A high-volume, high-speed single facer at a corrugated packaging plant located in California (USA) was having issues with poorly bonded board after starting up from a stoppage of any duration. The poor bond between the corrugated medium and liner was resulting in excess waste and lost production.
Using IR thermal imaging and other diagnostic tools, Kadant identified the root cause to be thermal bowing of the lower corrugating roll. The thermal bowing caused variability in the glue roll gap as the roll turned. A larger-than-required glue gap resulted in too little starch being applied to specific locations on the medium on each rotation leading to a poor bond between the liner and the corrugated medium.
An audit of the corrugator steam system was performed by Kadant Johnson. The audit provided a comprehensive assessment of the steam system components and processes to ensure the corrugator steam system met minimum design and performance standards and best practices could be implemented where they were lacking. As a result of the audit, Kadant Johnson identified the need to improve system control and heat transfer performance using a managed differential pressure control strategy for the corrugating rolls and upgraded the rotary joint and syphon system to the CorrPro® rotary joint with a rigid stationary syphon.
The managed differential pressure control strategy combined with the robust rotary joint and syphon system greatly reduced the amount of residual condensate in the roll when the machine stops. This eliminated the thermal bowing and allowed the machine to make salable production immediately after starting up. The improved control also provided more consistent operation across all grades and allowed for increased output while reducing waste.