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Book Reviews: World Class Manufacturing Casebook: Implementing JIT and TQC by Richard Schonberger

Schonberger is often credited as originator of the phrase “World Class Manufacturing”. Since the early 1980’s he has been publicly beating the Just-In-Time drum. Although the popularity of JIT in general and Kanban systems in particular has waxed and waned over the years (remember Quality Circles?), the basic concepts are here to stay:

Inventory hides problems and increases costs.

Cutting inventory forces you to solve these problems.

A ruthless depletion of inventory logically leads to a manufacturing line with closely coupled stations, where each station begins work only when the downstream station requires it. Thus inventory is pulled through the line rather than pushed through it.

In this casebook, Schonberger presents descriptions of 26 JIT implementations. The majority of the sites are in the U.S., with the remainder in Asia. None of the cases are wafer fabs, although several assembly/test facilities are included. Each case includes discussion questions (for Schonberger’s thoughts on the questions, see “Instructor’s Manual to Accompany World Class Manufacturing Casebook: Implementing JIT and TQC”). The casebook is designed as a companion to Schonberger’s “World Class Manufacturing: The Lessons of Simplicity Applied.”

Kanban implementations have been attempted in a number of wafer fabs, but the results have been decidedly mixed. In light of this, it seems worthwhile to periodically review the original JIT literature, both for useful principles and for explanations as to the difficulty of wafer fab implementation.

In terms of useful principles, Schonberger has a section on “JIT ratio analysis” that is worth reviewing. In it, he discusses three ratios:

Lead-time to work content: This measure is widely used in wafer fabs, and is commonly referred to as the “cycle time multiplier” or “X-factor” (the ratio of actual cycle time to raw process time).

Process speed to sales rate: This measure is not often seen in wafer fabs (probably because it is most applicable to assembly line layouts). It refers to the ratio of production rate to consumption rate. For example, if an upstream tool is capable of 60 wafers per hour while the downstream tool is only capable of 10 wafers per hour, the process speed to sales rate ratio would be 6. The JIT goal is to drive this ratio to 1, e.g. to achieve a perfectly balanced line. Theory-of-Constraints advocates will necessarily disagree with this particular Goal.

Number of pieces to number of workstations: This measure is not often seen in wafer fabs, but it does offer useful insight. It is similar to the “lead-time to work content” ratio, but viewed through a different window, namely counting inventory (in wafers) and dividing by the number of tools. A high ratio indicates excess inventory or numerous large batch tools (in either case, bad for cycle time).

In terms of JIT implementation difficulties in wafer fabs, a quick scan of the 26 cases reveals the following:

Most of the factories surveyed were able to move equipment with relative ease. In wafer fabs, moving a single tool (let alone many tools) is often difficult, with problems ranging from utility support lines to regulatory permits.

Most of the factories surveyed had relatively short manufacturing process flows, ranging in length from 5 steps up to 25 steps. Most wafer fab process flows involve hundreds of steps.

Although these factors do not mean that implementing JIT/Kanbans in a wafer fab is impossible, they do indicate there will be hurdles unique to wafer fabs. And in any event, we may still profit from a thoughtful application of JIT principles and concepts.

If you are interested in the history of JIT’s introduction to the US, this book is for you. If you are interested in the details of JIT implementation, and you don’t mind the dated nature of the examples, this book is a useful reference. If you are interested in applying JIT to wafer fabs, you’d best keep looking. Personally, we would like to see a follow-up to these cases, a JIT reunion of sorts, to learn the fates of these 26 factories.

If you would like to buy this book, just click on the following link to open a new window and go directly to The World Class Manufacturing Casebook on Amazon’s website. FabTime is an Amazon affiliate.