QUESTION: ANSWER TO THE QUESTION:

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1 QUESTION: How to erode a cavity using a rough and finisher electrode (two electrodes) 25mm deep and use a circular orbit to finish to 20 VDI (the second electrode will be in an automatic tool changer). ANSWER TO THE QUESTION: In order to understand PROGRAMMING of the machine, you should be a little familiarized with EDM Commands. All commands related with EDM can be found at appendices E to N of the Programming Manual (download it at Commands as TD (Ton), TS (Toff), C (Working Current), B (Ionisation Current), K (pulse control) and J (capacitor) are directly related with the Power Supply (in the manuals it is named as Current Pulse Generator). In appendix C of the Installation Manual you could see how MAC-EDM interfaces with Current Pulse Generator (download it at Upon a time you are familiarized with EDM Commands, you will see that, in order to simplify the Programming, MAC-EDM uses Canned Cycles (basically they are sub-programs filenamed as P&01.mac to P&99.mac that are called from edition/execution as M01 to M99 respectively). Once you have received the CNC unit and the CDs, we ll have already sent to you all Canned Cycles that Powertronics Co, Ltd. (2 nd company who uses our CNC for EDM) have used for their machines. You should concentrate on those that are mostly used (aside of those for switching on/off and so): M19: VDI selection (very much important because you MUST adapt it to your specific Current Pulse Generator). M25: Orbiting Canned Cycle. M26: Penetration Canned Cycle. After the present explanation you will see how easy will be to program a determined cavity. The Canned Cycle for the Tool Changer is so simply its implementation that you should keep in mind that subprogram M06 will do all needed things to leave the electrode and get the new one. M19 (Program name is "P&19.mac") is very simple to be follow, Depending on a determined Parameter value passed to the M19 (in this case it is used the User Parameter PU84) absolutely all variables related with the Erosion Process are selected and fixed by this Canned Cycle. The Edm manufacturer should adapt this Canned Cycle to its specific Power Supply. To do so, proceed as follow: 1.- Put CD named WiMAC and install "ACTUALIZACION". (You should only follow the typical instructions of any Windows program installation). You could also download it from You will see and ICON named as "MacEdit". Double click on it. (It is our program's editor similar to the NotePad but with special utilities and functionalities). 3.- From the MACEdit you will be able to do: 3.1. open any existing program and so, to see what is doing any Canned Cycles (P&19.mac for instant) edit any new program to be transmitted to the CNC afterwards. From now, shall we go to concentrate in the program you ask for: a cavity of 25 mm made with 2 electrodes in order to achieve a VDI of 20. Degraded curves to select erosion or VDI regimes (fixed by Powertronics for their specific machines) are presented below. We have 2 electrodes. Suppose we number them as #3 and #7 of a Tool Changer of 10 possible electrodes. For the roughing one (electrode #3), we ll use a strategy of type 1, that is: High wear but High efficiency (to make cavity fastest possible without taking into account the electrode wear). For the finishing one (electrode #7), we ll use a strategy of type 3: Low wear but low efficiency (here the most important is to leave the electrode (that means the work-piece) as perfect as possible. We ll combine degraded curve 4.54 for the electrode #3 and 4.57 for the electrode #7. You will be able to see in curve 4.54 that with VDI=33 we ll obtain a GAP=160 thousandths (um). In curve 4.57 we start with VDI=30 that represents a GAP=170 um. Keep in mind this because it will be needed afterwards to understand programming after we make the Tool Change in the program. 1

2 GAPS (Thousandths) Cu - steel Curve Path 1 : Path 2 : Path 3 : For penetrations greater than 60 mm For penetrations between 12 and 60 mm For penetrations less than 12 mm 2

3 GAPS (Thousandths) Cu - steel Curve VDI REGIME or ROUGHING Path 1 : Path 2 : Path 3 : For penetrations greater than 60 mm For penetrations between 12 and 60 mm For penetrations less than 12 mm 3

4 Steps that you should follow in order to see how practical and easy is our programming system will be presented next as a little TUTORIAL that we hope it can be useful to clarify all concepts you are wanted to know. Please double click on MacEdit.exe icon to open it. Once opened and operative, write P010 at the first line and G90G0F1000 at the 2 nd one just to reference to you that you can combine the program with ISO code as milling machines. 1. The PC screen should look something like this: Attention V 2. Rename the file as Cavity25.mac by saving as from the file menu. Attention V 3. By locating the cursor at the next line, press M key. All available Canned Cycles will appear. You should select M26. (Before to do that, take a quick look of all Canned Cycles dialogues are supplied to you): 4

5 4. By accepting it, you progress until the specific dialogue prepared for the 1 st step, i.e. the penetration that, afterwards, will fix the consecutives orbiting/penetrations. 5

6 5. By pressing ENTER key or any NUMERIC or the - sign keys, you will be allowed to modify 1 st parameter to be introduced. 1st parameter ask for the total depth of the cavity to be achieved: that is 25 mm in negative direction (the sign is very much important) 6. 2 nd parameter is the GAP value that will produce the VDI regime will be selected by the 3 rd parameter. By seeing the degraded curve 4.54, we ll start from VDI=46 and, because total depth is between 12 and 60 mm, we must start with the path named as 2 that means GAP=750. It Could be interesting to begin with slower VDI regimes in order to preserve better the cavity and the electrode. That is which it is indicated different points to start from point named as 2 or rd parameter is the selected VDI for this first penetration. On this example, we select the fastest process possible, i.e. start with the most powerful regime for the roughing electrode. Remember that we also select an strategy of High wear/high efficiency that is because we ll introduce 461 instead of 463 or 462 and not 46 as the VDI roughing regime would only need. ATTENTION: just to remember that M19 Canned Cycle (P&19.mac file) must be adapted to the specific Power Supply needs, it will be used another notation that produce to work improperly to the Powertronics s M19 one, It is advised that the strategy digit will be substituted from the last position to the first one and this is completely incorrect. So we introduce 146 and not 461 that are since it must be introduced just to remember M19 cycle must be modified.

7 8. The 4 th parameter is self explanatory. Penetration in Z axis represents to introduce 0 value. 7

8 9. Finally we obtain: 5 th parameter is quite simply to be understood (see pages 8 and 9 of the Canned Cycles Manual). Normally its value must be Upon a time all parameters have been introduced, by accepting them we finish the 1 st dialogue and at the editor side will appear: The line which starts with the [ character could be easily red because it only Loads in some determine parameters (&00 to &04) the values that they were introduced by means of the dialogue. M26 will call to the program P&26.mac that is already resident in the CNC s memory. 11. After 1 st penetration, we must reduce VDI (that is because it is named a DEGRADED TABLE), 8

9 changing the GAP and that means to introduce orbiting. Press again M key. All available Canned Cycles will appears again and, this time, select M25: 12. By accepting it, you progress until the specific dialogue prepared for the consecutive steps, basically orbiting cycles. 9

10 This Canned Cycle always works in conjunction with M26 (which stores determined values that afterwards are used and updated for each orbiting cycle). By seeing 4.54 curve it is clear the values presented on precedent picture. The 3 rd parameter should be used at the end of the cycle and it is intended to remain a determined among of time at the bottom of the cavity to finish better the front-end of the cavity. 10

11 13. After this, the program looks like. which is very simple to be understood. 14. Next steps are self explanatory. We ll proceed introducing as many Orbiting Cycles until we arrive the last VDI was fixed before by our strategy (VDI=33 with GAP=160 [um] that corresponds, more or less, to the 1 st step for electrode #7). The program, before change the electrode, will look like: 11

12 On that time It will be time to change the electrode! You must suppose we have already developed a Canned Cycled to do so (don t worry because we have a large experience on that type of gadgets). It will be as simple as the following command: [&84L7 M06 and, in the program would be:

13 16. Arrived here, it will be time to proceed with next electrode and new Degraded Curve Because the last GAP was 160 thousandths, it should be clear that VDI=30 with a GAP of 170 is the most appropriated start from this point. Remember that for this electrode (finishing), we ll use the Low wear/low efficiency strategy. By calling again consecutives Orbiting Canned Cycles as exactly was done before, we ll obtain: As a comment, to tell you that the Orbiting Canned Cycle, by means of TY command, already introduce some determine number of extra orbits anytime the bottom of each penetration has been achieved. In some cases, it could be recommended to stay at the bottom of the cavity for spark out, that is the reason because at the last step we fix a TIME of 5 minutes. 13

14 17. On that point, it is clear that the electrode should be retracted until it comes out of the cavity and afterward and by means of M15, we ll stop all is needed and specially the Current Pulse Generator and the program advising of that even (for example, by lighting a warning pilot). Mind that the character ; serves to introduce comments on the PC side, i.e. all characters following the : will be not transmitted to the CNC. 18. From the point of view of programming all things were done. You should finish edition and transmit this file to the CNC once it will be needed. 19. Other very much important thing to know will be how to prepare the machine to make the cavity in any exact place it is wanted. To do that is very simple too: we move the machine in X and Y (by the Remote Pocket Terminal or so) until the exact point it is wanted to do the hole. Placed on that point, we execute in M.D.I. (Manual Data Input) the following command: G92X0Y0 which fix the point where are located the axes X and Y as the Work-piece Origin for those only axes. Of course, you will have had the precaution to move Z axis until no possible collision has been produced. Anyhow, don t forget that you have G25 and G26 for Collision preventions. Once the machine has been located on the Work-piece origin in X and Y, we approach the electrode in -Z direction until a comfortable clearance distance and, if the wiring of the machine was prepared accordantly (see the Installation Manual) and by executing M10 Canned Cycle, automatically the Z axis is referenced to 0 when the electrode collide with the work-piece and it is moved up a security clearance distance automatically too of 2 mm. by the M10 cycle. As a simple comment, you could also compensate the electrode wear by using M75, M76 and M77, but we must proceed with calm and not to introduce all possible CNC performances at the same time. Remember that, by using the MacEdit.exe, you can also see the content of any Canned Cycle. We strongly recommend you that you take a look in P&19.mac by open it from the MacEditor. P&25.mac and P&26.mac are even difficult to be red by the own who develop it and for the moment is better to concentrate all effort on that is not already done (even thinking that all things can be improved, of course). 14