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The clearance flow in dry-running vacuum pumps is the main loss mechanism. To reduce the clearance mass flow rate in rarefied gas flows, sawtooth structures transversing to the direction of flow can be utilized. However, due to the sawtooth's structure size, micro-machining is necessary, whereby burr formation is a central challenge. First, the effectiveness of non-idealized sawtooth structures is investigated, demonstrating a high sensibility of the performance regarding the geometry of the tip. Therefore, burr formation in the cutting process must be minimized. For this reason, a 3D finite element (FE) chip formation model capable of predicting the burr formation is developed. An analysis of the burr formation zone showed positive triaxialities; thus, the triaxiality-dependent Johnson–Cook damage model is utilized. To minimize the mesh-induced error, a convergence analysis is conducted, showing no convergence of the maximum burr height. This is caused by the pathological mesh size dependence of local continuum damage models. A comparison of the cutting experiments and simulations revealed a reasonable prediction of cutting forces. In contrast, the passive force is predicted poorly, which is attributed to the underestimation of the ploughing force for non-elastic simulations. The prediction quality regarding the maximum burr height differs for the investigated cutting speeds, which can be explained by a built-up edge and a change in the machine tool compliance. Thereby, an analysis of the burr formation revealed that the burr height is captured by a non-physical remeshing algorithm and that the burr volume might be a more appropriate characteristic. [ABSTRACT FROM AUTHOR]

Pin fin-interconnected reentrant microchannels (PFIRM) of microchannel heat sink cooling systems provide a promising solution for efficient heat dissipation of high heat flux devices. They feature interconnected Ω-shaped reentrant configurations in cross-section, with large circular cavities at the bottom and diamond pin fins at the top. In this paper, a micro ball-end milling process was proposed to fabricate PFIRM. The burr formation process and deformation mechanisms during the micromilling process of PFIRM were investigated with experiments and finite element (FE) simulations. Results revealed that the burrs were mainly formed under the vertex of diamond pin fins on both up-milling and down-milling sides. The burrs on the up-milling side were pushed by the tool neck to the left side of feed direction, whereas the burrs on the down-milling side were thrusted by the flank face to the right side of feed direction. Besides, two unique types of chips, i.e., swallowtail-shaped chips and half swallowtail-shaped chips, were found to be formed during the micro ball-end milling process. Moreover, the effects of spindle speed and feed rate on the machining accuracy and surface roughness of PFIRM were also explored. The machining accuracy and surface roughness firstly increased and then decreased with increasing spindle speed. As the feed rate increased, the machining accuracy decreased in general, and the surface roughness firstly decreased and then increased. The present study suggested that the spindle speed of 15000 r/min and feed rate of 20 mm/min was optimal to improve the surface quality and machining accuracy. • Manuscript's Highlights. • Micro ball-end milling process was developed to fabricate pin fin-interconnected reentrant microchannels (PFIRM). • Burr formation process and deformation mechanisms of PFIRM were explored. • Swallowtail-shaped chips and half swallowtail-shaped chips were formed. • Effects of spindle speed and feed rate on machining accuracy and surface roughness of PFIRM were studied. [ABSTRACT FROM AUTHOR]

Fused deposition modeling (FDM) is widely applied in various fields due to its affordability and ease of use. However, it faces challenges such as achieving high surface quality, precise dimensional tolerance, and overcoming anisotropic mechanical properties. This review analyzes and compares the machinability of 3D-printed PLA, PETG, and carbon-fiber-reinforced PETG, focusing on surface roughness and burr formation. A Design of Experiments (DoE) with a full-factorial design was used, considering three factors: rotation speed, feed rate, and depth of cut. Each factor had different levels: rotational speed at 3000, 5500, and 8000 rpm; feed rate at 400, 600, and 800 mm/min; and depth of cut at 0.2, 0.4, 0.6, and 0.8 mm. Machinability was evaluated by roughness and burr height using a profilometer for all the materials under the same milling conditions. To evaluate the statistical significance of the influence of various processing parameters on surface roughness and burr formation in 3D-printed components made of three different materials—PLA, PETG, and carbon-fiber-reinforced PETG—an analysis of variance (ANOVA) test was conducted. This analysis investigated whether variations in rotational speed, feed rate, and depth of cut resulted in measurable and significant differences in machinability results. Results showed that milling parameters significantly affect roughness and burr formation, with optimal conditions for minimizing any misalignment highlighting the trade-offs in parameter selection. These results provide insights into the post-processing of FDM-printed materials with milling, indicating the need for a balanced approach to parameter selection based on application-specific requirements. [ABSTRACT FROM AUTHOR]

Polymer-metal hybrids are a lightweight solution for many industrial applications, especially in the automotive or aircraft sector. However, due to their poor chemical bonding the manufacturing of such compounds requires the use of adhesive layers or the conditioning of the metallic surface to achieve form closure and high joint strength. Ultrasonic Vibration Assisted Deformational Machining (UVADM) is a novel process that generates functional microstructures with high production rates, aiming to form defined burr structures with undercuts, that have a significant impact on the interlaminar strength of polymer-metal hybrids (PMH). A 3D FEM simulation using Abaqus/Explicit software was applied to design and analyze process conditions including tool geometry. Material deformation was described by the Johnson-Cook model. Simulation results were validated experimentally using two different MCD tools. For the UVADM experiments, specimens of the aluminum alloy EN AW-6082 were used. In the tests, a constant ultrasonic frequency (20.42 kHz), machining speed (100 m/min and 200 m/min), and peak-to-peak amplitude (7 µm) were used. Geometrical surface properties were analyzed by optical methods and SEM. The study demonstrates a conformity between simulated and experimental results, highlighting the potential of UVADM for an increased productivity in the surface conditioning for polymer-metal hybrids. [ABSTRACT FROM AUTHOR]

Additively manufactured aluminum alloy parts attract extensive applications in various felids. To study the machinability of additively manufactured aluminum alloys, micro-milling experiments were conducted on the additively manufactured AlSi7Mg and AlSi10Mg. By comparing the machinability of Al-Si-Mg aluminum alloys with different Si content, the results show that due to the higher hardness of the AlSi10Mg, the cutting forces are higher than the AlSi7Mg by about 11.8% on average. Due to the increased Si content in additively manufactured Al-Si-Mg aluminum alloys, the surface roughness of AlSi10Mg is 26.9% higher than AlSi7Mg on average. The burr morphology of additively manufactured aluminum alloys in micro-milling can be divided into fence shape and branch shape, which are, respectively, formed by the plastic lateral flow and unseparated chips. The up-milling edge exhibits a greater burr width than the down-milling edge. Due to the better plasticity of AlSi7Mg, the burr width of the down-milling edge is 28.1% larger, and the burr width of the up-milling edge is 10.1% larger than the AlSi10Mg. This research can provide a guideline for the post-machining of additively manufactured aluminum alloys. [ABSTRACT FROM AUTHOR]

Burr formation on the edge of the machined part during face milling is a common phenomenon. Highly precise and accurate parts are required to be burr free. Generally, deburring (secondary operation) is performed to remove the burr, which leads to the cost of the part. The aim of this study is to obtain minimum exit burr by optimising the input parameters at primary stage of the face milling operation. Effect of machining parameters (cutting velocity, feed per tooth, axial depth of cut), and machining strategies (rolling direction, cutter offset, soaking time during heat treatment) are taken into consideration. Taguchi's L27 matrix is selected for the design of experiments. Face milling of rolled steel (AISI 1040) is performed on vertical milling centre using titanium nitride coated carbide inserts. Exit burr is evaluated as a signal to noise ratio. The significance level and percentage contribution of parameters are calculated using analysis of variance. Cutter offset has shown maximum contribution followed by cutting velocity. Burr reduction of 58.4% is observed during a confirmation test. Finally, multi-variable linear regression is employed to generate second-order empirical model. Adequacy of model is checked by residual analysis. [ABSTRACT FROM AUTHOR]

Austenitic stainless steel has been widely used in various industries, such as aerospace, medical, and hydrogen energy, due to its high strength over a wide range of temperatures, corrosion resistance, and biocompatibility. However, stainless steel is a difficult-to-cut metal because its ductility and low thermal conductivity induce a strain hardening with significant plastic deformation at high temperatures. Burr formed at the back side of a plate is a critical issue which deteriorates the surface quality, especially in drilling. Burr removal operation, therefore, should be done in the machine shop. This study discusses the effect of strain hardening of austenitic stainless steel, SUS 316L, on burr formation. Hardness and cutting tests were conducted to compare the strain hardening effect for three types of workpieces: as-received, pre-machined, and tensile treated specimens. In the employed specimens, the tensile treated specimen is harder than the as-received specimen. Those specimens have uniform hardness in the depth direction from surfaces. Pre-machined specimen, in which the back side of the plate was finished by face milling, has a distribution of hardness in the depth direction from a surface. The highest hardness appears in the subsurface of the pre-machined specimen. The cutting forces in the steady processes, in which the entire edges remove material, were nearly the same as the tested specimens each other. However, remarkable differences were confirmed in the chip thickness and burr formation. The higher strain hardening of the tensile treated specimen is effective to suppress burr formation. The cutting characteristics are then identified to associate burr control with the shear plane model of orthogonal cutting using an energy-based force model. The shear stresses, shear angles, and friction angles of the tensile treated and as-received specimens are compared to discuss the effect of strain hardening on reduction of burr formation. [ABSTRACT FROM AUTHOR]

This article presents a comprehensive experimental investigation into the drilling behavior of Nomex®, a type of aramid fiber. The study specifically examines the impact of various cutting parameters and drill bit types on drilling outcomes. While Nomex® offers many advantages, difficult chip evacuation during drilling of aramid fiber composites can lead to surface defects and delamination. The research aims to explore how drilling parameters—such as spindle speed, feed rate—and four distinct drill bit types affect drilling performance. The analysis encompasses factors such as thrust force, torque, and surface roughness, studied under different drilling conditions and with various drill bit types. Moreover, the research assesses peeling and push-out delamination factors to gain insights into drill bit and coating characteristics. An examination of burr and chipping further enhances the comprehension of drilling performance. To determine the most effective drilling conditions, the study employs multi-response optimization. The optimal drilling performance is achieved with a combination of a 0.1 mm/rev feed rate, 1402.82 r/min spindle speed, and HSS-TiN drill type. This configuration successfully integrates responses, resulting in a composite desirability value of 0.95. [ABSTRACT FROM AUTHOR]

In the aviation and weapon industry, aluminum alloy thin-walled workpieces are widely used, and milling is a common manufacturing process for these thin-walled workpieces. In milling, many burrs generate on the entrances and exits of workpiece edges and the tops of slot on workpiece surface, which affect machining quality and assembly accuracy and produce more seriously tip discharge effect. To investigate the burr formation mechanism, an analyzed model of top burr thickness considering the tool deflection angle and workpiece deformation is proposed to elaborate the burr formation process in milling of thin-walled workpiece. In this process, top burr formation process is analyzed, and the burr thickness is expressed by the motion relationship between cutting tools and workpieces. Then, based on energy theory, a top burr thickness predicted model considering the tool deflection angle and workpiece deformation in milling of aluminum alloy thin-walled workpiece is proposed. Subsequently, under the determined milling condition, the top burr thicknesses are calculated for verification. Finally, several milling experiments are carried out for validating the feasibility and effectiveness of the proposed model. Experimental results show that the predicted top burr thicknesses are in good agreement with the measured value in milling, and the prediction accuracy of the top burr thickness by the proposed model reached 96.5%. [ABSTRACT FROM AUTHOR]

Fused Deposition Modeling (FDM) finds extensive application across various fields due to its cost-effectiveness and user-friendly nature. However, it does come with certain limitations, including challenges in achieving high surface quality, precise dimensional tolerance, and the characteristic anisotropic mechanical properties it exhibits. The aim of this paper is to investigate the machinability of 3D-printed PETG and analyze the roughness and burr formation that occurs as a result. A Design of Experiments (DoE) was developed with three factors: rotational speed, feed rate, and depth of cut. Each factor had different levels: rotational speed at 3000, 5500, and 8000 rpm; feed rate at 400, 600, and 800 mm/min; and depth of cut at 0.2, 0.4, 0.6, and 0.8 mm. The machinability was evaluated based on two response parameters: roughness (Sa), determined on the milled surface, and burr height, measured using a profilometer on both sides of the milled surface. The findings indicate that milling parameters strongly affect roughness and burr formation. However, the optimal conditions for minimizing roughness and burr formation are not coincident. The results were also compared to the machinability of PLA machined under similar conditions. [ABSTRACT FROM AUTHOR]

Titanium grade 9 (Ti-3Al-2.5V) stands out as a preferred material in various industrial applications because of its suitable properties. Its applications span diverse sectors, including precision manufacturing, where it is utilized to produce honeycomb structures for advanced aeronautics, as well as for certain biomedical components. In parallel, micro-milling has gained widespread utilization across medical, aerospace, and electronic industries due to the increasing demand for miniature products in these domains. This current research study aims to explore the impact of various micro-milling process parameters—specifically, feed rate, cutting speed, and depth of cut—on the surface quality, burr formation, and tool flank wear of titanium grade 9. Research findings reveal that the feed rate plays a major role in influencing surface roughness (contribution ratio (CR): 62.96%) and burr formation (CR: 55.20%). Similarly, cutting speed and depth of cut significantly affect surface roughness, contributing 20.32% and 9.27%, respectively, but are insignificant factors for burr width. Tool flank wear is primarily influenced by cutting speed (CR: 54.02%), with feed rate contributing 33.18%. Additionally, the feed rate and cutting speed are significant factors in determining the length of the burr, with contribution ratios of 77.70% and 7.77%, respectively. Confirmatory tests conducted at optimum parameters selected from the main effects plot validated the experimental results. [ABSTRACT FROM AUTHOR]

Fused deposition modeling (FDM) is widely applied in various fields due to its affordability and ease of use. However, it faces challenges such as achieving high surface quality, precise dimensional tolerance, and overcoming anisotropic mechanical properties. This review analyzes and compares the machinability of 3D-printed PLA, PETG, and carbon-fiber-reinforced PETG, focusing on surface roughness and burr formation. A Design of Experiments (DoE) with a full-factorial design was used, considering three factors: rotation speed, feed rate, and depth of cut. Each factor had different levels: rotational speed at 3000, 5500, and 8000 rpm; feed rate at 400, 600, and 800 mm/min; and depth of cut at 0.2, 0.4, 0.6, and 0.8 mm. Machinability was evaluated by roughness and burr height using a profilometer for all the materials under the same milling conditions. To evaluate the statistical significance of the influence of various processing parameters on surface roughness and burr formation in 3D-printed components made of three different materials—PLA, PETG, and carbon-fiber-reinforced PETG—an analysis of variance (ANOVA) test was conducted. This analysis investigated whether variations in rotational speed, feed rate, and depth of cut resulted in measurable and significant differences in machinability results. Results showed that milling parameters significantly affect roughness and burr formation, with optimal conditions for minimizing any misalignment highlighting the trade-offs in parameter selection. These results provide insights into the post-processing of FDM-printed materials with milling, indicating the need for a balanced approach to parameter selection based on application-specific requirements.

Nickel-based superalloys are among the most difficult materials to machine because they have high thermal strength, they are prone to hardening, carbides severely abrade the tool, and they have very poor thermal conductivity. Slot milling is a specific issue as it is characterized by rapid tool wear and frequent tool breakages. This is why reconditioned tools are frequently employed in industrial environments, as they can considerably decrease the expenses associated with tools. The chosen machining strategy also plays a crucial role in the tool's lifespan and the quality of the machined surface, making it essential to select the appropriate strategy. Hence, the authors have opted for two conventional trochoidal strategies, namely the circular and swinging toolpath, along with a contemporary toolpath known as the Autodesk Inventor HSM Adaptive strategy. The authors investigated the effects of technological parameters and toolpaths on cutting forces, tool wear, surface roughness and burr formation on machined edges. The results show that lower cutting parameters and adaptive strategies lead to the smallest tool loads, tool wear, the best quality of surface roughness and burr formation on machined edges. [ABSTRACT FROM AUTHOR]

During laser fusion cutting, burr forms when the molten metal does not sufficiently exit the interaction zone. When it forms on the lower edge of the cut flank, burr becomes a factor limiting quality. Previous research has shown that a temporally regular and spatially localized melt flow can prevent the formation of burr. However, the high dynamics of the subprocesses involved can cause intrinsic instabilities that disrupt the flow and reduce the efficiency of the melt ejection. This paper presents a study on the correlation between process parameters, melt flow properties, and burr formation. It includes an experimental observation of the melt-flow dynamics using high-speed videography. In addition, a Computational Fluid Dynamics model was set up to examine fundamental flow properties, some of which are not observable experimentally. The dependency of the burr formation on the liquid Weber and Reynolds numbers is analyzed, and it is demonstrated how the magnitude and allocation of vapor pressure gradients in the kerf decisively affect melt ejection and burr formation. Additionally, a previously unknown melt ejection regime is identified in the thick section range, which occurs at feed rates close to the maximum cutting speed under specific high-power process conditions. This regime is characterized by a significantly increased process efficiency that could open up a new high-speed process window. [ABSTRACT FROM AUTHOR]

Primary manufacturing processes like casting, forming, and shaping (forging, rolling, drawing, extrusion, sheet forming, and molding) further need any of the secondary manufacturing processes like turning, drilling, boring, planing, milling, grinding, etc. In order to produce superior quality products, and to enhance productivity, the selection of desirable process parameters is significant. The selection of suitable process parameters is essential for accomplishing the desired component. Based on the existing literature, this study examines the causes, effects, and variances regarding chip formation, tool geometry, thrust force, torque, surface roughness, drilling time, and other drilling quality characteristics in the most typical machining operations such as drilling. Developing a repository on these process parameters will guide the process planning engineer for ready reckon. Therefore, this work aims at the development of a detailed repository with the study of characteristics. Further, this literature review comprehends the characteristics of a behavior with its reasoning, which was detailed in the past decade. It reveals the beneficial process parameters for achieving better production rate and superior quality. [ABSTRACT FROM AUTHOR]

This study aims to optimize the cutting parameters for the micro-milling of titanium grade 9 (Ti-3Al-2.5V). The research employs Grey Relational Analysis (GRA) and Response Surface Methodology (RSM) techniques to find the optimal combination of cutting parameters to simultaneously minimize surface roughness, burr width, burr length, and tool wear, which are selected process outcomes. The findings from Grey Relational Analysis (GRA) identify experiment number 6, with cutting conditions of f (µm/tooth) = 0.45, Vc (m/min) = 25, and ap (µm) = 60, as the most productive experiment. Analysis of variance (ANOVA) is conducted to assess the significance and influence of the process cutting parameters on different process outcomes. ANOVA reveals that the feed rate and cutting speed are the most influential input parameters, with a contribution ratio (CR) of 24.08% and 14.62%, respectively. Furthermore, ANOVA indicates that the interaction among the process parameters also significantly influences the process outcomes alongside the individual cutting parameters. The optimized combination of cutting parameters obtained through the RSM technique produces superior results in terms of reducing the process outcomes. Compared to the best run identified by Grey Relational Analysis, there is a remarkable 36.25% reduction in burr width and an 18.41% reduction in burr length, almost half of the reduction achieved in burr width. Additionally, there is a 16.11% and 14.60% reduction in surface roughness and tool wear, respectively. [ABSTRACT FROM AUTHOR]

Present work describes machinability of lead free brass in high speed micro turning. Micro turning has been performed with cutting speed and chip load under minimum quantity lubrication. The surface topography, burr formation, chip formation, and tool wear have been investigated. Additionally, statistical model has been developed to evaluate the contribution of the process parameters on average surface roughness, peak-to-valley height, and average burr height. This study revealed that smoother surface finish has been achieved at higher cutting speed with reduced peak-to-valley height and burr height. Additionally, elevated chip breaking and flank wear have been found at high cutting speed. [Display omitted] • High speed micro turning has been performed on lead free brass using minimum quantity lubrication. • Surface topography, burr formation, chip morphology, and tool wear have been studied for different process parameters. • Regression equations for S a , S z , and B hp have been developed using ANOVA and optimum process parameters have been determined. • Smooth surface profile has been achieved at high cutting speed with favorable chip formation. [ABSTRACT FROM AUTHOR]

This paper deals with the study of top burr formation mechanism in downmilling operation on Ti6Al4V. Detailed and simplified flute locus in the milling operation has been elaborated with varying uncut chip areas during the entry and exit of the flute. The mechanism shows that top burr formed in downmilling is a combination of upmilling tear material and side bulging deformed material. Furthermore, various shapes of top burr formation at different cutting parameters have been explored based on the mechanism of formation. Three types of burr formation during downmilling (serrated, longitudinal and curly burrs) were found which were the major cause of poor surface finish after milling operation. Also, the effect of feed per tooth and depth of cut on the top burr formation & surface roughness has been analyzed through statistical technique ANOVA and an optimum parameter (top burr width: feed per tooth 8 µm, depth of cut 60 µm and surface roughness: feed per tooth 4 µm, depth of cut 40 µm) has been proposed which can help to plan to design the experiment to obtain better output response. [ABSTRACT FROM AUTHOR]

Carbon fibre-reinforced polymer (CFRP) composites have exceptional mechanical advantages such as high specific strength and stiffness, lightweight, and high damping capacity, making them very attractive for aircraft, aerospace, automotive, marine, and sporting applications. However, various defects such as delamination, burr formation, and surface roughness are observed during the drilling of CFRP composites, which are influenced by various drilling process parameters. In this work, the drilling quality of uni-directional CFRP composites. and the hybrid Al _2 O _3 and hybrid SiC nano-composites are investigated experimentally using different types of drills such as step drill, core drill, and twist drill, as there is a limited study done on the comparative analysis of the impact of the above drills on the delamination factor and burr area on the above CFRP and hybrid nano-composites. The design of the experiment table was developed using response surface methodology (RSM) for input process parameters of spindle speed, feed, drill diameter, and drill type. The output surface characteristics (delamination factor and burr area) of the hole were measured quantitatively using the stereo zoom optical microscope. The main effect plots, contour plots, and analysis of variance (ANOVA) were used to examine the effect of spindle speed, feed, drill diameter, and drill type on exit delamination and burr formation. The analysis of main effect plots, contour plots, and analysis of variance showcased the optimum process parameters, such as a high spindle speed of 5500 rpm, low feed of 0.01 mm/rev, and drill diameter of 4 mm. The step drill demonstrated the least damage mechanism among drill geometries, followed by the twist and core drills. The minimum drilling damage was observed for the Al _2 O _3 hybrid nano-composite compared to the neat CFRP composites.

The importance of cutting hardened materials without influencing their structural properties makes abrasive waterjet machining a favorable choice in certain applications in comparison with other manufacturing technologies. Using this technology, faulty surface structures and errors caused by high thermal loads such as burrs, burns and cracks, can be avoided. In this paper, the results of applying the abrasive waterjet technology for cutting of hardened steel and its advantageous properties in comparison with cut-off grinding will be presented. The influence of process parameters on surface properties and burr formation has been determined by experimental analysis. [ABSTRACT FROM AUTHOR]

This study investigated the 3D-printed PLA (Polylactic Acid) workability during the operation of milling. It is difficult to obtain as a result of a Fused Deposition Modeling (FDM) 3D printing a very strict tolerance, and a good roughness surface. A possible solution can be the usage of the last milling operation that can complete the workpiece in terms of desired roughness and dimension tolerances. A design of experiments (DOE) analysis has been applied to observe the optimizing result. Three factors have been analyzed: feed rate, depth of cut, and rotational speed. Two responses were investigated: roughness (Ra) and burr height. The results show that these two parameters present optimum results in two different values of the process parameters: the Ra is better at a higher feed rate and low depth cut, but the situation reverses for the burr height, for which lower heights are obtained when using higher feed rate and depth cut. [ABSTRACT FROM AUTHOR]

Titanium grade 9 (Ti-3Al-2.5V) stands out as a preferred material in various industrial applications because of its suitable properties. Its applications span diverse sectors, including precision manufacturing, where it is utilized to produce honeycomb structures for advanced aeronautics, as well as for certain biomedical components. In parallel, micro-milling has gained widespread utilization across medical, aerospace, and electronic industries due to the increasing demand for miniature products in these domains. This current research study aims to explore the impact of various micro-milling process parameters—specifically, feed rate, cutting speed, and depth of cut—on the surface quality, burr formation, and tool flank wear of titanium grade 9. Research findings reveal that the feed rate plays a major role in influencing surface roughness (contribution ratio (CR): 62.96%) and burr formation (CR: 55.20%). Similarly, cutting speed and depth of cut significantly affect surface roughness, contributing 20.32% and 9.27%, respectively, but are insignificant factors for burr width. Tool flank wear is primarily influenced by cutting speed (CR: 54.02%), with feed rate contributing 33.18%. Additionally, the feed rate and cutting speed are significant factors in determining the length of the burr, with contribution ratios of 77.70% and 7.77%, respectively. Confirmatory tests conducted at optimum parameters selected from the main effects plot validated the experimental results.

Technology like micro-hole drilling has progressed because of the machining industry's demand for high-precision micro components. Although micro drilling can be duplicated in theory, many challenges must be overcome before this becomes a reality. Micro-drilling with a thermal-mechanical interaction in the alloy is simulated in Abaqus. It looks at twist-bit modeling, material constitutive modeling, chip separation criteria, and element division. Focusing on work and tool electrode materials, hole specifications, micro hole types (through or blind holes), process parameters, performance measurements, and significant discoveries, this study presents a complete survey of the literature on spark methods for drilling microscopic holes. With an emphasis on spark erosion machining, drilling, and its modifications, this study seeks to aid researchers and academics by showcasing the potential of these methods to create extremely small holes. Microdrilling is critical for manufacturing miniaturized Nitinol components having applications in the medical field, robotics industry. Mechanical microdrilling offers a cost-effective and precise method over non-conventional ones. Thus, the model may identify the drilling performance's key process parameters. They can also help operators choose micro-drilling-optimal machining parameters. Modeling micro-drilling software helps in shaping an alloy., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Authors.)

This study aims to optimize the cutting parameters for the micro-milling of titanium grade 9 (Ti-3Al-2.5V). The research employs Grey Relational Analysis (GRA) and Response Surface Methodology (RSM) techniques to find the optimal combination of cutting parameters to simultaneously minimize surface roughness, burr width, burr length, and tool wear, which are selected process outcomes. The findings from Grey Relational Analysis (GRA) identify experiment number 6, with cutting conditions of f (µm/tooth) = 0.45, Vc (m/min) = 25, and ap (µm) = 60, as the most productive experiment. Analysis of variance (ANOVA) is conducted to assess the significance and influence of the process cutting parameters on different process outcomes. ANOVA reveals that the feed rate and cutting speed are the most influential input parameters, with a contribution ratio (CR) of 24.08% and 14.62%, respectively. Furthermore, ANOVA indicates that the interaction among the process parameters also significantly influences the process outcomes alongside the individual cutting parameters. The optimized combination of cutting parameters obtained through the RSM technique produces superior results in terms of reducing the process outcomes. Compared to the best run identified by Grey Relational Analysis, there is a remarkable 36.25% reduction in burr width and an 18.41% reduction in burr length, almost half of the reduction achieved in burr width. Additionally, there is a 16.11% and 14.60% reduction in surface roughness and tool wear, respectively.

Considering industrial applications, three main brass alloys including lead-free, low-lead and leaded are being deployed. However, as these materials are used in potable water applications, low-lead and lead-free brass alloy are becoming preferred to leaded ones due to their health effect. On the other hand, Lead is the element increases machinability of such materials. Machining efficiency of these type materials can be raised by using round edge cutting tools. This paper presents experimental results of the machining performance of lead-free, low-lead and leaded brass alloys in terms of cutting forces, surface roughness, and burr height during milling operations. Moreover, it also takes into account the edge radius of cutting tools and its role on machining the performance. Empirical equations are derived to predict the machining behavior for each material. Increasing the edge radius results in larger cutting forces and tool vibration during the process, but better surface quality. Furthermore, reduction/elimination of the Lead element in alloy content has concluded into higher burr size on the machined surface edges. [ABSTRACT FROM AUTHOR]

This work outlines an analysis of the surface integrity of aluminum honeycomb after milling using specific tools. This is the most common core material used for aircraft honeycomb structures. The machining of these materials is accompanied by some difficulties related to structural properties due to the weakness of local bending stiffness of the cell walls and the lightweight of material. This influences the surfaces quality after machining. Our analysis aims to shows the link between the surface integrity (burr, walls folding and tearing) and the machining conditions. To meet this objective a specific method based on microscopic observations is developed. [ABSTRACT FROM AUTHOR]

The top burr is the common problem that faced in micro milling and presents the significant effect on the machining quality. The top burr minimization is desired to achieve high precision machining in micro milling. In this paper, the top burr formation mechanisms are analyzed, and then micro milling experiments are conducted to investigate the effect of machining parameters on the morphology and size of top burr. It is found that the top burr formation is caused by the unexpected material plastic side flow at the top side, which is an unresisted free surface with low support stiffness during micro milling. The unseparated chips that are connecting on the top side greatly increase top burr. The optimal machining strategies are suggested to minimize top burr. [ABSTRACT FROM AUTHOR]

In precision manufacturing, especially in making of holes on the parts during drilling process for precision assembling of parts facing problems with burr formation. Drilling is one of the finishing operations in the production cycle, removal of burrs during drilling process is a time consuming and non-value added process to the manufacturing sector. In this paper, we developed an analytical models for thrust force, torque and burr size with variable clearance angle of drill bit geometry especially for Aluminium alloys used for automotive applications. An analytical model results were obtained by writing a code in MATLAB @ 2010 software for aluminium alloy series such as Al 6061, Al 2014 and Al 7075. In an economic front, de-veloped mathematical models are benefitted to reduce experimentation, these results reveal that at the beginning of the drilled hole due to indentation of chisel edge, more thrust and torque was identified, beyond that suddenly thrust force was lowered, cutting forces by the lip edges were increased from beginning of the process to progress of drilling process. The proposed model approach is helpful to the budding entrepreneurs in the related areas to select optimal combination of drilling parameters to attain multiple performance characteristics of responses especially in burr size to prevent the post finishing operations up to certain extent.

To reduce the size of exit burrs induced by broaching, it is possible to use a low value martyred part clamped to the functional one on the tool exit side. Thence, this research work deals with an in-situ analysis of the burr formation at a bi-specimens interface in orthogonal cutting configuration. New mechanisms of burr formation at the interface formed by Inconel 718 and cast iron specimens are identified. In addition, a post-machining study is carried out to quantify the burr size obtained with and without the martyred part. [ABSTRACT FROM AUTHOR]

SKD11 is widely used in manufacturing die. With the development of industrial level, the size of the die is further reduced, and the difficult processing problem of high aspect ratio (HAR) micro-structures is exposed. Micro-milling is a suitable method for machining HAR micro-structures; however, the inevitable generation of burrs deteriorates the machined surface. Previous studies have mostly focused on the burr formation process of shallow grooves but have ignored HAR grooves. This paper investigated the burr formation mechanism in HAR (2:1) grooves on harden steel (SKD11). Due to the fact that the burr formation process was difficult to be observed in the actual micro-milling process, a finite element model was established. A corresponding experimental research was conducted, which revealed a good consistency between simulation and experimental results. Moreover, a new burr type was formed on the sidewall of the HAR groove, which was transformed from top burrs and was named as side burr. The results demonstrated that the chip flow on the rake face of the micro-mill was hindered by the sidewall, which caused chip crumbling, chip accumulation, and surface scraping, seriously affecting the burr formation mechanism. This paper revealed the burr formation mechanism for HAR grooves on SKD11, which provides basic data for manufacturing die with complex structure and small size. [ABSTRACT FROM AUTHOR]

In this paper, the tool wear mechanisms for low-frequency vibration-assisted drilling (LF-VAD) of carbon fiber-reinforced polymer (CFRP)/Ti6Al4V stacks are investigated at various machining parameters. Based on the kinematics analysis, the effect of vibration amplitude on the chip formation, uncut chip thickness, chip radian, and axial velocity are examined. Subsequently, the effect of LF-VAD on the cutting temperature, tool wear, delamination, and geometrical accuracy was evaluated for different vibration amplitudes. The LF-VAD with the utilization of minimum quantity lubricant (MQL) resulted in a successful drilling process of 50 holes, with a 63% reduction in the cutting temperature. For the rake face, LF-VAD reduced the adhered height of Ti6Al4V by 80% at the low cutting speed and reduced the crater depth by 33% at the high cutting speed. On the other hand, LF-VAD reduced the flank wear land by 53%. Furthermore, LF-VAD showed a significant enhancement on the CFRP delamination, geometrical accuracy, and burr formation. [ABSTRACT FROM AUTHOR]

Manufacturers’ goal is to control, avoid or minimise burr during manufacturing. Burr control is used frequently, because it costs less and/or is less time-consuming. Based on the experimental results and simulations in the case of face milling it has been stated that exit order and planar exit angle have a significant influence on burr formation. A carefully planned tool path can provide constant exit angle. Setting the exit angle to an appropriate value or range, burr can be avoided or minimised. The exit angle can be determined approximately in a simple way, using a circle as a path of tool tip. The precise value of the error of the approximated calculation of exit angle has not been revealed yet. In this paper, this error is examined. The slope of a circle and the theoretically accurate cycloid curve can be expressed analytically. The difference between the two slopes can be calculated. Its maxima or minima give the value of the error which can be deducted into simple equations that are valid either for linear or circular feed. If the exit angle is changing, the chip thickness is also changing. With the help of the resulted expressions, a special workpiece contour can be designed, where the exit angle is constant and only the chip thickness is changing. In this way, the examination of the effect of the chip thickness on burr formation will be possible.

Abrasive reaming is a low-speed grinding process, which has been applied in precision machining of fuel nozzle holes of aero-engine. The burrs produced in abrasive reaming always have a great influence on the machining quality. In order to investigate the burr formation mechanism in abrasive reaming, a micro-cutting model of the single-particle abrasive was developed to simulate side burr formation. The model simplified the operation of abrasive reaming process and transformed the helical motion into the linear motion of the abrasive grains. The simulation results were also verified experimentally. The side burrs were characterized by four parameters, e.g., the side burr cross-sectional area S, the burr thickness bg, the burr height h0, and the burr root thickness br. The effects of the position (i.e., the entrance and exit of the nozzle), cutting speed, cutting-edge inclination, cutting depth, and cutting width on the side burrs were discussed. Accordingly, the formation mechanism of side burrs was explored based on the simulation results of single-particle abrasive micro-cutting behavior. Finally, the optimum processing parameters were obtained as follows: cutting speed vs = 0.4 m/s, cutting-edge inclination angle λs = −60°, minor cutting depth aps = 2 μm each time, and little cutting width bps = 2 μm each time. Under such condition, the burr is tiny in thickness, short in length, and easy to be dislodged. [ABSTRACT FROM AUTHOR]

In this study, the effect of tool geometry on the cutting forces, surface roughness, and burr formation in the micro-milling process is investigated. Three different geometric parameters (helix angle, number of cutting edges, and axial rake angle) that may affect the machining performance are taken into account. Inconel 718 superalloy was used as workpiece material, and the tests were performed under dry cutting conditions. According to the results obtained, the minimum cutting forces were obtained at a helix angle of 45°. The increase in the helix angle causes the forces in the Fz direction to increase. For the new cutting tool, increasing number of cutting edges and axial rake angle has little effect on cutting forces. For the worn tool, the cutting forces are lower in the four-edges cutting tool, and the cutting forces obtained in the negative axial rake angle are also higher. The dominant damage types in the cutting tool are abrasive wear and chipping. Increased cutting distance causes the edge and corner radii of the tool to increase. As a result, cutting forces, surface roughness, and burr formation also increase. Generally, the maximum top-burr width is obtained on the up-milling side for the new cutting tool. Maximum top-burr width occurs on the down-milling side in the worn tools. Increasing helix angle causes burr width to increase. It has been determined that low number of cutting edge and negative rake angle cause smaller burr width. [ABSTRACT FROM AUTHOR]

Recently, mechanical micro-milling is one of the most promising micro-manufacturing processes for productive and accurate complex-feature generation in various materials including metals, ceramics, polymers and composites. The micro-milling technology is widely adapted already in many high-tech industrial sectors; however, its reliability and predictability require further developments. In this paper, micro-milling related recent results and developments are reviewed and discussed including micro-chip removal and micro-burr formation mechanisms, cutting forces, cutting temperature, vibrations, surface roughness, cutting fluids, workpiece materials, process monitoring, micro-tools and coatings, and process-modelling. Finally, possible future trends and research directions are highlighted in the micro-milling and micro-machining areas. [ABSTRACT FROM AUTHOR]

Laser-based powder bed fusion (L-PBF) is a promising technology for the production of near net–shaped metallic components. The high surface roughness and the comparatively low-dimensional accuracy of such components, however, usually require a finishing by a subtractive process such as milling or grinding in order to meet the requirements of the application. Materials manufactured via L-PBF are characterized by a unique microstructure and anisotropic material properties. These specific properties could also affect the subtractive processes themselves. In this paper, the effect of L-PBF on the machinability of the aluminum alloy AlSi10Mg is explored when milling. The chips, the process forces, the surface morphology, the microhardness, and the burr formation are analyzed in dependence on the manufacturing parameter settings used for L-PBF and the direction of feed motion of the end mill relative to the build-up direction of the parts. The results are compared with a conventionally cast AlSi10Mg. The analysis shows that L-PBF influences the machinability. Differences between the reference and the L-PBF AlSi10Mg were observed in the chip form, the process forces, the surface morphology, and the burr formation. The initial manufacturing method of the part thus needs to be considered during the design of the finishing process to achieve suitable results. [ABSTRACT FROM AUTHOR]

According to the requirement of miniaturization and high precision of folded waveguide slow wave structure, D-Shaped micro-milling cutter with diameter of 50 μm is fabricated by WEDG with the self-developed μEM-200CDS2 combined high precision machine tool. The surface quality of the microgroove is studied by the process test on the pure copper workpiece. White-light interferometer, ultra-depth-of-field microscope and scanning electron microscope are used to observe the variation of surface morphology and roughness of micro-grooves with milling distance, and the surface quality and burr formation during micro-milling are analyzed. These results show that the revolving track of the groove bottom tool is firstly concentrated in the cutting direction of the tool, and with the tool wear, it turnes to the feed direction of the tool. The burrs on the milling side of the micro groove are more than those on the reverse side, and increases with the increase of milling distance. Additionally, the roughness of the groove bottom increases with the linear growth trend. [ABSTRACT FROM AUTHOR]

As contemporary emerging materials, fiber-reinforced plastics/polymers (FRP) are widely used in aerospace automotive industries and in other fields due to their high strength-to-weight ratio, high stiffness-to-weight ratio, high corrosion resistance, low thermal expansion and other properties. Drilling is the most frequently used process in industrial operation for polymer composite laminates, owing to the need for joining structures. However, it is a great challenge for operators to drill holes in FRP materials, due to the non-homogenous and anisotropic properties of fibers. Various damages, such as delamination, hole shrinkage, and burr and tool wear, occur due to the heterogeneous and anisotropic nature of composite laminates. Therefore, in this study, carbon fiber reinforced polymer (CFRP)/aramid fiber reinforced polymer (AFRP) hybrid composites (C-AFRP) were successfully synthesized, and their drilling characteristics, including burr generation and tool wear, were also mainly investigated. The drilling characteristics of CFRP and C-AFRP were compared and analyzed for the first time under the same operating conditions (cutting tool, spindle speed, feed rate). The experimental results demonstrated that C-AFRP had higher tensile strength and good drilling characteristics (low thrust and less tool wear) compared with CFRP. As a lightweight and high-strength structural material, C-AFRP hybrid composites have great potential applications in the automobile and aerospace industries after the slight processing of burrs generated during drilling. [ABSTRACT FROM AUTHOR]

Copper is one of the materials that are sought and requested in many sectors due to its high electrical and thermal conductivity values. Its high ductility makes it difficult to drill commercial purity copper and has a negative effect on hole quality. In this study, commercial purity copper material was subjected to drilling tests with HSS drills without using coolant. Surface roughness, deviation from diameter and deviation from cylindrical values were measured in varying drilling conditions and also modeled by regression analysis. Quantitative effects of the results were determined by analysis of variance. Also, wears occurring in the drill bits, burr formations at the entrance and exiting of the hole were examined. As a result of the regression analysis, it was observed that the feed rate on the surface roughness value, the coating status for the deviation from cylindrical and diameter had a significant effect on the results (P<0.05). It was observed that burrs formation in the hole entrances was insignificantly small, but the burrs formation increased at high feed rate values at the end of the holes, and decreased at high cutting speeds. It has been determined that the workpiece material tends to stick to the drill bits at increasing values of the feed rate and removal of the chips becomes difficult. [ABSTRACT FROM AUTHOR]

In this study, micro machinability of Mg5Sn4Zn (TZ54) alloy produced by a hot-pressing process (one of the powder metallurgy methods) is investigated. For this purpose, micro-milling experiments were carried out, considering different cutting parameters. In order to determine the appropriate cutting parameters, the variation of cutting forces, surface quality and burr width were investigated. The cutting forces obtained in micro-milling of the TZ54 alloy are relatively small compared to other biomedical materials. In terms of both cutting forces and surface roughness, the minimum chip thickness is between 7% and 34% of the tool edge radius. However, compared to alloys such as Ti6Al4V and 316 L, the burr width is about 80% smaller. An important contribution of the study is that the minimum chip thickness (0.1 μm) has been confirmed in terms of both cutting force and surface roughness. In addition, even at high material removal rates, the minimum cutting forces are important findings of the study. The predominant wear mechanism in the cutting tool is abrasive wear. In view of tool life, surface roughness and burr formation, it is envisaged that the TZ54 alloy can be an easy machinable, alternative biomedical material. [ABSTRACT FROM AUTHOR]

Miniature/micro-drilling of holes is increasingly utilized in manufacturing. While non-conventional machining methods (laser and spark erosion) were applied successfully for micro-drilling, mechanical drilling still of interest to industry due to its unmatched geometrical accuracy. However, tool wear and burr formation would hinder the economics of mechanical drilling supremacy. Hence, the need for understanding of tool wear, burr formation and cutting forces progression with process variables is a step towards comprehensive modelling of micro-drilling mechanics and subsequent enhanced process economics. The current research details experimental trials involving mechanical drilling of steel 1008/CR4 using twin-fluted twist drills of diameters 0.5, 1 and 1.5 mm. Full factorial design of experiments was utilized, and analysis of variance was accomplished to study the effects of feed rate and tool diameter (each of them at 3 levels) on tool flank wear and drilled hole quality. Entry and exit burr heights were increased by 80–150% when tool diameter and feed rate were two times higher. Progression of tool flank wear and usage of bigger tool diameter conversely reduced hole surface roughness. In addition, tool flank wear was increased when reducing of feed rate and using larger tool diameter. Catastrophic failure of 0.5-mm-diameter tool was noticed (after drilling of 46 holes at high feed rate level and after drilling of 97 holes at low feed levels) due to chip packing/jamming in the insufficient flute area. [ABSTRACT FROM AUTHOR]

Micro-milling is a micro-mechanical cutting method used to obtain complex and three-dimensional micro geometries. Micro-cutting tools are used in the manufacturing of micro-components and the type of workpiece is also important for good surface quality and minimum burr. In this study, micro machinability of Ti6Al4V alloy which is used most frequently in micro-component production is compared with Ti5553 alloy. Micro-milling of Ti5553 alloy and comparison of the minimum chip thickness with Ti6Al4V were performed for the first time in this study. Using different cutting parameters, the variation of surface roughness, burr width, and cutting forces were investigated. The cutting tests were carried out on a specially designed and high-precision micro-milling test system using a TiCN-coated two-flute end mill of 0.6 mm diameter. According to the results, minimum chip thickness is approximately 0.3 times the edge radius of the cutting tool and does not vary with the alloy type. At feed rates smaller than the minimum chip thickness, both the cutting forces increase and the surface quality decreases. For both alloys, reduced feed rate and increased depth of cut lead to increased burr width. The burr widths in Ti6Al4V alloy are higher. At the end of the study, the limits of the cutting parameters where plowing occurred for the both alloys are clearly determined. In addition, the limits of the cutting parameter causing plowing have been confirmed by cutting forces, surface roughness, and burr formation. [ABSTRACT FROM AUTHOR]