InformaApp - Publikationen

High-technology applications which are using high precision optic components in high and medium quantities have increased during recent years. One possibility to mass-produce e.g. such lenses is the precision glass molding (PGM) process. Especially for aspheric and free-form elements the PGM process has certain advantages. Premise is to manufacture accurate press molds, which have to feature smaller figure errors as the required lenses and may be made of materials, which are difficult to machine, like silicon nitride ceramics. These work pieces have to be machined in economical and steady process chains. However, due to the complex shapes and the corresponding accuracy an error dependent polishing is required. The Magnetorheological Finishing (MRF) as a high precision computer controlled polishing (CCP) technique is used and will further be presented in this work. To achieve the postulated demands a previous study of the material removal at selected machining parameters is needed. Changing machining parameters modify the removal, which is presented through values like the peak and volume removal rate. The value changes during the controlled variation of process parameters are described and discussed. Magnetorheological Finishing (MRF) provides one of the best methods to finish PGM molds that are relatively inaccurate to high precision in an economical, steady and efficient way. This work indicates the MRF removal selection and removal interference for the correction and finishing of precise silicon nitride molds for the precision glass molding.

F: Angewandte Naturwissenschaften und Wirtschaftsingenieurwesen F: Maschinenbau und Mechatronik I: Hochschulleitung und -einrichtungen

Beitrag (Sammelband oder Tagungsband)

Andreas Geiss, J. Slabeycius, Rolf Rascher, Markus Schinhärl, Peter Sperber, K. Fathima

Material influence of silicon nitride at Magnetorheological Finishing (MRF)

Proceedings of the 12th International Research/Expert Conference ”Trends in the Development of Machinery and Associated Technology” TMT 2008, Istanbul, Türkei, 26.-30.08.2008

2008

F: Angewandte Naturwissenschaften und Wirtschaftsingenieurwesen F: Maschinenbau und Mechatronik I: Hochschulleitung und -einrichtungen

Beitrag (Sammelband oder Tagungsband)

Andreas Geiss, K. Fathima, J. Slabeycius, L. Hajduchova, Rolf Rascher, Peter Sperber, Markus Schinhärl

Examination of surface and subsurface damages on silicon wafers using dimple polishing

Proceedings of the 13th International Conference on Problems of Material Engineering, Mechanics and Design, Rajeke, Slowakei, 26.-29.08.2008

2008

F: Angewandte Naturwissenschaften und Wirtschaftsingenieurwesen F: Maschinenbau und Mechatronik I: Hochschulleitung und -einrichtungen

Beitrag (Sammelband oder Tagungsband)

Andreas Geiss, Markus Schinhärl, Rolf Rascher, Peter Sperber, J. Slabeycius, K. Fathima, Christian Vogt

Magnetorheological Finishing of silicon nitride moulds

Proceedings of the 10th Anniversary International Conference of the European Society of Precision Engineering and Nanotechnology, Zürich, Schweiz, Volume 2

2008

F: Maschinenbau und Mechatronik

Zeitschriftenartikel

K. Fathima, M. Rahman, A. Senthil Kumar, H. Lim

Modeling of Ultra-Precision ELID grinding

Journal of Manufacturing Science and Engineering (ASME), vol. 129, no. 2, pp. 129-302

2007

Abstract anzeigen

The electrolytic in-process dressing (ELID) grinding is a new and an efficient process for ultra-precision finishing of hard and brittle materials. Unlike conventional grinding processes, the ELID grinding is a hybrid process that consists of a mechanical and an electrochemical process, and the performance of the ELID grinding process is influenced by the parameters of the above said processes. Therefore, it is necessary to develop a new grinding model for the ELID grinding, which can be used to avoid the cumbersome and expensive experimental trials. In this paper, the authors proposed a new grinding model for ultra-precision ELID grinding. The main focus is to develop a force model for the ultra-precision ELID grinding where the material removal is significantly lower than the conventional grinding. When the material removal rate is very low, it is very important to estimate the real contact area between the wheel and work surfaces. The developed grinding model estimates the real contact area by considering the wheel and the work surface characterization and the effect of the electrolytic reaction at the grinding wheel edge. The effects of the microstructure changes on the wheel surface by the electrochemical reaction have been implemented in the model in order to improve the efficiency of the developed model. The grinding model has been simulated and the simulated results are substantiated by the experimental findings.

F: Angewandte Naturwissenschaften und Wirtschaftsingenieurwesen F: Elektrotechnik und Medientechnik F: Maschinenbau und Mechatronik I: Hochschulleitung und -einrichtungen

Vortrag

Andreas Geiss, Markus Schinhärl, Elmar Pitschke, Rolf Rascher, Peter Sperber, K. Fathima, J. Slabeycius

Subsurface damages detecting on standard optical glass by dimple method

The 12th International Conference on Problems of Material Engineering, Mechanics and Design, Jasna, Slowakei

2007

F: Angewandte Naturwissenschaften und Wirtschaftsingenieurwesen F: Elektrotechnik und Medientechnik F: Maschinenbau und Mechatronik I: Hochschulleitung und -einrichtungen

Beitrag (Sammelband oder Tagungsband)

K. Fathima, Andreas Geiss, Rolf Rascher, Peter Sperber, Markus Schinhärl, Elmar Pitschke

Design and development of a novel computer-controlled power device for electrical-assisted optical grinding

Optifab 2007: Technical Digest, volume TD04

2007

F: Angewandte Naturwissenschaften und Wirtschaftsingenieurwesen F: Elektrotechnik und Medientechnik F: Maschinenbau und Mechatronik I: Hochschulleitung und -einrichtungen

Beitrag (Sammelband oder Tagungsband)

Andreas Geiss, Markus Schinhärl, Elmar Pitschke, Rolf Rascher, Peter Sperber, K. Fathima, J. Slabeycius

Subsurface damages detecting on standard optical glass by dimple method

Proceedings of the 12th International Conference on Problems of Material Engineering, Mechanics and Design, Jasna, Slowakei

2007

F: Angewandte Naturwissenschaften und Wirtschaftsingenieurwesen F: Elektrotechnik und Medientechnik F: Maschinenbau und Mechatronik I: Hochschulleitung und -einrichtungen

Beitrag (Sammelband oder Tagungsband)

Andreas Geiss, Markus Schinhärl, Elmar Pitschke, K. Fathima, Rolf Rascher, Peter Sperber, J. Slabeycius

Correcting silicon carbide and silicon nitride moulds by Magnetorheological Finishing

Proceedings of the 7th euspen International Conference, Bremen, Vol. 2

2007

F: Maschinenbau und Mechatronik

Zeitschriftenartikel

M. Rahman, A. Senthil Kumar, H. Lim, K. Fathima

ELID grinding technique for nano finishing of brittle materials

SADHANA - Journal of Engineering Sciences (Indian Academy of Sciences), vol. 28, no. 5, pp. 1-18

2003

F: Maschinenbau und Mechatronik

Zeitschriftenartikel

K. Fathima, A. Senthil Kumar, M. Rahman, H. Lim

A study on wear mechanism and wear reduction Strategies in grinding wheels used for ELID grinding

Wear, vol. 254, no. 12, pp. 1247-1255

2003

Abstract anzeigen

Metal-bonded superabrasive diamond grinding wheels have superior qualities such as high bond strength, high stability and high grindability. The major problems encountered are wheel loading and glazing, which impedes the effectiveness of the grinding wheel. Electrolytic in-process dressing (ELID) is an effective method to dress the grinding wheel during grinding. The wear mechanism of metal-bonded grinding wheels dressed using ELID is different form the conventional grinding methods because the bond strength of the wheel-working surface is reduced by electrolysis. The reduction of bond strength reduces the grit-depth-of-cut and hence the surface finish is improved. The oxide layer formed on the surface of the grinding wheel experiences macrofracture at the end of wheel life while machining hard and brittle workpieces. When the wheel wear is dominated by macrofracture, the wheel-working surface is free from loaded chips and worn diamond grits. When the oxide layer is removed from the wheel surface, the electrical conductivity of the grinding wheel increases, and that stimulates electrolytic dressing. The conditions applied to the pulse current influence the amount of layer oxidizing from the grinding wheel surface. Longer pulse ‘on’ time increases the wheel wear. Shorter pulse ‘on’ time can be selected for a courser grit size wheel since that type of wheel needs high grinding efficiency. Equal pulse ‘on’ and ‘off’ time is desired for finer grit size wheels to obtain stable and ultraprecision surface finish.

F: Maschinenbau und Mechatronik

Beitrag (Sammelband oder Tagungsband)

K. Fathima, M. Rahman, A. Senthil Kumar, H. Lim

A study on some factors affecting the mechanism of ELID grinding

International progress on advanced optics and sensors, Tokyo, vol. 40

2003

ISBN: 4-946443-76-2

F: Maschinenbau und Mechatronik

Zeitschriftenartikel

A. Senthil Kumar, H. Lim, M. Rahman, K. Fathima

A Study on the Grinding of Glass Using Electrolytic In-Process Dressing

Journal of Electronic Materials, vol. 31, no. 10, pp. 1039-1046

2002

Abstract anzeigen

Grinding of brittle materials such as glass is gaining importance due to the rapid developments in the areas of machining of storage devices, microlenses, and optical communication devices. Grinding of such glasses is difficult because grinding wheels wear out easily due to the hard and brittle nature of the materials being machined. Grinding wheels with fine abrasive size are required in order to achieve ductile mode grinding. Problems such as wheel loading and glazing can be encountered while grinding with fine abrasive wheels. Electrolytic in-process dressing (ELID) is an efficient method to dress the grinding wheel while performing grinding. In this paper, a fundamental study on the mechanism of the ELID grinding technique is discussed in detail. Several sets of experiments have been performed to determine the optimal grinding conditions. From the experiments, it has been established that surface roughness could be further improved if the current duty ratio to dress the grinding wheel were increased. The force patterns and the changes in the profile of the grinding wheel during machining are also presented and discussed in detail.

F: Maschinenbau und Mechatronik

Zeitschriftenartikel

H. Lim, K. Fathima, A. Senthil Kumar, M. Rahman

Fundamental study on the mechanism of electrolytic in-process dressing (ELID) grinding

International Journal of Machine Tools and Manufacture, vol. 42, no. 8, pp. 935-943

2002

DOI: 10.1016/S0890-6955(02)00023-8

Abstract anzeigen

Demands for high quality surface finish, dimensional and form accuracy are required for optical surfaces and it is very difficult to achieve these using conventional grinding methods. Electrolytic in-process dressing (ELID) grinding is one new and efficient method that uses a metal-bonded diamond grinding wheel in order to achieve a mirror surface finish especially on hard and brittle materials. However, studies reported so for have not explained the fundamental mechanism of ELID grinding and so it has been studied here by conducting experiments to establish optimal grinding parameters to obtain better surface finish under various in-process dressing conditions. In this research the results show that the cutting forces are unstable throughout the grinding process due to the breakage of an insulating layer formed on the surface of the grinding wheel; however, a smoother surface can be obtained using a high dressing current duty ratio at the cost of high tool wear. ELID grinding is efficient for feed rates of less than 400 mm/min, and surface cracks are observed when it exceeds this limit.

F: Maschinenbau und Mechatronik

Beitrag (Sammelband oder Tagungsband)

M. Rahman, A. Senthil Kumar, H. Lim, K. Fathima

Nano-surface finish using Electrolytic In-process Dressing (ELID) grinding

Keynote Paper

Proceedings of the Second International Conference on Precision Engineering and Nano Technology (ICPN2002), 28.-30.10.2002, Changsha, Hunan, China

2002

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Suche nach „[K.] [Fathima]“ hat 19 Publikationen gefunden

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