Production planning with capacitated resources and congestion

Abstract

The book gives a thorough and extensive overview of the research related to production planning. This is an important problem for industry, as the topic of production planning in practice still leaves much to be desired. Especially for job shops, production planning is seen as difficult, resulting in many inefficiencies and less-than-satisfying production performances. The first three chapters of the book serve as an overview and introduction, where the first chapter introduces the problem, the second chapter defines some relevant KPI, and the third chapter gives an overview of the different production planning frameworks. The book then starts to go deeper into the different frameworks for production planning. Chapter 4 focuses on the field of workload control, chapter 5 on models assuming fixed lead times, and chapter 6 on models for time-varying lead times. The subsequent chapters look deeper at clearing functions, with chapter 7 on univariate clearing functions, chapter 8 on multivariate clearing functions, chapter 9 on lot sizing in clearing functions, and chapter 10 on application of clearing functions before the final chapter 11 concludes the book. Overall, this book by the two authors who are well known in this field is a very thorough and extensive literature review of the existing research on production planning. It includes hundreds of references up to 2019. The aim of the book is to give a structured overview of existing research. In the authors own words, they want to ‘[... raise] more questions in the mind of the reader than [to answer ... ]’ (pg. 276). The target audience are academic researchers focussing on the field of production planning. The book is far up in the ivory tower, and has few uses for practitioners, either due to the limitations and assumptions of the models, or due to the mathematical complexity exceeding the ability of the average production professional. Even for academics it is a tough read, and most readers will likely focus on selected topics of the book rather than reading it cover to cover. Hence, it is not a large problem that the different sections are not well-integrated. For example, the mathematical nomenclature is not consistent even within chapters, and usually uses the variables as found in the source references. Some variables would also benefit from a more concise explanation or definition. Similar applies to the figures, which also frequently originate from the references and have vastly different styles. Other figures that seem original to the book lack rigour. The differentiation using colours will be lost in greyscale printing, lines are sometimes not straight, and text in figures is misaligned. In combination, this gives some illustrations and equations an unfinished appearance. It is a bit more problematic that the wording is also not consistent. For example, the lead time is often but not always called ‘cycle time’—which in industry often has a very different meaning than lead time. Variability and variance also seem to be sometimes used interchangeably. The book is also focussed very much on make-to-order production—admittedly the more difficult production planning topic—but is rather thin on make-to-stock related problems. The book focuses on lead time, which would be a less relevant KPI for make-to-stock production. Some other highly related topics like pull production and kanban get barely a passing mention. A few chapters include critical views, but most chapters leave it up to the reader to decide which method is most applicable. On the other hand, a thorough critique of the body of research in this field would be a monumental task on its own. Overall, this book is a structured guide to the available research in the field of production planning. It will help in fleshing out the literature review section for academic papers. However, it helps much less with the grunt work of actually digging through the papers and understanding the research and the mathematics behind them. For a deeper understanding, the original sources will continue to be necessary, but this book will helpfully guide the readers towards these sources.