Study reveals vital cartonboard characteristics

M-real Consumer Packaging said the analysis carried out by a research institute on dummy containers demonstrated that lightweighted carton boards were able to cope with real-life situations such as palletising and stacking.

“Good rigidity and high stacking strength are particularly needed when cartons are loaded onto pallets on top of each other, and secondary packaging, such as a corrugated case, is not being used,”​ said a statement from the Finland-based packaging supplier

Performance​

The study evaluated how a range of characteristics - including design elements, and humidity – affected the performance of cartonboard.

The researchers also examined how factors such as carton dimension and board fibre direction could affect the container’s strength. They found that changing carton size - height and width of the side panels – had no notable effect on the box compression test value, as the corners bear most of the load.

But rotating the fibre direction did make a “dramatic difference”,​ said the company. Most cartons use horizontal fibre direction to improve runnability on a packaging line and provide a more rigid feel when handled. Changing fibre direction to run parallel to compression boosted stacking strength by as much as 20 per cent. M-real acknowledged that such benefits have to be weighted against the machinability of horizontal fibre direction.

Humidity​

Board strength is also influenced by the level of relative air humidity because the packaging is made from a natural material – wood fibres, the tests revealed. Researchers found that both board and carton strength fell when relative humidity rose from 50 to 80 per cent. Box compression strength decreased 15-25 per cent, depending on board grade.

“This is important to consider when cartons are exposed to humid conditions during transport or storage”,​ said M-real.

Matthew Terry, company technical service manager, said: “Today, cartons are required to meet the standards of the retail chain in both quality and functionality. They not only need to protect and promote the product, but also to be cost efficient and enable efficient handling in the areas where the highest costs are incurred. Our studies have highlighted the critical points encountered in the packaging value chain, and established what demands they make on a board’s raw materials as well as on the finished carton.”​

The company added that it was vital to choose the right raw material for cartons to cut the amount of wasted products and even eliminate the need for slip sheets during stacking.