Simulation of the cast-on-strap process in a finite-element model

A decisive factor of the quality of lead/acid batteries, in terms of performance and life time, is the fusion of the plate lugs to the cast-on-strap (COS ). The fully automatic COS process is nevertheless complex and the resulting quality of fusion depends on a number of different parameters such as: the strap volume, the number of lugs, the thickness and the insertion depth of the lugs, the combination of strap and lug alloys, and the thermal parameters such as the temperatures of the melt and the strap mould. To further improve the understanding of this important manufacturing process we have used a finite-element analysis to determine the relative influence of some of these parameters on the thermal history and on the resulting quality of fusion. Simulating a technical process such as COS needs simplification and model assumptions and will not be complete without experimental verification. Details of our approach are given and representative results are discussed. It is concluded that COS simulation is a valuable tool for identifying robust process conditions and optimizing product quality.