MEMBER'S QUESTION:

At our corrugator and converting operations we know there are many TAPPI Test Methods that can be used to describe the properties of the linerboards and mediums we purchase.  What do you believe are the most important?

ASKRALPH! Responds:

Here are my thoughts on the most critical physical properties for each of the three major classes of containerboard that you purchase.  I believe that it is critical that you ask for actual reel positional data from each supplier.  As you buy narrow trim rolls from mills, you are more likely to obtain containerboards that are slit from the operator or drive sides of the paper machine.  Out on the edges of the paper machine, the physical properties are more likely to have higher variation indexes.

 

 

 Do not accept reel average specifications or physical property tests.  Push back on our upstream partners.  I can assist you in this effort and even lead the conversations with your mill reps.  There is a methodology for obtaining this infomation so that you can compare various product offerings.  Also seek out the upper and lower reject points for each of the physical properties.

 

Linerboard	Mediums	White Tops
CD Ring Crush	Basis Weight	Brightness
Caliper	CD Ring Crush	Caliper
Moisture	Caliper	Color
Smoothness	Hot Coefficient of Friction	Internal Bond
Basis Weight	MD Stretch	Basis Weight
Porosity	MD Tensile	Moisture
	Moisture	Smoothness
	Water Drop	Cobb- Top
	Ash Content	Cobb-Bottom

 

I would also suggest  performing a combined board audit.  This could also be called a process capability study of the way things are today.  You need to determine what level of "combinability" you achieve with the variety of containerboards you are now using as a raw material in striving to maximize the  Edge Crush and Flat Crush in your combined board constructions.