Archive for the ‘Testing and Specifications’ Category

Hazmat Linerboard Weight Tolerance

December 30, 2020

Dave asks,

What does the AICC hazmat guide say about tolerances on basis weight? Customer says they must run: “We must run the 31-31-35 hazmat board combo” but the corrugator no longer runs that combo.

The DOT has relaxed the “49 CFR 178.516 – Standards for fiberboard boxes” from +/- 5% to now allow +/- 10 percent basis weight tolerance in the linerboards.

Per the Legal Information Institute “UN4G combination packaging with outer fiberboard boxes and with inner fiberboard components that have individual containerboard or paper wall basis weights that vary by not more than plus or minus 10% from the nominal basis weight reported in the initial design qualification test report.” Click on this link to learn more at the Legal Information Institute.

How did your customer arrive at the 31-31-35 combination? Is it from a previous requirement? As long as they the meet the strength requirements for the content it should be acceptable to use another combination. The +/-10% relates to the base weight of the liner used and may not mean that you could directly substitute a 28lb for a 31lb. If a 28lb liner is used then the tolerance would be +/-10% of the 28.

So I think it would be important to first see if you can provide a combination that meets their strength requirements WHILE remaining while remaining within the +/-10% tolerance.

— Ralph

Roll Hardness Testing

June 12, 2020

Chris asks,

I was recently appointment QA manager at my company and have dove head first into the realm of Schmidt Hammer(roll hardness) testing.  A very significant issue we have is with warp.  I have noticed that most of the time when I see a difference of greater than 10 on the Schmidt Hammer test we suffer from unacceptable warp issues.   Since I’ve started hardness testing inbound rolls we have adopted a pass fail system where any roll that tests to greater than 10 is rejected.  To add to this problem our supplier has adhered to a system that says anything under 15 is acceptable by industry standards.

What is your take on this?  Do you feel that it is unreasonable to ask the mill to commit to less than a 10 difference?

Also, the mill is questioning my testing methods.  TAPPI T834 suggests to sample a roll every 6 inches across the roll (the mill uses this sample frequency).  I have always been taught that as for a scientific process that the larger sample size yields more accurate result.  With this being said, I chose to test my rolls at a frequency of every 3 inches which would increase my sample size.

Do you feel that my testing method is in some way negatively affecting the results?  As in, is my sample size causing the rolls to “fail” on a more frequent basis?

 

I love the three inch method. However, you would not be able to correlate to any of the 140 +\- containerboard machine out there. I would agree you are more likely to find a wet streak with your protocol, but mill specs usually call for moisture deviation to be six inches or less.

Do you have linerboard specification sheets from other companies?  You may want to investigate roll hardness from other manufactures. If your supplier is so entrenched in their thinking you might consider saving their rolls and having one of their Corrugator supervisors show you how to run the board without warp. It’s a bold move!

 

— Ralph

Corrugated Performance In Sub-Zero Temps

March 16, 2020

Jeff asks,

I have a client who is asking for specific information about corrugated performance at low temperatures (-20 degrees Celsius) for extended periods of time (up to 6 months).  I have not been given specific information about the contents of the boxes, but I suspect it to be clinical trial materials or something similar.  I expect them to be looking for some sort of performance guarantee.  Current board grade is 32 ECT C Flute.  Outside liner would be virgin paper.  The remainder of the box (medium and inside liner) is recycled paper.

Anything you can provide to help me with this?  Or can you direct me to the right place?  Thanks in advance for any help you can offer.

There just is not much out there, but here are a few things that we do know. Cold temperatures can cause strength degradation in corrugated packaging and other corrugated paperboard products. Moisture introduced from the repeated opening and closing of refrigerated units can also affect the strength of the corrugated container. Aqueous and UV coatings will certainly provide extended resistance to moisture on the boxes’ surface. However, what generally happens is the glue line is attacked by changes in atmospheric conditions. This is where we often see failure to the board itself.

Manufacture’s joints and/or flaps that are glued can also be subject to strength degradation at low temperatures. The same problem may be seen in boxes sealed with tape as the adhesives can become less tacky. There are tapes and glues that are marketed to offer better performances in both extreme low and high temperatures. While they may not help with the overall strength of the box, they contribute to the overall survivability and protection of the enclosed content.

Here is a link to the last industry wide study on freezer storage that we are aware of. It’s a bit over 70 years old, but still relevant. Note the added box strengths in the chart.

I’ll also include this link to the most recent report from the PMMI on the storage of Corrugated Packaging.

Does any of our other followers have any knowledge they care to share on their experience with long term or short term low temperature storage of products protected by corrugated containers?

— Ralph

Corrugated Performance In Sub-Zero Temps

January 28, 2020

Jeff asks,

I have a client who is asking for specific information about corrugated performance at low temperatures (-20 degrees Celsius) for extended periods of time (up to 6 months).  I have not been given specific information about the contents of the boxes, but I suspect it to be clinical trial materials or something similar.  I expect them to be looking for some sort of performance guarantee.  Current board grade is 32 ECT C Flute.  Outside liner would be virgin paper.  The remainder of the box (medium and inside liner) is recycled paper.

Anything you can provide to help me with this?  Or can you direct me to the right place?  Thanks in advance for any help you can offer.

There just is not much out there. Here is a Link to the last industry wide study on freezer storage which is over 70 years old, but still relevant. Note the added box strengths in the chart. Also here is a link to the most recent report from the PMMI on the storage of Corrugated Packaging.

As you stated, the contents of the box is critical and also is the introduction of any moist air from repeated open and closing of the storage unit. Use of aqueous or UV coatings will certainly provide extended resistance to moisture on the boxes’ surface. However, what generally happens is the glue line is attacked by changes in atmospheric conditions. This is where we often see failure under these conditions.

Does any of our other followers have any knowledge or experiences they can care to share on this subject? How about adhesives and sub-zero temperatures? How does temperature affect the difference adhesives we use in the corrugated industry?

— Ralph