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The trimming process of sheet metals has been used to prepare workpieces (steel coils) for subsequent forming operations: from very light components to heavy appliances and machinery. The present work is based on the quality of trimmed edge, which is affected not only by the material characteristics by itself, but also by process parameters such as: clearance between knives (upper and lower) and sharpness of the knives during the side trimming process. The present research has the objective of developing a model to explain the edge trimming behavior of flat rolled steel. In the present investigation, the edge trimming process is FEM-simulated using a rigid-plastic model, where a very localized plastic deformation near the upper and lower knife gives at certain stage, the driving force for cracking, being the cracks' direction a direct factor that affects the quality of the edges. A mechanical study was carried out to obtain the intrinsic mechanical properties such as the strain hardening exponent (n) and the strength coefficient (K), which were taken into account to obtain near-real simulation results; furthermore, a metallurgical and hardness study was made to take into account the microstructure and hardness behavior of the flat rolled steel. At last, a correlational study was performed, to develop a state of the art edge trimming model. The final proposed model gives high-confidence horizontal clearances values for the studied sheet steels; taking as principal factor, the energy (N-mm) expended during the edge trimming process. The final contour of every steel was analyzed and its trends over clearance. The proposed model gives results in agreement with the FEM simulations information. A model has been developed in order to help edge trimmer operators to adjust and control technological parameters of the process.