Counting cycles can be helpful in several ways. Past articles in The Optional Stop have shown two great applications. One will serve as a part counter. The other works nicely to help with tool life management issues.
With the part counter, we place a G65 command at the end of the cutting program to activate the part counting macro. One thing we didn’t previously show is how to make the custom macro work when more than one workpiece is machined per cycle. Consider this revised macro.
O0001 (Main program)
N500 G65 P1000 C300.0 M4.0
In this case, C represents the number of parts to be made. M represents the number of parts being produced per cycle. Here is the new custom macro.
#500 = #500 + #13 (Step counter by the number of parts per cycle)
IF [#500 LT #3] GOTO 99
#500 = 0 (Reset counter when finished)
#3000 = 101 (PART COUNT ACHIEVED)
When used for tool life management, the custom macro can count cycles for the purpose of stopping the machine whenever a critical tool (or series of tools) gets dull. We have even shown how this can be used with multiple tools.
So when else might you need to count cycles and stop the machine at appropriate times?
How about when the production run must be stopped for sampling inspections? Maybe you have a customer that requires 100% inspection to be done on a workpiece after every one-hundred parts are run.
How about with certain critical preventive maintenance tasks? Maybe chips are piling up on the machine’s table and after every fifty parts the operator must brush away the chips or else they will interfere with machining operations. Or maybe some kind of inspection must be done on the machine at certain intervals to ensure that the machine keeps running properly.
How about when you need to remind operators to do something every so often? It may be something unrelated to the CNC cycle, but you don’t want them to forget to do it. Possibly they are running a second, automatic machine that requires reloading of multiple workpieces every so often. Counting cycles on the CNC machine and generating an alarm at appropriate intervals will remind the operator to perform the required task.
While you don’t want to do something that will interfere with the CNC machine’s performance, this technique of counting cycles has more applications than simple part counting. Consider other applications for this helpful technique.