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Finding the solution to splitting medium

When an SCA Containerboard expert showed a customer how his stock could be simplified, it brought about significant savings and simplified stock warehousing.

In 2007, a customer of SCA Containerboard Aschaffenburg reported a problem. Single-ply medium sheets from Aschaffenburg were splitting after converting on a corrugator or laminating machine.

Sent to investigate were Alexander Fried, Technical Service Manager at Aschaffenburg, and Jörg Strauß of SCA Containerboard Technical Customer Service Central Europe.

They found that the problem wasn’t limited to Aschaffenburg containerboard. Paper from other suppliers was splitting too. What the papers had in common was a slightly higher moisture content of about 8%.

It seemed the wetter paper picked up a lot of water from the glue lines, which made the board much more moist. Alexander and Jörg determined that a rise in paper moisture of only 7% to 8% caused the board moisture level to increase dramatically from 9 to 15%. This significantly reduced caused z-strength, causing the medium to split. Indeed, further testing with climatised papers produced no splitting.

Tiny change, big result

The solution proposed by Alexander and Jörg was to reduce the moisture content of the Aschaffenburg medium from an average of 7.9% to 7.5%. This small adjustment made a big difference. No further splitting was detected.

“A number of trials were needed to determine the problem and solution,’ says Alexander, “and there was always good collaboration with the customer.” But the story doesn’t end here. Alexander and Jörg are continuing to check whether adjusting the forming and dewatering conditions could make the paper even more resistant to splitting.