sorry pete niklas grab the POCO EDM MANUAL from internet it shows fequencies ( or on&off times so you calculate ) off time is really dpendant on flushing conditions on time causes rougher finer surface finish so there is frequency but frequency is a result not a determinate parameter examples roughing Gr/St Positive Polarity 108uS on 12uS off finishing----------------------------------8uS on 12uS off you can calc the freq, i stopped thinking F when we still used TAU ( inverse of D% ;-) thinking on and off is as simple as thinking cutter flukes and space between flukes
tomp tjtr33 http://edmtechman.com/about.cfm www.oelheld.com/products/metalworking-fluids/dielectric.html scialert.net/fulltext/?doi=jas.2007.1608.1613&org=11 but just google 'electrical discharge machining frequency' and choose images for more info than you can read in a year! On 03/07/2016 02:13 AM, Pete_Gruendeman wrote: > Hi Nicklas: > I am not seeing any response on this forum regarding the erosion pulse > frequency. > Wikipedia mentions on their Electrical_discharge_machining page: >> Several hundred thousand sparks occur per second... > and in Ben Fleming's book on pulse type EDM, he shows frequencies that range > from 2.5kHz up to 40kHz for finishing burns. > > It's not yet clear to me that the servo response needs to be fast > enough to respond to every spark. It might be helpful here if I described > some of the basics of the process, based on personal experience and more so > based on others' info, sources unknown. > The EDM process removes metal by superheating it with electrical sparks, and > the collapse of said spark which per some authors blows out part of the metal. > The rapidly cooled workpiece surface becomes very hard and the surface finish > is not particularly integral. This is commonly called a re-cast layer. > The sparks while underway have very little resistance as measured in ohms. > The electrical supply must be stopped periodically (square wave or other) so > the present arc extinguishes and the next spark initiates at the next closest > point between electrode and workpiece. That spark path could include bits of > metal (called swarf) that have been blown out previously, resulting in a > longer arc path and unstable erosion. Flushing is important to minimize or > eliminate these alternate spark paths. > The electrode advances (sinks) in a manner that is nearly the same as a > bridge support caisson being sunk into a riverbed. The workers remove > whatever is in the way to allow the caisson to descend through the mud, > gravel and boulders down to and into the bedrock. See: > https://en.wikipedia.org/wiki/Caisson_(engineering) > <end of process particulars> > > Each spark or pulse will vary from the one following and the one > preceding it. My experience suggests that a little averaging is not a bad > thing, in order to keep the process from hunting constantly. This could be > mathematical averaging of erosion gap voltages or it might be a lower servo > response frequency or other solution. Also backlash and machine elasticity > needs to be considered. Even with a 40kHz servo response, the electrode to > workpiece gap is not likely to change at 40kHz. > TJ pointed reminded us that EDM is a very slow process. Whether it is > 99% of optimal or 99.99% of optimal won't change the burn times by much. If > the cost of 40kHz servo response on four axes is excessive and 1kHz servo > response is reasonable then I say we start with 1kHz on all four axes and let > experience inform us on how right or wrong that choice was. It's possible > that someone with hole popper work could run at 1 and 40kHz and report if > there is a noticeable benefit at 40kHz. > > > > -------------------------------------------- > On Thu, 3/3/16, Nicklas Karlsson <[email protected]> wrote: > > Subject: Re: [Emc-developers] EDM gap control (Control parameters) > To: "Pete_Gruendeman" <[email protected]>, "EMC developers" > <[email protected]> > Date: Thursday, March 3, 2016, 12:01 PM > > > ... 40kHz servo > response is very responsive but not necessary if the spark > frequency is less than that. > > Pete > Gruendeman > > I have a choice > between 40kHz servo thread inside driver or linuxcnc 1kHz > servo thread. For z motion only choice is simple but for > motion of several axis/joints for example wire EDM? > > > Nicklas Karlsson > > > ------------------------------------------------------------------------------ > _______________________________________________ > Emc-developers mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-developers ------------------------------------------------------------------------------ Transform Data into Opportunity. Accelerate data analysis in your applications with Intel Data Analytics Acceleration Library. Click to learn more. http://makebettercode.com/inteldaal-eval _______________________________________________ Emc-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-developers
