ABSTRACT
When we used the above values, the IQ (image quality) of the process was computed at 100, which was our goal. However, the ultimate goal of quality is to achieve the target value and do so consistently. We realize that it would be impossible to hold a temperature at 80.82 all the time. To do so would require very expensive feedback control systems. To be able to weigh the chemicals to their exact specifications would also be impossible and would impose a restriction on the production process that is too costly. A speed of exactly 10 ips may be accomplished with another system, but again, this is an imposition that a production process can’t afford. What we need is a toleranced specification. That is a midpoint with an acceptable degree of slope around it. This is a common practice in most industry. However, the practice of deriving the degree of variation printed on the specification is not often practiced in a scientific or even economic manner.
