MEMBER'S QUESTION:

I am trying to get a grasp on pin adhesion.  My starch supplier gave me the following minimums and targets to shoot for:

Grade                          Min                Target
26 lin- 35 lin                40#                  45#
42 lin                            45#                  50#
56 lin – 73 lin              52#                  57#

In a previous emai lyou stated “I like to see pin adhesion values average at 55#/linear foot of glue line, while others are willing to settle for 50#, the minimum values should not drop below 45#.”

I have tested 29 ECT and the DB Bottom Pan result was 41#.  Is 41# too low for 29 ECT?  The next day I tested 275 BC and the DB Bottom Pan result was 68#.  There were no changes to the starch settings on the machine between the two days. 

My question is: Why is there so much variability in the Pin Adhesion results and is that normal?  I check B flute and C flute pin adhesion once a week and there is always a large variance from week to week. 

 

ASK!RALPH RESPONDS:

You shared the critical observation in your e mail, “There were no changes to the starch settings on the machine between the two days.”    Every grade from every board machine at a mill must have its own recipe or formula on your corrugated.  Running with the same setting does not adjust for the physical property differences in the containerboards.  They cannot be treated the same.   Board temperatures and moisture levels and corrugating speed play a big role in maximizing the pin adhesion strengths.  If you need some engineering  protocols for conducting designed experiments to determine the proper setting for each combined board grade give me a phone call or returned e mail.  Every corrugator is different and you must set your own specifications!

You can achieve higher pins than stated by your starch supplier.  They are not helping you push the envelope.  Generally higher pins, higher ECTs, less fibre, more money in your pockets.

Thank you for the communication.