Optimization of aluminium laser welding using Taguchi and EM methods

Abstract

Effect of laser welding parameters such as power, out-of-focus length, speed, diameter of feeding wire and feeding speed on weld properties are studied. The process parameters and their respective and interactive effects on the final responses have been investigated simultaneously by minimizing the number of experimental runs. The results, indicating the interlateral relationship between laser process parameters and responses, have been used to optimize the laser parameters, to predict the responses and to increase the process robustness. Two millimetre thick plates of AA6061 were welded in fillet configuration using a cw/Nd:Y AG laser and AA5356 wire as the filler metal. Two different experiment-designing methods were used and compared to find the most efficient way to optimize laser welding. The Taguchi method that allows a multicriteria optimization, using orthogonal arrays, was used to reduce the number of trials necessary to cover the whole functional process parameters window. The same kind of optimization was then carried out with E.M. method in a more interactive way allowing a dynamic construction of the feasible domain throughout the data collection. The weld properties of interest were weld fillet size, penetration depth, concavity size and HAZ dimensions.

ND:YAG laser welding of AA6061: Experimental differences between the TEE and LAP joint configurations

“…This method takes a more interactive approach leading to the dynamic construction of the feasibility domain throughout the data collection. After these two steps, the feasibility domain was well known and the prediction equations were stable [12]. All regression equations modelling the different responses as function of the input parameters showed R2 regression coefficients above 70%, indicating a good fit.…”

“…The EM technique is based on building an euc1idian domain and modifying it in an interactive way, varying all the parameters at the same time (9)(10)(11). The combination of Taguchi and EM methods has already been used in aluminium laser welding (12]. This allows the investigation of e pr~cess parameters and their respective and teractlve ef~ects on the final responses (weld fillet IZ~,penetratIon depth, concavity size).…”