Archive for the ‘Containerboard’ Category

Outside Air Temp effect on Green Bond

May 23, 2022

Ron asks:

We had an overhead garage door installed prior to our 2018 corrugator project – the OEM had us install it for ease of bringing new equipment into the building. Certain times of the year, say April to October, the corrugator crews have the overhead door open and just have the screen door down to allow fresh outside air in.  This door is maybe 18′ from the corrugator stacker. Should we have any concern about green bond shock on a cooler morning. The stock coming off the hot plate section is 275 degrees +/- and if the outside air temp was 50 would you be concerned about that?  I haven’t been able to find any studies related to this. Your opinion would be greatly appreciated.

I would focus more on the final pin adhesion strength.  You should target values above 45 and up to 60 pounds per foot.  If the pH, viscosity, and starch temperatures in the pan are within your process parameters, green bond should not be an issue.

Let’s toss it out to our readers. Have any of our other corrugator operations had any experience with this scenario?

— Ralph

Linerboard Coefficient of Friction (COF) Target and Max

February 3, 2021

Cassie asks,

I’m doing some investigation to determine what is the minimum, target and maximum COF (coefficient of friction) for linerboard. Can you point me to any information on this?

Instead of answering your question directly from a mill process point of view, which we can do, here are a couple links to several specification sheets from domestic mills. (Domestic High Performance Linerboard, COF Spec Sheets or Slide Angle)

The Europeans do not seem to deliniate slide angle as a physical property characteristic.  Since they have been making linerboard from recovered fibre much longer than we have in the Americas, it may be just universally understood there.

Let me know more if you have more specific questions. I would also recommend membership in TAPPI’s Corrugated Board Technical Committee where you will have access to the best minds in this business.

—Ralph

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

Acceptable Reject Rates for Corrugated Packaging

March 19, 2020

Ed asks,

I wanted to run something by you and see if you could point me in the right direction.

We have a client who orders a lot of different sized RSC’s in quantities of 2500. At one point we were having some issues with gluing and had to re-glue the boxes. However, we addressed the issue and it seems to have fixed the problem. But now every time this customer finds a box that isn’t glued properly he expects us to re-glue it. I am not sure if we should be expecting every box to be perfect, or if we are shipping them some bad boxes but not billing them for it.

Do you have any information on acceptable “non-conforming” box rates? Is there an industry standard for this?

TAPPI’s Waste and Productivity Survey provides a lot of valuable information, but I saw nothing  specific to glue tab or manufacture’s joint failures.

I talked with Ken Robinson at Baumer hhs. Here are com points to consider.

  • If you have a contact system you will probably always have an issue.
  • Two percent failures are to be expected.
  • Pre-cleaning the glue tab before it hits the gluing station helps.
  • Operator training should be constant.
  • An inspection system can reduce the reject rate to 0.1%.

If there is not a published industry standard reject rate then it most likely will fall back on the contract/agreement between the boxmaker and the customer. Does your contract address percentage of rejects?

Customers, especially those running or supplying automated packing lines may be looking for zero defects. Of course every boxmaker strives to deliver the highest quality with minimum rejects at the most competitive price. However, there is a cost associated with ensuring the delivery of zero defect loads. Is the customer(s) willing to pay that price? They too are looking for the best, most competitive prices. However, if the cost of ensuring zero defects is less than the cost of lost productivity and products, then they may be.

— Ralph