Hot back is the binding book cover after the book back ironing drying. All covers covered with cold glue need to be hot backed to make the cover flat and firmly pasted on the book block and form the back shape. At present, there are two kinds of back ironing in book printing: flat ironing and hot ironing. Correspondingly, there are two kinds of back ironing machines: flat ironing and hot ironing.

(1) In the form of flat ironing, when the back is ironed, the back should be put down on the heating platform. Press the book board up and side to press the book stack tightly. Under the action of the heating platform, the glue liquid of the back should be dried and the back should be ironed. This method of back ironing is relatively slow and takes a long time to heat. The glue extruded from both ends of the book will stick to the page and contaminate the platform, causing damage to the surface of the back of the book. It is often necessary to remove the rubber from the table. In order to speed up the speed of back ironing, there are two electric heating tables on the worktable of book printing. At the same time, books are loaded and unloaded on one worktable, and back ironing and drying are carried out alternately on the other worktable to speed up the speed of back ironing.

(2) In the form of scalding, when the back is ironed, the back of the book is upward, pressed back and forth, and sent to the scalding part. The hot back part is composed of a group of heating steel rollers. The worktable carries the books to and fro, dries the glue and irons the back of the books. The scalding back ironing machine is fast and has a large amount of books. Automatic temperature control, less power consumption, short preheating time.