For a process normally distributed and a target located at the mid-point of a twosided tolerance interval, Vännman suggests a family of indices depending on two parameters. In order to choose the parameters which allow to obtain an index that is sensitive to departures of the mean from the target, we need to take the properties of its estimator into account. For a target not located at the mid-...

Process Capability indices have become popular for describing how well a process meets specified tolerances. The lack of affinity with the process nonconformance probability p and the difficulty of dealing with the sampling distribution of their natural estimators affect greatly the use of the traditional indices as Cp, Cpk, Cpm and Cpkm. In this paper, a capability index is proposed which is c...

Processcapabilityindicesareusedtoevaluatetheperformanceofthemanufacturingprocess.When thespecificationlimitsandthetargetvaluearenotprecise,theauthorscannotusethetraditional methodstoassessthecapabilityoftheprocess.Fortheprocesseswithasymmetrictoleranceintervals, somefuzzyprocesscapabilityindiceshavebeenintroducedsuchas  Cpk '' and  Cpmk...

a manufacturing process cannot be released to production until it has been proven to be stable. also, we cannot begin to talk about process capability until we have demonstrated stability in our process. this means that the process variation is the result of random causes only and all assignable or special causes have been removed. in complicated manufacturing processes, such as drilling proces...