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78 The PCB Magazine • July 2014 gling with wildly fluctuating revenue and unex- pected missed delivery dates. He was vexed. Here is the reality. Think of a hose. Does it have a bottleneck? Yes, its entire length is a bot- tleneck. Can you remove it? Yes, with the result being water shooting out of the spout. Can this bottleneck be removed? Yes, with disastrous re- sults. Even when you get to the giant aquifer or reservoir you have not removed the bottleneck; the capacity is much greater so your constraint on flow is at a much higher rate of flow, but there is still a constraint somewhere. There is always a bottleneck. Let's get back to the CEO who thinks he doesn't have a bottleneck. A great way to un- derstand his situation is from an example called Penny Fab 1, from the landmark text- book, Factory Physics ® , by Mark Spearman and Wally Hopp. Here you have four work stations to make a penny: punch, stamp, rim, and de- burr. And let's say each station takes two hours to complete with no variation. Figure 1 shows the plant layout for the discrete event model. I am not going to go through the detail of ex- plaining that the critical WIP for this scenario is four pennies, that the total process time is eight hours, and the bottleneck rate (where each sta- tion is the bottleneck) is 0.5 pennies per hour. In Figure 2, the blue line shows how the throughput changes with WIP (left scale). This is the "best case" scenario for throughput. It is impossible to have throughput better than Figure 1: the result of running the simulation for 1300 hours at a WiP level of 5. each station was 100% utilized with a process time of two hours per machine. the "best case" scenario is impossible to achieve. WHY REMOvING YOUR BOTTLENECK IS A BAD IDEA continues