G10 Data Setting Command

Transcription

1 G10 Data Setting Command Though it s barely mentioned in most basic CNC courses, the G10 command is an extremely important basic CNC feature It allows you to input data from within CNC programs This data can be in the form of tool offsets, geometry offsets, fixture offsets, and/or even parameter values Note that while Fanuc considers this G code to be an optional function, most machine tool builders make it part of their standard package of G codes How G10 works As stated, G10 allows you to enter data from within programs An L word in the G10 command tells the control what kind of data Note that the L word is a kind of code number, and it does vary from one Fanuc model to another It also varies among a given model, based upon which offset option the control has This means you ll have to confirm the L word numbering for the control/s you re working with With the 10M, 11M, and 15M Fanuc controls equipped with tool compensation memory A, for example, here is how the L word is specified L2 - fixture offsets L10 - geometry offsets (length and radius compensation) L11 - wear offsets (length and radius compensation) L50 - parameter entry Depending upon the kind of data entry, other letter addresses are used to specify the values being entered With geometry and wear offsets, for example, an R word specifies the value being set With fixture offsets, X, Y, and Z specify the values being set With parameters, an R word is used to specify the value A P word in the G10 command specifies the data number (offset number, fixture offset number, or parameter number) P5, for example, specifies data number five Note that the G10 command is also influenced by the current specification of absolute and incremental mode (G90 and G91 for most controls) If in the absolute mode, the control will overwrite the value in the data register with the value specified in the G10 command If in incremental mode, the control will increase or decrease the value in the data register with the value in the G10 command Here are a few examples (given for a 15M Fanuc control with tool compensation memory A) that should help you understand how G10 works G90 G10 L10 P1 R45 (Set tool geometry offset number one to 45) G91 G10 L10 P32 R0005 (Increase geometry offset number thirty-two by 0005) G90 G10 L2 P1 X Y Z (Set fixture offset number one to values given) Note that parameter setting is a little different The L50 specification sets a parameter entry mode that must be canceled by a G11 Here is an example of setting parameter number 5141 (final depth of cut for G76 threading cycle) to inch 1

2 G10 L50 N5141 R0020 G11 The N word specifies the parameter number and the R word specifies the value Note that if you have more parameters to set, you simply do so before the G11 command Also note that some parameters are related to axes and have one value per axis For these parameters, a P word in each value setting command specifies the axis number Entering tool length and cutter radius compensation values for machining centers Many CNC users assemble and measure cutting tools while the machine is in production In essence, they re getting ready for the next setup while the machine is still producing Most companies that do this have someone in the tool crib (commonly the tool setter) assembling and measuring tools That is, it is not commonly the responsibility of the CNC operator or setup person in these companies to assemble and measure cutting tools While this can dramatically reduce the amount of time the machine is down between production runs, many tool setters simply write down tool length and cutter radius compensation values and the setup person is expected to enter these values into the control during setup One great application for G10 will minimize (almost eliminate) the amount of time it takes to enter offsets into the CNC control It will also eliminate the setup person s potential for making mistakes while doing so After measuring each tool (length and/or radius), the tool setter can enter its value in a G10 command A special template program will really help It can be called up on a CNC text editor right at the tool setter s work station Here s an example of the template program: O5000 (Tool offset setting program) G90 G10 L10 P1 R200 (Set offset number one) G90 G10 L10 P2 R200 (Set offset) G90 G10 L10 P3 R200 (Set offset) G90 G10 L10 P4 R200 (Set offset) G90 G10 L10 P5 R200 (Set offset) G90 G10 L10 P6 R200 (Set offset) G90 G10 L10 P7 R200 (Set offset) G90 G10 L10 P8 R200 (Set offset) G90 G10 L10 P9 R200 (Set offset) G90 G10 L10 P10 R200 (Set offset) G90 G10 L10 P11 R200 (Set offset) G90 G10 L10 P12 R200 (Set offset) G90 G10 L10 P13 R200 (Set offset) G90 G10 L10 P14 R200 (Set offset) G90 G10 L10 P15 R200 (Set offset) G90 G10 L10 P16 R200 (Set offset) 2

3 G90 G10 L10 P17 R200 (Set offset) G90 G10 L10 P18 R200 (Set offset) G90 G10 L10 P19 R200 (Set offset) G90 G10 L10 P20 R200 (Set offset) M30 This template program assumes you have a machine will twenty tool capacity and you re using the tool s length as the offset value When the tool setter measures a tool, they will modify the corresponding R200 value, entering the actual value they ve just measured When they re finished, this program will be saved in the company s distributive numerical control (DNC) system The setup person will call up this program and run it once in order to have all the tool length and cutter radius compensation offset values entered Note the very large (20 inch) default value that is in each command If for some reason, the tool setter cannot assemble a given tool, they will leave the value twenty inches The setup person, seeing a twenty inch value in an offset will know that this tool must be measured at the machine But if they forget to do so and run the program with the 20 inch value in the offset, and since twenty inches is larger than the longest tool, the worst that will happen is that the machine may over-travel in the Z axis Again, this minimizes downtime between production runs and eliminates the potential for setup person entry errors But the tool setter could still make a mistake entering the tool offset value in the text editor For this reason, the setup person must still be cautious with each tool s first approach to the workpiece Note that some tool length and cutter radius measuring devices have the ability to output their current setting (the tool length or radius) through a communications (serial) port If interfaced with a computer and with a special computer program, the offset values can be automatically placed in G10 commands This further automates the process, eliminating the potential for tool setting person entry errors Most tool measuring device manufacturers offer the interface cable and special software needed for doing this Retaining fixture offset values for qualified setups If a machining center setup is truly qualified, the position of the program zero point will remain exactly the same from one time the setup is made to the next This means the same program zero assignment values that worked the last time the setup was made will work the next time it is made Yet many setup people (wastefully) measure program zero assignment values every time they make even a repeated qualified setup One obvious way to eliminate the repeated measurements is to document the fixture offset values for a qualified setup right on the setup sheet But as with tool length and radius offsets, this still opens the door to setup person entry errors - and of course - it takes time The G10 command can be used to automatically enter program zero assignment values If, for example, the program zero assignment values for a repeated qualified setup are in X, in Y and in Z, and if fixture offset number one (G54) is being used, the G10 command will be G90 G10 L2 P1 X Y Z

4 Note that many setup people will not wanting this command executed every time the program is run If any fine tuning of fixture offsets is necessary (though they shouldn t be if the setup is truly qualified), this command will overwrite whatever minor modifications they make A better way to include this command in the program yet ensure that it is only executed once (during setup) is to include it in a special series of commands after the end of program command (usually M30 or M02) Here is an example O0002 (Program number) (Normal cutting operations) N505 M30 (End of program) N999 G90 G10 L2 P1 X Y Z (Set fixture offset) N1000 M30 (Second end of program command) If the setup person wants to enter the fixture offset, they ll scan to N999 and execute from there The control will execute the G10 command and in line N1000, return to the beginning of the program It will never see line N999 again, unless the setup person manually scans to it Note that Fanuc controls have a special parameter that controls when the control will stop reading CNC programs from your distributive numerical control (DNC) system If the parameter is set to stop the read as soon as the control reads an M30, M99, or M02, the N999 sequence will not be loaded into the program If you intend to use this technique, you must confirm that the control will not stop reading the program until an end of file character (the percent sign for most controls) is read You may be questioning the ability to make truly qualified setups You may also be wondering what happens to the programmed G10 command fixture offset values if you have a crash and the machine is slightly out of position We ll discuss this application (qualifying setups) further during our discussion of fixture offsets (see G54 through G59) Running out of fixture offsets? Though Fanuc offers an option (of forty-eight) for fixture offsets, most Fanuc controls come with but six fixture offsets If you constantly find yourself wishing you had more, you should buy the option But for occasional problems we offer a technique that should help you keep from running out of fixture offsets In essence, you ll be creating a separate subprogram for each coordinate system (fixture offset) you wish to set In this subprogram you ll be using a G10 command to overwrite the registers for fixture offset number one Then you ll include a G54 to invoke the values just set (Only one fixture offset will be required for this technique!) From your main (cutting) program, you ll use an M98 to command that the appropriate subprogram be executed Here s an example 4

5 that should help you understand Though we re using but two subprograms, you can have as many as you d like Coordinate system setting subprograms: O6001 (Set coordinate system number one) G90 G10 L2 P1 X Y Z92138 (Set fixture offset number one as needed) G54 (Invoke fixture offset number one) M99 (End of subprogram) O6002 (Set coordinate system number two) G90 G10 L2 P1 X Y Z89947 (Set fixture offset number two as needed) G54 (Invoke fixture offset number one) M99 (End of subprogram) Note that when the setup person enters coordinate system values, they must do so in these subprograms This eliminates one important advantage of fixture offsets (separating program zero assignment from programs) and is the reasons why it s better to purchase the option for additional fixture offsets if you need them on a regular basis Here is the main program (first tool only) that machines two identical workpieces O0001 (Main program) N005 T01 M06 (Place center drill in spindle) N010 M98 P6001 (Invoke coordinate system number one) N015 G90 S1200 M03 T02 (Select absolute mode, start spindle, get tool two ready) N020 G00 X10 Y10 (Move to first XY position relative to coordinate system number one) N025 G43 H01 Z01 (Instate tool length compensation, move to just above work surface) N030 G81 X10 Y10 R01 Z-02 F50 (Center drill first hole) N035 X20 (Second hole) N040 X30 (Third hole) N045 G80 (Cancel cycle) N050 M98 P6002 (Invoke coordinate system number two) N055 G81 X10 Y10 R01 Z-02 F50 (Center drill first hole) N060 X20 (Second hole) N065 X30 (Third hole) N070 G80 (Cancel cycle) N075 G91 G28 Z0 M19 (Move to tool change position, orient spindle) N080 M01 (Optional stop) 5

6 Entering tool nose radius compensation values (turning centers) Many turning center programmers use tool nose radius compensation (G41 & G42) on a regular basis If you re one of them, and if you use a computer aided manufacturing (CAM) system to help you prepare programs, remember that you can have your CAM system generate the motions for single point turning tools and boring bars based upon the tool nose radius you intend to use, assuming your setup people and operators continue using this size tool nose radius throughout the production run (as most do) If you do, you will have no need for CNC control based tool nose radius compensation If you do use G41 and G42 in your turning center programs on a regular basis, your setup people must, of course, enter the tool nose radius and the tool type in the appropriate offset registers And if your setup people and operators will always be using the size of tool nose radius specified, you can eliminate the need to enter these offset values by using the G10 command Consider these commands for a Fanuc control N003 G10 P2 R00316 T3 N004 G10 P6 R00152 T2 These commands tell the control that tool number two is a 1/32 radius turning tool and tool number six is a 1/64 radius boring bar Having these commands in the program eliminates the possibility of a setup person forgetting to enter them manually What about reading offset values from within your programs? Unfortunately G10 is a one-way street with Fanuc controls You can only write to your offset table from within CNC programs with G10 However, there is a way, if you have custom macro, to read offset values from within your program Combined with the other features of parametric programming (variables, arithmetic, logic, and the ability to generate alarms), this has tremendous implications Since incorrect offset setting is the most common cause of crashes and scrapped workpieces, you can make your machines much safer to run if you fully understand parametric programming It s such an important topic, we devote an entire module of this course to parametric programming Setting parameters from within CNC programs We ve already mentioned the importance of parameters You now know that they control many CNC machine functions As you know, many parameters are related to how your programs function And with G10, you can even modify certain parameters (especially those related to CNC programs) right from within your CNC program Consider, for example, the G76 threading cycle on turning centers With most controls (except the 0 and 3 series), you have no way to control, from within a program, three important variables: the minimum depth of cut, the final depth of cut, and the number of spring passes (note that the 0 and three series controls do allow these important values to be modified in the G76 commands) Yet these values can be modified through parameter settings You might, for example, have two dramatically different threads on the same workpiece that require different settings for these important thread-related variables Prior to 6

7 machining the first thread, you can give the G10 commands that set the parameters in the manner you wish them set for the first thread After machining the first thread with G76, give the G10 commands that set the values for the second thread Then you can give the G76 command for the second thread Here s an example for a 15T control (remember, parameter numbers vary from one control model to another) G10 L50 N6218 R0030 N6219 R0002 N6220 R3 G11 N045 G00 X32 Z02 N050 G76 X292 Z-075 K0040 D0100 F00625 (Machine first thread) G10 L50 N6218 R0070 N6219 R0004 N6220 R2 G11 N055 G00 X52 N060 Z-28 N065 G76 X48 Z-075 K01 D0250 F01875 (Machine second thread) As you can see, these are two substantially different threads The first is a 1/16 pitch, 004 deep thread The second is a 3/16 pitch, 01 deep thread The minimum depth of cut (parameter 6218) is set to 0003 for the first thread but 0007 for the second The final pass depth (parameter 6219) is set to for the first thread and for the second And the number of spring passes (parameter 6220) is three for the first thread and two for the second Though the need to set parameters from within CNC programs is rare (we ll be pointing out a few more), it is quite important that you know it s possible 7