Assembly Planbook - July 2008 - (Page GM-11)

parts, such as doors and roofs, could be built-up as subassemblies. General Motors was one of the last automakers to switch to all-steel bodies in 1937. But, Fisher Body developed the auto industry’s ﬁrst onepiece all-steel roof, called the Turret Top, in 1934. Previously, car roofs had been built around a wooden frame covered with canvas, limiting both the vehicle’s structural integrity and its design potential. The new roof, formed from a single sheet of seamless steel, was introduced on all GM vehicles beginning with the 1935 Chevrolet lineup. In 1936, GM introduced the Unisteel body, which was formed by welding the steel inner and outer panels into a permanent, shock-resistant structure. In addition to experimenting with new types of materials, such as ﬁberglass, GM engineers pioneered new painting methods and techniques. Painting was a laborious process that created a big production bottleneck. Early car bodies were manually painted with 12 or more coats of varnish, with sanding and polishing in between. Drying time was a huge limitation on production capacity, because the multiple coats of varnish would require 3 to 8 weeks to dry. As a result, some manufacturers used black enamel, which dried faster, to reduce cost and boost production. But, that still required at least 4 days of drying time. In 1920, scientists at E.I. du Pont de Nemours & Co. (Wilmington, DE), a major GM shareholder at the time, developed a liquid celluloid laced with sodium acetate. The substance was capable of carrying extra pigment in suspension, thereby yielding much more brilliant colors. It could also be applied with a spray gun instead of a brush, and it dried in only a few hours. The new paint, called Duco, was far superior to traditional baked enamel. It was not susceptible to fading, cost less money and required less handwork than varnish did. The paint also didn’t require high-temperature drying ovens. Before Duco, an automaker assembling 1,000 cars per day needed 21 acres of covered space to hold 18,000 cars while they were undergoing drying and ﬁnishing, which took at least 3 weeks. Duco reduced drying time from 336 hours to 13.5 hours and, eventually, just a few minutes. The new paint helped GM shave 20 percent off the cost of a car body and 5 percent off the total cost of a car. Duco paint was introduced on Oakland models in 1924. By 1926, Chevrolet was using it on all of its cars. That served as a huge competitive advantage against its arch-rival, the all-black Ford Model T. Sensor Expertise is at the Heart of Your Process Sensor technology and application expertise is a key strategic weapon in today’s highly competitive automotive manufacturing environment. Customers are demanding cars that last well over 100,000 miles with virtually no maintenance. This means making perfect parts and assembling perfect vehicles all day, every day. That’s where Balluff can help. We’re experts in using sensors to error proof manufacturing processes to increase parts quality and improve process efficiency. Embed sensors for perfect parts every time Robots, Vision and Computers During the 1960s, GM was one of the ﬁrst manufacturers to make widespread use of robots and computers on the plant ﬂoor. In 1961, the automaker installed the world’s ﬁrst industrial robot used on a production line at its Ternstedt plant in Trenton, NJ, which made door and window handles, gearshift knobs, light ﬁxtures and other hardware for automotive interiors. Obeying step-by-step commands stored on a magnetic drum, the Unimate robot’s 4,000 pound arm sequenced and stacked hot pieces of diecast metal. A major breakthrough for robots occurred in 1964, when GM ordered 66 Unimates for its new Lordstown, OH, assembly plant. The spot welding robots boosted productivity and allowed more than 90 percent of body welding operations to be automated vs. only 20 percent to 40 percent at traditional plants, where welding was a manual, dirty and Use sensors to ensure total robot cell safety Use RFID to stop tool and part damage To find out how to increase your manufacturing productivity, go to: www.balluff.com/automotive www.assemblymag.com | July 2008/ASSEMBLY | GM - 11 http://www.balluff.com/automotive 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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