A new approach for evaluation of risk priorities of failure modes in FMEA

This paper presents a method for carrying out the calculus of the risk priority of failures in Failure Mode and Effect Analysis (FMEA). The novelty of the method consists of new management of data provided by the design team, normally given on qualitative scales, without necessitating an arbitrary and artificial numerical conversion. The practical effects of these issues are shown in an application example

Composition laws for learning curves of industrial manufacturingprocesses

The theory of learning curves is widely investigated in many fields related to production planning, quality improvement and cost analysis. Many different approaches to describe the learning mechanism of a process are reported in the academic literature. The aim is to analyse the behaviour of complex systems composed of a network of elementary processes whose learning curve is known. Composition laws of two basic aggregation structures, series and parallel, are discussed and analysed. The effects of these composition laws are shown in a series of practical examples

A New Forecasting Model for the Diffusion of ISO 9000 Standard Certifications in European Countries

ISO 9000 standards for quality system management are involving a higher and higher number of enterprises and organizations. This paper presents a detailed analysis of certification diffusion in Italy and in some European countries with similar economic structures. Benchmarking and evolution forecasts are based on the "logistic model", traditionally used for studying biological growth phenomena. The presentation is supported by many empirical data, which show that, in many countries, the phenomenon is going to be close to saturation. Finally, some considerations about new developments, after the present "certification era", are proposed

Qualitative ordinal scales: the concept of ordinal range

Many practical problems of quality control involve the use of ordinal scales. Questionnaires planned to collect judgments on qualitative or linguistic scales, whose levels are terms such as "good," "bad," "medium," etc., are extensively used both in evaluating service quality and in visual controls for manufacturing industry. In an ordinal environment, the concept of distance between two generic levels of the same scale is not defined. Therefore, a population (universe) of judgments cannot be described using "traditional" statistical distributions since they are based on the notion of distance. The concept of "distribution shape" cannot be defined as well. In this article, we introduce a new statistical entity, the so-called ordinal distribution, to describe a population of judgments expressed on an ordinal scale. We also discuss which of the traditional location and dispersion measures can be used in this context and we briefly analyze some of their properties. A new dispersion measure, the ordinal range, as an extension of the cardinal range to ordinal scales, is then proposed. A practical application in the field of quality is developed throughout the articl

Outsourcing: guidelines for a structured approach

Outsourcing is a management approach by which an organization delegates some noncore functions to specialized and ef®cient service providers. In the era of ªglobal marketº and ªe-economyº, outsourcing is one of the main pillars of the new way to conceive the relationships among companies. Despite outsourcing large diffusion, huge business cases and big deals of documentation available on network or press, there is no structured procedure able to support the govern of the evolution of a generic outsourcing process. In accordance with the principles of total quality management, this paper describes a proposal of a new approach for managing outsourcing processes. The model, which can be easily adapted to different application ®elds, has been conceived with the main aim of managing strategic decisions, economic factors and human resources. The approach is supported by different decision and analysis tools, such as benchmarking techniques, multiple criteria decision aiding (MCDA) methods, cost analysis, and other process-planning methodologies. An application of the method to a real case is also provide

A short survey on Air Quality Indicators: properties, use and (mis)use

Purpose - Analysis and comparison of three existing indicators of the air quality: the American air quality index, the French Atmo, and the Italian Indice di Qualita` dell'Aria. Design/methodology/approach - International general and organic regulations to control air quality do not exist yet. Consequently many countries have independently implemented specific indicators to monitor the air pollution and then alert people of resulting health risks. The paper focuses on three of them. Each one is independently presented showing the peculiarities. Therefore, these indicators are compared to identify the features they have in common, as well as those that set them apart, and to figure out which are either restrictive or permissive, and what are their qualities and drawbacks. Findings - The three mentioned indicators convert the real health risk due to air pollution into numerical information, in different ways. Doing this, they carry out some simplifications or assumptions, which can be questionable. The main difficulty is to understand if the indicators aggregate the different pollutant concentrations consistently with the real effects on human health. Research limitations/implications - This paper analyses only three specific indicators of the air quality, selected among the existing ones. Practical implications - Indicators should carefully be analysed to understand if they properly represents the real effects of pollutants on human health. The most critical aspect to consider is the aggregation of the different pollutant concentrations in one information. Originality/value - This paper analyses the efficacy of representation of some air quality indicators. It discusses if indicators aggregation is consistent with the real effects on human healt

An empirical investigation of learning curve composition laws for quality improvement in complex manufacturing plans

Learning behaviors related to quality improvement in manufacturing systems (i.e. reduction of defectiveness over production cycles) are widely investigated. Many different approaches have been introduced to describe the link between the learning mechanism and quality performance of a plant. In a previous study by the same authors, a set of learning "composition laws" for two basic structures were defined to provide a tool to forecast the behavior of complex manufacturing systems composed by a network of elementary processes. This paper presents an empirical investigation about these learning composition laws on a real case in the field of automotive exhaust-systems manufacturin

Corrective algorithms for measurement improvement in MScMS-II (Mobile Spatial coordinate Measurement System)

This paper presents a set of algorithms for the correction of measurement errors of a prototype system designed for Large Scale Dimensional Metrology (LSDM) applications. The system, developed in the Quality and Industrial Metrology Laboratory of Politecnico di Torino, is based on the principles of photogrammetry and consists of a set of cameras wirelessly connected to a central unit able to track the position of a portable contact probe. Due to its architecture the system is affected by several systematic error sources. This paper addresses some of them: the distortion of the lenses, the dimension of the probe tip and the kinematic of the probe. By means of the implementation of appropriate mathematical correction models, the overall system performance is significantly improved as shown by the conducted test

Classification of Performance and Quality Indicators in Manufacturing

A critical aspect in operations management is to represent the firm goals properly. This is usually done by translating the organisational results and objectives in ‘performance measurements'. The scientific literature shows many applications in different fields such as quality, production, logistics, marketing, etc. Nevertheless, a general theory formalising basic and application concepts is still lacking. This paper shows a classification of ‘performance indicators' in manufacturing, providing a mathematical structure to the concept of ‘indicator'. This approach is based on the formalism of the Representation Theory. All the mentioned concepts are explained and discussed through practical example