MEMBER: While I know there should be many ways to get there, could you suggest a reasonable paper combination to start with to achieve EC29 B flute board?
RALPH YOUNG: Thank you for a good question. Allow me to give you the engineering answer first and then the more practical answer after that.
The absolute minimum amount of combined ring crush thats needed in this structure would be 128 pounds. Given the normal combining and converting degradation factors adding 20% to this bare minimum to achieve a safe average brings the total ring crush from the three components up to 154 pounds. Striving for the best load sharing balance in the structure says that we should put 50% of the strength in the two liner facings and the other 50% into the medium.
Having said all that you should be able to over achieve your objective easily with typical 33# liners and 23/26# mediums. You could also achieve this ECT with typical 26# liners and a strong 30# medium. The options depends on your fibre costs and your combining efficiecy. If you want me to design the best model given the ring crush levels of the components you receive, have you lab manager get in touch with me.