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Process capability indices provide numerical measures on whether or not a process is able to produce products that meet prespecified quality targets and are often used by manufacturers to evaluate manufacturing performance. Although process yield is the primary focus of the performance criteria, a formula that combines the yield and the average process loss, called the quality yield index, has been developed. This index, the quality yield, can be viewed as the conventional process yield minus the truncated expected relative process loss within the specifications. Although cases with symmetric tolerances dominate in practical situations, cases with asymmetric tolerances can also occur. In this paper, we generalize the quality yield index for asymmetric tolerances. The generalization technique is justified, and some statistical properties of the estimated generalization are investigated. An application example on high-density light emitting diodes is also presented to illustrate the applicability of the generalization., 1. Introduction Process capability indices (PCIs) are widely used in manufacturing industries, to provide a numerical measure on whether or not a process is capable of producing items that meet [...]

Abstract: Air-oxidation behavior of a Zr50Cu43Al7 bulk metallic glass (ZCA7-BMG) was studied over the temperature range of 400–500°C. The oxidation kinetics of the ZCA7-BMG generally followed a multiple-stage parabolic-rate law with its steady-state parabolic-rate constants (k p values) decreasing with increasing temperature, indicative of the occurrence of kinetics inversion. The scales formed on the ZCA7-BMG were strongly dependent on temperature, consisting mostly of tetragonal ZrO2 and CuO, and minor amounts of monoclinic ZrO2 and Cu2O at 400°C, while Cu2O was completely absent at T ⩾450°C. In addition, a minor amount of Al2O3 was further observed after the oxidation at 500°C, whose formation is responsible for the lowest oxidation rate, as compared to those at T ⩽450°C. [Copyright &y& Elsevier]

The loss-based process capability index Cpm, sometimes called the Taguchi index, has been proposed to the manufacturing industry to measure process performance. In this paper, we propose a method to assess the performance of a normally distributed process. We implement the theory of testing hypothesis using the natural estimator of Cpm, and provide an efficient program to calculate the p-values. We also provide tables of the critical values for some commonly used capability requirements. Based on the test, we develop a simple step-by-step procedure for in-plant applications. [ABSTRACT FROM AUTHOR]

The loss-based process capability index Cpm, sometimes called the Taguchi index, has been proposed to the manufacturing industry to measure process performance. In this paper, we propose a method to assess the performance of a normally distributed process. We implement the theory of testing hypothesis using the natural estimator of Cpm, and provide an efficient program to calculate the p-values. We also provide tables of the critical values for some commonly used capability requirements. Based on the test, we develop a simple step-by-step procedure for in-plant applications. [ABSTRACT FROM AUTHOR]

Process capability indices Cp, Ca, Cpk and Cpm have been proposed to the manufacturing industry as capability measures based on various criteria including variation, departure, yield, and loss. It has been noted in recent quality research and capability analysis literature that both the Cpk and Cpm indices provide the same lower bounds on process yield, that is, Yield=2F(3Cpk)-1=2F(3Cpm)-1. In this paper, we investigate the behaviour of the actual process yield in terms of the number of nonconformities (in ppm) for processes with a fixed index value of Cpk=Cpm, but with different degrees of process centring, which can be expressed as a function of the capability index Ca. The results illustrate that it is advantageous to use the index Cpm over the index Cpk when measuring process capability, since Cpm provides better customer protection. [ABSTRACT FROM AUTHOR]

Process capability indices Cp, Ca, Cpk and Cpm have been proposed to the manufacturing industry as capability measures based on various criteria including variation, departure, yield, and loss. It has been noted in recent quality research and capability analysis literature that both the Cpk and Cpm indices provide the same lower bounds on process yield, that is, Yield=2F(3Cpk)-1=2F(3Cpm)-1. In this paper, we investigate the behaviour of the actual process yield in terms of the number of nonconformities (in ppm) for processes with a fixed index value of Cpk=Cpm, but with different degrees of process centring, which can be expressed as a function of the capability index Ca. The results illustrate that it is advantageous to use the index Cpm over the index Cpk when measuring process capability, since Cpm provides better customer protection. [ABSTRACT FROM AUTHOR]