Impact of inner liner on RDC stacking strength

July 31, 2015

Don asks:

Can you explain (technically) how bumping up the inside liner on an RSC box increases stacking strength has a big impact?

In most distribution environments corrugated boxes in compression situations fail in a two part mode. First the corners of the box take the load of the boxes above them and this is best predicted by ECT. Then the side walls of the box begin to bulge and we predict this by testing for four point bending stiffness or flexural stiffness.

This latter physical property is dependent on the caliper and the stiffness of the board. Since side wall deflection begins with the deformation of the inside liner this is the component that one should begin with to add basis weight, caliper and stiffness.

This is the scientific side of the construction, but medium is the most cost effective way to build more ECT. There is a balancing act. Of course this all depends on the corrugator’s ability to maintain the strength of the containerboards and preventing or minimizing crush to the sheets during converting.

— Ralph

Global Harmonization System Is Here

May 26, 2015

On June 1, 2015 the new International standard updates some OSHA UN HazMat labeling requirements. On this date every MSDS that you have will become outdated and needs to be replace with the Safety Data Sheets format as described by the GHS. You might, if you are not there already done so, begin to gather sheets from your containerboard supplies about the human health risk of “dust” or cellulose fibre. While there is a renewed concern and period of public and expert comment period of the combusted dust issue in “confined” spaces by OSHA and the National Fire Protection Association, the human health assessment is another initiative.

Also the labeling of corrugated and the shippers placards for hazardous materials has changed. Below is a web link to a white paper on the subject. Click here to download White Paper. We have many network contacts in the Chemical Packaging Committee of Institute of Packaging Professionals to come alongside you. Lonnie Jaycox is one of those people.

Printing on Hot Corrugated

March 3, 2015

Jason asks,

Could you explain why it’s not recommended to print on hot corrugate fresh from the corrugator?
I know this isn’t common practice, but there are times when it is necessary when a rush order comes in.

Once corrugated sheets come off the corrugator they should be allowed a bit of time to cure. This will allow the sheet time to stabilize and adjust to the relative humidity of the environment, etc. Slight size changes can take place during this time. If you go straight from the corrugator to the converting process, it is possible that you could end up with a finished product that doesn’t meet the customer’s specification.

Basically ink dries by absorption and evaporation. The chemical characteristics of the ink, mainly pH levels, and temperature, greatly influence drying as well. When you induce significant temperature change to the equation, such as hot board, you change the entire drying process. This will most likely result in ink drying before it has time to absorb into the fibres of the sheet, or it may cause the ink to dry on the plate. Both situations can result in poor coverage/print quality and excessive build up on the plates.

Hot sheets can also cause “baking” of the printing plates which will significantly reduce the plates’ ability to properly transfer ink as well as the overall life of the printing plates.

A hot sheet could also possibly experience more crush as it goes through the converting process than a cured sheet would, and therefore result in a degradation of product quality. A sheet that isn’t properly cured may also be more likely to create rolled scores.

Converting equipment can also be affected by hot sheets. The functional characteristics of urethane components such as feed belts or wheels, transfer belts, pull collars, and in some cases even cutting die rubber can be decreased by hot sheets. The coefficient of friction of feed belts and wheels can be reduced causing registration and skew issues. Die cutting rubber can be overheated causing reduced ejection rates and rubber life.

There are probably other issues that we’ve overlooked here, but I hope this gives you some idea of why running hot corrugated is not a good practice.

— Ralph

Be Prepared: Changing Shipping Regulations

March 3, 2015

AICC just returned from attending the winter meeting of the Chemical Packaging Committee of the Institute of Packaging Professionals. This committee is the one that monitors the global changes in hazardous material packaging and shipping regulations and acts as this Association’s major advocate with the US Department of Transportation. As new members of this committee, this was only AICC’s second time to engage with these experts. What keeps showing up on top of the agenda is the Global Harmonizing System. This is where the US will comply with the UN on the import and export packaging and labeling of hazardous materials.

So how does this impact a corrugated company? One is that the labeling and placards are changing and will need to comply with these global and now domestic requirements by December 31, 2016. The other is that a product that may not have been considered a hazardous material in the past may now be reclassified as a dangerous good. Add to this the changing requirements for food safety thru the Global Food Safety Initiative and all will be busy trying to stay ahead of customers’ needs. This latter issue may have a greater impact on folding carton and rigid box manufacturers.

The entire distribution environment and transportation modes have changed and are changing. So what’s happening with the aging stock of over the road truck drivers? These 55 plus year old men and women are not being replaced by younger drivers who are willing to accept $55-60,000 a year in earnings. This mode will probably seek higher freight rates to attack younger operators. Add to this that US ocean ports are not able to handle the newest and biggest ships. Then compound this with the evolving growth of the small parcel and e commerce shipping modes and a packing company going forward must be nimble to adjust. Maybe more reshoring will occur.

Another issue discussed by those who must handle explosive materials is the need for grounding in manufacturing processes that create static buildup to the extent that a spark can occur. While we do create negative charges in our industries, they are easily dissipated and are generally not an issue. However with OSHA moving in the direction of more dust containment regulations, grounding may move up the scale in importance.

Stay tuned.


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