Analysis and comparative study of factors affecting quality in the hemming of 6016T4AA performed by means of electromagnetic forming and process characterization

Hemming is commonly one of the last operations for stamped parts. For this reason it is of critical importance on the performance and perceived quality of assembled vehicles. However, designing the hemmed union is a complicated task and is deeply influenced by the mechanical properties of the material of the bent part. Significant problems can arise in this operation when bending aluminum alloys, because cracks can appear due to the localized strain during hemming as a result of the low ductility of automotive aluminum alloys. This paper presents the development of the electromagnetic forming (EMF) technology for auto body-in-white parts hemming. A relatively simple experimental procedure to perform a hemming operation based on the principle of EMF is presented in order to compare the variation in the quality parameters of a hemmed joint. The achieved results are compared with the corresponding geometry hemmed utilizing the conventional process. At the same time, the study is completed with the development of a new simulation method for the EMF technology. The results obtained during this study prove the capability of the EMF to obtain quality hem unions simplifying the complicated conventional hemming operation. In this study a loose coupling EMF hemming simulation method has been developed using Maxwell® 3D to solve the electromagnetic field computation and Abaqus® to solve the mechanical computation. This simulation method shows good agreement with the physical experiments. Finally, the EMF hemming process is characterized by analyzing the influence of main input parameters on the quality output parameters.