APSS - Software support for decision making in statistical process control

DOI nefunkční (7.1.2019)Purpose: SPC can be defined as the problem solving process incorporating many separate decisions including selection of the control chart based on the verification of the data presumptions. There is no professional statistical software which enables to make such decisions in a complex way. Methodology/Approach: There are many excellent professional statistical programs but without complex methodology for selection of the best control chart. Proposed program in Excel APSS (Analysis of the Process Statistical Stability) solves this problem and also offers additional learning functions. Findings: The created SW enables to link altogether separate functions of selected professional statistical programs (data presumption verification, control charts construction and interpretation) and supports active learning in this field. Research Limitation/implication: The proposed SW can be applied to control charts covered by SW Statgraphics Centurion and Minitab. But there is no problem to modify it for other professional statistical SW. Originality/Value of paper: The paper prezents the original SW created in the frame of the research activities at the Department of Quality Management of FMT, VSB-TUO, Czech Republic. SW enables to link altogether separate functions of the professional statistical SW needed for the complex realization of statitical process control and it is very strong tool for the active learning of statistical process control tasks.Web of Science223261

Complex Control Chart Interpretation

Abstract Identification of the assignable causes of process variability and the restriction and elimination of their influence are the main goals of statistical process control (SPC). Identification of these causes is associated with so called tests for special causes or runs tests. From the time of the formulation of the first set of such rules (Western Electric rules) several different sets have been created (Nelson rules, Boeing AQS rules, Trietsch rules). This paper deals with the comparison analysis of these sets of rules, their basic statistical properties and the mistakes accompanying their application using SW support. At the end of this paper some recommendations for the correct application of the runs tests are formulated

Methodology for the Application of Nonparametric Control Charts into Practice

Classical parametric statistical methods are based on several basic assumptions about data (normality, independence, constant mean and variance). Unfortunately, these assumptions are not always fulfilled in practice, whether due to problems arising during manufacturing or because these properties are not typical for some processes. Either way, when we apply parametric methods to such data, whether Shewhart’s or other types of parametric control charts, it is not guaranteed that they will provide the right results. For these cases, reliable nonparametric statistical methods were developed, which are not affected by breaking assumptions about the data. Nonparametric methods try to provide suitable procedures to replace commonly used parametric statistical methods. The aim of this paper is to introduce the reader to an alternative way of evaluating the statistical stability of the process, in cases where the basic assumptions about the data are not met. First, possible deviations from the data assumptions that must be met in order to use classical Shewhart control charts were defined. Subsequently, simulations were performed to determine which nonparametric control chart was better suited for which type of data assumption violation. First, simulations were performed for the in-control process. Then simulations for an out-of-control process were performed. This is for situations with an isolated and persistent deviation. Based on the performed simulations, flow charts were created. These flow charts give the reader an overview of the possibilities of using nonparametric control charts in various situations. Based on the performed simulations and subsequent verification of the methodology on real data, it was found that nonparametric control charts are a suitable alternative to the standard Shewhart control charts in cases where the basic assumptions about the data are not met

Design of methodology for application of statistical control on short run processes in metallurgy

So called short run manufacturing environment is now typical for many industrial branches including metallurgy. To be applicable in such nonstandard conditions classical control charts and capability indices must be modifi ed. In this paper the design of the methodology for the complex application of the statistical control on the metallurgical short run processes is presented and verifi ed in conditions of the bars rolling.Web of Science531848

Application of Bernoulli Process-based Charts to Electronic Assembly

The application of protective gel, which is a subprocess of the electronic assembly of the exhaust gas recirculation sensor, is a highly capable process with the fraction of nonconforming units as low as 200 ppm. Every unit is inspected immediately after gel application. The conventional Shewhart chart is of no use here, and the approach based on the Bernoulli process is therefore considered. The number of conforming items in a row until the occurrence of first or the r-th nonconforming is determined and CCC-r, CCC-r EWMA, and CCC CUSUM charts are applied. The aim of the control is to detect the process deterioration, and so the one-sided charts are used. So that the charts based on the geometric or negative binomial distribution can be compared, their performance is assessed through the average number of inspected units until a signal (ANOS). Our study confirmed that CCC-r EWMA and CCC CUSUM are able to detect the process shift more quickly than the CCC-r chart. Of the two charts, the first is easier to construct

Analysis and application of selected control charts suitable for smart manufacturing processes

Nonparametric control charts (NPCC) have shown great potential for monitoring processes in conditions of smart manufacturing with complex structures, various monitored characteristics and the need to process big data. Practical applications of NPCCs are very rare. The main reasons for this situation are a deficiency in software support and a lack of simple but complete instructions for their application. The introduction of such manual, which is based on the authors' own simulations of performance of wide spectrum of NPCCs in conditions of different violations of data prerequisites, leading to recommendations for the selection of the most effective NPCC in various practical situations, is the main goal of this paper. Compared to other similar studies, this approach covers a wider range of control charts, and it was applied to a wider spectrum of data assumption violations. As an integral part of these analyses, an examination of various control chart performance indicators such as ARL, MRL, x(5) and x(95) was performed using simulations to select the best of them. The designed methodology was verified using real data.Web of Science1211art. no. 541

Vybrané nástroje a metody z oblasti managementu kvality

Following paper describes selected tools and methods from Quality management field and their practical applications on defined examples. Solved examples were elaborated in the form of electronic support. This in detail elaborated electronic support provides students opportunity to thoroughly practice specific issues, help them to prepare for exams and consequently will lead to education improvement. Especially students of combined study form will appreciate this support. The paper specifies project objectives, subjects that will be covered by mentioned support, target groups, structure and the way of elaboration of electronic exercise book in view. The emphasis is not only on manual solution of selected examples that may help students to understand the principles and relationships, but also on solving and results interpreting of selected examples using software support. Statistic software Statgraphics Plus v 5.0 is used while working support, because it is free to use for all students of the faculty. Exemplary example from the subject Basic Statistical Methods of Quality Management is also part of this paper.Příspěvek popisuje vybrané nástroje a metody z oblasti Managementu kvality a jejich praktické aplikace na definovaných příkladech. Řešené příklady byly zpracovány ve formě elektronické podpory. Tato podrobně zpracovaná elektronická podpora, kterou ocení zejména studenti kombinované formy studia, poskytne studentům možnost více procvičit probíranou problematiku, připravit se na zkoušku a také přispěje ke zkvalitnění výuky. Příspěvek dále specifikuje cíle projektu, oblasti, které budou uvedenou sbírkou pokryty, cílové skupiny, strukturu a způsob zpracování zamýšlené elektronické sbírky příkladů. Při zpracování podpory je kladen důraz jak na ruční zpracování řešených úkolů, které mají studentům pomoci pochopit podstatu problému a souvislosti, tak na zpracování a interpretaci výsledků za použití softwarové podpory v podobě programu Statgraphics Plus v 5.0, který je studentům ve škole volně k dispozici. Součástí příspěvku je také vzorový příklad z předmětu Základní statistické metody managementu jakosti

Effective application of statistical process control (SPC) on the lengthwise tonsure rolled plates process

This paper deals with the eff ective application of SPC on the lengthwise tonsure rolled plates process on double side scissors. After explanation of the SPC fundamentals, goals and mistakes during the SPC implementation, the methodical framework for the eff ective SPC application is defi ned. In the next part of the paper the description of practical application of SPC and its analysis from the point of view of this framework is accomplished.Ovaj članak opisuje djelotvornu primjenu SKP na proces rezanja uzdužno namotanih limova na škarama s dvostrukom oštricom. Nakon objašnjenja osnova SKP, ciljeva i grešaka kod primjene SKP, metodski okvir za efektivnu primjenu SKP je defi niran. Sljedi opis praktične primjene SKP i njegove analiza sa stajališta da je opisani okvir primjene kompletan.Web of Science51114013

Návrh optimálního ewma regulačního diagramu s využitím vybraného statistického software

Today there are many statistical software packages wholly or partially specialized in statistical process control methods (SPC). They offer not only classical Shewhart control charts but also advanced methods suitable for non-standard situations when classical Shewhart methods fail. The ability to select the suitable control chart and insert data into the PC program is not sufficient for the effective and correct application of the selected control chart. The PC programs ask for some parameters whose optimal setting determinates correct application of the selected control chart. And information in Helps often is not sufficient. In this paper these problems are analyzed when designing optimal EWMA chart parameters using Statgraphics Plus, version 5.0.Dnes existuje řada statistických softwarových balíků, které jsou zcela nebo zčásti zaměřeny na metody statistické regulace procesu (SPC). Nabízejí nejen klasické Shewhartovy regulační diagramy, ale také pokročilejší metody vhodné pro nestandardní situace, ve kterých klasické Shewhartovy regulační diagramy selhávají. Pro efektivní a správnou aplikaci vybraného regulačního diagramu nestačí umět diagram správně vybrat a zadat data do počítače. PC programy dále vyžadují zadání určitých parametrů, jejichž správné stanovení rozhoduje o efektivnosti aplikace vybraného regulačního diagramu. Informace obsažené v Helpech programu často nejsou dostatečné. V tomto článku je uvedený problém analyzován v rámci návrhu optimálních hodnot parametrů EWMA regulačního diagramu za použití programu Statgraphics Plus, verze 5.0