Leanmanufacturing is a method of manufacturing goods aimed primarily at reducing times within the production system as well as response times from suppliers and customers. It is closely related to another concept called just-in-time manufacturing (JIT manufacturing in short). Just-in-time manufacturing tries to match production to demand by only supplying goods that have been ordered and focus on efficiency, productivity (with a commitment to continuous improvement), and reduction of "wastes" for the producer and supplier of goods. Lean manufacturing adopts the just-in-time approach and additionally focuses on reducing cycle, flow, and throughput times by further eliminating activities that do not add any value for the customer.[1] Lean manufacturing also involves people who work outside of the manufacturing process, such as in marketing and customer service.
Lean manufacturing is particularly related to the operational model implemented in the post-war 1950s and 1960s by the Japanese automobile company Toyota called the Toyota Production System (TPS), known in the US as "The Toyota Way".[2][3] Toyota's system was erected on the two pillars of just-in-time inventory management and automated quality control. The seven "wastes" (muda in Japanese), first formulated by Toyota engineer Shigeo Shingo, are the waste of superfluous inventory of raw material and finished goods, the waste of overproduction (producing more than what is needed now), the waste of over-processing (processing or making parts beyond the standard expected by customer), the waste of transportation (unnecessary movement of people and goods inside the system), the waste of excess motion (mechanizing or automating before improving the method), the waste of waiting (inactive working periods due to job queues), and the waste of making defective products (reworking to fix avoidable defects in products and processes).[4]
The term Lean was coined in 1988 by American businessman John Krafcik in his article "Triumph of the Lean Production System," and defined in 1996 by American researchers James Womack and Daniel Jones to consist of five key principles: "Precisely specify value by specific product, identify the value stream for each product, make value flow without interruptions, let customer pull value from the producer, and pursue perfection."[5]
Companies employ the strategy to increase efficiency. By receiving goods only as they need them for the production process, it reduces inventory costs and wastage, and increases productivity and profit. The downside is that it requires producers to forecast demand accurately as the benefits can be nullified by minor delays in the supply chain. It may also impact negatively on workers due to added stress and inflexible conditions. A successful operation depends on a company having regular outputs, high-quality processes, and reliable suppliers.
Fredrick Taylor and Henry Ford documented their observations relating to these topics, and Shigeo Shingo and Taiichi Ohno applied their enhanced thoughts on the subject at Toyota in the late 1940s after World War II. The resulting methods were researched in the mid-20th century and dubbed Lean by John Krafcik in 1988, and then were defined in The Machine that Changed the World[6] and further detailed by James Womack and Daniel Jones in Lean Thinking (1996).
Thus, the Japanese "leaned out" their processes. "They built smaller factories ... in which the only materials housed in the factory were those on which work was currently being done. In this way, inventory levels were kept low, investment in in-process inventories was at a minimum, and the investment in purchased natural resources was quickly turned around so that additional materials were purchased." Plenert goes on to explain Toyota's key role in developing this lean or just-in-time production methodology.[7]
American industrialists recognized the threat of cheap offshore labor to American workers during the 1910s and explicitly stated the goal of what is now called lean manufacturing as a countermeasure. Henry Towne, past president of the American Society of Mechanical Engineers, wrote in the foreword to Frederick Winslow Taylor's Shop Management (1911), "We are justly proud of the high wage rates which prevail throughout our country, and jealous of any interference with them by the products of the cheaper labor of other countries. To maintain this condition, to strengthen our control of home markets, and, above all, to broaden our opportunities in foreign markets where we must compete with the products of other industrial nations, we should welcome and encourage every influence tending to increase the efficiency of our productive processes."[8]
Shigeo Shingo cites reading Principles of Scientific Management in 1931 and being "greatly impressed to make the study and practice of scientific management his life's work".[9][need quotation to verify], [10][page needed]
Shingo and Taiichi Ohno were key to the design of Toyota's manufacturing process. Previously a textile company, Toyota moved into building automobiles in 1934. Kiichiro Toyoda, the founder of Toyota Motor Corporation, directed the engine casting work and discovered many problems in their manufacturing, with wasted resources on the repair of poor-quality castings. Toyota engaged in intense study of each stage of the process. In 1936, when Toyota won its first truck contract with the Japanese government, the processes encountered new problems, to which Toyota responded by developing Kaizen improvement teams, which into what has become the Toyota Production System (TPS), and subsequently The Toyota Way.
Levels of demand in the postwar economy of Japan were low; as a result, the focus of mass production on lowest cost per item via economies of scale had little application. Having visited and seen supermarkets in the United States, Ohno recognized that the scheduling of work should not be driven by sales or production targets but by actual sales. Given the financial situation during this period, over-production had to be avoided, and thus the notion of "pull" (or "build-to-order" rather than target-driven "push") came to underpin production scheduling.
Just-in-time manufacturing was introduced in Australia in the 1950s by the British Motor Corporation (Australia) at its Victoria Park plant in Sydney, from where the idea later migrated to Toyota.[11] News about just-in-time/Toyota production system reached other western countries from Japan in 1977 in two English-language articles: one referred to the methodology as the "Ohno system", after Taiichi Ohno, who was instrumental in its development within Toyota.[12] The other article, by Toyota authors in an international journal, provided additional details.[13] Finally, those and other publicity were translated into implementations, beginning in 1980 and then quickly multiplying throughout industry in the United States and other developed countries. A seminal 1980 event was a conference in Detroit at Ford World Headquarters co-sponsored by the Repetitive Manufacturing Group (RMG), which had been founded 1979 within the American Production and Inventory Control Society (APICS) to seek advances in manufacturing. The principal speaker, Fujio Cho (later, president of Toyota Motor Corp.), in explaining the Toyota system, stirred up the audience, and led to the RMG's shifting gears from things like automation to just-in-time/Toyota production system.[14]
Just-in-time/TPS implementations may be found in many case-study articles from the 1980s and beyond. An article in a 1984 issue of Inc. magazine[21] relates how Omark Industries (chain saws, ammunition, log loaders, etc.) emerged as an extensive just-in-time implementer under its US home-grown name ZIPS (zero inventory production system). At Omark's mother plant in Portland, Oregon, after the work force had received 40 hours of ZIPS training, they were "turned loose" and things began to happen. A first step was to "arbitrarily eliminate a week's lead time [after which] things ran smoother. 'People asked that we try taking another week's worth out.' After that, ZIPS spread throughout the plant's operations 'like an amoeba.'" The article also notes that Omark's 20 other plants were similarly engaged in ZIPS, beginning with pilot projects. For example, at one of Omark's smaller plants making drill bits in Mesabi, Minnesota, "large-size drill inventory was cut by 92%, productivity increased by 30%, scrap and rework ... dropped 20%, and lead time ... from order to finished product was slashed from three weeks to three days." The Inc. article states that companies using just-in-time the most extensively include "the Big Four, Hewlett-Packard, Motorola, Westinghouse Electric, General Electric, Deere & Company, and Black and Decker".[citation needed]
By 1986, a case-study book on just-in-time in the U.S.[22] was able to devote a full chapter to ZIPS at Omark, along with two chapters on just-in-time at several Hewlett-Packard plants, and single chapters for Harley-Davidson, John Deere, IBM-Raleigh, North Carolina, and California-based Apple Inc., a Toyota truck-bed plant, and New United Motor Manufacturing joint venture between Toyota and General Motors.[citation needed]
John Krafcik coined the term Lean in his 1988 article, "Triumph of the Lean Production System".[25] The article states: (a) Lean manufacturing plants have higher levels of productivity/quality than non-Lean and (b) "The level of plant technology seems to have little effect on operating performance" (page 51). According to the article, risks with implementing Lean can be reduced by: "developing a well-trained, flexible workforce, product designs that are easy to build with high quality, and a supportive, high-performance supplier network" (page 51).
Three more books which include just-in-time implementations were published in 1993,[26] 1995,[27] and 1996,[28] which are start-up years of the lean manufacturing/lean management movement that was launched in 1990 with publication of the book, The Machine That Changed the World.[29] That one, along with other books, articles, and case studies on lean, were supplanting just-in-time terminology in the 1990s and beyond. The same period, saw the rise of books and articles with similar concepts and methodologies but with alternative names, including cycle time management,[30] time-based competition,[31] quick-response manufacturing,[32] flow,[33] and pull-based production systems.[34]
3a8082e126