The trimming process is an important step to achieve good dimension and shape of a final product. However, it requires a systematic study of the various parameters involved in material separation. The finite element method was utilized to simulate the trimming process of aluminum sheet materials in aspects of material properties, tooling conditions and process parameters, including different tool configurations, clearances and punch speeds. Punch load versus displacement diagrams and cut edge morphologies obtained from representative clearances and tool configurations were investigated. A two-dimensional plane strain trimming was analyzed using a rate independent material model. An experimentally measured fracture strain was utilized in FE modeling for fracture initiation and development using element deletion technique. A thermally coupled material model was tentatively tested. Results from simulations were compared with experiments and good agreement was obtained for most of the studied conditions. Optimal trimming process parameters such as specific tool configuration, clearance and punch speed are suggested.