Preventive Maintenance of KOMORI LS29

KOMORI Lithrone LS29

Jogging and Knocking

It is a single operation completed in two stages. Jogging is the method of piling the sheets into neatly laid edges. It is one of the most important operations in the printing and binding department. The non-stop feeding of sheets on any automatic machine mainly depends upon the exactness of jogging and knocking.

      A bunch of sheets (say 100 to 200) are held in between thumb and fore-fingers from the two opposite corners by both hands, turned upward so that the edges get fanned, pressed and stretched to allow the air it be filled in between the sheets. The air filling separates each sheet and facilitates in knocking. The edge of papers towards the binder is knocked against the table top to align them plane parallel. The same process is repeated for the second adjacent edge of the papers. In the case of printed sheets, the papers are knocked at the gripper edge and the side lay so that these edges are properly aligned. The jogging and knocking of sheets can also be done with the help of automatic meant for the purpose. A small pile (500-600 sheets) of paper is kept at a time on the slanting tray of the machine. The pile is allowed to rest against the gripper edge and the side lay and the machine is switched on. All the sheets in the pile get straightened and aligned at both edges within a few seconds by the vibrating and knocking action of the electro-mechanically vibrating tray of the machine. The jogged and knocked sheets are lifted from the machine and arrange one above the other on a separate platform. These machines are capable of jogging and knocking about 20000 to 25000 sheets per hour. The following table shows the average speed of jogging and knocking by hand:-

            Sheet Size                                                       Average Speed per Hour

      A0  (841 x 1189mm)                                             2500 sheets

      A1 (594 x 841mm)                                                            3000 sheets

      A2 (420 x 594mm)                                                            5000 sheets

      A3 (297 x 420mm)                                                            10000 sheets

Counting

The sheets received from the printing department are first of all counted in the binding department to ensure that each forme is complete in its quantity. It is most important because even if one sheet is less, it causes shortage of one complete book in binding. In manual counting, the binders count 4 to 5 sheets at a time and arrange them in piles of 100, 250, 500 or 1000 sheets stacked on each other. In the modern and large binding houses counting is done with the help of machines. The electronic counting device of the machine is fitted against one corner of the pile. The sheets are counted from top to bottom of the pile in a few minutes time only.

      The speed of counting by hand is affected by the size of the paper. But the machines with electronic counting device can count upto 100000 sheets per hour irrespective of their size. The following table shows the scale for counting sheets by hand:-

Sheet Size                                                                         Average Speed per Hour

A0        (841x1189mm)                                                     5000 sheets

A1        (594x841mm)                                                       6000 sheets

A2        (420x594mm)                                                       8000 sheets

A3        (297x420mm)                                                       10000 sheets