Understanding milling tandem control

Considerable work has been done over the years to automatically control the operation of the milling tandem. Control can be achieved by utilising relatively simple algorithms. Chute-level control, added-water rate control and speed and torque control of each mill drive are the main elements of the control system. Factory rate control can be achieved by controlling the prepared cane level in the chute of the first mill and controlling the first-mill speed to a set point that may vary depending on factory capacity constraints. Added water rate should vary with the objective of maintaining a relatively constant ratio to the cane-fibre rate, with a potential advantage to extraction by increasing further when pol in cane is high. For rate, performance and protection, the speed of and torque on each milling unit drive should be controlled.