Top Burr Formation Research Articles

Experimental and statistical investigation into surface characteristics in micro milling of bottom pouring/gravity stir cast Al6061 alloy

Micro milling offers the best way to create micro channels; however, the burr formation and surface roughness of the micro channel are difficult to control. Micro channel fabrication and their characterization of stir cast Al6061 are rarely investigated. In the present study, Al6061 alloy was processed by the bottom pouring stir casting method. The micro channels were fabricated on a base and stir cast Al6061 alloys using TiSIN-coated micro end mill tools. The influence of micromachining parameters such as spindle speed, feed rate, and depth of cut on burr formation, cutting force, burr size, and surface roughness was investigated. A comparison was made between the findings obtained from the micro milling of the base and stir cast Al6061 alloys. The surface morphology of fabricated micro channels was analysed and correlated with the roughness profile to understand the channel profile and burr formation. The top burr formation mechanism in stir cast Al6061 alloy was investigated in detail. Low feed rate, low depth of cut, and high spindle speed produced the micro channel with fewer burrs, low surface roughness, and low cutting forces. At the optimum parameter, stir cast Al6061 alloy showed an approximate 420%, 16%, and 300% increase in Fy, Fz, and Ra, respectively, as compared to the base Al6061 alloy. Adhesion wear, built-up edge, and microchipping were found to be the main tool wear mechanisms in micro machining of stir cast alloy. This study directs the choice of cutting parameters for the stir cast micro milling process.

Tribological effects of micromilling of hardened AISI D2 steel on tool wear and top burr formation

Tribological effects of micromilling of hardened AISI D2 steel on tool wear and top burr formation

Investigation of Top Burr Formation in Micromilling for Surface Quality Improvement

Investigation of Top Burr Formation in Micromilling for Surface Quality Improvement

Characteristics and Mechanism of Top Burr Formation in Micro-Milling LF21

Abstract During micro-milling aluminum alloy LF21 process, it tends to produce large top burr usually detected at the top of slot walls. Therefore, the machining accuracy and quality of the micro-parts are difficult to satisfy. To suppress burr and achieve the higher machining quality of machined LF21 micro-parts, this paper using the Johnson–Cook constitutive model establishes a two-dimensional finite element simulation model to obtain a better recognition of burr formation mechanisms and a three-dimensional finite element simulation model to better simulate burr formation process and measure top burr height. Furthermore, effective validation experiments for the proposed models are conducted, good agreements are achieved in the cutting force and top burr height between the experiments and simulation results. The study explores the formation mechanism of top burr in micro-milling LF21 and reveals the influence law of cutting parameters on top burr height based on the simulation and experimental results. The research guides the selection of cutting parameters in micro-milling LF21 process.

Laser hybridizing with micro-milling for fabrication of high aspect ratio micro-groove on oxygen-free copper

High aspect ratio (HAR) micro-grooves are of great significance for vacuum electronic devices. However, the fabrication of HAR micro-groove on oxygen-free copper remains challenge since the high surface quality is hard to achieve. Aiming to improve the surface quality, a hybrid and successive method, obtained by combining nanosecond laser and micro-milling (NLMM), was presented. The nanosecond laser achieves the maximum workpiece removal rate, while the subsequent micro-milling provides the desired machining quality. Compared to one-way full slot micro-milling (FSMM), the presented manufacturing method (NLMM) could improve the surface quality, namely the top burr formation and the bottom and sidewall surface roughness. Furthermore, the NLMM displayed a lower tool wear rate compared to FSMM. Finally, a desired S-shaped groove with an aspect ratio of 2.5, a width of 0.2 mm, and the cycle number of 30 was successfully fabricated. The study offers a promising aspect for improving the HAR micro-groove fabrication quality.

Investigation on the modelling and characterization of top edge burr formation in slotting finned tube

In this study, a three-dimensional finite element model is utilized to analyse the top edge burr formation in orthogonal slotting copper finned tubes. To describe the top edge burr generation, a conceptual model is developed to explain the material shear failure. The normalized Cockroft-Latham criterion is employed for a general understanding of the plastic behaviour and burr formation, and the critical damage value is obtained to qualify the burr geometries by tensile tests. Based on material side flow and the progressive deformation behaviour, the characteristics and mechanism of top edge burr formation are further investigated. The results show that the top edge burr is formed by a combination of material tear and sideward flow. The top edge burr formation process can generally be divided into three phases: the initiation of the deformation bulge, the development of the deformation bulge, and tear formation. The characteristics of the top edge burr also consist of three parts: basal deformation area, tensile area, and top tear area. The three parts of the burr characteristics correspond to the three phases of the burr formation process. Additionally, the influences of rake face, feed rate, and cutting speed on the burr size are studied based on a quantitative method. The study provides a basis for the minimization of top edge burr formation and optimization of machining parameters.

Research on Parameter Optimization of Micro-Milling Al7075 Based on Edge-Size-Effect.

In the process of micro-milling, the appearance of the edge-size-effect of micro-milling tools cannot be ignored when the cutting parameters are smaller than the cutting edge arc radius (r0) of the micro-milling tool or close to it, and it could easily lead to low cutting efficiency and poor surface quality of the micro-slot. Through micro-milling experiments on Al7075-T6 materials, the change of milling force in the plough zone and shear zone during micro-milling was studied, and the minimum cutting thickness (hmin) range was determined to be 0.2r0–0.4r0 based on r0 of the micro-milling tool. Subsequently, the effect of fz/r0 (fz denotes feed rate per tooth) on the top burr formation of the micro-slot, the surface roughness (Ra) of the micro-slot bottom, and the milling force was studied, and a size-effect band of micro milling was established to determine the strong size-effect zone, transition size-effect zone, and the weak size-effect zone. Finally, two different fz/r0 in the strong size-effect zone and the weak size-effect zone are compared, which proves that the main purpose of the cutting parameters optimization of micro-milling is to avoid cutting parameters locating in the strong edge-size-effect zone. The above conclusions provide a theoretical basis for the selection of micro-milling cutting parameters, and an important reference in improving the surface quality of micro-milling.

An investigation on the top burr formation during Minimum Quantity Lubrication (MQL) assisted micromilling of copper

Micromilling is one subtractive manufacturing process where excess material is gradually removed from the workpiece in the form of micro-chips with the help of a miniaturized cutting tool in order to fabricate three-dimensional micro-features. Burr formation in micromilling is one important problem as excessive burr hampers dimensional accuracy and functional requirements of the miniaturized features. Top-burr formation in micromilling is attributed to the lateral plastic deformation of the workpiece material when a rounded edge of the tool compresses it. This article explores the role of spindle speed and axial depth of cut on top-burr formation during micromilling of industrially pure copper samples using 0.5 mm TiAlN coated tungsten carbide micro end mills in MQL cutting environment. It is observed that down milling side top-burrs are significantly wider and larger as compared to that of the up milling side. For constant spindle speed, the average top-burr width is found to increase with axial depth for both up and down milling sides. However, the average top-burr width decreases marginally with the increase in spindle speed. In both up and down milling sides, the influence of depth of cut on top-burr width is more pronounced as compared to the influence of spindle speed. It was also observed that the difference between down milling top-burr width and up milling top-burr width does not vary appreciably with spindle speed.

Modeling of Top Burr Formation in Micro-End Milling of Zr-Based Bulk Metallic Glass

Abstract In this study, an analysis is presented for the formulation of a model in top burr formation to estimate the width of the top burrs formed in micro-end milling process. In this analysis, the width of the top burrs, considered to be the measure of burr size of top burrs, represents the extent of burr formation. The model is applied to quantify the burr formation in Zr-based bulk metallic glass, an amorphous metallic alloy. In this study, micromilling experiments were carried out on the bulk metallic glass work material at different levels of feed rate, axial depth of cut, and cutting speed to compare the experimental values of top burr width with the predicted values. Analysis is carried out to characterize top burr formation based on the experimental results of burr sizes in the up-milling and down-milling side edges, and the influential effects of the cutting parameters on the burr formation are analyzed.

Experimental investigation of top burr formation in high-speed micro-milling of Ti6Al4V alloy

Miniaturization with superior quality product of super alloy is the demand of the industry. Ti6Al4V is the demanding super alloy due to its excellent material properties, although this super alloy is known for poor machinability in terms of burr formation, low tool life, and poor surface finish. Therefore, being a popular super alloy, it comes under the difficult-to-cut material. In the current work, burr formation on the machining of Ti6Al4V has been studied. Experimental investigation and characterizations of top burr formation on Ti6Al4V alloy using end milling process were carried out. A scanning electron microscopy identifies the burr formed on the machined surface. A new technique has been introduced to measure the top burr width (i.e. equivalent width) accurately. Equivalent burr width calculated as the ratio of total area of burr generated to the total height. It was observed that equivalent burr width in up milling was increased by 120%, while in down milling, it was decreased by 50% as the speed varies from conventional to high speed. Furthermore, the effects of different cutting parameters and tool parameters on top burr formation have been analyzed to establish correlation among them.

Investigation on chip formation and surface integrity in micro end milling of maraging steel

3J33B maraging steel is a high-strength steel which is used for fabricating precision elastic components. In this paper, experiments were carried out to investigate chip formation, surface roughness, and top burr formation in micro end milling of 3J33B from an energy perspective. Chip formation and surface roughness in the centerline position of the slots were analyzed based on the average specific cutting energy. Surface roughness and burr size of the two sides of the slots were compared to the variation of the instantaneous specific cutting energy in a half cutting revolution. It was found that the chips became more fragmentized with an increase in the specific cutting energy due to the plowing effect. The formation of the down-milling side required more specific energy than that of the up-milling side. It was proven that the increment of the specific energy on the down-milling side was related to the better surface finish and greater size of top burrs. At last, some suggestions on parameter selection for surface improvement were proposed according to the research results.

Experimental investigation of top burr formation in high-speed micro-end milling of titanium alloy

ABSTRACTSuperalloys with burr-free parts are most preferably used in biomedical, aerospace, marine and automotive applications. In order to reduce the global pollution content, industries strive to execute stringent green manufacturing technologies. There is a need to investigate the different available tools in high-speed micro-milling process to achieve desired burr free with good surface finish on super alloys without using traditional coolants. In machining of titanium and its alloys, because of low thermal conductivity and reactivity with tool materials instigate the burr formation on work material and lowers the tool performance. The main objective of this article is to investigate the top burr formation in high-speed micro-end milling of alpha + beta-titanium alloy-grade 23 ELI (Ti-6Al-4V) under dry cutting conditions using Uncoated and physical vapor deposition coated AlTiN, TiAlN tungsten carbide end mills. Machining performance of the three cutting tools was compared. From the comparison of cutting tools for machining titanium alloy-grade 23, it is found that coated TiAlN tools produce less burr formation than coated AlTiN and uncoated tungsten carbide tools.

Investigations into the effect of process parameters on surface roughness and burr formation during micro end milling of TI-6AL-4V

As micromachining is finding a lot of applications in various fields such as biomedical, avionics, optics, and electronics, it is necessary to produce parts with good surface finish and minimum burr. In this paper, experimental investigations on the effect of spindle speed, feed and depth of cut on various responses such as surface roughness and top burr formation during the micro milling of Ti-6Al-4V with two different carbide tools with a diameter of 0.5 and 1 mm have been carried out. Three levels of cutting parameters with full factorial design were used for the experimentation. The burrs formed on the up milling side of the micro slot were analyzed in this study. A scanning electron microscope (SEM) was used to analyze the burrs formed and was quantified in term of its kerf width. The analysis of variance (ANOVA) was used to find the level of significance of cutting parameters on surface roughness and top burr formation. In addition, statistical predictive models were also developed to predict the responses in terms of cutting parameters. Finally, a cutting strategy was postulated to minimize the top burr in the micro end milling of a slot and was verified for a slot of 0.75-mm width.

Experimental study on a novel minimization method of top burr formation in micro-end milling of Ti-6Al-4V

This paper investigates the top burr formation mechanism and minimization method in the micro-end milling of titanium alloy Ti-6Al-4V. The top burr formation procedure has been systematically deduced to reveal the reason for the occurrence of a top burr considering the cutting trajectory of the micro-milling tool, the chip thickness h, and the variation in the micro-milling force Fp. A new method to minimize the top burr in micro-end milling of Ti-6Al-4V is proposed in this study: resin coating is fabricated to control and reduce the top burr size by absorbing the Wp energy. A series of micro-end milling experiments were performed to test this new method. The experimental measurement results prove that the method in this study significantly reduces the top burr size in the micro-end milling of Ti-6Al-4V. Two different top burr formation modes during micro-end milling have been found, and the effect of the minimum chip thickness hm on the top burr size is revealed. When h is below hm, large squeezing and tearing result in a poor surface and large top burrs; when h is above hm, the top burr size suddenly decreases. The relations between the top burr size variation bl, bw, and the cutting-force work Wp are determined and discussed. Based on the new technology that this study develops, a series of micro-milling surfaces with the smallest top burr size to date worldwide are achieved. The knowledge obtained from this study is expected to be an important contribution to top burr minimization in micro-machining.

Workpiece surface integrity when slot milling γ-TiAl intermetallic alloy

Slot milling is presented as a potential manufacturing route for aerospace component feature production when machining γ-TiAl intermetallic alloy Ti–45Al–2Mn–2Nb+0.8vol.% TiB2XD using 2mm diameter AlTiN coated WC ball nose end milling cutters. When operating with flood cutting fluid at v=88m/min, f=0.05mm/tooth, d=0.2mm, maximum flank wear was ∼65μm after 25min. SEM micrographs of slot surfaces show re-deposited/adhered and smeared workpiece material to a length of ∼50μm. Brittle fracture of the slot edges was restricted to <10μm with sporadic top burr formation observed up to ∼20μm. Cross sectional micrographs of the slot sidewalls showed bending of the lamellae limited to within 5μm.

Micro-end milling of NiTi biomedical alloys, burr formation and phase transformation

• Cutting parameters effect on burr formation is observed using design of experiments. • An increase of feed per tooth implies a decrease of top burr height and width. • An increase of width of cut implies an increase of top burr height and width. • A thin layer under surface machined of NiTi alloys is affected by micro-milling. • An explanation of top burr formation is proposed. This paper focuses on burr formation in micro-end milling of two nickel–titanium shape memory alloys (SMA), an austenitic and a martensitic NiTi. Phase transformation during machining is also examined. The experimental design approach was used to study the effect of cutting parameters on burr formation. The studied parameters were cutting speed, feed per tooth, depth and width of cut, machining strategy and initial material phase of the NiTi alloy. Different types of burrs were formed during micro-end milling of NiTi alloys; it was observed that top burrs are the most important. The height of top burrs can reach values close to those of the depth of cut. Burrs were observed and characterized using a Scanning Electron Microscope (SEM), confocal and optical microscopes. The affected layer under the machined surface, and phase transformation were investigated by using SEM. The results of the analysis of variance showed a significant formation of burrs, deeply influenced by the feed per tooth and width of cut. An increase in the feed per tooth and a decrease of width of cut tend to decrease the height and width of the top burr. In a thin layer under the machined surface, phase transformation was observed for the martensitic NiTi.

Characteristics and mechanism of top burr formation in slotting microchannels using arrayed thin slotting cutters

Abstract This paper investigates the characteristics and mechanism of top burr formation, and the influence of cutting conditions on top burr formation in slotting microchannels on stainless steel (SS304L) using arrayed thin slotting cutters. Saw-like top burr that is a combination of Poisson part and tear part was observed in the experiments. A 3D finite element model was developed for analysis of the top burr formation processes. The mechanism of top burr formation was proposed based on a series of stress contours and the progressive deformation of microchannel edge obtained from simulation. The process of top burr formation can be divided into four stages: Poisson part initiation, Poisson part development, tear part formation and tear part toppling. The top burr height was found to be largely determined by feed and cutting speed, while the top burr width was found to be strongly influenced by cutting depth, feed and cutting speed.

Effect of side edge angle and effective rake angle on top burrs in micro-milling

Abstract Experimental investigations on the effect of side wall edge strengthening, to reduce top burr formation, in micro-milling slots in Al-6061 alloy using a carbide tool are reported here. The side edge is strengthened by increasing the edge angle to a value higher than the usual 90°. Side edge angle is varied in two ways: one, by changing the work geometry and two, by introducing a taper into the milling tool. The burrs formed are examined qualitatively in a scanning electron microscope and quantitatively using a surface profiler. The analysis of the results shows that top burrs are reduced both by strengthening the side edge and also by the effect of the taper angle in the micro-milling tool. The effect of the side edge angle in the tool can be attributed to the edge strengthening. On the other hand, an analysis of the tapered tool geometry indicates that the velocity rake, normal rake and effective rake angles increase with the taper angle and can hence explain the observed burr reductions.

Investigation of the size effect on burr formation in two-dimensional vibration-assisted micro end milling

In precision and micro cutting processes, the tool cutting edge radius is generally quite large compared to the undeformed chip thickness, which can cause ploughing/rubbing between the tool and the workpiece and thus affect surface finish, tool wear, and burr formation. This paper investigates the effect of the size effect on top burr formation in two-dimensional vibration-assisted micro end milling (2D VAMEM). This is achieved by studying the effects of the ratio of undeformed chip thickness to the cutting edge radius, and the ratio of the time when the undeformed chip thickness is less than the minimum chip thickness to the total cutting time on top burr formation, using a model that integrates the chip thickness model of the 2D VAMEM and the minimum chip thickness prediction model. The corresponding experiments are carried out to verify the integrated model. It is found that feed per tooth has a significant effect on the height of the top burr, and the use of vibration-assisted cutting in micro end milling can minimize the size effect and improve the cutting performance, thereby reducing the height of the top burr. In addition, selecting suitable vibration parameters can significantly decrease the height of the top burr. The integrated model can be used to optimize the machining parameters to reduce burr size and further study the size effect on cutting force, surface roughness, and tool wear in 2D VAMEM.

Modeling and experimental analysis of microburr formation considering tool edge radius and tool-tip breakage in microend milling

The microburr formation in the microend milling of aluminum alloy Al2024-T6 using tungsten-carbide cutter is investigated in this article. The three-dimensional finite element model is developed to analyze microburr formation in microend-milling process. This model predicts the effects of various tool edge radiuses and tool-tip breakage on the burr formation. The microburr formation is dynamically simulated. The simulation results show that there are three basic types of burrs (entrance burr, top burr, and exit burr) along the feature edges. The burrs formed in microend milling are larger than those formed in conventional milling in certain range. The effect curve of tool edge radius on the top-burr height is obtained. Various tool edge radii are found to have significant influence on the top-burr formation. The salient size effect of microburr morphologies is observed in the experiment and simulation. Experimental verification of the simulation model is carried out in the process of microend milling of aluminum alloy Al2024-T6. The simulation for influence of various tool edge radii (new tool and worn tool) and tool-tip breakage on the exit-burr height has been verified in experiments. Top-burr heights in simulation and experiments have maximum error about 10%. The experimental results also show that the model is suitable for predicting the morphologies and dimensions of microburrs.