Score Cracking Revisited – Again

There is much delight when one of us on staff is asked to share our knowledge or perspective on various at security analyst conferences, AICC national meetings or summits, Fastmarkets/RISI gatherings, or in this case, a fellow trade association: the International Association of Diecutting and Diemaking (IADD).

In preparing for the conversation with IADD members, the following question came in to the Ask Ralph! blog just days before. We presented this timely case study to those in attendance at the IADD meeting:

I have a customer that is having a white box randomly split (outside liner) in the vertical scores (corners of the box). Typically, the split in the outer liner tears/splits in the vertical score. We have examined the process from the corrugator and the die cutting operation.

• Corrugator advises that they check moisture content in paper rolls but not the corrugated sheets.
• We die cut and fold the sheets into a box (outside liner is white).
• Anvil surfaces are routinely rotated and replaced.
• In the winter months (Nov–Mar), we typically get the splits reported by the customer.
• Die was built for a 42White board (42W-36medium-35inner).
• Last run of 42W-40Med-31 processed well and did not split (March 2021).

Corrugators and converters often forget that containerboards have an elongation or stretch property of each of the components, which should be known. This is discussed in TAPPI Test Method T-494. MD/CD moisture profiles with very little variation are critical in forming scores without cracks. It was suggested that the corrugated sheets from the corrugator be converted within four hours, while there may still be some additional moisture in the sheets. Since we provided feedback to this member, they bought a new die, and the issue has been resolved. The original die was 16 years old!

The following AICC resources were also shared with the member:

• Score Cracking: Causes, Characteristics, & Cures (available at bit.ly/3BNSE94).
• Understanding the Key Characteristics of Linerboard and Medium and Their Impact on Combined Corrugated Board (available at bit.ly/3BSV46j).

IADD shared that when die cutting a sheet where the medium has more basis weight and fluted strength than the inside liner, the single-face liner will crack. Another observation was that there is no significant loss of box strength when score crack is allowed to occur than from crushing the flutes around the score. The group also confirmed that different die specifications are needed for different combined board weights and ECT variations. Makes sense, right?

There is one commercial testing lab that could actually quantify the strength loss from overcrushing the corner area and the score cracking corner. Contact me.

Other dialogue, questions, and answers at the IADD forum included:

• Global economic containerboard conditions.
• Domestic containerboard conditions, economics, and capacities, and changing physical properties.
• Environmental, social, and governance.
• The busiest person today? HR directors.
• Which companies own the lion’s share of production of containerboards?
• There are now 140-plus machines in North America, all with unique characteristics.
• Imports from unconventional sources with different physical properties may impact scoring and die cutting.
• All new production is 100% recovered fiber.
• Different levels of sophistication exist in containerboard manufacturing. • Changes in fiber collection options— residential mixed waste and “cow manure.”
• Basis weights keep dropping.
• Newer corrugators are more sophisticated.
• Issue with sheet feeders.
• Follow the paper trail.
• AICC resources—e-learning and white papers.
• Extended producer responsibility is in the U.S. now, following Ontario. It was recently established in Maine in July and then in Oregon in August. Producers of corrugated are now responsible for its collection and reuse—or pay to play!

Ralph Young is the principal of Alternative Paper Solutions and is AICC’s technical advisor. Contact Ralph directly about technical that impact our industry at askralph@aiccbox.org.