If we look at Powder Mixed Electrical Discharge Machining using nanoparticles and analyze, then we would not have to handle any electrical discharge machining because even the most removal-solid particulate components are in the micron range.
Abrasive electrical discharge machining is also called sinking or powder EDM. Hybrid method, in which free abrasive particles are added to the basic EDM process, which gives us powder EDM, as we have shown in the screen. Both the mechanisms where abrasive action will also take place and the EDM action will also take place and that gives enhanced result of the process . So, it is a variant process of EDM.
http://textofvideo.nptel.iitm.ac.in/112107078/lec21.pdf
The abrasive component is always regarded as the primary. Especially with nanoparticles, I would imagine, are changing the breakdown conditions of greater importance. Another meaning comes to the small working gap, because the ratio of particle size to gap width increases at the micro- and nano-machining significantly.
Dear Dr. Schulze, I think basically you are right, in EDM we commonly remove the debris by flushing in order not to have the negative influence such as formation of arcs in the gap which reduces the accuracy of machining or even destroys the integrity of the machined surface. So I cannot see what should be the actual benefit of the adding particles in "abrasive EDM" method. maybe due to arc formation we have higher cutting speed but what are the side-effects ?
The next point is what happens to an abrasive particle (should be probably something non-conductive) in the region of the plasma channel, it will be either molten or even evaporated, both actions either change the shape (sharp edges are eliminated and the particles get spherical and lose their abrasive qualities) of the abrasive particle or even completely eliminate them.
I agree with your answer in complete agreement, but would attach a small supplement. Small solid particles in the gap in not too strong concentration lead to an electric discharge can separate and multiple plasma base points (with lower energies) are formed on the workpiece. This allows effective per craters smaller "pulse energies" are used. The small disadvantage is that the splitting is stochastic and therefore can not be expected to average pulse energy, but only with a maximum (without splitting).
Dear Schulze
I agree Frank and you, however do not forget that when is used a "new dielectric", without debris particles, and after some use the process is more stable passing to a phase that need the change of filters. Therefore, in my opinion the effect of is increase the thermal conductivity of discharge "plasma" channel that increases heat flux going to the electrodes having an effect no linear.
I have not worked in this area of EDM. But we do use EDM in our lab, to make samples for mechanical testing. I do hope the following references may be useful. Dr. Schulze, you may be already knowing these references, since you have been working (and an expert) in this area. If you have come across these references, please ignore it.
1)" A REVIEW ON EMERGING AREAS OF INTEREST IN ELECTRICAL DISCHARGE MACHINING", Bhaskar Chandra, Hari Singh, Jatinder Garg, International Journal of Advanced Engineering Technology, IJAET/Vol.II/ Issue III/July-September, 2011/1-9.
2) "Investigation of material removal mechanisms in EDM of composite ceramic materials", B. Lauwers, J.P. Kruth, W. Liu, W. Eeraerts, B. Schacht, P. Bleys, Journal of Materials Processing Technology 149 (2004) 347–352.
1) Also please see in ResearchGate: link: http://www.google.com/url?url=http://www.researchgate.net/profile/Yanzhen_Zhang3/publication/261237304_A_review_of_the_current_understanding_and_technology_of_powder_mixed_electrical_discharge_machining_(PMEDM)/links/0a85e538dbc7f19dc2000000.pdf&rct=j&frm=1&q=&esrc=s&sa=U&ei=cEnLVKDrD4SE8gWulIGgCA&ved=0CCQQFjAD&usg=AFQjCNHU2KPfcSl-Jf0H99Y8BPdr-HVyKQ
2) Paper downloaded from RG site and is attached: "A Review of the Current Understanding and Technology of Powder Mixed Electrical Discharge Machining (PMEDM)" by Yanzhen Zhang et al., 2012 IEEE International Conference on Mechatronics and Automation, ISBN: 978-1-4673-1275-2
Conference Paper A review of the current understanding and technology of powd...
Powder is added to disperse discharge energy, therefore produce smaller craters. I would think one difference between EDM and powder EDM is that the amount of added powder would be more than the amount of ejected debris produced in EDM, which makes a difference because they're more uniformly scattered. Another difference would be that added powders are usually made of materials different from both electrodes.
It would be interesting to see some reports on the powder deposition situation. And better if visual confirmation of pulse energy dispersion is available.
First of all, thanks for the references.
The main problem with this article is that only the purely technological results are compared, but most follow any physical explanations.
Dear Feng, of course, is the addition of particles in a different order of magnitude than the removal, particularly in post-processing. Also, the fact that the appended powder usually very hard particles, does not agree with the contamination by the removal process. My thought is therefore likely that a splitting (Leader, streamer) in the pre-discharge phase is observed which can at times seem more active plasma channels.
MR. Schulze,
I am also ofthe same opinion as yours that Filters used in EDM are of microns levels and cannot remove debris lower than filter size. Hence, addition of nanoparticles may not have that much of influence on the output.
the micro sized debris suspended in to the dielectric tend to like powder mixed dielecric and may affect the process performance accordingly.
However, addition of nano/micro powders externally for EDM process are intended for surface modifications by deliberate infiltration of some elements to form special oxide,carbide or other metallic compounds.
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