Search

With the progression in technologies, conventional cutting of metal with flood cooling is superseded by some other means, viz. minimum quantity lubrication (MQL). Here, in this current work, we present that hexagonal boron nitride (hBN) nano-fluid particles are used in terms of percentage mixed in SAFCO lubricant oil. The factors, viz. cutting velocity, depth and percentage of nanoparticles are varied to obtain the mathematical models and optimisation of responses, viz. temperature and surface roughness. Desirability function analysis (DFA) approach is adopted for the optimisation process, and regression analysis is executed for the mathematical modelling. Also, criteria importance through inter criteria (CRITIC) approach was implemented to evaluate the weightage of responses first before the DFA application. The analysis of variance reveals that all the factors taken into the existent are significantly affecting the outcomes, and nanoparticles percentage being the most one. The percentage increase of nanoparticles in oil leads to better surface conditions, as depicted by the result. The ideal settings for the optimisation of responses undertaken may be expressed as follows: 600 rpm cutting speed, 0.1 mm of depth and 2% nanoparticle percentage in MQL. The mathematical modelling confirms that first-order linear models are sufficient for both the responses under the given set of design of experiments. [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]

Heat-assisted Incremental Sheet Forming (HA-ISF) is a viable forming technique that uses the heat-source to form the sheet materials incrementally and progressively. The hard-to-form sheet materials may be formed effectively using the HA-ISF method which are otherwise difficult to form at the room temperature. HA-ISF may enable the greater formability of the formed sheet-parts and reduce the required forming forces for fabricating the sheet components. These possibilities have motivated the researchers to explore various aspects of HA-ISF and the effects of process factors on the various outcomes. In this review article, various dimensions and methods of this emerging technique of sheet forming have been explored. Each method of HA-ISF has been studied against the hard-to-form materials to establish a trend on the outcome like forming force, surface roughness and formability. The capabilities of these methods of warm forming have also been discussed for the hard sheet materials along with the mechanisms of the obtained results. Results shows that the nature of materials and the mode of heating the sheet during the forming process can affect the formability, surface roughness and the required deforming loads effectively. An attempt has also been made by the authors for providing and establishing the criteria to estimate the deforming loads that are required to deform the sheet material by using the analytical and predictive modelling approach. Available analytical models show difficulty in the prediction of the input parameters for desired output parameters. While the development of numerical models is very time-consuming and has significant deviation in result for the upper range of input parameters due to variation in material properties with varying temperature. Whereas, empirical modelling can be a viable approach to predict the HA-ISF process. In addition, various applications of the HA-ISF have also been discussed for streamlining this novel technique for industries to produce customized products from hard-to-form materials. Results also shows that the HA-ISF process is efficient for increasing the formability of hard sheet materials and for reducing the required deforming loads. Achieving the better dimensional accuracy and good surface finish is still the challenge in HA-ISF and researchers may focus on these areas for enhancing the capability of this technique of warm forming. [ABSTRACT FROM AUTHOR]

The abrasive waterjet machining process was introduced in the 1980s as a new cutting tool; the process has the ability to cut almost any material. Currently, the AWJ process is used in many world-class factories, producing parts for use in daily life. A description of this process and its influencing parameters are first presented in this paper, along with process models for the AWJ tool itself and also for the jet–material interaction. The AWJ material removal process occurs through the high-velocity impact of abrasive particles, whose tips micromachine the material at the microscopic scale, with no thermal or mechanical adverse effects. The macro-characteristics of the cut surface, such as its taper, trailback, and waviness, are discussed, along with methods of improving the geometrical accuracy of the cut parts using these attributes. For example, dynamic angular compensation is used to correct for the taper and undercut in shape cutting. The surface finish is controlled by the cutting speed, hydraulic, and abrasive parameters using software and process models built into the controllers of CNC machines. In addition to shape cutting, edge trimming is presented, with a focus on the carbon fiber composites used in aircraft and automotive structures, where special AWJ tools and manipulators are used. Examples of the precision cutting of microelectronic and solar cell parts are discussed to describe the special techniques that are used, such as machine vision and vacuum-assist, which have been found to be essential to the integrity and accuracy of cut parts. The use of the AWJ machining process was extended to other applications, such as drilling, boring, milling, turning, and surface modification, which are presented in this paper as actual industrial applications. To demonstrate the versatility of the AWJ machining process, the data in this paper were selected to cover a wide range of materials, such as metal, glass, composites, and ceramics, and also a wide range of thicknesses, from 1 mm to 600 mm. The trends of Industry 4.0 and 5.0, AI, and IoT are also presented. [ABSTRACT FROM AUTHOR]

In an effort to enhance the quality of mechanized endodontic instruments, various thermal treatment methods, and design modifications have been suggested. However, upon evaluation, these endodontic instruments may exhibit microscopic irregularities. The objective of this in vitro study was to analyze the cutting capacity, surface finish, and mechanical properties of Nickel-Titanium 25/.04 Rotate (VDW GmbH, Munich, Germany) and LOGIC 2 (Easy Equipamentos Odontológicos, Belo Horizonte, MG, Brazil) rotary instruments. Twenty rotary instruments were divided into 2 groups: GR, the group with ROTATE instruments (n = 10); and GL2, the group with LOGIC 2 instruments (n = 10). They were evaluated for roughness, using a profilometer, for bending resistance, buckling resistance, and cutting capacity using a universal testing machine, as well as for torsional strength (torque and angular deflection) using a torquemeter. The instruments were visualized before and after the mechanical tests through scanning electron microscopy. GR showed better surface finish in terms of roughness, greater cutting capacity, and greater angular deflection than GL2 (P <.05). However, GL2 showed better flexibility than GR (P <.05). GL2 and GR did not show statistically significant differences in terms of buckling and torque (P >.05). The ROTATE and LOGIC 2 rotary instruments differed in their surface finish, cutting capacity, and mechanical properties, except for their buckling resistance and required fracture torque. [ABSTRACT FROM AUTHOR]

Selective laser melting (SLM) can produce complex metal components with high densities, thereby surpassing the limitations of traditional machining methods. However, achieving accurate dimensions, geometries, and acceptable surface states in parts fabricated through SLM remains a concern as they often fall short compared to traditionally machined components. As a solution, a hybrid additive-subtractive manufacturing (HASM) method was developed to effectively utilize the advantages of both techniques. In this study, SLM-made 316 L stainless steel was machined under distinct cooling conditions to investigate the effects of roughness and tool wear. After a thorough investigation, the dual-MQL strategy was evaluated and compared with dry and MQL cutting strategies. The findings showed that the dual-MQL condition led to a significant reduction in flank wear by 54–56% and 29–34%, respectively, associated with dry and MQL cutting techniques, making it a highly promising key for machining SLM-made steel components. Machine learning techniques are potential tools for prediction and classification capabilities in machining processes. For milling SLM-made 316 L SS, multilayer perceptron (MLP) proved to be the most effective prediction model and for classification MLP and Random forest performed better.

Additive Manufacturing (AM) is receiving widespread attention from both industry and academia who are looking to benefit from the numerous advantageous possibilities that AM processes have to offer, such as the potential to design and produce highly complex bespoke geometries with minimal material wastage. Yet, despite this, AM also has some drawbacks. Some of the most significant include the presence of process-induced defects and the inherent surface roughness of an AM built component, both of which can have a considerable influence on the mechanical properties of the final product. This research will investigate the role of an as-built surface on the fatigue properties of AM Ti–6Al–4V manufactured by electron beam melting (EBM), laser powder bed fusion (L-PBF) and laser metal deposition with wire (LMD-w). Fatigue results have been generated alongside advanced surface profilometry, microstructural, defect and fractographic analyses that have revealed that whilst the surface roughness in the majority of instances is the primary factor impacting the fatigue performance on AM material, it cannot be considered alone. It was found that the inherent as-built (AB) surface finish was significantly different across the various AM processes, inducing a range of effective stress concentrations and thus, a contrasting impact on the resulting fatigue performance. Results from each variant have been compared against a machined and polished equivalent, to provide a further consideration as to whether the as-built surface would be suffice from a time and economical viewpoint. Statistical analysis of the generated results also allowed for an extrapolation of predicted fatigue lives in the very high cycle regime for the alternative AM Ti–6Al–4V variants.

This study evaluates the use of gingelly oil as an eco-friendly cutting fluid for the turning operation. Experiments were conducted to determine the effect of nose radius, and rake angle on tool wear, surface formation, and cutting force. In addition, different lubrication techniques, such as cutting fluids and bio-oils, were investigated to determine their potential for minimising friction, heat generation, and tool wear during machining. In comparison to dry cutting, and conventional petroleum-based lubricants, the results demonstrate that gingelly oil consistently produces smoother surface finishes, and reduces cutting forces. The relationships between cutting parameters, and surface finish were analysed using statistical modelling, with R-square and p-values used to quantify correlations and predictor significance. The findings highlight the viability of gingelly oil as a cutting fluid and the significance of optimising process parameters for increased machining efficiency.

In this study, mahogany seed oil was sourced and prepared, and the performances were compared with mineral oils. The extracted oil was characterized to recognize properties related to pyto-chemical, physio-chemical lubricity and thereafter used along with mineral oil for the formulation of cutting fluid using emulsifying agent, anti-corrosive agent, biocides, and anti-foam agent as additives. These additives were added to oil and water by using 24 full factorial design to achieve the optimal combination. In addition, central composite design (CCD) was adopted for the experimental design, and the performance of the mahogany oil-based cutting fluid (MBCF) was investigated in terms of surface finish, cutting temperature, material removal rate, machine sound level, and chips formation and, thereafter, compared with conventional mineral oil (CBCF) in turning of AISI 304 steel under flood cooling technique. Experimental data were analyzed using analysis of variance (ANOVA) and grey relational analysis (GRA). The experimental findings showed that optimal multi-response performance of the MBCF can be achieved using spindle speed, feed rate and depth of cut of 1100 rev/min, 0.27 mm/rev, and 0.23 mm, respectively, while optimal multi-response performance of CBCF can be achieved with spindle speed, feed rate, and depth of cut of 900 rev/min, 0.62 mm/rev, and 0.23 mm, respectively. [ABSTRACT FROM AUTHOR]

The effect of surface roughness and polishing orientation on fatigue life is investigated. Fully reversed bending fatigue tests are conducted on ASTM A1008 specimens having surface roughness asperities ranging from mirror finish (Ra = 0.05 μm) to coarse (Ra = 1.5 μm). Two polishing directions (i.e., orientations) are examined. For the range of roughness values tested, the results suggest that polishing orientation has a strong influence on fatigue life. Specifically, within the range of surface roughness values tested, fatigue life was found to be relatively insensitive to surface roughness asperities when the roughness orientation was parallel to the direction of surface stress but sensitive to surface roughness asperities when the orientation crossed the direction of surface stress. Results are generalized using the concept of fracture fatigue entropy (FFE). It is shown that, unlike fatigue life, FFE is independent of polishing orientation, a noteworthy result. To explain the behavior of FFE in relation to surface roughness asperities, a fatigue thermodynamics theory is presented that hypothesizes that all specimens of the same material fail at equivalent entropy levels. Highlights: The influence of surface roughness on fatigue life is investigated.Extensive fully reversed bending fatigue tests are performed.Surface roughness lay has a pronounced influence on fatigue life.Fracture fatigue entropy (FFE) is sensitive to the roughness regardless of its lay. [ABSTRACT FROM AUTHOR]

Displacement mapping is a computer graphics technique that enables the design of components with regularly or randomly textured surfaces that can be quickly materialized on a three-dimensional (3D) printer when needed. This approach is, in principle, more flexible, faster, and more economical compared to conventional texturing methods, but the accuracy of the texture depends heavily on the parameters used. The purpose of this study is to demonstrate how to produce a surface-textured part using polygonal (mesh) modeling software and a photopolymerizable resin and to develop a universal methodology to predict the dimensional accuracy of the model file log combined with a resin 3D printer. The printed components were characterized on a scanning confocal microscope. In the setup used in this study, the mesh size had to be reduced to 10% of the smallest feature size, and the textured layer had to be heavily (×4.5) overexposed to achieve the desired accuracy. As a practical application, two functional stamps with a regular (honeycomb) and a random texture, respectively, were successfully manufactured. The insights gained will be of great benefit for quickly and cost-effectively producing components with innovative patterns and textures for a variety of hobby, industrial, and biomedical applications. [ABSTRACT FROM AUTHOR]

This study investigates the mechanical properties, surface integrity, and chemical configuration of PVD-coated high-speed steel (HSS) cutting tools, with a particular focus on titanium nitride (TiN) and titanium aluminium nitride (TiAlN) coatings. A range of characterisation methodologies were employed to examine the impact of pre-coating surface conditions on the resulting coatings. This impact includes the effects of gas bubble production and unequal distribution of elements, which are two unwanted occurrences. Notwithstanding these difficulties, coatings applied on surfaces that were highly polished exhibited more consistency in their mechanical and elemental characteristics, with a thickness ranging from 2 to 4 µm. The study of mechanical characteristics confirms a significant increase in hardness, from an initial value of roughly 1000 HV0.5 for untreated tools to 1300 HV0.5 for tools with physical vapour deposition (PVD) coatings. Although PVD coatings produced on an industrial scale might not exceed the quality of coatings manufactured in a laboratory, they do offer substantial enhancements in terms of hardness. This study highlights the significant importance of thorough surface preparation in achieving enhanced coating performance, hence contributing to the efforts to prolong the lifespan of tools and enhance their performance even under demanding operational circumstances. [ABSTRACT FROM AUTHOR]

The objective of this paper was to evaluate the effect of some cutting parameters on surface finish of bright mild steel (BMS). Samples were cut into the required piece with dimension 50mm x 200mm and the turning operation done using a tungsten carbide tip tool. The cutting variables include speed of the spindle, feed rate and depth of cut. The result obtained shows that a feed rate of 0.75mm/rev affects the surface finish the most with a roughness value of 3μm, while the combination of a depth of cut of 0.2mm and maximum speed 700rpm have the minimum effect on the surface finish (Ra value of 1.1μm) of low carbon steel. [ABSTRACT FROM AUTHOR]

Copyright of Bulletin of the Chinese Ceramic Society is the property of Bulletin of the Chinese Ceramic Society Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Granite edge finishing through grinding is a common process in the granite processing industry, crucial for achieving the final desired shape and edge quality of products. This study focuses on the granite industry, specifically delving into the significance of grinding and polishing for improving aesthetics and extending material longevity. The experimental design entails a comprehensive factorial experiment plan involving two workpiece materials (white and black granite samples) and two cutting tool edge shapes (chamfer and concave), each with two grit sizes: G150 and G600. The cutting conditions varied and consisted of variations in spindle speeds (1500, 2500, 3500 rpm), feed rates (500, 1000, 1500 mm/min), and lubrication modes (wet/dry). The results uncover intricate relationships among these parameters and part quality, underscoring the pivotal role of tool geometry in achieving superior surface finishes and in controlling the cutting forces. These findings contribute to a nuanced understanding of the dynamic interplay between tool characteristics, material properties, and machining conditions within the granite industry. [ABSTRACT FROM AUTHOR]

This study focuses on improving the surface properties of Aluminum (Al) sheets for imaging and optical applications. To achieve high efficiency and low damage, novel CNC abrasive lapping (CNC AL) techniques were proposed and tested. The experiments investigated the impact of various parameters, such as spindle speed, feed rate, and depth of cut, using two types of abrasives (PCD and hybrid PCD with Al2O3) on the surface quality (Ra) and reflectance (R) of the Al sheets. Optimal parameters were determined using Taguchi L9 and (S/N) analysis, favoring low spindle speed, low feed rate, and high depth of cut. Surface roughness was measured with Surfcom1400G, while SEM EDX, AFM, and 3D profilometer were used to assess surface microstructures. Significant improvement of 35-96% was observed in the highly reflective Al sheets using UV-VIS spectrophotometry and texture analysis in MATLAB. [ABSTRACT FROM AUTHOR]

The Gas Additive Powder Mix near Dry Electric Discharge Machining (GAPMND-EDM) serves a manufacturing purpose, specifically for cutting hard materials. This involves the removal of material from a workpiece via fusion, ablation, and evaporation caused by the heat energy generated through electric sparks during energy supply. The process offers several advantages in terms of performance and characteristics. This research project aims to optimize key process parameters, including material removal rate, surface roughness, residual stresses, and microhardness. The study employs a methodology that combines the standard deviation-based objective weighting method with GRA (Gray Relational Analysis) optimization to enhance the hybrid GAPMND-EDM process when applied to EN-31 material. Experimental runs were conducted to evaluate the impact of various input factors, such as pulse-on time, discharge current, dielectric fluid pressure, and metallic powder concentration. The taguchi-based GRA method was utilized for this purpose, and the experimental design followed an L-27 orthogonal array with the assistance of Minitab-19 software. A total of 27 experiments were performed, encompassing diverse combinations of process parameters. Subsequently, an ANOVA (Analysis of Variance) was executed to analyze the influence of pulse-on time, discharge current, dielectric fluid pressure, and metallic powder concentration on Material Removal Rate (MRR), Surface Roughness (SR), Residual Stress (RS), and Microhardness (MH). The result shows the optimal combination of parameters, denoted as A2B2C2D1, was identified as the preferred configuration. [ABSTRACT FROM AUTHOR]

Laser shock peening (LSP) uses plasma shock waves to induce compressive residual stress at the surface of a component which has the potential to improve its fatigue properties. For AM parts, the existence of internal defects, surface roughness, and tensile residual stresses leads to noticeably lower fatigue strength compared to materials produced through conventional processes. Furthermore, there is a tendency for greater scatter in the fatigue behavior of these parts when compared to traditionally manufactured components. In this study, the effect of LSP on the roughness and fatigue behavior of Ti-6Al-4V alloy constructed through Laser Powder Bed Fusion (L-PBF) technique was investigated. Two types of samples were designed and tested: as-built surface air foil samples for four-point bending tests and machined surface straight gage samples for uniaxial fatigue testing. Two sets of process parameters, optimized and non-optimized, were also used for the fabrication of each sample type. It was found that LSP had negative effects on the smooth (i.e., machined) surface samples, whereas for as-built surfaces the roughness was enhanced by decreasing the sharpness of the deep valleys and partially remelting the loosely bonded particles on the peaks. It was found that the scatter of the fatigue data decreased for optimized machined samples, while no clear improvement was observed in their lives. However, all non-optimized samples showed improvements in fatigue lives after the LSP process. [ABSTRACT FROM AUTHOR]

The objective of this paper was to evaluate the effect of some cutting parameters on surface finish of bright mild steel (BMS). Samples were cut into the required piece with dimension 50mm x 200mm and the turning operation done using a tungsten carbide tip tool. The cutting variables include speed of the spindle, feed rate and depth of cut. The result obtained shows that a feed rate of 0.75mm/rev affects the surface finish the most with a roughness value of 3µm, while the combination of a depth of cut of 0.2mm and maximum speed 700rpm have the minimum effect on the surface finish (Ra value of 1.1µm) of low carbon steel.

In the course of grinding, conventional grinding fluid is frequently utilised, which leads to excessive consumption and negative environmental effects. MQL, or minimum quantity lubrication, is a possible replacement for traditional dry and fluid coolant application. It is well known that the MQL grinding process's effectiveness depends on the lubricating and cooling capabilities of fluid. A water-based Al2O3 nanofluid was used in this work to grind materials due to its outstanding convective heat transfer and thermal conductivity qualities. Hardened steel's grinding properties are examined and contrasted with those of MQL grinding done in wet, dry, and pure water. Al2O3 nanofluid MQL grinding using water dramatically lower the grinding temperatures, minimise grinding forces, and enhance the ground surface finish. [ABSTRACT FROM AUTHOR]

The hybrid Electric Discharge Machine (PM-EDM) is the latest advancement in the removal of hard materials from workpieces while enhancing their performance and characteristics. This research project is focused on optimizing key process parameters, including material removal rate, tool wear, residual stresses, and surface finish. The approach utilized in this study involves employing the standard deviation-based objective weighting method in conjunction with GRA (Grey Relational Analysis) optimization to improve the hybrid PM-EDM process when applied to EN-31 material. Experimental runs were conducted to assess the impact of various input factors such as pulse on time, duty cycle, discharge current, and concentration of metallic powder. The GRA (Grey Relational Analysis)-based Taguchi method was employed for this purpose, and the experimental design followed an L-27 orthogonal array within the framework, facilitated by the use of minitab-20 software. A total of 27 experiments were conducted, encompassing diverse combinations of process parameters. Subsequently, an ANOVA (Analysis of Variance) was performed to scrutinize the impact of various inputs of discharge current, pulse on time, duty cycle, and powder concentration on MRR (Material Removal), TWR (Tool Wear), Ra (surface finish), and Rs (Residual stress). [ABSTRACT FROM AUTHOR]

This article analyses the influence of tool orientation on the geometry and surface finish obtained during the machining of thin-walled curved freeform surface parts on multitasking machining centre. These complex surfaces parts have direct application in blade manufacturing for the aeronautical sector, which has very high quality standards and are difficult to achieve. In addition, the material used is Ti6Al4V which adds a challenge due to its difficult machinability. Tool orientation has a significant effect on the accuracy of multi-axis machining reducing the theoretical force in a 6.17 % have achieved a dimensional improvement of a 7.84 %. [ABSTRACT FROM AUTHOR]

The purpose of this study was to determine whether the chemical compositions of Alnico alloys had any effects on the electrical discharge machining (EDM) performance and the surface finish. This article compares the behavior of three different Alnico alloys in electrical discharge machining. The experiments were conducted under different conditions using a BP93L EDM machine (ZAP BP, Końskie, Poland), applying an additional rotary motion to the electrode. A Box–Behnken experimental design was employed to analyze the influence of three factors, i.e., the spark current, the pulse-on time, and the pulse-off time, at three levels for three Alnico alloys. The material removal rate (MRR) was calculated for the different process parameters. After the EDM, the surface roughness was studied using a Talysurf CCI Lite non-contact profiler (Taylor–Hobson, Leicester, UK). The next step of the experiments involved preparing metallographic specimens to be observed by means of scanning electron microscopy (SEM) and optical microscopy (OM). Measurements of the nanohardness were also performed. The experimental data were then analyzed using Statistica software version 10 (64-bit) to determine and graphically represent the relationships between the input and output parameters for the three Alnico alloys. The chemical compositions of the Alnico alloys affected the thickness of the white layer (higher cobalt content, lower white layer thickness) and the material removal rate. The higher the cobalt content, the thinner the white layer and the lower the material removal efficiency. Moreover, the cobalt content in Alnico alloys influenced the shape of the precipitates; these ranged from spheroidal (13% Co) to mix-shaped (21.3% Co) to flake-shaped (32.2%). The hardness of the resulting white layer was 874 HV at10 mN. [ABSTRACT FROM AUTHOR]

Turn -milling is a new process that uses, turning and milling operations together, so that the tool and the work piece rotate simultaneously, for this reason, it has a wide ability in machining curved and complex surfaces. The Main subject of this research is Conducting research on the effect of changes in machining parameters, including work piece rotational speed, tool rotational speed and feed rate, on cutting parameters such as cutting force, cutting pressure, and surface finish parameters. The order and the number of experiments is designed based on the full factorial method. Experiments for each of the mentioned parameters were performed at three levels, which includes 27 tests in total. The results were analyzed with the help of Minitab software. The mentioned process was performed with a φ6 diameter end mill on a steel work piece 1.7225. As a result, increasing feed rate by three times increases the machining force by about two times and reduces the cutting pressure by about 27%, Also, the surface finish quality parameters 𝑅 𝑎 and 𝑅 𝑧 increased by 74% and 61%, respectively. The upward or downward trend of cutting forces, cutting pressure and the surface finish quality did not occur with the increase in the rotational speed of the work piece and the rotational speed of the tool, in fact, an extremum range was achieved in the increasing trend of the mentioned speeds. So that the minimum resultant force and also the cutting pressure were observed in the range of rotational speed of 950rpm of the tool and 300rpm of the work piece. [ABSTRACT FROM AUTHOR]

Nickel-based alloys are used in marine and aerospace applications due to their mechanical strength and chemical stability at high temperatures. Inconel 800 resists high-temperature corrosion such oxidation and carburization. Inconel 800 is utilised in deaerators, heaters, valves, heat exchangers, pumps, and more. Grinding responses was investigated since these applications demand a clean surface finish. In this study, surface grinding was performed on Inconel 800 under three different cooling conditions: dry, wet, and Nano-MQL. Wheel Speed(vs), feed(f), and Depth of cut(ae) were taken as input parameters, while Surface roughness(ra), the microhardness of the Workpiece, and temperature were taken as output parameters..NMQL circumstances yielded 0.42 μm surface finish and 60–62°C cutting temperature. The microhardness values on the machined surface under different cooling conditions reflect residual stress, which depends on the machining zone temperature. The material's surface residual stresses were tested to determine how grinding affected its mechanical qualities and performance. [ABSTRACT FROM AUTHOR]

Uniform poly-α-methylstyrene (PAMS) hollow core microcapsules (HCMs) are widely used as templates to fabricate glow discharge polymer (GDP) fuel capsules, which are fundamental devices for inertial confinement fusion (ICF) engineering. The sphericity and surface finish uniformity of PAMS HCMs are critical for achieving high-quality GDP fuel capsules. In this work, millimeter-scale PAMS HCMs were fabricated by a microencapsulation technique. The sphericity and surface finish uniformity were concurrently improved using di-t-butyl peroxide (DTBP). The mechanisms of these effects were also experimentally and theoretically investigated. The results show that DTBP distributes at the O-W2 interface of W1/O/W2 compound droplets, which resists the diffusion of molecules through the O-W2 interface bidirectionally. The resisted diffusion of H2O molecules into the O phase eliminates PAMS HCM surface defects. Additionally, the resistance of fluorobenzene (FB) molecules from diffusing from the O phase into the W2 phase can effectively extend the solidification of W1/O/W2 compound droplets and thus improve the spherical uniformity of the HCMs. Using these improved PAMS HCMs, GDP fuel capsules meeting the stringent requirements for ICF engineering are prepared, and the quality of which is beyond the National Ignition Facility standard.

This study investigates the mechanical properties, surface integrity, and chemical configuration of PVD-coated high-speed steel (HSS) cutting tools, with a particular focus on titanium nitride (TiN) and titanium aluminium nitride (TiAlN) coatings. A range of characterisation methodologies were employed to examine the impact of pre-coating surface conditions on the resulting coatings. This impact includes the effects of gas bubble production and unequal distribution of elements, which are two unwanted occurrences. Notwithstanding these difficulties, coatings applied on surfaces that were highly polished exhibited more consistency in their mechanical and elemental characteristics, with a thickness ranging from 2 to 4 µm. The study of mechanical characteristics confirms a significant increase in hardness, from an initial value of roughly 1000 HV0.5 for untreated tools to 1300 HV0.5 for tools with physical vapour deposition (PVD) coatings. Although PVD coatings produced on an industrial scale might not exceed the quality of coatings manufactured in a laboratory, they do offer substantial enhancements in terms of hardness. This study highlights the significant importance of thorough surface preparation in achieving enhanced coating performance, hence contributing to the efforts to prolong the lifespan of tools and enhance their performance even under demanding operational circumstances.

Displacement mapping is a computer graphics technique that enables the design of components with regularly or randomly textured surfaces that can be quickly materialized on a three-dimensional (3D) printer when needed. This approach is, in principle, more flexible, faster, and more economical compared to conventional texturing methods, but the accuracy of the texture depends heavily on the parameters used. The purpose of this study is to demonstrate how to produce a surface-textured part using polygonal (mesh) modeling software and a photopolymerizable resin and to develop a universal methodology to predict the dimensional accuracy of the model file log combined with a resin 3D printer. The printed components were characterized on a scanning confocal microscope. In the setup used in this study, the mesh size had to be reduced to 10% of the smallest feature size, and the textured layer had to be heavily (×4.5) overexposed to achieve the desired accuracy. As a practical application, two functional stamps with a regular (honeycomb) and a random texture, respectively, were successfully manufactured. The insights gained will be of great benefit for quickly and cost-effectively producing components with innovative patterns and textures for a variety of hobby, industrial, and biomedical applications.

PurposeDesigning and optimizing scintillator-based gamma detector using Monte Carlo simulation is of great importance in nuclear medicine and high energy physics. In scintillation detectors, understanding the light transport in the scintillator and the light collection by the photodetector plays a crucial role in achieving high performance. Thus, accurately modeling them is critical.MethodsIn previous works, we developed a model to compute crystal reflectance from the crystal 3D surface measurement and store it in look-up tables to be used in the Monte Carlo simulation software GATE. The relative light output comparison showed excellent agreement between simulations and experiments for both polished and rough surfaces in several configurations, that is, without and with reflector. However, when comparing them at the irradiation depth closest to the photodetector face, rough crystals with a reflector overestimated the predicted light output. Investigating the cause of this overestimation, we optimized the LUT algorithm to improve the reflectance computation accuracy, especially for rough surfaces. However, optical Monte Carlo simulations carried out with these newly generated LUTs still overestimate the light output. Based on previous observations, one probable cause is the erroneous assumption of perfect couplings between the reflector and crystal and between the crystal and photodetector, which likely results in an important overestimation of the light output compared to experimental values. In practice, several factors could degrade it. Here, we investigated possible suboptimal optical experimental configurations that could lead to a degraded light collection when using Teflon or ESR reflectors coupled to the crystal with air or grease. We generated look-up tables with a mixture of air and grease and showed the effect of three possible sources of light loss: the presence of a small gap between the crystal and the reflector edges close to the photodetector face, the infiltration of grease in the crystal-reflector coupling, and the presence of inhomogeneities in the photodetector-crystal interface.ResultsThe strongest effect is linked to the presence of a small gap of grease between the edges of the reflector material and the crystal (light loss of 10%-12% for 0.2 mm gap). The optical grease infiltrating the crystal-reflector air coupling decreases the light output, depending on the infiltration's extent and the amount of grease infiltrated. Five percent of air in the crystal-photodetector coupling can cause a light output decrease of 2% to 4%. The individual and combined effect of these advanced models can explain the discrepancy of the relative light output obtained with ESR in simulations and experiments. With Teflon, the study indicates that the light output loss strongly depends on the reflectance deterioration caused by grease absorption.ConclusionsOur results indicate that when studying scintillation detector performance with different finishes, performing simulations in ideal coupling conditions can lead to light output overestimation. To perform an accurate light output comparison and ultimately have a reliable detector performance estimation, all potential sources of practical limitations must be carefully considered. To broadly enable high-fidelity modeling, we developed an interface for users to compute their own LUTs, using their surface, scintillator, and reflector characteristics.

Grinding is a finishing process typically done in most metallic manufacturing centers, primarily to achieve precision and surface improvement. Currently, the grinding process of titanium alloys generally requires flood coolant application. Electron Beam Powder Bed Fusion (EB-PBF) is an additive manufacturing process that uses an electron beam as the heat source to melt and fuse powder particles to build layer by layer to build a three-dimensional component. Grinding is a major secondary process applied to additively manufactured metals, but with the current methodologies, grinding may impart tensile residual stress on the surface, and thus the performance of the material under fatigue conditions is reduced. In this paper, a targeted cutting fluid application approach for grinding an additively manufactured titanium alloy is used to possibly impart a compressive residual stress upon the subsurface while also providing an improved surface roughness. This study uses samples ground with a traditional flood coolant and samples with targeted cutting fluid applications developed by the researchers. Metrics such as surface residual stress, surface roughness, microstructure, and microhardness were used to determine imparted qualities using the various grinding cooling methodologies. The results show that the subsurface maximum principal residual stresses decreased by 108%, the average surface roughness decreased by 33%, and the microhardness at 5 μm increased by 1% using targeted air as the cutting fluid compared to flood cooling while grinding additively manufactured Ti6Al4V. Overall, the targeted grinding cooling fluid application induced compressive subsurface residual stresses and reduced the average surface roughness.

316L stainless steel is known for its high corrosion resistance and extensively being used for biomedical implants and for the fabrication of the parts in nuclear reactors, and fuel cells. In the current study, 316L stainless steel samples were grounded using different grades of surface grits (400, 1200, and mirror-finished) by mechanical polishing, and influence of surface finish on the wear and corrosion characteristics was studied. The dry sliding wear experiments were carried out on ball-on-plate setup against hardened steel ball and the corresponding friction curves were obtained and specific wear rates were measured. The wear mechanisms were identified by examining the worn-out surface using scanning electron microscope and Raman spectrometer. It was evident that the formation and removal of iron oxides is the dominant mechanism for material loss from the samples during wear tests. The higher wear resistance of the mirror-finished sample was attributed to the formation of stable chromium oxide layer on the wear track. Potentiodynamic polarization tests were performed on the samples and better corrosion resistance was observed for the mirror-finished sample. [ABSTRACT FROM AUTHOR]

In this study, wire electrical discharge machining of aluminium matrix composites has been experimentally investigated. A metal matrix composite Al/Al2O3/22 p has been machined at various combinations of machining parameters such as pulse on-time, off-time, wire speed and wire tension. Empirical models have been developed to predict the cutting rate, surface roughness and kerf width of the machined composite material. The models were developed by using the technique of response surface methodology. The experiments were conducted in standard roughing mode by using carefully planned response surface design matrix (central composite design). The model predictions are in good agreement with the experimental results. The R2 values of the proposed cutting rate and kerf width models are above 0.99, where as it is 0.98 for the surface roughness model. The pulse on-time was found to influence cutting rate and surface finish significantly. Kerf width was found to be affected by pulse on-time, off-time, wire speed and wire tension. In addition, a model was developed to correlate the multiple performance characteristic called as grey relational grade and the process parameters. The grey relational grade was significantly affected by pulse on-time and off-time time. The R2 value for the grey relational grade model was 0.94. Optimal parameter setting was determined for the multiple performance characteristic. The improvement in cutting rate was significant with reasonably smooth surfaces and narrow kerf width. However, the surface finish was found to be dominated by the presence of protruding ceramic particles on the machined surfaces. [ABSTRACT FROM AUTHOR]

Wire electric discharge machining (WEDM) is a famous machining process for manufacturing intricate and 3D complex geometries on tough difficult-to-machine superalloys and composites. Stainless steel 304 (SS 304) alloy has excellent corrosion resistance and forming faces which is used in aerospace, chemical, petrochemical industries, etc. The present work focuses on WEDM of SS 304 using a brass wire electrode of ϕ 0.25 mm with rough cut trailed by trim cuts to improve the machinability. WEDM experiments were conducted as per Taguchi's L9 experimental design with four-factor and three-level. The effect of pulse on time (Ton), pulse off time (Toff), current and wire offset during trim cuts on machinability characteristics, namely surface roughness, material removal rate (MRR), kerf width and microhardness, was analysed. Experimental results showed that trim cuts with varying wire offsets produced better surface finish, high MRR with hardness, and low kerf width compared with rough cut. Furthermore, surface characteristics of rough cut with trim cut surfaces were analysed using scanning electron microscope (SEM) images. Finally, grey relational analysis (GRA) was used to find the optimal input parameter combination and simultaneously optimize the selected machinability responses. [ABSTRACT FROM AUTHOR]

To improve the localization of material dissolution and fabrication of microstructures with better surface finish, high process complexity, such as different tool shapes, electrolyte flow, and tool insulation, has been utilised in electrochemical micromachining (EMM). Improvement of mass transport, sludge removal, and continuous dissolution are challenging tasks for EMM because bubbles and sludge increase the shielding effects. To solve the problems and achieve precision machining with a better surface finish, a new multi-step pulse waveform (MSPW) is designed indigenously. By incorporating three different peak voltages with a short duration time in the pulse on time of MSPW, potential fluctuation is intentionally induced during machining. Thus, more pulse fall times, short peak voltage duration times, and fluctuations of potential can improve the reduction of bubble size and its detachment rate. Due to it, ion transport phenomena improve, sludge is properly removed from the machining zone, and material dissolution rates increase. The effects of MSPW in EMM are compared with conventional rectangular pulse waveform (RPW). From mathematical estimation, it is found that the power transmission of MSPW is less than RPW, which plays a significant role in stray current minimization. The proposed method is verified by simulation, where it can be observed that current density decreases with increasing bubble size. By capturing images, it is also noticed that the size of gas bubbles decreases, accompanied by a higher detachment rate. Utilising MSPW, precise microdimples are fabricated with minimum surface roughness (Ra), i.e., 0.0241µm, whereas Ra is 0.251µm for RPW. Further, it is identified from the machined microdimples that etch factor improves, diameter minimises, depth increases, no irregular machining appears on the bottom surface, and surface finish also improves as compared to RPW. These improvements are also observed in machined microholes. [ABSTRACT FROM AUTHOR]

The impact of four typical surface finishes on electrochemical migration in printed circuit board production was studied using a modified water drop test, and the electrochemical migration phenomena of each surface finish at different bias voltages were analyzed. Based on the analysis of the experimental results, the four surface finishes were ranked in terms of their ability to resist electrochemical migration, as follows: electroless nickel/immersion gold (ENIG) > lead-free hot air solder leveling (HASL) > HASL > Cu. For the lead-free HASL, HASL, and Cu surface finishes, the growth of dendrites was mainly related to the hydroxide solubility product of metal ions, with a smaller solubility product leading to a larger area of precipitates, which further hindered the emergence and growth of dendrites. The electrochemical migration process of ENIG differed from other surface finishes. Gold was not involved in the electrochemical migration process, and no typical cathodic dendrite growth phenomenon was observed. Only nickel hydroxide and oxide formed from the anode edge and migrated toward the cathode with low conductivity, resulting in high electrochemical migration resistance for the ENIG surface finish. [ABSTRACT FROM AUTHOR]

Natural gut harp strings are made from twisted bundles of gut strips, which are dried, ground, and varnished. The effects of varying the twist angle and surface finishing on the mechanical properties of gut harp strings have been explored. Strings were tested over a range of twist angles from 23.5 ∘ to 58.3 ∘ , and with all four combinations of ground or unground and varnished or unvarnished surface finishing. The principal effects of varying the degree of twisting were that the breaking strength and tensile Young's modulus both fell as the twist angle was increased. String makers must therefore make a compromise between sound quality and string strength and durability. Leaving the string unvarnished dramatically increased the sensitivity to changes in humidity, which, in turn, affected the thermal tuning sensitivity and creep behaviour. Grinding the string surface prior to varnishing had no significant effect on the behaviour, but did make some difference to the thermal tuning sensitivity if the string was left unvarnished. Increasing the humidity frequently triggered episodes of additional string creep. There appeared to be a threshold effect, with the additional creep triggered when the string linear density exceeded its previous maximum. When the string was not creeping, there appeared to be a strong coupling mechanism between changes in the linear density and complementary changes in the string tension, such that there was almost no net effect on the string frequency. This behaviour was independent of the twist angle and the surface finishing, suggesting that whatever the coupling mechanism was, it was not dependent on the twisted structure of the string. [ABSTRACT FROM AUTHOR]