CTP--New Tools, Old Theories
According to the Theory of Constraint, we would conclude that demand exceeds capacity in the proofing area (bottleneck), but capacity exceeds demand in the platemaking area. Thus, according to the Theory of Constraint, the remedy to this ailment is a strategy known as the drum-rope-barrel theory of scheduling.
This theory ties (with a rope) the amount of work down past the bottleneck (platesetter) to the amount of work in progress in the queue (or barrel) before the platesetters.
You create this queue of work-in-progress after digital proofing and before platemaking. Since the platesetter is faster then the bottleneck, when the queue (barrel) gets low, you turn it off—and use the platemaking people in another area that is bottlenecked (digital proofing). After you turn off platemaking, the work in the queue (barrel) is rising. The benefit is the reassigned staff (platemakers helping in digital proofing) are overcoming the bottlenecked work in the proofing area, increasing overall throughput.
When the pile of "OKed" digital proofs in the barrel gets to a certain height, you get the platemaking staff to return to the platesetter. Due to the increased capacity (speed) of the platesetter, the platesetter will quickly out-run the queue, and the process begins again.
Of course, shutting down the platesetting operation would NOT result in a high utilization rate, but, by synchronizing the operation of all the resources, it would increase the overall throughput, and you would get more pages proofed and printed.
As another example, let's take a printing operation where the platesetter is the bottleneck. In this case, it is important to keep the platesetter as busy as possible. For this company, measuring the utilization rate is important and useful for management decisions. Although oversimplified in many cases, this information can be used to help make decisions about number of shifts, staffing levels, where to implement QC inspection steps and if another piece of equipment is warranted.