Tool wear modeling in machining processes is one of the important tasks in manufacturing to establish an automation based system. This will be helpful in Flexible Manufacturing Systems (FMS) and Computer Integrated Manufacturing (CIM) systems. Taking attention to this reality, a fuzzy model for predicting worn tool cutting forces in machining without the need for any worn tool calibration tests is presented in this paper. An AISI 4140 type steel was used for machining operation. Cutting times were measured during the machining in different cutting parameters including cutting speeds (V), feed rates (f) and cutting depths (d). For generalizing the model, full factorial method was applied for arranging the cutting parameters. For creating the prediction model a fuzzy logic model was developed based on the cutting parameters and machining time. The estimated tool flank wear using of the fuzzy logic model was compared with the measured values. Based on the comparison of the results, the model confirms the measured tool flank wear rates with an acceptable reliability.