November 29, 2016
In the last issue of BoxScore, we shared that a four-man team presented in Mexico about the no-longer-emerging market for properly made corrugated with just the correct amount of fiber balance among the three to five components. In the article before that one, we stated that 13.5 percent of the containerboard produced in the United States was at 32#/MSF and below. Has this been your experience?
We realize that there may not be one solid description for “right weight,” so I will offer one up:
Definition:
Right weighting is using the right strength selections of linerboards and medium(s) in combination with a choice of single-wall or double-wall options, as many as a dozen different flutes, design, graphics, interior support, and knowledge of the distribution environment, to create the right package with the least amount of fiber and cost.
Example:
It can be a 72# performance grade of linerboard substituting for a 90# mullen grade all the way to 18# linerboards in a double-wall combination to engineer a 32# ECT or 40# ECT combined board option. The opportunities have never been greater to look to the strength and combining characteristics of containerboard to obtain the right package or carton. The downward shifting of fiber consumption and upward focus on generating the maximum strength per pound of fiber was demonstrated decades ago with the corrugated clamshell, the AC Delco parts carton, and the Nike footwear box.
The contents of the chart above are somewhat arbitrary, but you understand the structure. These are North American grades and are not typical of what Europeans produce and convert. With Smurfit Kappa’s presence here in the United States, one might expect them to seek out the equivalent grades here with options to combine in their own facilities. There are 10 different machines in the United States, three in Canada, and two in Mexico that offer linerboards from the last category in the chart. If you wish to learn more about the range in properties among the mills, contact me directly.
History:
The “right weighting” began in North America in the late 1970s, when Owens-Illinois’ Forest Products Division (now G-P and PCA) began to substitute stronger, higher-STFI grades of medium and to reduce linerboard weights for combined board and boxes. What they were doing was redistributing the vertical compression load sharing of the components. They were using less expensive medium to replace more expensive linerboard weights and strengths.
In 1991, rail and truck shipping regulations allowed for the use of any combination of components, as long as minimum ECT levels were met based on the content weight and dimensions of the corrugated box. So, over the years we have seen reductions in liner weights by some mills from 42# to 35# to 33# to 31# and a few mills that can achieve a 32# ECT using 29# liners.
Then it was called source reduction, then sustainability, reducing over-packaging, and fit for use, and now we are entering the realm of right weight packaging and containerboards focused on smaller package sizes, e-commerce, and shelf-ready, retail-ready, and corrugated substitutional opportunities for solid fiber packaging. It is usually in the arena of small- and microflute packaging and using modern high-strength grades using a range of 18–33# fiber combinations. Combiners and converters who embrace this developing trend will need to digest some new physical property terms to distinguish among the different offerings.
If we look to selected European websites, we can observe process controls that no longer use ECT as a predicator of box performance, but rather use the DST instrument, which measures torsional stiffness and the impact of medium degradation at the single and through the converting operation. And in the area of the lightest weight combinations and smallest flute methodologies—such as block compression, corner crush, and Taber—stiffness might offer better analyses. It is not about measurable caliper.
Ralph Young is the principal of Alternative Paper Solutions and is AICC’s technical adviser. Contact Ralph directly about technical that impact our industry at askralph@aiccbox.org.
