Re: [Emc-users] another (possibly silly) EDM question
Hi Ralph On 02/14/17 23:13, Ralph Stirling wrote: > Thanks, Tom. Since the 3d printed metal part is made from > sintered powder, I would think it would have a lot of little > points for the EDM to work on. The question is whether it > would smooth them, or merely erode surface particles to > reveal new particles, leaving the same finish roughness. > Hypothetical at present, as I don't have access to either > a metal 3d printer or an EDM machine yet :-). well edm would expose the granularity of the sintered material it will not be smoother than the parent material (in general, edm does not smear ;-) example materials , honeycomb used in wings, and metal foam I think this will be true of any noncontact subtractive machining To smooth such a part may require adding material or contacting the material > I am on the staff of the School of Engineering at Walla Walla > University. My time is split between laboratory development > (designing, building, and installing equipment and working > with faculty on lab curriculum), and teaching (Manufacturing > Systems and Intro to EE CAD at present). I am an EE who > has been playing at ME for the last 18 years or so. sounds like a sweet job, i bet you love it i was an industrial teacher and it was great my bro taught a course for cad students on manufacturing processes, his responsibility was to teach how drawn things get made, and show how that really influences design ( or how some drawn things are not possible to make, or are really expensive to make. the disjunction of cad and manufacturing, why round parts are cheaper and deeper holes more expensive ) re: walla walla ... http://al007italia.blogspot.com/2006/12/deck-us-all-with-boston-charlie.html > -- Ralph > tomp tjtr33 -- 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
Re: [Emc-users] another (possibly silly) EDM question
Thanks, Tom. Since the 3d printed metal part is made from sintered powder, I would think it would have a lot of little points for the EDM to work on. The question is whether it would smooth them, or merely erode surface particles to reveal new particles, leaving the same finish roughness. Hypothetical at present, as I don't have access to either a metal 3d printer or an EDM machine yet :-). I am on the staff of the School of Engineering at Walla Walla University. My time is split between laboratory development (designing, building, and installing equipment and working with faculty on lab curriculum), and teaching (Manufacturing Systems and Intro to EE CAD at present). I am an EE who has been playing at ME for the last 18 years or so. -- Ralph From: TJoseph Powderly [tjt...@gmail.com] Sent: Monday, February 13, 2017 9:29 PM To: Enhanced Machine Controller (EMC) Subject: Re: [Emc-users] another (possibly silly) EDM question 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 -- 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
Re: [Emc-users] another (possibly silly) EDM question
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
[Emc-users] another (possibly silly) EDM question
For you EDM experts out there: How well would it work to do sinker EDM with a 3D printed metal part? 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. Am I even correct that EDM would give a better finish than the raw SLS surface? 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. Thanks, -- Ralph -- 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
