2.) On-line, non-productive tasks:
These are tasks that occur during the machining cycle that do not actually further the completion of the workpiece. The first thing Computer Numerical Control people often target for improvement is wasted program execution time. These are the things like rapid movements, tool changes, M-code execution and spindle acceleration/deceleration. Reducing program execution time in this area is usually easy.
It often takes nothing more than carefully monitoring the production run for a few workpieces to find those times when the program can be modified to eliminate noticeable pauses during the cycle. Although keep in mind that the worker for these machines must not overlook other processes for they may be so concerned with minimizing program execution that they overlook other operations, resulting in severe wastes of cycle time.
3.) Off-line, non-productive tasks:
These are the tasks performed in the machining cycle that do nothing to further the completion of the workpiece. Since these types of tasks are done while the machine is producing workpieces, they do not actually add to the cycle time. It is possible to free the operator of the machines of performing off-line productive tasks if they have little, or nothing to do during lengthy machine cycles.
4.) Off-line, productive tasks:
These are the tasks done away by the CNC machine, while the machine is producing workpieces, which would further the completion of the workpiece. This is extremely helpful during lengthy CNC cycles, tasks in this category can reduce the time it takes to complete the production run dramatically, which would effectively reduce cycle time.