On 02/14/17 09:04, Ralph Stirling wrote: > For you EDM experts out there: How well would it > work to do sinker EDM with a 3D printed metal part? at first i thought you meant a 3D printed electrode... thats been tried, there are papers but after a couple years have passed, i hear no adoption of the idea ( printing graphite, printing copper ) > In other words, have a part printed to "near net shape", > and use a machined (graphite or copper) electrode and > EDM to take off just enough material to get it to the final > shape with a smoother surface finish. hmm... hurdle one, the 3D printer person has to be able to produce and electrode usuially that involves miling/turning and maybe grinding the surface of the electrode is smoother than the resulting edm surface but not a lot smoother look at edm surface finish charts, like VDI 20 to 10 https://www.flickr.com/photos/colorgroup/20716534781 https://www.flickr.com/photos/60055955@N06/16652242101
often the work gets 'scuffed' before edm-ing (esp if polished or plated ) > Am I even correct > that EDM would give a better finish than the raw SLS > surface? afaik edm can do finer than SLS ( and rougher too ;-) see the vdi charts above > I've seen titanium parts that were CNC machined > smooth after 3d printing (I think using electron beam > melting process), but I'm wondering about using EDM > instead of CNC machining for the finishing step. edm is less efficient on already smooth surfaces since it works on the principle of sparking to the closest point, it has problems when it cant find the closest point because _all_ points appear the same distance. this is called ( cant see the mountains ;-) thats what happens when the work is shiny smooth it can be done but presents a control problem in the classic voltage drop gap-width controller. poor gap-width controls begin to hammer the work work has been done with a type of ecm and salt baths to super finish large flat-ish surfaces but for highly contoured cavities ( say a molex din connector ) very accurate electrodes and time are required to edm finish my advice: stop edming as soon as possible and hand polish it! keep those old mold makers and polisher in work. nudge nudge wink wink > Thanks, > -- Ralph > --------------------------------------------------------------------- Ralph what do you do at WallaWallaU ? ( sorry it reminds me of a Rocky&Bullwinkle line :-) tomp ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, SlashDot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
