Every process consists of a set of identifiable flows and value-added activities that are comprised of information flow, physical flow and financial flow. True or False? Meeting customer expectations requires a shift from a functional organization to a process orientation.
If the takt time is 5 minutes, and it takes 4 hours (240 minutes) to make the part, then you need to have more than one in work at the same time. 420 minutes / 5 minutes = 84. This means that you need 84 units to be in work at any given time if you need to finish one every 5 minutes.
If you are only processing one unit every 100 minutes, you need much less than one person to do this job. Your labor utilization / waiting time (one is the inverse of the other) would depend on whether this person had other things to do.
That equals 61,800 seconds. You have to produce 1615 units of “Product A” in that time. 61,800 seconds available / 1615 units = a takt time of ~38 seconds. This means you must complete one Product A every 38 seconds to succeed.
Continuing to produce is overproduction, and just means you run out of work sooner if you have a good day tomorrow. – If there are issues, the use the buffer time for its intended purpose. – If there are more issues than buffer time, there is an operational decision to make. Have a policy in place for this.
And, of course, “cycle time” is used to express the work cycle of a single person, not including end-of-cycle wait time. None of these definitions is wrong. The source of confusion is when the users have not first been clear on their context. Therefore, it is critically important to establish context when you are talking.
Takt time is just a tool for doing this. It is, however, a very effective tool. It is so effective, in fact, that it is largely considered a necessary fundamental. Honestly, in day to day conversation, that is how I look at it. I made the above statements to get you to think outside the mantras for a minute.
It is not, and never has been, a pure customer demand signal. Customers do not order the same quantity every day. They do not stop ordering during your breaks, or when your shift is over. What takt time does, however, is make customer demand appear level across your working day. This has several benefits.