Three important comparisons to consider
There are three relatively simple comparisons you can do in order to evaluate a machine’s productivity level – that is – its level of effectiveness. And this, in turn, will provide you with information about how much potential there is for improvement for a given machine.
Time in setup versus time in production
This easy-to-do comparison will tell you which area provides the most potential for improvement – and should help you make a decision on where to start with any kind of improvement program. Simply determine whether the machine is in setup or running production for the majority of time. The greater that difference, the more obvious the choice.
If, for example, a machine is in production for 90% of the time, it wouldn’t make much sense to try to improve setup since there would not be much room for improvement. Even if setup could be completely eliminated, you would only be saving 10%.
Time to perform physical setup-related tasks versus total time the machine is down between production runs
Physical tasks include things like mounting the fixture, assembling cutting tools, loading programs, and entering offsets. It’s pretty easy to determine how long they take to complete. And the related time tends to be pretty consistent from one time a setup is made to the next.
It is not uncommon for the time require to perform all physical setup tasks to be but a fraction of the time a machine is down between production runs. It may, for instance, take only twenty minutes to perform all of the physical tasks, but two hours later your people are still trying to get a workpiece to pass inspection.
The goal here is to find ways to draw the total time a machine is down between production runs down to the time it takes to perform the physical tasks. One example has to do with gathering components needed for upcoming setups. If all components can be gathered up-front, the setup person won’t have to leave the machine during setup at all. Other improvements are usually possible in the area of program verification – providing trial machining help so the setup person can ensure that the first workpiece being produced is a good one.
Button-to-button time versus production run throughput time
Button to button time is one definition of cycle time. It includes the running of one workpiece and the loading of the next. But it is not an inclusive definition of cycle time. We define cycle time (better termed as production run throughput time) as the time it takes to complete a production run divided by how many good workpieces were made.
As with the setup-related physical tasks, it is not unusual for button-to-button time to be but a fraction of production run through-put time. There are many things that happen during a production run that don’t occur in every cycle. And there may be things that you expect your operators to do that take longer per cycle than button-to-button time.
Similarly, the goal is to draw production run throughput time down to button-to-button time. Simplifying tasks and truly engineering the production run in a way that the operator can feasibly keep up with the machine are examples of doing so.