Shrinkage, imposed strain rate and (lack of) feeding are considered as the main factors which determine cavity formation and/or the formation of hot tears. A hot tearing model is proposed which will combine a macroscopic description of the (direct-chill) casting process and a microscopic model. Since implementation of the macro-model which should provide the temperature and strain rate evolution, has not yet taken place, the micro-model is presented with a constant strain rate which is in the range corresponding with DC casting. The micro-model predicts whether porosity will form or a hot tear will develop. Results for an Al-4.5Cu alloy are presented as a function of (constant) strain rate.