Introduction to Lean Software Development

Editor's Notes

• #3 Eli Whitney is most famous as the inventor of the cotton gin ( cotton gin is a machine that quickly and easily separates the cotton fibers from the seeds). However, the gin was a minor accomplishment compared to his perfection of interchangeable parts. Whitney developed this about 1799 when he took a contract from the U.S. Army for the manufacture of 10,000 muskets at the unbelievably low price of $13.40 each.For the next 100 years manufacturers primarily concerned themselves with individual technologies. During this time our system of engineering drawings developed, modern machine tools were perfected and large scale processes such as the Bessemer process for making steel held the center of attention.Frederick W. Taylor began to look at individual workers and work methods. The result was Time Study and standardized work. Taylor was a  controversial figure. He called his ideas Scientific Management. The concept of applying science to management was sound but Taylor simply ignored the behavioral sciences. In addition, he had a peculiar attitude towards factory workers.Frank Gilbreth (Cheaper By The Dozen) added Motion Study and invented Process Charting. Process charts focused attention on all work elements including those non-value added elements which normally occur between the "official" elements. Lillian Gilbreth brought psychology into the mix by studying the motivations of workers and how attitudes affected the outcome of a process. There were, of course, many other contributors. These were the people who originated the idea of "eliminating waste", a key tenet of JIT and Lean Manufacturing.The Ford SystemAnd then, there was Henry Ford. Starting about 1910, Ford and his right-hand-man, Charles E. Sorensen, fashioned the first comprehensive Manufacturing Strategy. They took all the elements of a manufacturing system-- people, machines, tooling, and products-- and arranged them in a continuous system for manufacturing the Model T automobile. Ford was so incredibly successful he quickly became one of the world's richest men and put the world on wheels. Ford is considered by many to be the first practitioner of Just In Time and Lean Manufacturing.The Allied victory and the massive quantities of material behind it (see "A Bomber An Hour") caught the attention of Japanese industrialists. They studied American production methods with particular attention to Ford practices and the Statistical Quality Control practices of Ishikawa, Edwards Deming, and Joseph Juran.At Toyota Motor Company, TaichiiOhno and  Shigeo Shingo, began to incorporate Ford production  and other techniques into an approach called Toyota Production System orJust In Time . They recognized the central role of inventory.The Toyota people also recognized that the Ford system had contradictions and shortcomings, particularly with respect to employees. With General Douglas MacAurthur actively promoting labor unions in the occupation years, Ford's harsh attitudes and demeaning job structures were unworkable in post-war Japan. They were also unworkable in the American context, but that would not be evident for some years. America's "Greatest Generation" carried over attitudes from the Great Depression that made the system work in spite of its defects.Toyota soon discovered that factory workers had far more to contribute than just muscle power. This discovery probably originated in the  Quality Circle movement. Ishikawa, Deming, and Juran all made major contributions to the quality movement. It culminated in team development and cellular manufacturing.Another key discovery involved product variety. The Ford system was built around a single, never changing product. It did not cope well with multiple or new products. Shingo, at Ohno's suggestion, went to work on the setup and changeover problem. Reducing setups to minutes and seconds allowed small batches and an almost continuous flow like the original Ford concept. It introduced a flexibility that Henry Ford thought he did not need.All of this took place between about 1949 and 1975. To some extent it spread to other Japanese companies. When the productivity and quality gains became evident to the outside world, American executives traveled to Japan to study it. They brought back, mostly, the superficial aspects like kanban cards and quality circles.  Most early attempts to emulate Toyota failed because they were not integrated into a complete system and because few understood the underlying principles.World Class ManufacturingBy the 1980's some American manufacturers, such as Omark Industries, General Electric and Kawasaki (Lincoln,Nebraska) were achieving success. Consultants took up the campaign and acronyms sprouted like weeds: World Class Manufacturing (WCM), Stockless Production, Continuous Flow Manufacturing (CFM), and many other names all referred to systems that were, essentially, Toyota Production. Gradually, a knowledge and experience base developed and success stories became more frequent. Lean ManufacturingIn 1990 James Womack wrote a book called "The Machine That Changed The World". Womack's book was a straightforward account of the history of automobile manufacturing combined with a study of Japanese, American, and European automotive assembly plants. What was new was a phrase-- "Lean Manufacturing."Lean Manufacturing caught the imagination of manufacturing people in many countries. Lean implementations are now commonplace. The knowledge and experience base is expanding rapidly.The essential elements of Lean Manufacturing are described at our page "Principles of Lean Manufacturing." They do not substantially differ from the techniques developed by Ohno, Shingo and the people at Toyota. The application in any specific factory does change. Just as many firms copied Ford techniques in slavish and unthinking ways, many firms copy Toyota's techniques in slavish and unthinking ways and with poor results. Our series of articles on implementation includes a "Mental Model" to assist the thinking process and guidance on strategy and planning.There is no cookbook for manufacturing. Each firm has its own unique set of products, processes, people, and history. While certain principles may be immutable, their application is not. Manufacturing Strategy will always be a difficult, uncertain, and individual process. Strategy ("The General's Art") is still, largely, an art. But, that should not prevent us from bringing the available science to bear on the problem.
• #5 Requirements that will never be implementedUnnecessary documentationOvercomplicated functionalityOvercomplicated designManaging defect queues Polishing estimations
• #6 Cannot avoid it sometimes due to specialized expertise. Need to recognize it and work on reducing a need for sharing resources.
• #12 Share partially complete design informationUse modulesUse interfaces, parameters, abstractionsSeparate concernsEncapsulate variationsDefer implementation of future capabilities Avoid extra features
• #14 This equation gives us a clear idea of how to do that. One way to decrease cycle time is get things done faster increase the average completion rate. This usually means spending more money. If we don't have extra money to spend, the other way to reduce cycle time is to reduce the number of things in process. This takes a lot of intellectual fortitude, but it usually doesn't require much money.[5]Variation and UtilizationLittle's Law applies to stable systems, but there are a couple of things that make systems unstable. First there is variation stuff happens. Variation is often dealt with by reducing the size of batches moving through the system. For example, many stores have check-out lanes for "10 items or less" to reduce the variation in checkout time for that line. Let's say you have some code to integrate into a system. If it's six weeks' worth of work, you can be sure there will be a lot of problems. But if it's only 60 minutes of work, the amount of stuff that can go wrong is limited. If you have large projects, schedule variation will be enormous. Small projects will exhibit considerably less schedule variation.Decreasing variability earlier in the process has larger impact than decreasing variability late in the process
• #15 Google 80% utilizationHigh utilization is another thing that makes systems unstable. This is obvious to anyone who has ever been caught in a traffic jam. Once the utilization of the road goes above about 80 percent, the speed of the traffic starts to slow down. Add a few more cars and pretty soon you are moving at a crawl. When operations managers see their servers running at 80 percent capacity at peak times, they know that response time is beginning to suffer, and they quickly get more servers.
• #16 Another way to minimize inventory
• #17 Zara keeps its capacity not fully loaded to be able to change product line every two weeks