Table 1: Control factors and levels.

FactorCoded symbolLow (−1)High Middle (0)

CNT : xGnP
(weight ratio)
A20
20 (CNT) : 80 (xGnP)
80
80 (CNT) : 20 (xGnP)
50
50 (CNT) : 50 (xGnP)
Roller rpmB90180135
No. PassC102015