“…The authors first conduct designed experiments. The Taguchi design of experiment is often used to reduce the time and cost of the experiments [12,13], but the central composite [14] and the full factorial design of experiments [1] are also used. The main purpose of designed experiments is to monitor the influence of controlled parameters on surface roughness [1,[15][16][17][18], but some authors also add other parameters like chip's characteristics [12], pre-tool wear vibrations [19], workpiece-tool vibration [20], lubrication-cooling condition [21] etc.…”