Center for Mechatronics and Automatization

Saarbrücken, Germany

Center for Mechatronics and Automatization

Saarbrücken, Germany
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Weinmann M.,Saarland University | Weber O.,Saarland University | Weber O.,Center for Mechatronics and Automatization | Bahre D.,Center for Mechatronics and Automatization | And 3 more authors.
International Journal of Electrochemical Science | Year: 2014

One benefit of Pulse Electrochemical Machining (PECM) is the residual stress-free processing of complex geometries which are difficult to produce by conventional techniques. However, a major inconvenience by applying PECM is the realization of the cathodes, when sophisticated microstructures are required. The potential of a new and innovative process chain combining photolithography, electroforming and PECM is investigated to overcome this difficulty by providing a reproducible and high precision tool manufacturing. The master microstructure is realized by photolithography and is subsequently used as template in an electroforming process to realize reproducible workpieces which serve as tools within the PECM process. © 2014 The Authors.


Bahre D.,Saarland University | Weber O.,Center for Mechatronics and Automatization | Rebschlager A.,Center for Mechatronics and Automatization
Procedia CIRP | Year: 2013

In this contribution, the potential of Pulse Electrochemical Machining (PECM) for the machining of lamellar cast iron is investigated with regard to the machining performance during electrolysis with sodium nitrate as electrolyte and stainless steel as cathode. Therefore, the material removal characteristics of lamellar cast iron with PECM are determined by performing systematic design of experiments techniques applying an industrial PECM machine system (PEMCenter8000) to fulfill the effective utilization of the process and to minimize the number of trials. An analysis of the precision of the manufactured geometries and the possibility of generating defined surface qualities are contents of this study. © 2013 The Authors.


Rebschlager A.,Center for Mechatronics and Automatization | Kollmannsperger R.,Center for Mechatronics and Automatization | Bahre D.,Saarland University
Procedia CIRP | Year: 2014

Pulse Electrochemical Machining (PECM), a nontraditional process, using pulse-lengths in the low millisecond range as well as feed overlaid mechanical vibration, allows more precise tolerances and geometric precision through narrowing the working gap compared to conventional sinking ECM. With small working gaps in ranges down to 10 μm, the anodic shape evolution during machining is getting difficult to monitor. Therefore understanding the shaping phenomena during the PECM process is key factor in achieving precision during the manufacturing of dies and molds, as well as precision parts in e.g. automotive or aircraft industry. In this contribution an experimental approach towards visual in-process observations of the PECM shaping process during the use of mechanical vibrations up to 50 Hz and high pulsed current densities will be presented. Recording the process with a precisely clocked high speed camera system allowing precise μs shutter times, visual observations are conducted and being used as input for detailed downstream data analysis. The experimental study incorporates one of the most widely used flushing conditions in PECM as well as an outlook into the comparison between recorded in-process data and a static FEM simulation based on the monitored shape are given. In all experiments stainless steel of type AISI 304 (X5CrNi18-10) is used as anode and cathode material and for all PECM experiments a commercially available PEMCenter8000 with sodium nitrate as electrolyte was used. The concept presented will help to better link experiment and modelling of the PECM process, by simultaneously providing process relevant electrochemical data as well as the directly corresponding geometric shaping information during experiments. © 2014 Elsevier B.V. © 2014 Published by Elsevier B.V.


Steuer P.,Center for Mechatronics and Automatization | Steuer P.,Saarland University | Rebschlager A.,Center for Mechatronics and Automatization | Weber O.,Saarland University | Bahre D.,Saarland University
Procedia CIRP | Year: 2014

EDM (Electrical Discharge Machining) and PECM (Pulse Electrochemical Machining) provide unique possibilities for the machining of many different materials. Whereas EDM is able to machine any material above a minimal electrical conductivity, though with a certain degree of tool wear and heat influence, PECM has difficulties machining materials that build a passive layer or have chemically indissoluble contents. However, PECM has the advantage of working nearly wear-free. Based on this fact, a process chain can be built up that first structures copper electrodes by PECM and then uses them in EDM. When worn out, the electrodes can be restructured by PECM to keep a high reproducibility and constant quality of the machined geometry. In this contribution, the heat-affected zone of the tool electrode resulting from an EDM process and its potential influence on the machinability in the following PECM process are investigated for different copper alloys. © 2014 The Authors. Published by Elsevier B.V.


Bahre D.,Institute of Production Engineering | Rebschlager A.,Center for Mechatronics and Automatization | Weber O.,Center for Mechatronics and Automatization | Steuer P.,Center for Mechatronics and Automatization
Procedia CIRP | Year: 2013

Pulse Electrochemical Machining (PECM) is known to produce finished surfaces with a typical roughness in the region of conventional machining methods like grinding or lapping. Furthermore, the process characteristics support the leveling of a rough anodic surface by using an either smoother, equally rough or even rougher cathode. This research focuses on an empirical investigation of the contrary approach, since for some applications surfaces with a well-defined roughness within small tolerances are needed. Examples are forms for injection molding, medical implants and friction pairs. In this contribution the copying accuracy to specifically produce and reproduce a localized as well as adjustable rough surface structure in steel is analyzed under different process conditions. The surface structure and roughness of the used PECM cathodes are initially produced by Electrical Discharge Machining (EDM) using copper as electrode. This study will show how surface roughnesses can accurately be produced with PECM in a range of typical conventional and non-conventional machining methods. Furthermore, the possibility of adding a surface texture by PECM is pointed out which will create a similar result as an EDM process but without the disadvantages of heat affected zone, tool wear and long machining time for fine finishes. The changes of the surface roughness during the process chain-producing the electrodes by turning, machining the PECM cathodes with EDM and finally machining the parts with PECM - are measured in all stages and correlated to the process conditions and influencing parameters. For all PECM experiments a commercially available PEMCenter8000 with sodium nitrate as electrolyte and for all EDM experiments a FORM20 with IonoPlus IME-MH as dielectric was used. © 2013 The Authors.

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