Evaluation of process capability indices of linear profiles

Abstract

PurposeIn profile monitoring, which is a growing research area in the field of statistical process control, the relationship between response and explanatory variables is monitored over time. The purpose of this paper is to focus on the process capability analysis of linear profiles. Process capability indices give a quick indication of the capability of a manufacturing process.Design/methodology/approachIn this paper, the proportion of the non‐conformance criteria is employed to estimate process capability index. The paper has considered the cases where specification limits is constant or is a function of explanatory variable X. Moreover, cases where both equal and random design schemes in profile data acquisition is required (as the explanatory variable) is considered. Profiles with the assumption of deterministic design points are usually used in the calibration applications. However, there are other applications where design points within a profile would be i.i.d. random variables from a given distribution.FindingsSimulation studies using simple linear profile processes for both fixed and random explanatory variable with constant and functional specification limits are considered to assess the efficacy of the proposed method.Originality/valueThere are many cases in industries such as semiconductor industries where quality characteristics are in form of profiles. There is no method in the literature to analyze process capability for theses processes, however recently quite a few methods have been presented in monitoring profiles. Proposed methods provide a framework for quality engineers and production engineers to evaluate and analyze capability of the profile processes.

Process Capability Analysis in Non Normal Linear Regression Profiles

“…While the quality control procedures for monitoring profiles have been studied considerably, capability analysis for profiles has not been explored much. Hosseinifard and Abbasi (2012) studied process capability analysis for simple linear profiles with consideration of common assumption of linear regression models. However, there has been no discussion on analyzing process capability of profile data with violation of normality assumption.…”

Process Yield for Multivariate Linear Profiles with One-sided Specification Limits

“…Measuring the process capability in the manufacturing industry is a very important task for quality assurance. Several indices for linear and nonlinear profiles under single characteristic with two‐sided and one‐sided specification limits can be found in the literature . Ebadi and Amiri presented three existing indices to measure the process capability for multivariate simple linear profiles with two‐sided specifications .…”

Process Capability Indices for Logistic Regression Profile

“…proposed a method to determine the capability of simple linear profiles. Hosseinifard and Abbasi used the proportion of nonconforming items to estimate PCI of linear profiles. Hosseinifard and Abbasi estimated the PCI of linear profiles under non‐normal conditions by using Gamma distribution as well as Burr distribution.…”