Line bending of Al2O3 coated and uncoated aluminium thin sheets

A novel 'hybrid' forming process, consisting of a fluidized bed (FB) pre-treatment to coat with Al2O3 and pre-curve aluminium thin sheets and of a diode laser forming to perform the proper line bending of FB pre-treated sheets, is defined and investigated in this paper. A comparison with the diode laser forming of untreated aluminium thin sheets is also carried out. An experimental investigation is performed varying, in the laser forming process, output power, scan speed and number of passes and, in the 'hybrid' process, besides the laser parameters, even the treatment time in the FB system. Consistent trends of bending angles according to laser operative parameters are achieved for both the forming processes. A significant saving of laser power necessary to form the specimens, an increase in maximum angles achievable as well as an improvement of aesthetic aspect of the final products characterize the 'hybrid' forming process, if compared with the laser forming process. As a result of dissimilar forming technologies, completely different bending mechanisms are highlighted, with the 'hybrid' forming giving rise to an unexpected inversion in bending direction. Finally, the opportunity for further applications of the 'hybrid' technology is also discussed, stating the basis for a wider industrial diffusion of the non-conventional forming technologies even for the manufacturing of basic commodities. (c) 2005 Elsevier B.V. All rights reserved.