Product Quality Performance Research Articles

Constructing BCa Bootstrap Confidence Interval for the Difference between Two Non-normal Process Capability Indices C Npmk

ABSTRACT Process capability index is a highly effective means of assessing product quality and process performance. Among many developed process capability indices, C p , C pk , C pm , and C pmk are the four most popular indices under normally distributed processes. Engineers always emphasize applicability and accuracy when a capability index is used to measure how a process performs. However, using these traditional indices to evaluate a non-normally distributed process often leads to inaccurate results. Thus, C Np , C Npk , C Npm , and C Npmk were proposed to overcome this shortcoming under non-normally distributed processes. Pearn and Kotz (1994) compared the index C Npmk to C Np , C Npk , and C Npm as well as found C Npmk is more restrictive and sensitive with regard to process median deviation from the target value than the other indices. Thus, this study employed an appropriate index C Npmk to evaluate non-normally and normally distributed processes. However, the exact probability distribution of C Npmk is too complicated to be derived. Consequently, the related hypotheses testing and confidence interval cannot be developed. For this reason, the applicability of C Npmk is limited. The main purpose of this study is to utilize bootstrap simulation method to construct a 100(1 − 2α)% BCa confidence interval for the difference between two indices, C Npmk1 − C Npmk2. The proposed bootstrap interval can be effectively employed to determine which one of the two processes or suppliers has a better process capability. Moreover, engineers without much statistics background can also easily adopt the proposed index and related procedures to compare processes or select suppliers. If this research procedure performs effectively, the industries can use it to analyze the capabilities of any process distributions in the future.

Simulation-based optimization of thermal systems

This paper considers the design and optimization of thermal systems on the basis of the mathematical and numerical modeling of the system. Many complexities are often encountered in practical thermal processes and systems, making the modeling challenging and involved. These include property variations, complicated regions, combined transport mechanisms, chemical reactions, and intricate boundary conditions. The paper briefly presents approaches that may be used to accurately simulate these systems. Validation of the numerical model is a particularly critical aspect and is discussed. It is important to couple the modeling with the system performance, design, control and optimization. This aspect, which has often been ignored in the literature, is considered in this paper. Design of thermal systems based on concurrent simulation and experimentation is also discussed in terms of dynamic data-driven optimization methods. Optimization of the system and of the operating conditions is needed to minimize costs and improve product quality and system performance. Different optimization strategies that are currently used for thermal systems are outlined, focusing on new and emerging strategies. Of particular interest is multi-objective optimization, since most thermal systems involve several important objective functions, such as heat transfer rate and pressure in electronic cooling systems. A few practical thermal systems are considered in greater detail to illustrate these approaches and to present typical simulation, design and optimization results.

Robust design of digital multiple dynamic systems

Robust design is a widely employed methodology in many different industries for improving product quality and process performance of both static and dynamic systems. Problems where the output varies depending on the input are classified as dynamic systems. If both input and output have only two digital values (0 and 1) with the possibility of committing two types of errors, such a problem is called digital dynamic system. The SIS ratio recommended by Taguchi is based on the errors with the same loss coefficient to optimize the problem. However, the losses due to the two types of errors are not equal in practice, especially in the field of chemistry. This paper proposes a general model for optimizing parameter design and selecting threshold value in the digital multiple dynamic systems. The implementation and the effectiveness of the proposed approach are illustrated through a case study.

Integrated Analysis of Quality and Production Logistics Performance in Asynchronous Manufacturing Lines

The evaluation of quality and production logistics performance measures in production lines has been traditionally considered by two separate research areas. However, the industrial reality shows that quality control strategies have an impact on the system production logistics performance as well as the system configuration has an impact on the quality control system reactivity. Therefore, in order to support the phase of design, operation and management of production lines, integrated methodologies and tools able to capture these bilateral relations and to evaluate the overall system performance are needed. The paper presents a new approximate analytical method developed to estimate the quality and productivity performance measures of asynchronous production lines in which quality control chart are present. The control action performed to prevent machines from working out of control is integrated in the manufacturing system model and the delay in the transmission of the quality information, due to the system architecture, is directly taken into account. The method is proved to be accurate and useful to derive new insights regarding the behavior of the considered systems. The proposed approach paves the way to the development of innovative methodologies to design production systems, jointly achieving the required product quality and system productivity performance.

Plant location, ISO 9000 certifications and quality management practices

PurposeThe main purpose of this study is to examine the impact of the country in which a manufacturing plant is located on its ability to achieve one or more of the ISO certifications, and the extent to which six other quality management practices have been implemented. It also examines the impact of achieving world class manufacturing status (WCM) on product quality. Product quality was measured by finished‐product first‐pass yield, scrap and rework costs, and warranty costs as percentages of sales.Design/methodology/approachThe analyses are based on empirical data collected from more than 2900 manufacturing plants in the USA Canada, and Mexico.FindingsThe results show that there are significant differences in the plants' efforts to achieve quality certifications. Significant differences were also found in the extent to which six other quality management techniques are implemented. More important, our results show that there are significant differences in product quality performance among plants with different levels of progress toward achieving WCM status.Originality/valueThe findings of this study have many implications for both academic and practitioners who are interested in studying the impact of ISO 9000 and Quality Management practices.

Authentication of vegetable oils on the basis of their physico-chemical properties with the aid of chemometrics

In food production, reliable analytical methods for confirmation of purity or degree of spoilage are required by growers, food quality assessors, processors, and consumers. Seven parameters of physico-chemical properties, such as acid number, colority, density, refractive index, moisture and volatility, saponification value and peroxide value, were measured for quality and adulterated soybean, as well as quality and rancid rapeseed oils. Chemometrics methods were then applied for qualitative and quantitative discrimination and prediction of the oils by methods such exploratory principal component analysis (PCA), partial least squares (PLS), radial basis function-artificial neural networks (RBF-ANN), and multi-criteria decision making methods (MCDM), PROMETHEE and GAIA. In general, the soybean and rapeseed oils were discriminated by PCA, and the two spoilt oils behaved differently with the rancid rapeseed samples exhibiting more object scatter on the PC-scores plot, than the adulterated soybean oil. For the PLS and RBF-ANN prediction methods, suitable training models were devised, which were able to predict satisfactorily the category of the four different oil samples in the verification set. Rank ordering with the use of MCDM models indicated that the oil types can be discriminated on the PROMETHEE II scale. For the first time, it was demonstrated how ranking of oil objects with the use of PROMETHEE and GAIA could be utilized as a versatile indicator of quality performance of products on the basis of a standard selected by the stakeholder. In principle, this approach provides a very flexible method for assessment of product quality directly from the measured data.

The role of the Therapeutic Goods Administration and the Medicine and Medical Devices Safety Authority in evaluating complementary and alternative medicines in Australia and New Zealand

Currently, the regulation of complementary and alternative medicines and related health claims in Australia and New Zealand is managed in a number of ways. Complementary medicines, including herbal, minerals, nutritional/dietary supplements, aromatherapy oils and homeopathic medicines are regulated under therapeutic goods/products legislation. The Therapeutic Goods Administration (TGA), a division of the Commonwealth Department of Health and Ageing is responsible for administering the provisions of the legislation in Australia. The New Zealand Medicines and Medical Devices Safety Authority (Medsafe) administers the provision of legislation in New Zealand. In December 2003 the Australian and New Zealand governments signed a Treaty to establish a single, bi-national agency to regulate therapeutic products, including medical devices prescription, over-the-counter and complementary medicines. A single agency will replace the Australian TGA and the New Zealand Medsafe. The role of the new agency will be to safeguard public health through regulation of the quality, safety and efficacy or performance of therapeutic products in both Australia and New Zealand. The major activities of the new joint Australia New Zealand therapeutic products agency are in product licensing, specifying labelling standards and setting the advertising scheme, together with determining the risk classes of medicines and creating an expanded list of ingredients permitted in Class I medicines. A new, expanded definition of complementary medicines is proposed and this definition is currently under consultation. Related Australian and New Zealand legislation is being developed to implement the joint scheme. Once this legislation is passed, the Treaty will come into force and the new joint regulatory scheme will begin. The agency is expected to commence operation no later than 1 July 2006 and will result in a single agency to regulate complementary and alternative medicines.

Effects of Firms’ Relationship-Oriented Behaviors on Financial Performance: A Case of the Restaurant Industry

The business-to-business and business-to-customer relationship marketing literature includes little effort to develop a conceptual framework for understanding both supplier and customer relationship-oriented behaviors. The purpose of this study is to investigate how a firm’s supplier and customer relationship-oriented behaviors affect its financial performance through three relationship performance outcomes: supplier relationship performance, product and service quality performance, and customer relationship performance. The authors critically revisit extant knowledge on the subject, develop a conceptual framework integrating supplier and customer relationship management practices, and test the framework in the independent restaurant industry context. Results support the usefulness of the framework and suggest that building relationships with suppliers and customers plays an important role in providing values to restaurant firms and stakeholders such as suppliers and customers, leading to high financial performance of the restaurant firms.

Value-Based Differentiation in Business Relationships: Gaining and Sustaining Key Supplier Status

Many business customers today consolidate their supply bases and implement preferred supplier programs. Consequently, vendors increasingly face the alternative of either gaining a key supplier status with their customers or being pushed into the role of a backup supplier. As product and price become less important differentiators, suppliers of routinely purchased products search for new ways to differentiate themselves in a buyer–seller relationship. This research investigates avenues for differentiation through value creation in business-to-business relationships. The results suggest that relationship benefits display a stronger potential for differentiation in key supplier relationships than cost considerations. The authors identify service support and personal interaction as core differentiators, followed by a supplier's know-how and its ability to improve a customer's time to market. Product quality and delivery performance, along with acquisition costs and operation costs, display a moderate potential to help a firm gain and maintain key supplier status. Finally, price shows the weakest potential for differentiation.

Value-Based Differentiation in Business Relationships: Gaining and Sustaining Key Supplier Status

Many business customers today consolidate their supply bases and implement preferred supplier programs. Consequently, vendors increasingly face the alternative of either gaining a key supplier status with their customers or being pushed into the role of a backup supplier. As product and price become less important differentiators, suppliers of routinely purchased products search for new ways to differentiate themselves in a buyer–seller relationship. This research investigates avenues for differentiation through value creation in business-to-business relationships. The results suggest that relationship benefits display a stronger potential for differentiation in key supplier relationships than cost considerations. The authors identify service support and personal interaction as core differentiators, followed by a supplier's know-how and its ability to improve a customer's time to market. Product quality and delivery performance, along with acquisition costs and operation costs, display a moderate potential to help a firm gain and maintain key supplier status. Finally, price shows the weakest potential for differentiation.

A parameters design approach to improve product quality and equipment performance in hot rolling

This study presents the application of parameters design to improve both the product quality and the equipment performance in a hot sheet rolling plant. Three empirical models were developed to predict and explain the relationship between variation in some process parameters and the type and range of product defects together with equipment disorders observed. The investigation is based on the analysis of the results of a set of designed experiments. The most critical process parameters were set at specified values and the effect of the change in these parameters, on rolled sheets quality and rolling equipment performance is evaluated. The three process parameters considered are the reduction ratio (Rd), the slab temperature ( T s), and the exit strip speed (Sp). The quality characteristics considered are: profile and flatness of rolled sheets and distance between chatter marks, the performance indicators considered are: rolling force, vibration measurements, and the rolling mill wear rate. Through optimization of process parameters, it was possible to reduce chattering. Consequently, chatter marks and roll wear were greatly reduced. Product flatness and profile were improved. Plant down time and production scrap was considerably reduced. This investigation proved that it is possible to improve both product quality and equipment performance in the hot rolling plant through the parameters design approach.

Genetic Selection for Heat Tolerance and Low Temperature Activity of the Entomopathogenic Nematode–bacterium Complex Heterorhabditis Bacteriophora–Photorhabdus Luminescens

The entomopathogenic nematode–bacterium complex Heterorhabditis bacteriophora–Photorhabdus luminescens is used in commercial biocontrol of insect pests. Tolerance and activity of the nematodes at extreme environmental conditions can limit the shelf life, quality and field performance of nematode-based products. To overcome these limitations, the potential for genetic improvement of the heat tolerance and the activity at low temperature was investigated. Heat tolerance and cold activity are quantitative traits, influenced by several genes and environmental factors. The breeding success for such traits depends on the genetic proportion on the phenotypic variability, the heritability, which was determined by recording the variability within and between homozygous inbred lines. The heritability for heat tolerance was 0.68 and for activity at low temperature 0.38. To increase heat tolerance, 4 selection steps were carried out, which increased the mean tolerated temperature from 38.5 to 39.2 °C. The mean temperature at which the dauer juveniles of H. bacteriophora were active, could be reduced from 7.3 to 6.1 °C during the first 5 selection steps. However, for unknown reasons, it increased during the following 5 steps to 7.1 °C. A screening among different P. luminescens isolates for growth at low temperature resulted in several cold-adapted strains from North America, which reached considerable cell density at 6 °C.

Improving Cut/Chip/Chunk Resistance in Truck Tyres by the Use of Para-Amid Chopped Fibres

The tyre industry is continually striving to improve the cut/chip/chunk resistance of tyre treads while simultaneously maintaining a high level of product quality and product performance. Several approaches have been explored in which the fillers are varied, the cure package is optimised or polymers and their blend ratios are changed, but although each approach provides improvements with regard to cut/chip/chunk resistance, this is at the expense of hysteresis, heat buildup and fatigue properties. With its complete portfolio of aramid fibres, p-aramid (Twaron and Technora) and m-aramid (Teijin Conex), the company Teijin Twaron is the world leader in the field of chopped fibre rubber reinforcement. These chopped fibres provide rubber compounders with a potent tool for expanding the performance of rubber products beyond their current horizons

Internal and External Integration for Product Development: The Contingency Effects of Uncertainty, Equivocality, and Platform Strategy

ABSTRACTEffective product development requires firms to unify internal and external participants. As companies attempt to create this integrated environment, two important questions emerge. Does a high level of internal integration lead to a higher level of external integration? In the context of product development, this study considers whether internal integration in the form of concurrent engineering practices affects the level of external integration as manifested by customer integration, supplier product integration, and supplier process integration. External integration, in turn, may influence competitive capabilities, namely product innovation performance and quality performance. Second, using contingency theory, do certain contextual variables moderate the linkages between integration strategy (external and internal) and performance? Specifically, this study considers whether uncertainty, equivocality, and platform development strategy change the relationships among internal integration, external integration, and competitive capabilities. Data collected from 244 manufacturing firms across several industries were used to test these research questions. The results indicate that both internal and external integration positively influence product innovation and quality and ultimately, profitability. With respect to contingency effects, the results indicate that equivocality moderates the relationships between integration and performance.

Adaptable Design

Increasing competition for better product functionality, quality, features, customization, environmental friendliness, lower cost and shorter delivery time presents unprecedented challenges for product manufacturing enterprises. These challenges cannot be completely addressed by advanced manufacturing technologies alone as some of which are originated from product design. Advanced design technologies and tools for early product design processes are critically needed where most important decisions are made with respect to the product functionality, quality, manufacturability, cost and environmental performance. This paper discusses adaptable design (AD) as a design paradigm for both business success and environmental protection. Adaptable design aims at developing products that are adaptable in their design and/or their production. Adaptability is defined as the extension of the utility (service) of products. Two types of adaptabilities are proposed as product adaptability and design adaptability. Two types of design adaptations are also identified, which include foreseeable specific adaptations and unforeseeable general adaptations. The former can be described by specific adaptability and the latter by general adaptability. Three key elements of AD are presented including functions independence, a measure of adaptability and a function based design process model of the AD. Based on these concepts and design objectives, adaptable design methods and general design guidelines are proposed. Examples are included to illustrate the concepts, design methods and guidelines.

The relationship between TQM practices, quality performance, and innovation performance

This empirical study examines the relationship between total quality management (TQM) and innovation performance and compares the nature of this relationship against quality performance. The empirical data were obtained from a survey of 194 managers in Australian industry encompassing both manufacturing and non‐manufacturing sectors. The structural equation modeling technique was used to examine the relationships between TQM and quality performance as well as innovation performance, simultaneously. The findings suggest that TQM significantly and positively relates to both product quality and product innovation performance although it appears that the magnitude of the relationship is greater against product quality. In addition, significant causal relationships between quality performance and innovation performance were found, suggesting that achievement of one aspect of performance could impact the other.

Measuring banking operation performance by applying a process capability index

Service quality is important when selecting a banking service. Many factors affecting service quality are not measurable, and it is difficult to consistently evaluate front-line personal operation performance in the banking system. Consequently, most of the banks use Methods Time Measurement (MTM-C) to improve banking operation quality and reduce customer service time. From the perspective of consumers, standardizing operation time is an important criterion when selecting a banking service, and the specification of banking service quality is in accordance with the process capability index Cpu applied in the manufacturing industry. The Cpu index is a powerful and effective tool for evaluating product quality or process performance. Hence, this paper attempts to measure banking operation quality via the process capability index Cpu, by setting standard operation times as an upper specification limits for each front-line operation item, and to provide useful information for the operations performance management in the banking system

Quality control of precast concrete products - a road owner’s perspective

Precast concrete components make up a significant portion of the road network infrastructure. In Queensland alone several billion dollars have been invested in various precast concrete products such as bridge girders, piles, culverts, pipes, retaining walls and noise barriers. However, unlike structures built for other industries, bridge and road infrastructure is required to provide a relatively long service life of a hundred years or more. The in-service maintenance of bridges can also be difficult and expensive, involving significant costs and inconvenience to the community, particularly if road closures are involved.So how can road authorities ensure the quality and long-term performance of precast concrete components in today’s price-driven market place? What effect do price-based purchasing policies, increased reliance on quality assurance systems, use of non-standard designs, global trading and inspection have on the quality of high-end precast products?This paper gives an overview of the effects of current policies and market trends, discusses recent problems in Queensland and outlines what Main Roads is doing to ensure high quality and longterm performance of precast concrete products.

Product quality, environmental accounting and quality performance

Quality has typically been regarded as a key strategic component of competitive advantage and, therefore, the enhancement of product quality has been a matter of prime interest to firms. Quality provides a basis for strategic advantage, and thus improvement in product quality may lead to enhanced performance. However, a frequent concern is that product quality no longer provides enduring competitive advantage; instead, it has become essentially a competitive prerequisite. Hence, an assessment of whether improvements in product quality are reflected in greater quality performance is likely to be of considerable interest to organizations. Suggestions have been made that the implementation of environmental accounting also contributes to the enhancement of quality performance. Argues that the greater the integration of environmental issues into financial decision processes, the better the performance of the firm. Investigates the extent to which product quality and the implementation of environmental accounting positively influence quality performance.

Applied product quality knowledge and performance

This research challenges the idea of an unconditional and positive influence of knowledge on performance without regard to environmental uncertainty. We focus on applied product quality knowledge spanning the supply chain (i.e. supplier, internal, and customer quality sources are considered). A survey of 208 manufacturing firms examined the moderating influence of product churning (uncertainty) and demand unpredictability on the association between applied product quality knowledge and firm performance. We also controlled for firm size and production technology. Firms that can determine a fit between their product quality knowledge application and the types of environmental uncertainty they face will perform better in terms of market and financial performance indicators.