bead geometry evolution and significantly improve the surface roughness of the as-built walls, thus reducing the need for further postprocessing of the wall surfaces. Although the microstructure constituents of the as-built wall structures with and without machining interventions are similar, the machining interventions result in finer grains in the interior of the part. Machining interventions are found to yield a statistically significant increase in microhardness, indicating increased strength compared to Wire Arc DED alone. In addition, the spread of the microhardness distribution is reduced in Hybrid Wire Arc DED, indicating improved homogeneity of the grain size distribution compared to Wire Arc DED alone. The study shows that the proposed hybrid manufacturing technique has the potential to control and improve the geometric and mechanical properties of additively manufactured metal components. [ABSTRACT FROM AUTHOR]

Surface finishing applications are still cumbersome manual tasks, therefore, robotization of the process is of great interest as it allows for automation and increased versatility. However, finishing processes are difficult to automate, mainly because of the variation in material removal. In particular, the variables involved undergo changes that modify the material removal rate. This paper proposes a methodology for modeling material removal automatically based on experimental data. The procedure consists of monitoring the material removed from the parts under study that are in an automated precision measuring system during the finishing process. Based on the experimental models, a control algorithm for continuous material removal is presented. It guarantees a homogeneous surface finish by varying the robot feed rate. Finally, the results of several experimental material removal models under different process conditions and the validation of the proposed control algorithm are presented. The results show that the proposed method achieves a substantial improvement in the homogeneity of the finish. [ABSTRACT FROM AUTHOR]

Ceramic matrix composites (CMCs) are highly promising materials for the next generation of aero-engines. However, machining of CMCs suffers from low efficiency and poor surface finish, which presents an obstacle to their wider application. To overcome these problems, this study investigates high-efficiency deep grinding of CMCs, focusing on the effects of grinding depth. The results show that both the surface roughness and the depth of subsurface damage (SSD) are insensitive to grinding depth. The material removal rate can be increased sixfold by increasing the grinding depth, while the surface roughness and SSD depth increase by only about 10%. Moreover, it is found that the behavior of material removal is strongly dependent on grinding depth. As the grinding depth is increased, fibers are removed in smaller sizes, with the fiber length in chips being reduced by about 34%. However, too large a grinding depth will result in blockage by chip powder, which leads to a dramatic increase in the ratio of tangential to normal grinding forces. This study demonstrates that increasing the depth of cut is an effective approach to improve the machining efficiency of CMCs, while maintaining a good surface finish. It provides the basis for the further development of high-performance grinding methods for CMCs, which should facilitate their wider application. HIGHLIGHTS: • Both surface roughness and subsurface damage depth are found to be insensitive to the depth of cut. • The dependence of material removal behavior on grinding depth is revealed. • A technique for high-performance grinding of ceramic matrix composites is demonstrated. [ABSTRACT FROM AUTHOR]

This paper describes a method for generating toolpaths based on machining strategies for five-axis controlled machining using special tools. Traditionally, most toolpath generation studies focused on ball-end mills, proposing strategic methods to achieve high-quality machining while avoiding tool interference. Recently, special finishing tools with large cutting edge radii have gained interest for achieving higher machining efficiency. These special tools can produce smooth finished surfaces even with large pick-feed widths, leading to higher productivity. However, unlike conventional machining with ball-end mills, five-axis controlled machining using special tools lacks standardized work design procedures. This study proposes a generic tool-geometry data format for defining special tool geometries and a method for generating toolpaths using this data format. This method strategically treats special tools as conventional ball-end mills. Consequently, five-axis controlled machining for new tool geometries can be achieved using existing operational procedures. To generate toolpaths, this study utilizes a two-dimensional configuration space (C-Space). For special tools with multiple cutting edge radii, the relationship between the tool posture and cutting edge contact point is clarified by mapping the cutting edge radius information onto the C-Space. By employing this mapped cutting edge information, we can determine the interference-free tool posture corresponding to the chosen cutting edge section based on the machining strategy. Finally, the paper presents machining simulations and experiments conducted to confirm the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

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The Experimental study investigates the impact of ultrasonic-assisted face turning (UAFT) on cutting forces, tensile residual stress, and surface topography. The primary objective is to identify optimal cutting parameters that yield a smoother surface finish while concurrently reducing cutting forces and tensile residual stress. The tests were conducted on a lathe machine equipped with ultrasonic assistance, using 1.7225 steel as the workpiece material. Various cutting parameters, including feed rate, spindle speed, and turning state, were varied. The results illuminate the significant efficacy of ultrasonic assisted face turn (UAFT) in improving surface topography, compared to conventional turning (CT). The optimal turning parameters for achieving the smoothest surface finish were determined to be a higher spindle speed and lower feed rate. Moreover, the introduction of ultrasonic vibration led to a substantial reduction in cutting forces, primarily attributable to the diminished attrition between the cutting tool insert and the work part. Overall, the experimental study demonstrates the effectiveness of ultrasonic-assisted face turning in enhancing surface topography, with an improvement of approximately 39%. Additionally, the study demonstrated a reduction in cutting forces by approximately 50% and a decrease in tensile residual stress by approximately 33.8%. These findings underscore the potential of ultrasonic vibration as a tool for optimizing cutting parameters to achieve desired surface finishes in machining applications. [ABSTRACT FROM AUTHOR]

This study presents a highly efficient chemical and magnetorheological fluid (C-MRF) hybrid polishing process established by using an eco-friendly slurry of malic acid, Fe3O4–SiO2 abrasive particles, and hydrogen peroxide (H2O2) as an oxidant, all mixed with purified water, highlighting its efficacy in a wide range of polishing applications. Herein, the polishing processes of Ti–6Al–4V alloy utilizing C-MRF with on Fe3O4–SiO2 abrasives are detailed, and the polishing performance is assessed by investigating the influence of oxidizing agent H2O2 and acid malic to the surface finish of the Ti–6Al–4V alloy. The linear variable magnetic field by improved Halbach array was proposed to improve the material removal rate and surface quality and create a polishing process with a highly efficient magnetic field source. Single-factor and orthogonal experimental analysis methods are applied to provide the technological parameters factors with varying influences on surface quality and material removal ability. [ABSTRACT FROM AUTHOR]