Assembly Planbook - March 2009 - (Page 28) Assembly in Action addition, because they were no longer being held in place by the clips, the four 3-millimeter pins could be standardized at a single length. In terms of parts numbers, Norica Laurona reduced the number of part types from six to two and the number of parts from 15 to five. During installation, a coiled spring pin is compressed so that it will fit easily in the hole, or holes in which it is being installed and then allowed to relax. The pins’ inherent flexibility allows them to absorb wide manufacturing tolerances and makes them self-retaining. In operation, the fasteners serve as a kind of “mini shock absorber,” in that they help isolate the assemblies in which Three-robot Cell Welds Crane Outriggers Like many heavy equipment manufacturers, Manitowoc Cranes (Manitowoc, WI) is having a difficult time finding enough skilled welders to meet its production needs. It is also continually looking for ways to improve the quality and consistency of its products while cutting its manufacturing costs. Recently, the company accomplished all these objectives by implementing a three-robot tandem-arc welding cell at its plant in Shady Grove, PA. The system assembles outrigger beams for the company’s construction cranes, and has been configured to weld 26 different beam types measuring from five to 12 feet. The finished beams, which are made of mild steel, weigh 500 to 1,700 pounds. “The results have been stellar,” says Manitowoc senior manufacturing engineer Peter Johnson. “Beams with seven to 10 welds…that formerly took three to four hours to weld manually can now be welded on average in 17 to 18 minutes, with some parts finished in as little as 13 minutes.” In addition, Johnson says the cell has allowed his company to do some of the welding work that it had previously been forced to outsource. “We’ve been able to bring production back in-house, saving the company a tremendous amount of time and money. Having the robots has also allowed us to redeploy skilled manual welders elsewhere in the plant,” Johnson says. The workcell includes three sixaxis HP20 robots from Motoman Inc. (West Carrollton, OH), each of which provides a 20-kilogram payload, a reach of 1,717 millimeters and 28 ASSEMBLY / March 2009 www.assemblymag.com http://www.sealantequipment.com http://www.sealantequipment.com http://www.assemblymag.com
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