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McDonnell Douglas Aircraft in St. Louis, MO manufacturers various transport and fighter military aircraft such as the C-17 and the F/A-18. With shrinking military budgets and increased competition, market forces demand high quality parts at lower cost and shorter lead times. Currently, a large number of different fastener types which include both solid rivets and interference bolts are used to fasten these assemblies. The majority of these fasteners are installed by hand or by using manually operated C-Frame riveters. MDA engineers recognized that in order to reach their goals they would be required to rethink all phases of the assembly system, which includes fastener selection, part fixturing and fastener installation methods. Phase 1 of this program is to identify and to develop fastener installation processes which will provide the required flexibility. The EMR fastening process provides this flexibility.

Northrop Corporation manufactures body panels for the Boeing 747 aircraft. There are 1259 different stringer configurations used on the three 747 models with an average of 839 stringers per ship set. Until recently, all drain holes and skin coordination pilot holes were drilled manually using plastic application template tools (PATTS). Inventory costs were high and manual drilling errors led to excessive scrap and rework rates. Northrop engineers recognized that automating the stringer drilling process would produce higher quality parts at a lower cost. Northrop worked with Electroimpact, Inc. to develop the Automatic Stringer Drilling System (ASDS). The ASDS automatically clamps and drills all straight and contoured stringers used on the 747. Stringers are mounted on a rotating platform that provides +/- 90° of motion. Two servo-servo drills are mounted on a cantilevered arm with 25 feet of X-axis travel.

The Handheld Low Voltage Electromagnetic Riveter(HHER) has been under development for the past three years. The HHER is an impulse device deriving its power from the discharge of a bank of capacitors through a pancake coil. This gives the HHER the advantage of an accurate and repeatable output force, which results in exceptional consistency in rivet upset dimensions. The rivet/hole interferences obtainable with the HHER have been shown in many cases to be superior to traditional rivet driving techniques, resulting in riveted joints that exhibit excellent fatigue life.(5) Typically, two opposing guns are used on either side of the rivet. These are synchronized through a control cable of arbitrary length. This feature allows accurate installation of slug rivets by hand, a function that in many cases is not possible with existing handheld tools.

Hand installation of 3/8", 5/16" and 1/4" diameter fatigue head style fasteners is required on some areas of 747 section 11 (center wing). The 3/8" diameter fasteners can require between 45-60 seconds to upset using conventional pneumatic riveting guns. As part of Boeing’s continuing effort to reduce cycle time and improve the factory working environment, a Boeing Quality Circle Team proposed using LVER technology as an alternative to conventional pneumatic percussion riveting hammers The hand operated HH500 system was developed in response to this request. The HH500 single shot upset reduces installation time as well as the noise levels and vibration experienced by the operators. The design of this system and the integration onto the factory floor are presented. The LVER forming rate is significantly higher than that of conventional pneumatic and hydraulic processes.