askralph

Bruce asked,

 Do you have any information on singleface lam vs. corrugate with regards to stacking strength? Also, if a corrugated box is in 44 ect what would we run in the litho world to come up with the same board combination?

Thanks for the question. Okay, here we go. This made me do some a few new searches, make some new network contacts, and dust off some old paper files.  Click here to download a file created with the CD ring crush values for coated white top linerboards, C1S offset label, and SBS.  The latter two were difficult to find since the “white” products are measured for Taber stiffness and not with the methods we use in the containerboard and corrugated industry.  I had to reach out to my contact at the Renewable Bioproducts Institute at Georgia Tech for a comparison.

Be careful about converting from double wall to singlewall. With the loss of spring back caliper in the board construction, one will lose bending stiffness, while ECT may be the same.  Both physical properties make up box compression and performance.  Have you considered B/E double wall with ultra lightweight components?  Kapstone makes these grades at Longview, and maybe Port Townsend also.

So to construct a minimum 40 ECT a corrugator needs to combine a minimum of 216# of CD ring crush in the three or five components. Corrugators vary in their ability to maximize the inherent strengths in the linerboards and medium from plus 15% to minus 25%.  Do you know your sheet feeder’s profile?  To achieve a minimum 44# ECT the suppliers need a minimum of 235# of CD ring crush.

Converters vary in their ability to maintain the incoming ECT by plus 0 to minus 35%. Have you benchmarked your presses, people and process?  The Chalmers DST is an excellent instrument to measure your degradations factors.

Under ideal circumstances, corrugators and converters can obtain a minimum 40 ECT B flute with 36/30/36 and a minimum 44# ECT B flute with a 36/36/36 or a 42/26/42 combination. I prefer to put more substance and strength into the medium.  30/23/26/23/30 will give you more than enough for 44# ECT.  Is this a cost effective alternative?  Usually we see a 5-85 fibre savings.

— Ralph

This entry was posted on October 24, 2014 at 12:12 pm and is filed under Containerboard, Testing and Specifications. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.