“…The experiments in the studies were carried out adopting a full factorial design (Sivaprakasam et al, 2014;Barman et al, 2017;Alavi, & Jahan, 2017;Ali et al, 2012;Kuriachen, & Mathew, 2016;, Box Behnken design (Kuriachen, & Mathew, 2016;Kuriachen & Mathew, 2015;, central design of experiment ( Sapkal & Jagtap, 2018), rotatable central composite design (Tiwary, Pradhan, & Bhattacharyya, 2014), or orthogonal array design (Krishnaraj, 2016). The machining factors were varied almost in all experiments at three levels.…”