Current Questions & Answers

MEMBER: We have had issues bonding liner from one particular mill.  We have reversed the roll on the rewind stand and still have not been able to develop an adhesive bond.  We have spliced in rolls from other mills and they combine well on the corrugator.  We have therefore concluded that there are no issues with our starch or corrugating procedures.  We contacted the problem mill and were told that our rolls were produced in a production run were sizing was used so the the linerboard would meet the UN Cobb Test.  Will you please explain this to us?

RALPH YOUNG: The UN Cobb requirement establishes a maximum amount of water absorption on the outer liner of a converted box. You mill may have used either too much sizing or tried a different sizing.  In either case I would ask that mill what the absolute grams of water absorption was on the finished linerboard for that particular production run.  You may also want to ask the mill about its porosity values for that production.

If you had combining issues, others may also be having issues.  Linerboard with sizing can with time continue to increase it's moisture hold out and porosity.  Check the age of the rolls.

MEMBER: I have a question.  We have been working very hard to reduce waste in our plant, and we have been successful in our efforts for the majority of items.  One area we have not been able to reduce on a significant or consistent basis is laps cut off rolls before they are put on the unwind stand.  Do we have access to any information that talks about average waste percentages in AICC corrugator plants?  I know there are questionnaires the AICC sends out, and if you participate in them, then you get to see the results.  If there is, please let me know and we will participate. Thanks for your help.  Hope to see you again soon.
 
RALPH YOUNG: The Corrugated Board Technical group of TAPPI years ago developed recommended guidelines for board mills about roll hardness, steel band widths, and placement of the bands on the rolls.  This was designed that rolls could endure the rigors of transport and not arrive at converting facilities with very minimum edge damage.

Ideally the only roll damage you should be occurring is some "cigar peeling" on the outer wrap from the rolls "spinning" while traveling over the roads and rails.  This should be limited to three wraps only. If this is not the case you need to go back to your roll stock supplies and have them investigate their blocking and bracing procedures of the rolls in the cars and trailers.  The entire waste stream at the corrugator should not exceed three percent.  While the AICC does not collect and report on box plant waste, TAPPI does.

Member’s Question: We are experiencing a significant amount of waste as a result of “rolling edges” by running a labeled carton through our flexo-folder-gluer. The specific item is a 32 ECT RSC with a mottled white outside liner with two large spot labels that are placed in panels 1 & 2 and panels 3 & 4.Our current routing through our facility includes the placement of both labels at the same time through our EM model Automatan and then finished off with our 66” McKinley FFG. We have tried increasing score pressure, using “scores” on the print cylinder to score both the inside and outside and using a variety of speeds.  The interesting outcome was that we would cycle through say 5 to 10 good boxes and then 2 or 3 “bad” boxes. Also, we were told by two cutting die vendors that moving this to a full die cut on the FFG would not be of any help…

 

ASK Ralph Responds:

Member Question:

 

We are a Canadian company that sells corrugated boxes for just in time deliveries. One of our clients is requesting me to supply him the strength, meaning the weight a box can support, based on certain information such as the box style if an RSC, its dimensions, the paper combination and flute profile. I wonder if you know where I would be able to find such a formula. Thanks in advance for your help.

 

ASKRalph Responds: