2. Use of the TM for selecting suitable conditions - The TM is a powerful and efficient method for designing processes with a minimum number of trials. - The L18 OA experimental design was selected as the most suitable for the study, requiring 18 experiments for seven factors with three levels and one factor with two levels.3. Use of the CCRD to optimize condition- CCRD coupled with RSM was used to optimize the three independent variables (initial pH, amount of used shot blasts, and initial cutting oil concentration). - CCRD experiments were conducted with five levels for each independent variable, resulting in a total of 16 experiments.