Lean Compendium

The TPS has become the reference of modern high performance manufacturing systems. It has been spread and adopted in Europe under the American label of Lean Manufacturing (LM) also among other industries than the automotive because of its superior performance. Apart of the Kaizen-based continuous improvement management philosophy, the underlying TPS theory bases on a Just-in-time (JIT) type manufacturing approach. This manufacturing approach bases on “flow on pull” with Heijunka-pitch scheduling, i.e. self-controlled mixed-product cells, which performance is by far higher than those of traditional computer-controlled and optimized MRP 2-type (manufacturing resource planning) or ERP-type (enterprise resource planning) systems relying mainly on push “batch & queue” (B&Q) manufacturing. Indeed, Lean stands in contradiction to the western “high performance” thought of B&Q manufacturing of large batches to minimize setup downtimes and reducing cost per piece, exploiting equipment output, keeping blue collar workers busy and hurrying, i.e. showing an apparent high productivity. But the high level of busyness may contain a lot of non-necessarily needed activities, such as searching, bringing, handling, piling, waiting, so-called non-value add activities or inefficiencies which the Japanese call Muda (waste). Fujio Cho has defined waste as “anything other than the minimum amount of equipment, materials, parts, space, and worker’s time, which are absolutely essential to add value to the product”. Instead of a hurrying activism, the Japanese prefer not a calm but a waste-less sequence of activities at a constant pace resulting at the end of the day in a higher efficiency and efficacy.

In the following sections we will introduce the reader to the complexity of production systems. We will revisit the emblematic “two-pillar” temple model of the TPS giving to the systemic characteristics of the TPS also a suitable systemic representation by introducing an integrated “mono-pillar” model. This new Lean-systemic TPS model will be “le fil rouge” across this compendium to describe production theory of Lean. Furthermore, based on physical analogies we will enter into the basic concept of flow and define a thermodynamics-derived system of Lean Governing Principles.

In the following sections we develop some taxonomies regarding production, manufacturing and transfer principles. We introduce the queuing theory and related WIP formation defining the bottleneck and the general production requirements for OTD, constituting the cardinal concepts of production.

After having introduced the three basic laws of production, given by the

In Chap. 4 we have developed the performance metrics of manufacturing and process lead time applied to SPF and B&Q principle enunciating the following theorems for a mono-product cell:

In Chap. 5 we have developed the concept of multi-product, also called mixed-product, manufacturing cell, to maximize cell utilization and to increase at the same time the flexibility of a self-controlled manufacturing unit enouncing the following theorems:

In Chap. 6 we developed the concepts of linking different manufacturing cells to an entire production system. Supermarkets were introduced to decouple demand and supply due to different call-off and replenishment rates. We enounced the

In the previous chapters we have been going through the manufacturing theory, which stands at the base of the systemic mono-pillar Lean model of Fig. 2.​3. The enounced theorems, corollaries and lemmas represent the theoretic foundation of a complex and at the same time most performant manufacturing system. Nevertheless, it is the implementation of such a Lean manufacturing system and the continuous improvement which represents the real challenge.