SHEET METAL AND METAL FORMING Copyright Goodheart-Willcox Co., Inc. Chapter 17 Cold Forming Metal Sheet 287 replaced by a coil. Energy is obtained by capacitor dis- charge through the coil. Properly designed equipment can be used to perform either electrohydraulic or elec- tromagnetic operations. Highly conductive metals can be formed easily using electromagnetic forming. Less conductive materials can be formed if they are temporarily wrapped or coated with a highly conductive material. As very high electric currents are passed through the coil, an intense magnetic field develops. This mag- netic field causes the work to collapse, compress, shrink, or expand, depending on the design and placement of the coil, Figure 17-28. A capacitor bank similar to those used for elec- trohydraulic forming serves as the power source for electromagnetic forming. The spark gap, however, is Goodheart-Willcox Publisher Figure 17-25. Using electromagnetic forming to expand a bearing sleeve into a connecting rod. Coil Bearing Connecting rod Goodheart-Willcox Publisher Figure 17-26. Compressing a torque tube on an automotive drive shaft using electromagnetic forming. Coil Drivee ve Dr D shafth aft s Torque tube Driveve Dr D shaft aft ha s Goodheart-Willcox Publisher Figure 17-27. Flat forming applications (forcing sheet metal into a die) require a pancake coil to provide uniform magnetic pressure. Die Pancake coil Circular r work k blank Goodheart-Willcox Publisher Figure 17-28. A magnetic field can be employed to shrink or squeeze parts together. To power source body Steel e ring Aluminum m Coil