Sam asks,
Do you have any formal reference of what the ideal pin adhesion test result should be. For agro boxes (vegetables) we currently use values of 55 to 60 (pound/inch) and in industrial 40 and higher.
We have a particular customer that has experienced some delamination failures. The PAT test value is 27 (pound/inch) which we believe to be too low. However, we are lacking established information to back up our opinion.
I could not agree with you more. I prefer a minimum, not average, of 45 for industrial application. My technical associates at TAPPI like this 45 value while I would rather have 55 on all corrugated bonds. It is most important to know where the failure is occurring: linerboard, medium, or in the starch itself. Under ideal conditions we want 100% liner failure. As you can see in these photos a very low PAT value can have disastrous results. There is very little liner pull and very little glue with a poor bond.
A good reference for the PAT is the most recent version of TAPPI document TM 821 (TM 821-0M 17 at this writing), Pin adhesion of corrugated board by selective separation.
— Ralph
