Effects of humidity and heat of combined papers on the quality of corrugated board

Effects of different humidity and heat content on the quality of corrugated board, was investigated. Optimal treatment variables include: corrugators speed (50, 100 and 150m/min), wrapping angle of the paper around pre heaters (90,180 and 300 degree) and moisture of paper (6.5%, 7% and 8.5%). Papers that treated for this purpose included: 125gsm Kraft liner, 127gsm medium paper and 140gsm test liner paper. A flute type of 3ply corrugated board was selected for this study. Moisture of paper was measured in 3 places: Paper on roll stand before single facer, paper after single facer pre heater and paper before incoming double facer in hot plate unit. Also temperature was measured in corrugator's rolls, hot Plates in double facer and final board after exiting of the machine. Results show that, warp of final board decreased in speed 50 and 100m/min, moisture 7% and 1800C wrapping angle of the paper around pre heater. That means lower speeds and higher wrapping angles cause more heat on corrugated board and decreasing in warp content resulted. It should be noted that lower humidity than 7% and increase wrapping angle over 180 degree cause over drying and intensive moisture decrease which in turn cause reverse warp in the final board.