MODELING THE PRESSURE DIE-CASTING PROCESS WITH THE BOUNDARY-ELEMENT METHOD - DIE DEFORMATION MODEL FOR FLASH PREVENTION

In pressure die casting, the thermal loads, injection pressure and cla mping forces cause the individual blocks of a die to deform. This defo rmation results in gaps between the interface surfaces which, if big e nough and in the vicinity of the cavity, permit material to seep into the gaps, causing Bash. This paper describes a thermoelastic model to predict the deformation of the die so that it can be machined to preve nt flash. The model is based on the boundary element method and allows the use of linear isoparametric or quadratic subparametric elements. Each die block is analysed as a separate problem. To avoid the occurre nce of Bash, the model suggests the amounts that should be machined fr om each die block. The predicted deformation has been experimentally v erified by measuring the profile of a test die using displacement tran sducers and die impressions. It is shown that there is good agreement between the predicted and experimental results for different operating conditions. By machining the amounts suggested by the model, the test die was run without flash at operating conditions that had previously resulted in flash.