Application of Response Surface Methodology and Central Composite Inscribed Design for Modeling and Optimization of Marble Surface Quality

Table 2

Coded/actual levels of factors.

Factors	Symbol	Coded/actual variable level
		Lowest	Low	Centre	High	Highest
		−1.682	−1	0	1	1.682
Belt speed (m/min)		0.80	1.07	1.48	1.88	2.15
Pressure of the polishing head (bar)		0.50	0.80	1.25	1.70	2
Rotational speed of the polishing head (rpm)		409	445.69	499.50	553.31	590