A STUDY OF QUEUING THEORY IN LOW TO HIGH REWORK ENVIRONMENTS WITH PROCESS AVAILABILITY

In manufacturing systems subject to machine and operator resource constraints the effects of rework can be profound. High levels of rework burden the resources unnecessarily and as the utilization of these resources increases the expected queuing time of work in process increases exponentially. Queuing models can help managers to understand and control the effects of rework, but often this tool is overlooked in part because of concerns over accuracy in complex environments and/or the need for limiting assumptions. One aim of this work is to increase understanding of system variables on the accuracy of simple queuing models. A queuing model is proposed that combines G/G/1 modeling techniques for rework with effective processing time techniques for machine availability and the accuracy of this model is tested under varying levels of rework, external arrival variability, and machine availability. Results show that the model performs best under exponential arrival patterns and can perform well even under high rework conditions. Generalizations are made with regards to the use of this tool for allocation of jobs to specific workers and/or machines based on known rework rates with the ultimate aim of queue time minimization

The lot sizing problem: A tertiary study

This paper provides a survey of literature reviews in the area of lot sizing. Its intention is to show which streams of research emerged from Harris' seminal lot size model, and which major achievements have been accomplished in the respective areas. We first develop the methodology of this review and then descriptively analyze the sample. Subsequently, a content-related classification scheme for lot sizing models is developed, and the reviews contained in our sample are discussed in light of this classification scheme. Our analysis shows that various extensions of Harris' lot size model were developed over the years, such as lot sizing models that include multi-stage inventory systems, incentives, or productivity issues. The aims of our tertiary study are the following: firstly, it helps primary researchers to position their own work in the literature, to reproduce the development of different types of lot sizing problems, and to find starting points if they intend to work in a new research direction. Secondly, the study identifies several topics that offer opportunities for future secondary research

Real time implementation of learning-forgetting models for cycle time predictions of manual assembly tasks after a break

Industry 4.0 provides a tremendous potential of data from the work floor. For manufacturing companies, these data can be very useful in order to support assembly operators. In literature, a lot of contributions can be found that present models to describe both the learning and forgetting effect of manual assembly operations. In this study, different existing models were compared in order to predict the cycle time after a break. As these models are not created for a real time prediction purpose, some adaptations are presented in order to improve the robustness and efficiency of the models. Results show that the MLFCM (modified learn-forget curve model) and the PID (power integration diffusion) model have the greatest potential. Further research will be performed to test both models and implement contextual factors. In addition, since these models only consider one fixed repetitive task, they don't target mixed-model assembly operations. The learning and forgetting effect that executing each assembly task has on the other task executions differs based on the job similarity between tasks. Further research opportunities to implement this job similarity are listed

Application of Optimization in Production, Logistics, Inventory, Supply Chain Management and Block Chain

The evolution of industrial development since the 18th century is now experiencing the fourth industrial revolution. The effect of the development has propagated into almost every sector of the industry. From inventory to the circular economy, the effectiveness of technology has been fruitful for industry. The recent trends in research, with new ideas and methodologies, are included in this book. Several new ideas and business strategies are developed in the area of the supply chain management, logistics, optimization, and forecasting for the improvement of the economy of the society and the environment. The proposed technologies and ideas are either novel or help modify several other new ideas. Different real life problems with different dimensions are discussed in the book so that readers may connect with the recent issues in society and industry. The collection of the articles provides a glimpse into the new research trends in technology, business, and the environment

An empirical investigation of manufacturing flexibility and organizational performance as moderated by strategic integration and organizational infrastructure.

The purpose of this study is empirically investigating four research questions related to manufacturing flexibility. 1) What are the components of manufacturing flexibility? 2) Is there a relationship between manufacturing flexibility and organizational performance? 3) Do integrated strategies strengthen the relationship between manufacturing flexibility and organizational performance? 4) Are there organizational characteristics that strengthen the relationship between manufacturing flexibility and organizational performance? This study used a cross-sectional survey design to collect data from manufacturing organizations in multiple industries. Organizational performance was quantified using common manufacturing measures. Strategic integration and organizational infrastructure were also measured. Data were collected using a self-administered questionnaire. Factor analysis, correlation analysis, and regression were used to analyze the data. The results indicate the variables and expected relationships exist as hypothesized. This study contributes to the manufacturing flexibility body of knowledge by identifying relationships between the manufacturing flexibility component, performance, strategic integration, and organizational infrastructure. The instrument development in this study is of particular value as there are few rigorously developed and validated instruments to measure the manufacturing flexibility components and performance. Understanding these relationships will help practitioners make better decisions in manufacturing organizations as well as enable application of the concepts in this study to other contexts such as service organizations

Lean and performance: an assessment on North-East Italy

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Production capacity increase planning and strategy: The case study of Wingsys

In times of global uncertainty, when all business areas are dueling with fierce competition, as a result of global and more than ever democratic digitalization, it is necessary and relevant to rethink production capacity in a holistic way. Without ever forgetting the external stakeholders and naturally the customers, it is often in the internal stakeholders that the key to unlock higher revenues, while reducing costs and waste, can be found. Based on Lean Manufacturing concepts and Value Stream Mapping technique, the main goal is to provide to Interactive Equipment Manufacturer Wingsys a comprehensive strategy and action plan with relevant solutions that can be effectively implemented and that will allow the production capacity to increase in a level that is sustainable, cost-efficient and a win-win between the company, its personnel, and its customers.Numa era de incerteza Global, em que todas as empresas se debatem com uma competição feroz em todas as áreas de negócio, fruto de uma digitalização cada mais democrática e global, é necessário e relevante repensar o conceito de capacidade produção de forma holística. Sem nunca esquecer os parceiros externos e, naturalmente os clientes, é frequentemente internamente que se encontra a chave para alcançar maiores receitas, ao mesmo tempo que se reduzem custos, e, sobretudo, desperdício. Baseado no conceito de Produção Lean do Sistema de Produção da Toyota e na técnica de Value Stream Mapping, o objetivo principal deste documento é fornecer à empresa produtora de equipamento interativo Wingsys uma estratégia completa e um plano de ação com soluções relevantes que possam ser implementadas de modo a permitir um aumento de capacidade de produção de maneira sustentável, economicamente viável e com benefícios para a empresa, os seus colaboradores e os seus clientes