Burr Formation Mechanism Research Articles

Burr Formation in Metal Cutting Operations and some Deburring Methods

Remained burrs on edges of the parts after metal cutting operations may cause many problems in the production process and in the quality of products, therefore the burrs must be completely removed. In the paper, the authors give an outline of the elements and the technical and economical influences of the burr formation, and the characteristics of the burrs and the burr formation mechanisms. The authors present some special processes that are suitable for deburring of small pieces (e.g. Magnetic Abrasive Deburring), and a frequently applied mechanical process: power brushing. The authors have carried out many investigations regarding the magnetic abrasive deburring of small, blanked sheet metal parts, furthermore the machine deburring of large-sized metal workpieces by carbide-reinforced cylindrical brushes. The detailed conditions, data, results and conclusions of these deburring experiments are treated in the paper too.

Development of a micro-drilling burr-control chart for PCB drilling

A drilling burr-control chart (DBCC), based on experimental results, is a tool for the prediction and control of drilling burrs for a large range of drilling parameters. A micro-drilling burr-control chart (M-DBCC) was developed for a standard double-sided copper-clad laminated (CCL) printed circuit board (PCB) with laminated fiber-reinforced plastic (FRP) substrate. This chart will assist in the selection of favorable drilling parameters for predicting and achieving preferred types of burrs. Burr classification was carried out according to the burr geometric characteristics, burr formation mechanisms, burr height, and drill bit breakage while drilling. The design of experiment (DOE) technique based on the Taguchi method was used to find the most significant drilling parameter affecting burr height. The results show that the drill diameter makes a statistically significant contribution to burr-height variation.

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.

Reducing Shaping Burr by Beveling Exit Edge of 45C8 Steel

Production of high precision components needs constant attention to both the generation of machined surfaces without a burr and undertaking deburring operation. A machining process usually produces burr. In shaping, burr formation occurs when the cutting tool exits the workpiece. Absence of necessary back up support around an edge is the possible reason behind it. Several research works have been done on burr formation mechanism, its minimization, and deburring. A number of experiments is performed in this work on medium carbon steel (45C8) flats in dry condition to note the effects of burr formation on the workpiece with beveled exit edge. The experimental result shows that at 15o edge bevel, negligible burr formation is obtained. Analysis of variance is conducted on the experimental results to find out the relative influence of each process parameter on burr height observed. The regression analysis is also done with the experimental data and the regression equation gives fairly good estimate of experimental results.

An innovative method for surface defects prevention in micro milling and its implementation perspectives

A novel method was presented to prevent surface defects, mainly burrs generation, in micro milling process. Burr formation mechanism was analysed in machining and it was found that negative shear plays a critical role in burr generation, especially near the workpiece boundaries. In order to eliminate its effect, low melting point alloy was selected to extend the boundary of the workpiece as auxiliary support. Therefore, burrs were formed on low melting point alloy, which were removed by melting it off afterward and the burrs-free component was thus achieved. Experiments were carried out on a micro milling machine and aluminum alloy was machined with micro end milling tools. The results revealed that most burrs were prevented and there was no contamination on the workpiece surface. The paper concluded with further discussions on the potential applications of the method.

Factors governing burr formation during high-speed slot milling of wrought aluminum alloys

Burr formation and edge finishing are research topics with high relevance to industrial applications. To remove burrs, however, a secondary operation known as deburring is usually required. Deburring is more complex and costly when dealing with milled parts, because multiple burrs form at different locations with various sizes. Therefore, proper selection of process parameters to minimize the burr size is strongly recommended. Therefore, this requires an understanding of milling burr formation mechanism and the governing cutting parameters on milling burrs. In this article, a multilevel experimental study is arranged to investigate the effects of machining conditions, tooling and workpiece materials on burr size (height and thickness). Statistical tools are then used to determine the dominant cutting parameters on burr size and to effectively prescribe an operational window to control and minimize burr formation. It was found that optimum setting levels of process parameters to minimize each burr are different. The analysis of results shows the significant effects of cutting tool, feed per tooth and depth of cut on slot milling burrs.

Experimental investigation of microdrilling of printed circuit board

PurposeThe purpose of this paper is to investigate the cutting mechanism of drilling printed circuit board (PCB) and to optimize the drilling parameters for decreasing burr size and thrust force.Design/methodology/approachAn experimental study was carried out to investigate the effect of drilling parameters on thrust force and burr formation. The drilling process of PCB was divided by the variation of drilling force signals. Analysis of variance (ANVONA) was carried out for burr size and thrust force. Desirability function method was used in multiple response optimization, to find the best drilling parameters.FindingsEnter burr and exit burr have different morphologies and types. The generation of enter burr is mainly caused by burr bending which can be observed in micrographs, whereas the generation of exit burr is more complicated than enter burr; both burr breakup and burr bending are observed in exit burrs. In the selected area, the optimized spindle speed and feed rate for drilling PCB is 12 krev/min and 6 mm/s, respectively.Research limitations/implicationsIn this paper, hole wall roughness and tool wear were not considered in the optimization of drilling parameters. The future research work should consider them.Originality/valueThis paper investigates the mechanism of burr formation and thrust force in drilling PCB and then optimizes the drilling parameters to decrease the burr formation and thrust force.

Micro cutting of V-shaped cylindrical grating template for roller nano-imprint

The roller nano-imprint technology is considered as efficient and low cost method for the large scale micro-pitch grating fabrication. The surface quality of the V-shaped grooves for roller grating template developed by diamond tool cutting process is investigated. The surface quality of the micro V-shaped grating is optimized with minimized burr formation by optimizing the cutting tool's shape design and the micro-cutting process, based on the chip morphology and non-free chip interference analyses. Burr shows different variation with the grating pitch of 10–20μm and less than 2μm. The burr formation mechanism for V-shaped micro-cutting is studied by material (H62 Copper) metallography and homogeneity analyses. Finally, high precision grating template with various pitches is successfully achieved.

Evaluation of the effects of tool geometry on tool wear and surface integrity in the micro drilling process for Inconel 718 alloy

Mechanical micro machining of nickel-based super alloys is challenging due to limited tool life, but promising in terms of quality of machined component. Despite present advances in micro machining, milling and drilling tool designs still need to be tailored to specific applications. The study reported here investigated the effect of different tool geometry parameters on tool wear and workpiece surface integrity in micro drilling of nickel-based super alloy. For the cutting tests, 0.5 mm diameter twist drills were used to drill through holes on a 2.5 mm plate. Analysis of variance (ANOVA) was used to evaluate the statistical significance of drill point angle and helix angle and their interactions on tool wear and burr size. Burr formation mechanism was investigated supported by material microstructure evaluations. The results show that a complex relationship (interaction) exists between point angle and helix angle which drive tool wear, burr formation and surface and subsurface deformations. An optimum value of 150° point angle and 40° helix angle results in reduced tool wear rate, burr formation and subsurface plastic deformation. The results also show that subsurface deformation is influenced by the size effect. The study defines the significance of tool geometry on the micro drilling performance for nickel-based super alloys.

Simulation and Control of Two Side Direction Burr

A finite element model was developed for simulation of two side direction burr formation process. Based on strain distribution, a two side burr formation mechanism was proposed. Burr form and burr size of simulation are close to that's of experiment. Finite element model generated here provided a numerical analysis method to solve the prediction of burr and chip formation and physical insight into the fundamental burr formation mechanism. The stain in two side direction of material near the side face decides the shape and the size of two side direction. Multi-workpieces are machined at the same time with side face closely by each others can control the formation of two side direction strain and two side direction burr.

Analysis of the Feed Direction Burr in Turning Based on FEM

A finite element model was developed for simulation of feed direction burr formation process in turning. Based on a series of stress and strain contours the progressive change of geometry at the edge of workpiece edge from simulation, a turning feed direction burr formation mechanism is proposed and divided into four stages: normal cutting stage, deformation of workpiece edge stage, continues cutting stage and final developed stage. The removal of the remaining part of allowance takes place close to the tool tip as the material has sufficient rigidity to allow cutting only in this area in final developed stage and secondary burr will be formed; primary burr will be formed in final developed stage if the remaining material has no rigidity to allow cutting continually in final developed stage. The burr size and burr shapes form simulation results are consistent with the experimental results. Finite element model generated here provided a numerical analysis method to solve the prediction of burr formation and physical insight into the fundamental burr formation mechanism.

Characterization and modeling of burr formation in micro-end milling

Abstract Mechanical micromachining is increasingly finding applications in fabrication of components in various fields, such as, biomedical devices, optics, electronics, medicine, communications and avionics. In order to ensure adequate functionality, there are stringent requirements for form and finish in case of biomedical devices like cochlear implants and metallic optics. This necessitates that the post machined surface must be burr free. To address these issues in micromachining, this paper presents results of an experimental study to investigate the influence of main process parameters i.e. speed, feed rate, depth of cut, tool diameter and number of flutes on the formation of the various types of burrs i.e. exit burrs and top burrs produced during micro-end milling operation. The experiments performed using Taguchi method shows that three types of burr formation mechanisms prevail during micro-end milling operations; these are: lateral deformation of material, bending and tearing of the chip. Also, three types of burrs were observed include: Poisson burr, rollover burr in down milling and tear burr in up milling. Further, it is observed that the depth of cut and the tool diameter are the main parameters, which influence the burr height and thickness significantly. However, the speed and the feed rate have small to negligible effect on the burr thickness and height. Besides the experimental analysis, the paper presents an analytical model to predict the burr height for exit burr. The model is built on the geometry of burr formation and the principle of continuity of work at the transition from chip formation to burr formation. Note that prediction of burr height in micro-end milling is extremely challenging due to the complex geometry of material removal and microstructural effects encountered during cutting at that length scales. The model fares well and the prediction errors range between 0.65 and 25%.

Study on Burr Formation Mechanism When Turning Nickel-Based Alloys

The aim of this paper was to introduce the study on burr formation mechanism of nickel-based Hastelloy C-276 in the turning process. The process is monitored using a high-speed camera mounted on a computer numerical control (CNC) turning machine. The captured photographs show that the burr starts appearing on the edge of an uncut surface when the engagement with the chip—workpiece contact area is complete and increases accordingly during the process of hitting the cutting edge and causing chipping wear. The study shows that the initializing of chip burr formation can be divided into two stages: creating and mounting up. Creating of burr formation is characterized by the “reaction of shear formation” of the cutting force on the edge of chip for an unmachined surface, while mounting up increasing in size and forcing the chip to change its direction shoots up the rake face. This edge of the burr will separate and re-attach with the burr edge again during mounting up, thus creating a chain web shape on the edge of the uncut surface and causing edge chipping. The results show that the approach angle has a significant effect on burr formation.

Burr formation in milling cross-connected microchannels with a thin slotting cutter

This paper studies the burr formation mechanism in milling cross-connected microchannels, and investigates the influences of radial depth of cut ae, cutting speed v, feed speed vf and mesh size on the burr formation. A thin slotting cutter is carried out to fabricate cross-connected microchannels in a metal plate of thickness H. Two kinds of large burrs are produced in the meshes formed by two sets of perpendicular and cross-connected microchannels: flake-like burr and curl-like burr. Results indicate that when ae is equal to or slightly larger than H/2, flake-like burrs are formed. When ae is much larger than H/2, curl-like burrs are produced. Furthermore, curl-like burrs formed at low v are relatively longer than those formed at high v. High vf is unfavorable for the occurrence of long curl-like burrs. In addition, larger mesh is in favor of longer burrs due to its larger capacity.

Aspects of burr formation in bandsaw teeth manufactured by milling operation

Steel manufacturers and stockholders prefer bandsawing for cutting off raw materials compared to other techniques as it enjoys competitive advantages of higher accuracy of cut, better surface finish, lower kerf loss, better straightness of cut, long tool life and high metal removal rate. Along with the geometries of the bandsaw tooth, bandsaw cutting edge condition (e.g., edge sharpness and burr) significantly affects the cutting performance of a bandsaw. Currently the production of bandsaw is largely done by milling operation due to the scale of manufacturing and the economics of milling compared to other processes (e.g., grinding). Ideally, the bandsaw teeth should possess sharp cutting edges with no burr. In general, two types of burr are commonly seen in the bandsaw teeth manufactured by milling operation namely tooth tip burr and side burr. Current research undertaken at Northumbria University in collaboration with a major bandsaw producer is focused on the mechanism of burr formation in the bandsaw teeth. This paper briefly outlines the factors affecting the burr formation in bimetal (High Speed Steel edge wire and soft steel backing material) bandsaw teeth manufactured by milling process and suggests the necessary steps to be considered for manufacturing burr free bandsaw with sharp cutting edges. The investigation showed that flank wear in the milling cutter has a major influence on the side burr formation in the bandsaw teeth, whereas tooth tip burr was influenced by both flank wear and “V” type notch wear found at the crossover point on the flank face. It was also concluded that TiN coating on the milling cutter could control the burr formation in bandsaw teeth to some degree.

Latest Trends in Deburring Technology

This paper details the standardization of edge quality in Japan, its meaning to design, burr formation mechanisms and their control, and deburring methods to provide burring technology basics and trends. Deburring is essential to designing functional edges, and the principles of machining, such as edge shape, require that burr formation be minimized. Selecting the appropriate deburring method is vital and requires that many factors be considered. Microdeburring is increasingly in demand, as exemplified by the dissemination of Aero Lap shot blasting.

Optimization of the cutting conditions (Vc, fz and doc) for burr minimization in face milling of mould steel

The aim of the present work is to investigate the burr formation mechanisms at the edges (lateral and exit) during face milling of mould steel using carbide tools. The effects of the cutting parameters were studied and strategies of burr minimization were discussed. The proposed minimization was achieved by optimizing the cutting conditions: cutting speed (Vc), feed per tooth (fz) and depth of cut (doc), with the aid of surface response technique.

Influences of End Surface Angle of Workpiece on Burr Formation in High Speed Machining

The end surface angle of workpece is one of key factors that affect burr sizes and shapes. In this paper, the burr formation process of different end surface angle is simulated with elastic plastic nonlinear element method based on ABAQUS. The influence of end surface angle of workpiece on burr formation processes in high-speed machining 2024 Aluminum alloy is analyzed. The influence of end surface angle on burr sizes and shapes is studied based on equivalent shear strain and negative shear angle. The results have investigated the mechanisms of burr formation fundamentally, which is the basis of burr minimization.

Burrs—Analysis, control and removal

Increasing demands on function and performance call for burr-free workpiece edges after machining. Since deburring is a costly and non-value-added operation, the understanding and control of burr formation is a research topic with high relevance to industrial applications. Following a review of burr classifications along with the corresponding measurement technologies, burr formation mechanisms in machining are described. Deburring and burr control are two possible ways to deal with burrs. For both, an insight into current research results are presented. Finally, a number of case studies on burr formation, control and deburring along with their economic implications are presented.

Burr Formation in milling with minimum quantity lubrication

In milling, burrs are formed on entry and exit edges of the workpiece to be machined like in all material removal processes. In the subsequent production these burrs have to be removed. Understanding the influencing factors and burr formation mechanisms can help to avoid or reduce burrs. Another possibility for saving costs is to reduce the process materials, for example, cutting fluids. This can be realised by using minimum quantity lubrication or dry machining. The investigations show which influence both methods have on burr formation.