Assembly Planbook - July 2008 - (Page GM-10)

This PUMA robot was developed by GM engineers in the 1970s to assemble small, lightweight components. became the industry’s top seller, with sales topping 752,000 units. By the late 1920s, Chevrolet sold more than 1 million vehicles and became the No. 1 brand in the United States. Some GM executives had wanted to get rid of the money-losing Chevrolet division. But, under Knudsen’s leader- In the days before computers, GM engineers used 3D model boards to design assembly lines and equipment. The model was scaled 0.25 inch to the foot. ship, Chevrolet became the foundation for GM’s long-term production strategy. “He built an organization and production system that could accommodate change and expansion,” says David Hounshell, professor of technology and social change at Carnegie Mellon University (Pittsburgh). Knudsen pioneered the concept of ﬂexible mass production. At the time, manufacturing at GM was far more decentralized and much less vertically integrated than at Ford. “Sloan had reasoned that GM would have to make the same proﬁt on capital invested in plant and equipment for the manufacture of its various components as outside suppliers charging reasonable prices for these components,” says James Flink, author of The Automobile Age (MIT Press). “So, GM depended more on outside suppliers. This alone gave GM far more ﬂexibility than Ford.” When Knudsen began to revamp Chevrolet’s assembly lines, all old machines were discarded. “New heavy standard machines (not single purpose) were installed, and the ﬁxtures strengthened so as to withstand the spring, which is the greater factor [in causing inaccurately machined parts] than wear,” Knudsen wrote in an article published in Industrial Management magazine in 1927. “Sequence lines were established . . . to pave the way for the conveyors which were to follow.” “This new direction allowed limits of precision to be lowered, resulting in the reduction of scrapped material,” says Hounshell, who is the author of From the American System to Mass Production, 1800-1932 (Johns Hopkins University Press). Machines were not permanently dedicated to a single part or operation. Instead, their operations were dedicated through jigs and ﬁxtures, which were much less expensive to replace or update. Under Knudsen’s ﬂexible automation strategy, each plant manager was responsible for selecting and purchasing production equipment. He also convinced GM executives that a Fisher Body plant should be attached to each assembly plant so that body production could be coordinated precisely with the daily output of each plant. In late 1928, when Chevrolet switched from a four- to a six-cylinder engine, the entire changeover only took 3 weeks. As a result, when the new model was introduced in January 1929, buyers did not have to wait. Within 8 months, GM plants turned out more than 1 million sixcylinder engines. “Knudsen and his Chevrolet production men achieved the desired high volume by replacing old machine tools with new ones and adopting sequence lines or, as Knudsen called it, ‘getting all noses pointed in the same direction,’” says Hounshell. “Knudsen played a critical role in raising the level of General Motors’ mass-production know-how.” All that effort eventually paid off for Knudsen. He was promoted to president of the Chevrolet division in 1924, and served as president of GM from 1937 to 1940, when President Franklin D. Roosevelt asked him to oversee the government’s national industrial defense production operations. Photo from ASSEMBLY Archives Hard, Colorful Bodies When GM was founded 100 years ago, wood ruled in the auto industry. Bodies, chassis and wheels were made from ash, elm and maple following centuries-old carriagebuilding techniques. After they were sawed and shaped, individual pieces of wood were glued and screwed together in a laborintensive process. Until the mid-1930s, most car bodies were framed in wood and covered with sheet metal skins. But, it was an expensive and time-consuming process. Among other things, wood took months to cure and required special kilns to reduce moisture. The auto industry consumed more hardwood lumber than the furniture and building trades combined. Fisher Body, a division of GM that pioneered “closed” cars for Cadillac, used 250 million board feet of lumber in 1924 alone. To supply that thirst, it owned huge tracks of timberland in Arkansas and Michigan, and operated several saw mills. Engineers at Fisher Body developed jigs and ﬁxtures for mass-production applications. As a result, large body GM - 10 | ASSEMBLY/July 2008 | www.assemblymag.com http://www.assemblymag.com

Table of Contents Feed for the Digital Edition of Assembly Planbook - July 2008

Assembly Planbook - July 2008 Contents Editorial Quality in Assembly Station to Station Assembly Lines Assembly in Action Surviving the Roller Coaster The Human Side of Manufacturing Do Your Fasteners Need a Preapplied Thread-Locker? Manufacturing Innovation A Century of Progress Trendsetting Plants Pulse Tools Get Smart Plastics: Design for X Product Reviews Products Advertisers Index Classified Leading Lean

Assembly Planbook - July 2008

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