Nanomanufacturing and Metrology (2018) 1:96–104 https://doi.org/10.1007/s41871-018-0010-2 (0123456789().,-volV)(0123456789().,-volV)
ORIGINAL ARTICLES
Wear Mechanisms of Ceramic Vibratory Finishing Media Eckart Uhlmann1 • Alexander Eulitz1 Received: 8 December 2017 / Revised: 12 February 2018 / Accepted: 23 February 2018 / Published online: 29 March 2018 Ó International Society for Nanomanufacturing and Tianjin University and Springer Nature 2018
Abstract Vibratory finishing is a common manufacturing process that can be used for many applications such as deburring, edge rounding and polishing of surfaces. In this process, material removal is caused by an irregular relative motion between workpieces and a bulk of loose abrasive media. A wide variety of media is used, i.e. different shapes, sizes and compositions. The composition of media differs in terms of the binder which can either be resin or ceramic, and the abrasive grains typically being aluminium oxide or silica. Ceramic media, which is the focus of this publication, is the most common media because of its low cost and high material removal rates. At present, there is no sound understanding of the wear of ceramic media. During a vibratory finishing process, each particle of media is in contact more frequently with other particles than with the workpieces. This induces media wear resulting in decreasing media size and under certain conditions, lowering cutting rates. Up to now, wear mechanisms of vibratory finishing media are scarcely understood. In this publication, it is shown that wear mechanisms of conventional grinding tools can be observed on vibratory finishing media too. Media condition is observed at several different times-of-use starting from zero (fresh media) up to 300 h. For the first time, single media particles are tracked over a long time-of-use. This allows for observing certain abrasive grains. Based on microscopy and topographic analyses, wear can be identified on grain level. This reveals the prevailing wear mechanisms of the ceramic media. Keywords Grinding Finishing Vibratory finishing Mass finishing Wear
1 Introduction Mass finishing is a versatile machining process that is used to improve the surface topography of a wide range of workpieces. In this process, material removal is caused by an irregular relative motion between workpieces and a bulk of loose abrasive particles. The use of media induces wear resulting in decreasing media size and under certain conditions, lowering cutting rates. The focus of this report is set on topography changes of media particles. Changes of size and shape, for example, because of edge rounding, are
& Alexander Eulitz
[email protected] Eckart Uhlmann
[email protected] 1
Institute for Machine Tools and Factory Management, Technische Universita¨t Berlin, Pascalstraße 8-9, 10587 Berlin, Germany
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not considered here. For further information on these aspects, it is referred to a prior investigation [1].
2 Vibratory and Drag Finishing Mass finishing is classified in the German standard DIN 8580 [2] as cutting with geometrically undefined cutting edge and defined as a process where cutting is caused by an irregular relative motion between workpieces and a bulk of loose abrasive particles [3]. A wide variety of mass finishing processes is industrially established. Examples are tumble, centrifugal barrel, centrifugal disk and vibratory finishing, which are designed to process several workpieces simultaneously in a bulk. Other processes are drag finishing and spindle finishing, where the workpieces are individually mounted [4]. A special set-up is robot-guided drag finishing, which was invented by Uhlmann et al. [5], where an industrial six-axis robot is used to guide workpieces through resting or vibrating media, resulting in unique adaptability, kinematic freedom and higher material
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removal rates than vibratory finishing processes [6]. The focus in this paper is set on vibratory and drag finishing.
2.1 Ceramic Vibratory Finishing Media Preformed ceramic media is the most common media because of its low costs and high material removal rates. For that reason, it is the focus of this report. Preformed ceramic media is available in different shapes, sizes and compositions. There are not many manufacturers that produce preformed ceramic media. In contrast to other grinding processes, where tool nomenclature is standardized, each manufacturer offers media in his own quality levels. These are based on the material removal rate and the limiting roughness that can be achieved by the media. Additionally, those quality levels depend on the abrasive grains used. The composition of media is not published by manufacturers. In this report, triangular straight-cut ceramic media FSG 10 9 10 TRI (Walther Trowal GmbH & Co. KG, Haan) with base height and extrusion length of 10 millimetres is being used. The quality level of this media is FSG. According to the manufacturer, this quality level has medium limiting roughness and material removal in comparison with other quality levels being offered. As shown in a prior report [1], this media contains approximately 7.1% abrasive (aluminium oxide) in a mullite bond with 4.7% of porosity. Based on cross-section polishes, a grain size distribution has been determined [1]. According to this, the mean diameter of grains is 42.1 lm (median), the maximum diameter 123.4 lm and the minimum diameter 10.2 lm, respectively.
2.2 Experimental Setting and Measuring Devices For the investigations, two different machine set-ups are used. First, a vibratory finishing bowl R220DL, Ro¨sler Oberfla¨chentechnik GmbH, Untermerzbach, filled with 200 kg media FSG 10 9 10 TRI (Walther Trowal GmbH & Co. KG, Haan) and 13 weight per cent of workpieces (so-called wear cylinders, length and diameter of 80 mm; stainless steel 1.4301) is used for causing defined wear at media particles, this is called wear experiment. In this experiment, fresh media is being used until a total time-ofuse of 300 h is reached. The experiment is interrupted after 15, 30 and 90 h of processing. At each of the considered times-of-use (0; 15; 30; 90; 300 h), media roughness at multiple particles is measured and reference tests (so-called cutting tests) for determining the cutting performance of the media are conducted. For the cutting tests, the same bowl and media are used in combination with a 6-axis robot NJ 370, Comau S.p.A., Turin. Workpieces are clamped with a chuck mounted at the end of the robot. The robot is used to drag workpieces through the bulk media on
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a given circular path. Workpieces in this set-up are stainless steel rods (1.4301) with a diameter of 39.5 millimetres and a set surface topography, resulting from turning with constant feed rate (Rz & 26 lm). Based on the change in roughness at the rods, a material removal rate and hence the cutting performance of media can be determined, as described by Uhlmann et al. [7]. After 300 h of use, the particle tracking experiment is conducted. For this purpose, some particles of the same media are tagged. Then, the wear experiment is continued for 9 h, during which the tagged particles are being analysed regularly. Several measuring devices are used for the investigations presented in this paper, that is, a tactile roughness measuring system (skid tracing system) SJ 210, Mitutoyo Deutschland GmbH, Neuss, for determining roughness at the rods and the wear cylinders. Furthermore, surface topography of media is measured with an Infinite Focus G4, Alicona Imaging GmbH, Graz (50 9 objective magnification) based on focus variation. It is noted that the presented microscopy pictures and topography measurements are representative of all drawn samples. Pictures have been taken from top down in a rectangular area at the side face of the triangular particles.
2.3 Wear of Ceramic Media Up to now, only few researchers published on wear of vibratory finishing media. This may be due to two reasons. First, the fact that mass finishing is a process that in general has not been in the focus of extensive international research for the past years, resulting in a comparatively small amount of publications. Second, there is no common classification of wear mechanisms that occur in mass finishing as it is the case for other manufacturing processes like turning or grinding. This impedes the scientific discussion. An extensive literature review with focus on vibratory finishing in the aviation industry was published by Mediratta et al. [8], recently. Concerning wear, results have been reported by different research groups. From Spelt’s research group, Wang et al. [9] measured roughness on spherical ceramic media with 7, 9 and 11 millimetres diameter (Abrasive Finishing Inc., Chelsea, MI, USA) using an optical surface profilometer RST Plus, Wyko, Arizona, USA, and a measuring length of 0.3 millimetres at five particles in each case. They compared roughness for fresh media and media that has been used for 20 and 40 h, respectively. For the 9 millimetres media, the mean arithmetic average of absolute values for fresh media Ra0h= 22.0 lm decreased to Ra20h = 15.4 lm and finally to Ra40h = 13.8 lm. That is, roughness of media is decreasing with time-of-use. It should be noted that the same media has been used in dry, wet and lubricated condition. From
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the same research group, Baghbanan et al. [10] measured roughness on spherical ceramic media (Abrasive Finishing Inc., Chelsea, MI, USA) using a stylus and a measuring length of 0.8 millimetres. They compared the results for 30 particles of fresh and used media under dry and wet conditions. Fresh media had a mean arithmetic average of absolute values Ra0h = 6.6 lm ± 1.5 lm, whereas media that was used for 30 h shows a mean arithmetic average of absolute values Ra30h = 3.0 lm ± 1.1 lm. The decrease in terms of Ra with process time confirms the previous findings of Wang et al. [9]. Additionally, an increase in the kurtosis and a decrease in the skewness of the surface profile were observed. It should be noted that media has been used for 22 h under dry and 8 h under wet conditions. The difference in the initial media roughness Ra0h of Wang et al. and Baghbanan et al. is most likely caused by the use of different quality levels. Domblesky’s group reported some results on media wear in centrifugal disk finishing. This is a high-energy mass finishing process. Because of the high-energy, elevated material removal rates can be achieved at the cost of extraordinary high wear rates. Evaristo [11] studied the durability of ceramic media in this process. He was looking for a ceramic media with a very high durability that ensures that wear effects would be negligible during his further trials. After comparing triangular, cylindrical and spherical media with differing content of aluminium oxide, he found that a higher percentage of aluminium oxide results in a decrease of durability for all considered shapes. Furthermore, spherical media without any aluminium oxide showed the highest durability and was used for his further trials. After 6 h of use, an arithmetic average of absolute values Ra6h = 3.7 lm was measured at the spherical media without any aluminium oxide. The initial media roughness is not stated. In addition, Cariapa et al. [12] found that ceramic media with a higher number of edges or faces (e.g. triangular media) shows a greater weight loss than media with less edges or faces (e.g. cylinders or spheres). In summary, several researchers consistently reported a decreasing roughness of media during its use. Furthermore, wear of media is depending on its composition and geometry. In most of the investigations that were published on mass finishing, wear was not even considered as a nuisance factor. This may have led to some findings that were based on results biased by wear. Incorporating wear into existing process models could improve model qualities a lot, especially for high-energy mass finishing operations. Recently, Uhlmann et al. [1] reported on wear of media in mass finishing processes. They investigated shape and topography changes of media particles during their use and their effect on roughness of finished workpieces. Additional results of their investigations are shown in this paper. Furthermore, the proposed methodology is applied for
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single media particles that were tracked over their time-ofuse. A first framework for classification of wear mechanisms in vibratory finishing processes is presented.
2.4 Classification of Wear Mechanisms Up to the present, there is no classification of wear mechanisms that occur in mass finishing. For that reason, the classification of wear mechanisms of conventional grinding tools is used as a basis. In Fig. 1, wear mechanisms are shown that should be observable on vibratory finishing media too. First of all, these mechanisms can be divided into grain and bond wear. Wear at grain level can either be caused by the chipping of grains, i.e. small particles break off the grain whereby the grain gets blunted, or fragmenting of grains, i.e. the grain is fracturing and bigger segments of the grain separate resulting in new sharp edges at the remaining grain. Wear at bond level can either be induced by full grain pull-out or chipping of bond material. Because of the low temperatures and pressures in mass finishing processes, flattening of grains (not presented in Fig. 1) is not expected to occur. It is checked in this report whether these wear mechanisms can be observed in vibratory finishing using ceramic media, too.
2.5 Media Topography Changes Due to Use To understand wear at ceramic media, topography changes during its time-of-use are observed. Fresh media is being run in during the first several hours of use. This can be seen in Fig. 2. In the upper row of Fig. 2, representative microscopy pictures of different media particles are shown for zero and 30 h of use. In the bottom row of Fig. 2, surface topography measurements are overlaid at the same locations as in the corresponding picture at the left side. It can be seen that fresh media has a rougher surface topography media that has already been used. This is due to the manufacturing process of media. Peaks of the surface topography can be found at grains and at bond regions. It can be seen that there is a distinct change in surface topography during the first 30 h of use. After that time, media’s topography is becoming more even. This is because protruding regions have been cut off due to initial wear. In Fig. 3, a comparison of microscopy and topography pictures of two 1.76 9 1.76 mm2 areas at media’s surface for 20 and 300 h of use is shown. It can be seen that after 20 h of use, there are no distinct protruding regions that coincide with the location of grains. The increasing amount of bright areas at bond regions in microscopy pictures for higher times-of-use indicates that the bond topography is changing during media’s use, see, for example, position 1 in Fig. 3. Comparing topography
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Grain wear
Chipping of grains (Micro grain fracture)
Bond wear
Full grain pullout
Fragmenting of grains (Grain fracture)
Chipping of bond material
Fig. 1 Wear mechanisms of vibratory finishing media on the basis of conventional grinding according to Peklenik [13]
Workpieces: Process: Media: Cylinders (stainless steel 1.4301) Walther Trowal FSG 10x10 TRI Vibratory finishing Diameter dN = 80 mm Time-of-use tsk Compound KFL; 2 Vol.-% Excitation frequency f a = 50 Hz Length lN = 80 mm Measuring area Height in µm 150 µm -10 tsk
=
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tsk
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Fig. 2 Microscopy picture and topography of representative particles after 0 and 30 h of use
pictures, it is obvious that this is caused by a smoothening of bond regions due to further use. This is also confirmed by surface topography measurements, see Fig. 3. In Fig. 4, a grain with a grain-bond protrusion of approximately 1 lm is shown. The media particle shown in this figure has been used for more than 300 h. It is noted that most of the grains that were analysed in this report did not have a notable grain-bond protrusion. Furthermore, only about 7% of the particles consist of grains. Hence, material removal at the workpieces is not expected to be preponderantly caused by protruding grains. A second phenomenon that is typical for the investigated media can be seen at the margin of the grain in Fig. 4. Bond material has chipped there, exposing the grain. More examples of this are given in Fig. 5. The reason for the chipping of bond material at the margin of grains may be the difference in hardness between the bond and grains in combination with their brittleness.
In consequence of external load, cracks are initiated in the brittle bond material at the interface between the hard grain and the comparatively soft bond. Thus, bond material is chipping, exposing the grain. This explains the observation of Evaristo [11], who found that a higher percentage of grains results in a decrease of durability of media. Because bond chipping is concentrated at the margin of grains, more grains provoke an accelerated wear of media.
2.6 Cutting Performance and Limiting Roughness of Media for Different Times-ofuse In compliance with the findings of other researchers, roughness of fresh media is decreasing during its time-ofuse. This is confirmed by the results of wear experiment, see Fig. 6a. Starting at about 2.14 lm, the arithmetic average of absolute values Ra of fresh media is being
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tsk = 20 h Process: Vibratory finishing Excitation frequency fa = 50 Hz Workpieces: Cylinders (stainless steel 1.4301) Grain Diameter dN = 80 mm Length lN = 80 mm Media: Walther Trowal FSG 10x10 TRI Compound KFL 2 vol.-%
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Fig. 3 Microscopy picture and topography of representative particles after 20 and 300 h of use
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Fig. 4 Microscopy picture, topography and cross section of a grain with slight grain-bond protrusion
highly reduced during its time-of-use. The strongest decline in roughness of media can be observed during the
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first 30 h of use. Media is being run in during that time. In Fig. 6b, results of the cutting tests for different times-ofuse of media are shown. It becomes apparent that the average distance between the highest peak and lowest valley over all sampling lengths Rz at the workpieces is being reduced the most for fresh media (tsk = 0 h), i.e. the initial Rz value at the workpieces is being reduced by approximately 50% after 15 min of drag finishing. It can be assumed that the change in roughness at the workpiece is proportional to the cutting performance of media for a given process. Results of the cutting tests show that the cutting performance of media is decreasing until a time-ofuse of 90 h is reached. It can be shown that there is a strong linear correlation between the roughness and the cutting performance of media. The corresponding Pearson correlation coefficient is ? 0.872 at a p value of 0.1%. Surprisingly, roughness of media decreases between 90 and 300 h of use, whereas the cutting performance slightly increases concurrently. It has been assumed by Uhlmann et al. [1] that the cutting performance is also influenced by changes of media shape which may occur due to wear. They found that especially orthogonal edges of the triangular media are rounded during vibratory finishing, but it could not be finally resolved why roughness and cutting performance of media diverge after a long time-of-use.
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Fig. 5 Microscopy picture and topography of exposed grains
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50 µm
Height in µm
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Fig. 6 Results of media with different times-of-use; a roughness of media; b improvement of workpieces’ roughness in cutting tests
Media: Walther Trowal FSG 10x10 TRI Compound KFL; 2 vol.-% Workpieces: Cylinders (stainless steel 1.4301) Wear experiment Diameter dN = 80 mm Length lN = 80 mm Cutting test Diameter dN = 39.5 mm Length lN = 250 mm
2.4 Wear experiment (media) µm 1.2 0.6 0 0
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Improvement of initial roughness Rzi of workpieces
Arithmetic average of absolute values Ra of media
Process: Wear experiment Vibratory finishing Total time-of-use tsk,tot = 300 h Excitation frequency f a = 50 Hz Cutting test Robot-guided drag finishing Process time tp,cut = 15 min Workpiece speed v w = 30 m/min Excitation frequency f a = 50 Hz Submersion depth ze = 52 mm
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Time-of-use of media tsk
By measuring roughness at the wear cylinders after 15, 30, 90 and 300 h of use, the limiting roughness of media in a vibratory finishing process could be determined, see Fig. 7. Media that has been used for 15 h has a limiting roughness Rzlim,15h & 1.47 lm. This strongly decreases after 30 h of use to Rzlim,30h & 1.10 lm. Afterwards, limiting roughness nearly linearly decreases by approximately 0.12 lm each 100 h of media use. Apparently, limiting roughness is depending on media
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60 Cutting test (workpieces) % 40 30 20 0
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Time-of-use of media tsk
wear. Comparing Figs. 6 and 7, it can be assumed that cutting performance and limiting roughness are correlated, too. The corresponding Pearson correlation coefficient is ? 0.672 at a p value of 6.8%. This indicates a weak positive linear correlation. After 300 h of use, the limiting roughness decreases to Rzlim,300h & 0.78 lm. It can be assumed that the limiting roughness will still decrease when continuing wear experiments.
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Fig. 7 Limiting roughness of media for different times-of-use
2.4 Roughness Rz of wear cylinders
Limiting roughness µm 1.2 0.6 0 0
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Process: Vibratory finishing Total time-of-use t sk,tot = 300 Excitation frequency f a = 50 Media: Walther Trowal FSG 10x10 TRI Compound KFL; 2 vol.-% Workpieces: Cylinders (stainless steel 1.4301) Diameter dN = 80 Length lN = 80
h Hz
mm mm
Time-of-use of media t sk
2.7 Tracking of Single Media Particles As shown in Fig. 3, there are no grains that considerably stick out of the surrounding bond level after running media in. To check how grains and bond of vibratory finishing media wear, single media particles are tracked for 9 h of use. The same media as in the wear experiments is used. Hence, the time-of-use of the particles at the beginning of the particle tracking experiment is 300 h. Based on microscopy and topography analyses, wear can be identified on grain and bond level. This reveals the prevailing wear mechanisms of the ceramic media. In Fig. 8, microscopy and surface topography pictures of a particular grain are shown for different times-of-use. The observed wear mechanisms are highlighted in the pictures. At the beginning of the tracking experiment, the grain at the right side of the picture is considerably exposed but again there is no appreciable grain-bond protrusion considering the overall bond level. It is expected that the surrounding bond chipped during the previous time-of-use. In contrast to this, the grain at the left side of the picture is covered and nearly completely surrounded by bond material. During the next 80 min, a small segment at the right side of the grain fragments (position 1). Furthermore, the topography at the grain has changed due to chipping (e. g. position 2). Concerning the bond, topography has changed too. This can be seen clearly at the lower left side of Fig. 8b–c (position 4). The covered grain at the left side of the picture is not wearing at the same time. During the next 265 min, the grain at the right side is pulled out completely, Fig. 8c (position 3). The remaining bond at the grain could not hold it in place anymore. At the same time, a fragment of the covered grain is removed (position 5). After further 230 min, the bond is chipping in the proximity of the former right grain, Fig. 8d (position 6). It is noted that no appreciable bond material is chipping in the cavity of the former right grain. In Fig. 9, another example for chipping and fragmenting of grains is given.
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Again, there is no appreciable grain-bond protrusion and bond material around the grain chipped, forming cavities. The texture of the bond material has also been tracked on a single particle level, see Fig. 10. In this figure, the same location at a specific particle after different times-of-use is shown. It is noted that the same phenomena have been observed at other particles, too. The texture of the bond material is continuously changing during the media’s time-of-use, even for comparatively short times. This can be confirmed by comparing the microscopy pictures after different times-of-use, see highlighted region in Fig. 10. It has already been shown in Fig. 8 at positions 4 and 6 that a change in the texture of the bond material being observed in microscopy pictures goes in hand with a change in the surface topography. This is also the case for the area shown in Fig. 10. Comparing bond textures at different locations at different particles, it has been observed that mostly small particles of bond material are removed due to wear, whereas fragmenting of larger bond material particles was observed scarcely. There is a permanent wear of bond material during vibratory finishing.
3 Summary A comprehensive literature review on wear of vibratory finishing media is given. In this report, wear experiments are conducted that cause defined wear at media particles. Media condition is observed at several times-of-use starting from zero (fresh media) up to 300 h. This covers cutting tests for determining the cutting performance of the media as well as surface topography analyses. In compliance with findings of other researchers, media roughness is decreasing during its time-of-use. The strongest decline in roughness of media is observed during the first 30 h of use. Cutting performance is decreasing during the first 90 h of use. Afterwards, a steady state is reached. Most of the grains that were analysed in this report did not have a
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(a) tp =
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Fragmenting Full grain pullout
Chipping of:
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Fig. 8 Microscopy and surface topography pictures of a particular grain for different times-of-use
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(a) tp =
0 min
(b) tp = 137 min
(c) tp = 302 min
(d) tp = 532 min
50 µm Fig. 10 Texture of bond material at the same location on a tracked particle for different times-of-use
notable grain-bond protrusion after being run in. Media wear also affects the limiting roughness. Following a strong decrease during the first 30 h of use, limiting roughness is nearly linearly decreasing by approximately 0.12 lm each 100 h of use. Furthermore, a first framework for classification of wear mechanisms in vibratory finishing processes is given. By tracking single media particles, wear is identified on a grain level. Based on microscopy and topography analyses, it is shown that chipping of bond material is the prevailing wear mechanism of the ceramic media. Besides, chipping and fragmenting of grains as well as full grain pull-out are observed. Acknowledgements This work is supported by the German Research Foundation (DFG), Projects UH 100/145-2 and UH 100/180-1.
References 1. Uhlmann E, Eulitz A, Ma¨nnel C (2017) Verschleiß an Gleitschleifko¨rpern (engl.: wear mechanisms of ceramic mass finishing media). wt Werkstattstechnik online 107(6):441–447 2. DIN 8580 (2003) Manufacturing processes—terms and definitions, division. Beuth, Berlin 3. DIN 8589-17 (2003) Manufacturing processes chip removal— part 17: barrel polishing—classification, subdivision, terms and definitions. Beuth, Berlin 4. Gillespie LK (2007) Mass finishing handbook, 1st edn. Industrial Press, New York 5. Uhlmann E, Hasper G, Mihotovic V, Fraunhofer Gesellschaft, TU Berlin (2011) Verfahren und Vorrichtung zum Gleitspanen eines Werkstu¨cks. Patent DE 10 2009 024 313 6. Uhlmann E, Dethlefs A (2011) Polieren komplexer Bauteile (engl.: polishing of complex parts). WB Werkstatt ? Betrieb 144(6):28–31 7. Uhlmann E, Dethlefs A, Eulitz A (2014) Investigation of material removal and surface topography formation in vibratory finishing. Procedia CIRP 14:25–30 8. Mediratta R, Ahluwalia K, Yeo SH (2016) State-of-the-art on vibratory finishing in the aviation industry: an industrial and academic perspective. Int J Adv Manuf Technol 85:415–429 9. Wang S, Timsit RS, Spelt JK (2000) Experimental investigation of vibratory finishing of aluminum. Wear 243(1–2):147–156 10. Baghbanan MR, Yabuki A, Timsit RS, Spelt JK (2003) Tribological behavior of aluminum alloys in a vibratory finishing process. Wear 255(7–12):1369–1379
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11. Evaristo A (2001) Characteristics of material removal by ceramic media on metallic coupons for mass finishing applications. Dissertation, Marquette University 12. Cariapa V, Park H, Kim J, Cheng C, Evaristo A (2008) Development of a metal removal model using spherical ceramic media in a centrifugal disk mass finishing machine. Int J Adv Manuf Technol 39(1–2):92–106 13. Peklenik J (1958) Untersuchungen u¨ber das Verschleißkriterium beim Schleifen (engl.: Investigations on wear criteria for grinding processes). Industrie-Anzeiger 27:397–402
Eckart Uhlmann is a professor at the Technische Universita¨t Berlin, Chair for Machine Tools and Manufacturing Technology, Institute for Machine Tools and Factory Management (IWF) and Director of the Fraunhofer Institute for Production Systems and Design Technology (IPK). He obtained Dr. Engineering in 1993 at Technische Universita¨t Berlin. Between 1994 and 1997 he was Vice President, Director of the Research and Development Division and of the Application Technology and Patent Division at Hermes Schleifmittel GmbH & Co. in Hamburg. Since 1997 he is professor at the Technische Universita¨t Berlin. Amongst others he is member of the International Academy for Production Engineering (CIRP), the German Academic Society for Production Engineering (WGP) and the Association of German Engineers (VDI). Alexander Eulitz received his BS and MS degrees at the Technische Universita¨t Berlin. Since 2014 he is working as research engineer at the Institute for Machine Tools and Factory Management at the Technische Universita¨t Berlin. His main research topic are several mass finishing processes with focus on the material removal mechanisms and media design.
