All About Pull Production: Designing, Implementing, and Maintaining Kanban, CONWIP, and other Pull Systems in Lean Production

Abstract

The whole push versus pull conundrum has been made unnecessarily complicated by academics and practitioners alike. As such, this book promises to challenge the readers’ understanding of pull production – a core tenet in lean manufacturing. In doing so, it aims to bring some clarity to this confusion, and is set to become THE standard reference book on pull systems. With practical experience from Toyota, Bosch, and McKinsey & Company, combined with academic experience from Karlsruhe University of Applied Sciences, the author Prof. Dr. Christoph Roser has done a great justice in sharing more than 400 pages of actionable knowledge about different types of pull system and the various environments in which they can operate. From my personal experiences as a lean teacher, researcher, practitioner, and consultant, I have encountered many individuals that simply equate pull with make-to-order. This is of course in direct contradiction with the original supermarket pull systems developed to support just-in-time production, and one of several misconceptions of pull that are presented and explored by Prof. Roser in his book. As John Shook (Chairman, Lean Global Network) quite rightly points out in the foreword of the book, the widely accepted academic definition of a pull production system, ‘one [a system] that explicitly limits the amount of work in process that can be in the system’ (Hopp and Spearman 2004), is incorrect and has done more harm than good in many practical implementations. In this respect, Roser makes a valiant attempt to right such wrongs, and presents a detailed overview of several alternative, mainstream pull systems, including Kanban, CONWIP, POLCA, and even Drum-Buffer-Rope (DBR). It is also very interesting to read about COBACABANA – a less mainstream approach to pull but still worthy of a mention. And in (Braglia, Marrazzini, and Padellini 2020) you will find the real-world implementation of COBACABANA you are looking for, Christoph! Before going into the precise details of each of these different types of pull system and how one might go about implementing them, Roser provides a very useful assessment tool for practitioners wanting to select an appropriate pull system for their specific application area – be it make-tostock, make-to-order, flow shop, or job shop, for example. The book also covers the fundamentals of the first-in-firstout (FIFO) sequencing method and its alternatives, as well as provides some useful examples of pull systems applied in non-manufacturing settings, such as in Healthcare, Project Management, and Construction. As a fan of the Toyota Production System (TPS) and an avid lean advocate, I am impressed by the sheer extent of knowledge contained within this book regarding the original Kanban system – the history, origins, fundamentals, and variants, including digital Kanban (or e-Kanban, which funnily enough has become popular with the onset of Industry 4.0 but was implemented at Toyota already in 1993!). For those interested in the maths behind pull systems, the book also delivers here – with worked examples for Kanban, POLCA, CONWIP, and Reorder Point calculations; aptly supported with an abundance of figures and illustrations for those of us that are not as numerically gifted as others! Roser concludes that although pull is one of the powerful tools for lean manufacturing – ‘it is still only a tool’. He suggests that companies should rather start with a problem and work towards a solution – which I agree with completely. However, in rethinking lean as a learning system, we have come to realise that the lean tools that are often implemented as solutions for operational excellence instead become learning frames, and as such, pull should otherwise become a means of rapidly surfacing problems (quality, delivery, or otherwise), helping to build further lean capability – fostering a process of discovery, improvement, and learning for everyone in the organisation, every day. Nevertheless, this book – filled to the brim with practical guidance and useful examples – will certainly encourage managers to rethink their strategies, providing the means to create World class supply systems, anywhere, and in any industry.