Experimental study of burrs formed in feed direction when turning aluminum alloy Al6061-T6

The paper represents an experimental study of the burr formation mechanism in feed direction. The influence of tool angles and workpiece angles, as well as and other cutting conditions on burr dimensions is considered. The work contains experimental graphs of burr cross-sections obtained using a laser measurement system at various stages of burr formation. The analysis of the experimental work shows that, depending on the cutting conditions, a few mechanisms of burr formation can be discerned: sideward burr formation, bending of the uncut part of allowance, and the shearing of residuary material at the final stage. This study could be useful in the search for optimal tool geometry for burr minimization and for the modeling of a burr formation mechanism.     

单工步与三工步无飞边冲孔工艺的对比研究

研究了一种单工步无飞边冲孔工艺，对该工艺与三工步无飞边冲孔工艺进行了对比研究，其模具结构简单，操作方便，制造精度及费用低，孔剪切口光洁剪切带长度达到材料厚度的80％，提高了孔的尺寸及形位精度，在工程生产中具有很高的实际应用价值。     

Taguchi optimization in drilling of AISI 316L stainless steel to minimize burr size using multi-performance objective based on membership function

Burr in drilling plays an important role on product quality and hence it is essential to minimize the burr size at the production stage. This paper presents the application of Taguchi optimization method for simultaneous minimization of burr height and burr thickness influenced by cutting conditions and drill geometry. The approach of Taguchi design for drilling optimization problem is based on multi-performance objective, which employs the membership functions. In the present work, optimal values of cutting speed, feed, point angle and lip clearance angle are determined for selected drill diameter values to minimize burr height and burr thickness during drilling of AISI 316L stainless steel workpieces. The effectiveness of the proposed approach is demonstrated through simulation results and experimental verifications.     

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 minimizing scheme in drilling

In conventional drilling, burr formation can be changed by varying the drill’s geometry, i.e. the step angle and point angle. To minimize burr formation, it is proposed that a step drill be used. The step drill performs front edge cutting before step edge cutting. The burr formed in first cutting by front cutting edge can be removed in second cutting by step edge. In particular, new burrs are formed through the second cutting. They can be minimized by changing the drill’s geometry. A laser sensor is used to measure the burr formed in the drilling.     

Mechanistic models of thrust force and torque in step-drilling of Al7075-T651

In the aerospace industry, burr removal is an important and expensive part of the manufacturing process. One approach to minimizing burrs is to lower the thrust force in drilling through suitable modification of the drill geometry such as the use of step drills. This paper focuses on the modeling of thrust force and torque for step drills. A mechanistic model capturing the various material removal mechanisms, i.e. oblique cutting, orthogonal cutting, and indentation, active on different sections of the step drill is developed. Subsequently, a series of experiments is conducted to calibrate and validate the model. The validation results show that the predicted thrust and torque values are in good agreement with measured values, although the torque is slightly underestimated. The validated model was further used to investigate the effects of step drill geometry parameters on the thrust force and torque. The model predictions suggest that the thrust force increases and the torque decreases for larger secondary point angles and inner diameters.     

A New Burr Formation Model for Orthogonal Cutting of Ductile Materials

This paper proposes a new model to predict the full formation of a burr in orthogonal cutting. The model is based on the theory of slip-lines, the equilibrium equation, and experimental observations of burr formation with relevant data gathered from previous studies. Unlike with existing models, the proposed model considers the influence of the deformation rate on burr formation as well as the compression factor of the exit surface during burr development. A Mathcad program was created based on the model. The program can visualize burr formation and can predict the geometrical characteristics of the burr. The results of visualization are presented in the paper. The influence of the tool rake angle, the workpiece angle and the undeformed chip thickness, on burr dimensions have been verified in experiments. The experimental results show that the model is suitable in the cutting of ductile materials.     

Prediction of Parameters for the Burr Dimensions in Short-Hole Drilling

The following paper presents a method for the determination of the burr dimensions to be expected in short-hole drilling, simultaneously taking the parameters into consideration which influence the burr formation. These parameters are yield stress, forces and the geometry of the inserts. The method is based on empirical cutting examinations and takes account into the correlation between different burr parameters and the machining conditions such as cutting speed, feed and tool geometry. Using Schaefer's burr value g, it is possible to make a quantitative evaluation of the burr dimensions. The method was verified for the materials 16 MnCr 5 and Ck 45 in case of dry machining.     

Burr formation in intersecting holes

Regarding intersecting holes, the edges of cut are often difficult to access, as they are located inside the components. Hence it requires a lot of time and money to deburr them. In addition, burrs which come off in the later operation can lead to resultant damages. Examinations of intersecting holes showed that the effective exit surface angle, the angle between drill wall and exit surface, is crucial for burr formation. Based on the burr calculation for exit surfaces perpendicular to the drill axis, a method of calculation was developed out of the experimental results. By means of this calculation method the burr value g can be predicted for the short hole drilling of intersecting holes.     

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.     

Experimental observation and analysis of burr formation mechanisms in face milling of aluminum alloys

The purpose of this paper is to study the burr formation mechanisms in face milling process, and to investigate the influence of cutting conditions on burr formation in face milling of aluminum alloys. The fly milling cutter is used to carry out single-tooth face milling tests. Three aluminum alloys were tested: Al 1100 (cold drawn), Al 2024-T4 and Al 6061-T6. It is found that the burr geometry is strongly dependent upon the in-plane exit angle. Five types of burrs were observed in the experiments: knife-type, wave-type burr, curl-type, edge breakout and secondary burr. Formation mechanisms of each type of these burrs are discussed in details. The relationship between their existence and the machining condition is indicated. The machining guideline in face milling is given at the end of the paper to reduce burr size effectively through the formation of secondary burr.     

二重顶角钻头抑制钻出毛刺的应用研究

从精益生产的角度强调在加工过程中主动控制钻孔毛刺的重要性,进一步充实了少无毛刺切削三原则的内涵;重点分析了二重顶角钻头在抑制钻孔出口处毛刺的5个优势,初步总结了二重顶角钻头主要参数的确定方法。     

Monitoring of drilling for burr detection using spindle torque

This work proposes and evaluates a monitoring method, based on internal signals from spindle torque, to detect non-desired burr formation during drilling operations. Five features of this signal showed to be related to burr height. The selected features were sensitive to the exit burr while comparatively insensitive to changes in process parameters. The experiments were performed in aeronautics aluminium, Al 7075-T6, under dry high speed conditions. A thresholding algorithm has been developed to distinguish if burr height is below or above a previously established onset. The predictability of the developed algorithm is above 92% for the tested range of process parameters. An appropriate implementation of this monitoring system can be used as an effective quality control of drilling operations.     

Optimization and control of drilling burr formation of AISI 304L and AISI 4118 based on drilling burr control charts

Control charts for drilling burr formation for stainless, AISI 304L, and low alloy steel, AISI 4118, were developed. Split point twist drills are used for the experiments of this work. A Drilling Burr Control Chart, based on experimental data, is a tool for prediction and control of drilling burrs. Burr classification was carried out based on the geometric characteristics, burr formation mechanisms and sizes of the burrs. New parameters consisting of cutting condition variables and drill diameter were developed, and used to show unique distributions of the burr types. Burr types and the resultant burr size showed great dependence on the new parameters regardless of the drill diameters. Through the chart, burr type can be predicted with given cutting conditions. Also cutting conditions that are believed to create preferred burr types can be selected.     

Suppression of burrs in turning with ultrasonic elliptical vibration cutting

The approximate cutting force models in three-dimensional separating type ultrasonic elliptical vibration cutting are proposed in present paper. The theoretical models of the stresses of deformation zone on the workpiece edge in burr formation in ultrasonic elliptical vibration cutting are derived based on three-dimensional cutting model, and the reason for the burr being suppressed by applying ultrasonic elliptical vibration is clarified theoretically. Finally, the effect of ultrasonic elliptical vibration cutting on the burr is verified experimentally.     

Design of a deburring tool for intersecting holes in aluminum alloys

A deburring tool for intersecting holes is proposed. The tool has a hemispherical cutter head mounted on a pivoted shaft which is loaded against the burr edge by a set of springs. The cutter head is inserted into an intersecting hole up to the burr edge and is subsequently rotated counterclockwise with a return stroke. The cutter head size is selected such that the cutter head has maximum accessibility to the three dimensional burr edge. The cutting edge is designed to maintain proper ranges of rake angle and relief angle during deburring. The efficiency of the tool in terms of deburring speed is verified by a set of deburring tests on Al6061-T6. The measured depth of cut on the burr edge confirms the complete removal of burrs.     

The effect of using a sprung stripper in sheet metal cutting

Sheet metal cutting with punch and die is one of most fundamental processes in sheet metal presswork, and in many modern tools such as progression tooling a sprung stripper is used to help the punch withdraw from the strip after separation. The vast quantity of practical information which is available about the cutting process does not document whether the use of a spring stripper affects the cutting process. In this work, a tool with a sprung stripper was modified so that the sprung stripper was held back from the strip. Burr height readings were taken before and after the modification, as were electron micrographs of the cut edge. These were compared to determine the effect, if any, that a sprung stripper would have on the proportions of shear and tensile fracture and the burr height formed. When a sprung stripper was used, maximum burr was half as high as without. Process consistency was over twice as good with a sprung stripper. When a sprung stripper was used, burr was found to protrude into the hole, which did not happen otherwise. With a sprung stripper, there were more patches of secondary shear fracture than with no stripper contact. It is suggested that the use of a sprung stripper altered the path of tensile fracture and the amount of drawing in of the strip during cutting, thus altering the burr height and width.     

无毛刺冲孔反顶装置液压动力系统研究

对无毛刺冲孔反顶装置的液压动力系统进行了分析、比较，为工程实际应用提供了系统设计依据。