Goble, Joann (1987, ASQC) Questics Inc., Troy, MI
Statistical methods are typically introduced into a manufacturing or assembly process on an operation-by-operation basis with little regard for interrelationships of operations. People generally discover these interrelationships as they respond to out-of-control signals at individual operations and investigate their special causes. The transition from a firefighting, chaotic mode to a state of statistical control can sometimes be long, frustrating, and costly; particularly for complex products.An approach is provided for integrating statistical thinking into a complex manufacturing or assembly environment. This concept uses traditional statistical methods. Its focus, however, is on the interrelationships within and between operations, both upstream and downstream. All processes are viewed as a total entity instead of a series of isolated operations.The implementation of SPC can best take place in an environment whereby, prevention systems replace detection systems and a target philosophy rather than the traditional tolerance philosophy has been adopted. The focus of the system is to achieve control of all characteristics rather than so-called "critical" characteristics.A process control plan is the result of a series of structured activities conducted by a team of individuals associated with a particular product or process. After gathering preliminary data on the process the team is able to logically construct a plan for achieving statistical control of the process. These steps and the plan structure are also described.