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In many machining operations burrs cannot be avoided. They can affect the functionality and the safe handling of the workpiece in the subsequent processing, and have to be removed by a special deburring process. Toleration of burrs, which are not part of functional edges, depends on their respective shape and size. High inspection effort is necessary to guarantee the workpiece quality. Therefore, the research results on burrs, with a focus on burr analysis and control as well as on cleanability and burr removal based on the presentations held at the conference are valuable for researchers and engineers in manufacturing development.

Inhaltsverzeichnis

Frontmatter

Keynotes

Frontmatter

A Review of Burr Formation in Machining

One of the major concerns in deburring technology is centered on how to predict the size and shape of burrs to insure uniform removal and, if this is possible, how to design the process or product in advance to minimize or control the burr size. This paper reviews some of the research done over the past several years on this important topic. The paper includes a discussion of burrs in conventional machining, process planning for burr minimization as well as micromachining applications.

D. Dornfeld, S. Min

Burr Minimization Strategies in Machining Operations

Reducing burr formation in machining operations is of vital importance as they can decrease the functionality of components and can cause injuries. Nowadays, additional processes for deburring are often necessary. To avoid deburring, the modification of machining processes is a promising approach. Here, different parameters have a significant influence on burr formation. For example, the use of alternative machining processes or the reduction of the workpiece temperature near the edge of the workpiece shows high potential for burr reduction. This temperature reduction causes a change in material properties which decreases burr formation. In this paper, methods for burr minimization in various cutting processes are presented. Burr reduction strategies for turning, drilling and milling of different materials are presented.

D. Biermann, M. Heilmann

Burr Formation and Avoidance for Robust Circular Blade Sawing of Thin Walled Extruded Aluminum Profiles

Thin walled extruded aluminum profiles are usually cut by sawing processes to appropriate length and angles. Burrs can be a problem for the robustness of this process, as well as for handling and function of the parts. Deburring processes after sawing (manually or automatic) will be an additional cost. This paper shows analysis of bur formation after circular blade sawing of thin walled extruded aluminum profiles and the effects of changing process parameters such as cutting speed and saw tooth geometry. The paper shows how substantial improvement could be achieved through small investments on new sawing blades and saw blade motors with higher rotation speed.

K. Martinsen, G. Ringen

Mechanics, Modeling and Simulation of Burr Formation

Frontmatter

Burr and Cap Formation by Orbital Drilling of Aluminum

In orbital drilling the tool (special end mill) moves relative to the workpiece on a helical course. Because of the three dimensional tool path and the superimposed rotary cutting motion a complex machining motion results which determines the contact conditions of the tool. In the aircraft industry this process is used for cutting composite materials (CFRP/Aluminum) with automated drill and rivet machines, for example in the manufacturing of flap tracks and vertical tail planes. A key problem in the industrial manufacturing of closed structures is the cap and the burr formation on the bore exit side. All caps and chips must be able to remove by vacuum, in addition a minimum burr height is required. The objective of this study is to describe the effects of orbital drilling on cap and burr formation in the exit composite material, primed clad aluminum 2024. The influence on cap and burr formation with different tool geometries, different coatings, different cutting parameters, tool wear and minimum quantity lubrication were examined.

E. Brinksmeier, S. Fangmann

Cutting Force Model for Analysis of Burr Formation in Drilling Process

Burr formation in the drilling process is discussed with the cutting force and the chip flow direction. An analytical model is presented to predict the cutting force based on the minimum cutting energy. Because the burr occurs on the backside of the machined plate in drilling, burr formation is associated with the axial component of the cutting force at the exit of the drill from the workpiece. The chip should also be controlled to flow toward the radial direction of the drilling tool. The lip geometry of the twist drill is discussed to reduce burr formation with the curved edges in the cutting simulation.

T. Matsumura, J. Leopold

Burr Formation in Microstructuring Processes

Due to high form accuracy and flexibility concerning the structure geometry, cutting is predestined to produce structures in the micron range. At the Institute of Production Engineering and Machine Tools (IFW), a fly-cutting process is used for manufacturing microstructures. These structures are used to improve the tribological performance of thermo mechanically highly stressed surfaces. The structures thus produced are able to hold some lubricant and can also be used to increase the hydrodynamic pressure built up between the friction partners already at low sliding speeds.

When machining the small structures, material of the compression zone in front of the cutting edge is squeezed in the direction of the free lateral surface areas and causes burrs. For an unrestricted functionality of the structured surface and for avoiding down-stream finishing processes, these burrs have to be minimized. In this paper, the basic relationship between the cutting edge geometry and the burr formation in machining ductile materials with depths of cut below 50 μm will be investigated. In particular, the influences of the material, the tool cutting edge radius and the tool cutting edge angle on the cutting forces and burr formation will be described. Based on these correlations, a special cutting edge microgeometry will be developed which prevents material flow in the direction of the lateral free surface areas.

B. Denkena, L. de Leon, J. Kästner

Analytical Modeling and Experimental Investigation of Burr Formation in Grinding

Increasing industrial requirements on the precision of edge geometry lead to the investigation of burr formation, particularly in finishing operations such as grinding. In the presented paper the burr formation process at the workpiece edges during surface grinding is analyzed. Based upon a geometrical examination of the macroscopic contact situation between grinding wheel and workpiece, a qualitative analytical process model of burr formation is developed. Following experimental investigations verify this qualitative model and enable quantitative results. Several so called “grinding stops” are realized by specifically interrupting the grinding process. Thereby, the burrs at the edges of the temporary contact area are detected. To analyze the burr formation, metallographic sections of the workpiece edges are prepared and characteristic burr parameters are measured. Based on experimental results, a thermal impact on burr formation in grinding can be detected.

H. Sudermann, I.G. Reichenbach, J.C. Aurich

Developing a Process Model for Abrasive Flow Machining

Abrasive flow machining (AFM) is a unique machining method used to achieve high surface quality on inner, difficult-to-access contours and on outside edges. Using AFM, it is possible to deburr complex shaped intersecting holes and to realize pre-defined edge rounding on any brittle or hard material. Moreover it is easy to integrate into an automated manufacturing environment. Reproducibility of results saves various time and cost consuming manual operations in industrial applications. However for an implementation in new applications costly and time-consuming preliminary investigations are required that have to be carried out by trained staff. Therefore the aim of recent research activities is to identify the fundamentals of the process, the functional correlations between setting parameters and work results. This paper presents an approach using a numerical simulation to develop a process model. Furthermore a model is introduced that describes the fundamental principles of the deburring process using AFM.

E. Uhlmann, V. Mihotovic, H. Szulczynski, M. Kretzschmar

Modeling and Simulation of Burr Formation: State-of-the-Art and Future Trends

Modeling and Simulation of Burr Formation is one of the main topics in contemporary basic scientific investigations. Using state-of-the-art numerical methods, the process of burr-development can be investigated with 2D-simulations and increasingly for 3D-applications. The aim of the numerical analysis (e.g. FE simulation) of burr formation is burr minimization.

Until the present time, numerical simulations of burr formation, especially for 3D-applications – have been very time consuming.

Hence, in contrast to fundamental research investigations into the material removal process during burr formation, more practical methods of predictive modeling are need for industrial purpose. In view of Virtual Manufacturing, the response time must be dramatically faster than usual in numerically calculations. The most relevant methods currently applied to burr formation modeling and simulation are accurately reported and discussed in this paper.

J. Leopold, R. Wohlgemuth

Burr and Chip Formation Mechanisms

Frontmatter

Interfacial Burr Formation in Drilling of Stacked Aerospace Materials

Interfacial burr formation during through-hole drilling in stacked aluminum sheets is a common problem in aircraft assembly operations. Burrs formed at the interface of the sheets are removed through non-value added de-stacking and deburring operations that increase the overall assembly time and costs. This paper presents experimental work aimed at understanding the impact of drilling parameters including drill geometry, cutting conditions, clamping configuration and drill wear on interfacial burr formation. Specific conclusions regarding the influence of these parameters on burr sizes and drilling forces are presented.

S.N. Melkote, T.R. Newton, C. Hellstern, J.B. Morehouse, S. Turner

Burr Formation in Drilling Intersecting Holes

The increasing power density in engine manufacturing as well as the complexity of parts in automotive production demand for an entire control of burr formation especially in regard of intersecting holes. This paper presents an approach to control burr formation concerning reproducible generation of burrs depending on intersecting geometry and process parameters. Therefore two process models describing burr formation and burr cap formation and results of experimental investigations of different workpiece materials (AISI 4140H (42CrMo4), 226D AlSi9Cu3)) were combined.

L. Leitz, V. Franke, J.C. Aurich

Chip Breakage Prediction by a Web-based Expert System

Chip control is essential for the manufacturing with geometrical defined cutting edge to avoid interruptions of the process, damages on the machine or injuries of the machine operator. Hereby the prediction of the chip shape is highly relevant and scope of the present research work. High speed filming of the flowing chips, analyses of the contact zones between cutting tool and chip; as well as cutting simulations using the software DEFORM 3D

are conducted to achieve an understanding of fundamental relations and the effectiveness of different chip groove geometries. A newly developed web-based expert system searches for similar datasets in a database with captured applications and is furthermore able to predict the chip shape for a planned application. Therefore the chip breakage borders for many tool-material-combinations are determined empirically and captured in the database. The software judges by these borders, if for a certain parameter set point, either chip breakage or unfeasible chip shapes occurs. Inter- and extrapolations for so far unknown datasets are also based on the borders. These operations are operating with correction values and the data output is combined with a declaration of the output accuracy. Beside the search for similar applications and the prediction of chip breakage, the expert system is also capable to evaluate the effectiveness of chip groove geometries of cutting tools.

F. Klocke, D. Lung, C. Essig

Parameters with Influence on Burr Formation

Frontmatter

Size Effects in Drilling Burr Formation

Despite the existence of numerous competing technologies, drilling is the most common and still highly demanded manufacturing process in production industries. Mostly, the manufacturing of a through bore-hole is attended by the formation of an entrance and an exit burr. Thereby, the dimension of the exit burr exceeds the entrance burr considerably. Due to the hangover on the drill exit surface, the quality of the workpiece is reduced significantly. For this reason, the removal of the burr is often required. But in case of micro-drilling no appropriate tools are available. In addition, the manual removal of the burr, which is often used for conventional drill sizes, is impossible for such small geometries.

An efficient method for solving the burr problem in conventional machining is the reduction of the burr size to a tolerable size level by adapting cutting parameters, tool properties or workpiece properties. Numerous investigations have been presented on this field in the last years, but the reached expertise can’t be transferred to micro-machining. Based on the rising influence of the grain structure in micro-machining, certain size effects occur when scaling the cutting process from the macroscopic to the micro level. As soon as the drill diameter is smaller than 1000 μm the feed per tooth and the cutting tool geometry comes into the order of magnitude of the grain structure. Thus, the characteristic of the workpiece material switches from homogeneous to anisotropic. Since there only exist investigations to a few discrete diameter ranges, the resulting influences on the burr formation are widely unknown. In this paper the size effects of the drilling burr formation are investigated in systematic scaled drilling series over a wide range of drilling diameters (Ø 0.01 mm–14 mm).

R. Neugebauer, G. Schmidt, M. Dix

Burr Formation and Surface Characteristics in Micro-End Milling of Titanium Alloys

Titanium base alloys are used for aircraft structures, turbine blades and medical implants. The surface of these parts can be functionalized by micro-structuring e.g. to get a more energy efficient turbine or to get a better biocompatibility for medical implants. Micro-end milling with end mills down to 300 μm is already efficient and reliable for microstructuring ductile materials. We developed and manufactured carbide micro end mills with a smallest diameter of 7 μm to improve the spectrum of functional structures.

This paper describes micro end milling experiments of the difficult to machine titanium alloys Ti-6Al-4 V and Ti-6Al-7Nb with 48 μm micro-end mills. Large areas are machined to observe the micro structure on the surface and the influence on surface quality. The burr formations in slot milling is observed and compared to still existing models. Up milling and down milling at the sidewalls were compared.

G.M. Schueler, J. Engmann, T. Marx, R. Haberland, J.C. Aurich

Influence of Minimum Quantity Lubrication on Burr Formation in Milling

Workpieces that are manufactured by machining processes often have to be deburred with considerable effort. This rework involves time and costs. The avoidance or at least minimisation of burr formation offers potential for a more economical production. Another possibility to save costs is to use minimum quantity lubrication. The investigation into the burr formation in milling with minimum quantity lubrication combines these two approaches. The test results presented in this paper show the influence both procedures have on burr formation.

U. Heisel, M. Schaal, G. Wolf

Burr Formation and Removal at Profile Grinding of Riblet Structures

Compared to smooth surfaces, ideal riblet structures have proven to reduce skin friction and wall shear stresses in turbulent flow by up to 10%. Investigations in the wind tunnel show that the tip radius of the riblets has a significant influence on the reduction of the skin friction. One promising process for the production of riblets on large surfaces is profile grinding. In the first experiments conducted only a minimum tip radius of 8 μm was reached. Micrograph sections of the workpiece show that the radius results from a rolled burr. The contact area between the grinding wheel and the workpiece is simulated in order to identify the mechanisms of the burr formation. It is observed that the contact area is asymmetric. Thus the removed material mainly flows to one side of the groove and forms a burr. In the following, the influence of the grinding strategy, the grinding wheel specifications and the grinding parameters on the size of the burr is investigated. The experiments have shown that the burr formation in up grinding process is quite unsteady in comparison to down grinding. The cutting speed and the feed rate as well as the grinding wheel specifications have no significant influence on the burr size. However, the burr size develops linear to the depth of cut, i.e. an increase in the depth of cut leads to an increase in the burr size. The burr can be removed by a spark-out process after the grinding process. Furthermore, the burr size decreases with an increasing feed rate during the spark-out process. Thus a riblet tip radius below 2 μm is achieved.

B. Denkena, L. de Leon, B. Wang

Burr Measurement

Frontmatter

Burr Measurement Systemfor Drilled Hole at Inclined Exit Surface

Burr is an undesirable projection as a result of plastic deformation in metal cutting and blanking operation. Burr minimization and effective deburring process are required strongly to improve the efficiency of machining and the quality of product. The necessity of a suitable measurement device for inspecting drilled hole from micro to macro burrs is required. The burr measurement system uses conoscopic holography sensor which offers certain advantages over interferometry, triangulation and dynamic focusing, for point-by-point distance mapping. In terms of this work, the improvement of burr measurement system which has ability to measure burr on curved and inclined exit surfaces which causes the out of range signals will be introduced and discussed in this paper.

H.P. Hoang, S.L. Ko

Burr Measurement: A Round Robin Test Comparing Different Methods

Remaining burrs after machining pose a severe risk for components life, if the burrs get loose. To reduce or eliminate burrs several deburring technologies are applied. To choose a deburring system and to reveal the results of deburring it is necessary to be able to measure burrs. The results of a round robin test conducted within the working group of burrs within the CIRP (International Academy for Production Engineering) to compare different burr measurement systems are presented.

V. Franke, L. Leitz, J.C. Aurich

Deburring Processes – Fundamentals

Frontmatter

Deburring with CO2 Snow Blasting

Injection molding is one of the most common production processes for polymer products. The geometries of the moulded parts are more and more complex, which leads to multipart casts and therefore to more burrs. Deburring plastics by using blasting with solid carbon dioxide (CO

2

) was investigated in this paper. Solid CO

2

has a low hardness and therefore it is suitable for machining sensitive surfaces. The investigations have shown that deburring plastic parts by CO

2

snow blasting is an alternative to common deburring methods. The achieved results were satisfying and proved to have a high potential for industrial use. Further development takes places in a public funded research project. The goal is to provide a market ready system and to establish this system in the next three to four years.

E. Uhlmann, M. Kretzschmar, F. Elbing, V. Mihotovic

A Study on Deburring Inconel 718 Using Water Jet Technology

One of the most significant problems encountered in machining is that of burr formation. All edges must be completely defect-free, with generous radius, for operational, safety and aesthetic reasons. The machining operation or CNC grinding process that shapes the component produces burrs and sharp edges. The deburring process is intended to remove these imperfections and produce specific edge profiles. Disadvantages of manual deburring methods include the cost of labor, time taken to deburr the component, quality and health and safety issues. A promising method for deburring is the use of water jet technology. Water jet machining is now providing a simple and economical approach to selectively removing burrs from areas that are difficult to access with consistent results and absolute uniformity. This paper is aimed at evaluating the process of water jet deburring of Inconel 718. Trials conducted to study the effect of water jet deburring process proved to be effective.

F. Boud, J. Folkes, N. Tantra, S. Kannan, I.W. Wright

Ice Blasting – An Innovative Concept for the Problem-Oriented Deburring of Workpieces

The paper describes the development of an operational alternative for particle blasting with deep frozen ice, an in this form solid and hard blast medium. Primarily the practical realization of this processing step for the above described case is presented, especially in less accessible locations on complex components. The procedure investigated in this article is essentially a blasting procedure using a solid blast medium. The innovative idea lies in the use of ordinary ice as a blast medium. The advantage of ice is its property not to leave any solid residue behind. Consequently it is applicable to the blasting treatment of complex component geometries. The use of conventional blast media for purposes of blast deburring entails the subsequent removal of blast medium residue. In the case of complex component geometries, complete removal of said residue is not feasible. The objective is to create the potential to implement the above-described procedure of blasting by use of deep-frozen ice. This requires a new form of equipment which allows for specialized fabrication of suitable ice. The ice blasting procedure examined here must not be confused with dry ice blasting, which uses frozen carbon dioxide CO

2

as a blast medium.

B. Karpuschewski, M. Petzel

Deburring Processes – Applications

Frontmatter

Study of Internal Deburring of Capillary Tubes with Multiple Laser-machined Slits

Laser micromachining processes cut material by melting the workpiece with thermal energy. The solidified material adheres to the cut edges and forms burrs, which cause many serious problems in manufacturing. Using existing conventional techniques, it becomes difficult to remove the heat-affected hard burrs that project inside capillary tubes. The aim of this research is to develop a deburring process for burrs that project into areas hard to reach by conventional techniques. This research applies the magnetic abrasive finishing process to capillary tube deburring. Through the manipulation of the magnetic field at the finishing area, the process controls the motion of the magnetic abrasive introduced into the tubes. This study includes a discussion of the principle for the internal deburring process of tubes with multiple slits and the refinement of the finishing machine. Experiments demonstrate the deburring characteristics of multiple laser-machining burrs projected inside 0.0165 in (419 μm) inner diameter tubing.

H. Yamaguchi, J. Kang

Robotic Deburring Based on On-line Burr Measurement

A new approach is presented in this paper for modeling and control of an automated deburring process that utilizes a hybrid robot and a compliant toolhead. The robot is used for motion control while the toolhead is used for force control. This toolhead has a pneumatic spindle that can be extended and retracted by three pneumatic actuators to provide the tool compliance. The model for deburring process is developed based on the dynamics of the compliant toolhead and the micro-contact model. By integrating a linear encoder, this toolhead can be used for on-line burr measurement through sensing the tool length variation due to burrs. For the deburring control, a closed-loop tool length controller is developed to regulate the tool length through the tool length sensing. This control method has been modeled, simulated, and implemented. Both simulation and experiment results demonstrate the effectiveness of the presented method.

L. Liao, F. Xi, S. Engin

Deburring Machine for Round Billets – Equipment for Efficient Removal of Burrs from Billets

Cutting burrs attached to round metal strands cause serious problems for the further processing in rolling mills and finishing lines. Therefore the removal of the cutting burrs is a necessary pass. State of the art methods for removal of burrs from round billets are manual treatment with pneumatic breakers or flame cutting devices. The introduced deburring machine is a new invention which is designed to automatically remove burrs from circular strand casting billets.

M. Schnabl

Removal and Cleanability

Frontmatter

Formulation of the Chip Cleanability Mechanics from Fluid Transport

The presence of solid particle contaminant chips in high performance and complex automotive components like cylinder heads of internal combustion engines is a source of major concern for the automotive industry. Current industrial cleaning technologies, simply relying on the fluid transport energy of high pressure or intermittent high impulse jets discharged at the water jacket inlets of the cylinder head, fail to capture the dynamics of interaction between the chip morphology and the complex workpiece landscape. This work provides a preliminary insight into an experimental investigation of the mechanics of chip transport at play, and how it can be used to build an effective chip optimization model that significantly aids in improving the cleanability of contaminant chips. The objective is to relate the mechanics of chip transport with the chip form parameters as much as possible, which makes the objective and constraints in the optimization model quantifiable. The end objective is of course to transmit this information upstream of the manufacturing pipeline in the form of a Design for Cleanability (DFC) feedback, which highlights the industrial cleaning problem as a design centric issue.

S. Garg, D. Dornfeld, K. Berger

Burr Minimization and Removal by Micro Milling Strategies or Micro Peening Processes

Micro milled mold inserts made from hardened and tempered steel can have burrs in the size order of 50 μm at the edges. These burrs often prevent the easy demolding of green bodies from micro powder injection molds. Further surface treatments on the molds are necessary to improve surface quality thus facilitating demolding processes. In the present study, three different processes: micro milling, abrasive micro peening and ultrasonic wet peening, have been investigated for their suitability as viable solutions for reducing or eliminating burrs. The tool used for the micro milling process is capable of removing existing burrs but creates new burrs which are inherent to the tool movement over the machined surface. While abrasive micro peening leads to a reduction of burrs on the mold surface, the material below the impacted surface is plastically deformed. Ultrasonic wet peening showed the best effectiveness at removal of burrs of a wide variety of complex geometries in a short processing time and without plastic deformation of the edge zones.

A. Kienzler, M. Deuchert, V. Schulze

Assessment of Deburring Costs in Industrial Case Studies

Owing to the fact that deburring is considered a non-added value operation, little attention is paid to estimating its real cost. However, deburring expenses in manufacturing processes can be significant depending on the workpiece or sector considered. They can vary from 2 to 3% for mass production of relatively common parts in automotive sector to 9–10% in the case of aeronautics for small batches series or mass production of complicated parts. This figure can reach even higher values in other sectors such as medicine.

Seven case studies from different manufacturing sectors (aeronautics, automotive, heavy transport, oil piping transport…) will be outlined in this paper in an attempt to assess real deburring costs and other issues dealing with the reasons why deburring is carried out and the methods used for burr removal.

P.J. Arrazola

Backmatter

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