Hi Ralph,
I've read some of your responses to the ASK Ralph service.  I'm a packaging engineer for a US based manufacturer of computers and preferrials.  Products we have build and packaged in China are having box compression failures.  We specify a minimum box compression strength on our drawings.  Test results performed by the supplier at the time of manufacture are passing.  We are using a safety factor of 4.5 to 5.5 that should account for all the environmental and conversion effects acting on the box to degrade it's performance.  However, after arrival at our distribution centers in Americas and Europe, the box is failing under load.

My research so far seems to point to the recycled material China uses in their box board paper.  This material looses it's bond strength after cyclic exposure to high heat and humidity.  BCS at time of manufacture is not the same after this type of exposure, and is much worse that industry experience with typical virgin or re-cycled softwood fiber.

If I could add a minimum stiffness requirement on my drawings (per TAPPI 836), do you think I would have a way to manage the use of recycled content board such that my expected box compression performance is not compromised over time?  If yes, how would I create a table of expected stiffness requirements?  Should it be related to board combo caliper, by flute size, by ECT or Mullen test values, etc?

Thank you for your advice,

ASK!Ralph Responds

Thank you for the inquiry and contacting the AICC.

Where have the boxes failed in the supply chain?  Do you have any pictures that you can share so I can offer an opinion on the type of box compression failure?

Your idea of stiffness is exciting, but I doubt that they (China) have a four point testing device to measure and monitor. Your evaluations of the fibre quality, combining and converting efficiencies are probably correct.  I would agree that the BCT loss for Chinese corrugated packaging probably has a faster compression loss curve over time that does US produced packaging.

Can you tell me anything about the containerboard components?  The box supplier may not be engineer the best load sharing design for your needs.  Do you have any combined board test results?

Together, we can solve this issue for you.  Yes, I do have two HP printers and a big laptop.

TO BE CONTINUED