This study aims to solve the chip breaking problem and reduce tool costs by determining the suitable insert and cutting parameters for 304L stainless steels, which are difficult to machinable and have chip breaking problem during turning. In the study carried out to minimize flank wear and improve surface roughness values in the machining of 304L stainless steels; cutting speed, feed and cutting depth values recommended by the manufacturers were used for each cutting tool. In the experiments, five different inserts, five different cutting speeds, two different feeds and three different cutting depths were taken as input parameters, while flank wear and surface roughness were taken as output parameters. A vortex tube was used as a cooling method to suply environmentally friendly production. Intermediate value estimation and optimization studies were carried out using different methods for the measurements obtained. The estimation results were examined and the method suitable for the experimental data set was chosen with the square root of the sum of the squares of the errors. Having different methods reinforces the chosen method. The optimum parameters were taken separately and together for flank wear and surface roughness from evaluation methods. Confirmation experiments were performed for optimum parameters. The confirmation experiments were found to agreement with the actual and predicted values.