Quality improvements to publication and board grades by hot calendering with induction heating

The application of single and tandem induction heating systems on conventional calenders on mechanical pulp publication grades and high-quality board grades optimizes the calendering process on conventional calenders with increased roll temperatures. Hot calendering provides many improvements in sheet printability, strength, bulk, elimination of two-sidedness and optimized calender configuration. The papermaker can also benefit from an increased moisture average, flat caliper profiles, and improved calender, winder and pressroom runability. A system known as Advanced Finishing Technology (AFT) encompasses the CD control system actuators and algorithms for hot calendering. AFT also includes advanced control techniques to take full advantage of the unique opportunity presented by the use of these new calendering tools by coordinating their actions. This paper will focus on the application of single induction heating systems on linerboard and folding boxboard machines, and of tandem induction heating systems on newsprint and groundwood paper machines, as well as the benefits obtained to date.