Box Compression

MEMBER'S QUESTION;

I noticed your question & answer section on the AICC website and I was hoping you couldhelp me.  I’m trying to learn as much as I can about box strength for shipping purposes. I work for a global snowboard company and I’m trying to figure out shipping specifications that we can send to our shipping partners around the world.

We’re using large coffin boxes to ship the snowboards. The boxes have a top and a bottom that measure below:

Tele Top- 66-1/2 x 40 x 12 ECT 86 Kraft
Tele Bottom- 66-1/2 x 40 x 12 ECT 86 Kraft

I’m trying to figure out how much weight is ok in each box, as well as how much weight can be stacked on top. I’ve seen the charts for ECT and Burst Testing, but I’m not sure if I’m reading them correctly. I was hoping you could help.

I appreciate your time.

ASK!RALPH RESPONDS:

One of the critical elements in determining compression is flexural stiffness which
is best predicted by the caliper of the combined board.  Can you provide me with the board combinations, flutes and final caliper of the construction.  Thank you.  You can have your provider/member contact me directly.

MEMBER'S UPDATE MORE INFORMATION:

I appreciate your help. Here’s the additional information I was able to find
about the Board Coffin Box that we use to ship our Snowboards.

Independent Test Labs

Independent Testing Labs February 2009                                                                                                
               
Advanced Packaging Technology     
Tony White       
847-520-4343   
http://www.advanced-labs.com/                          
twhite@advanced-labs.co

Advance Packaging Corporation
Tom Staal       
616-949-6610   
http://advancepkg.com/ISTA-testing-services/index.html
tstaal@advancepkg.com

Cal Poly State University
Dr. Jay Singh       
805-756-2129   
http://calpack.calpoly.edu/packminor.html           
jasingh@calpolly.edu

Container-Quinn Testing Labs
Steve Powell       
847-537-9470   
na                                                  

Independent Test Labs

Independent Testing Labs February 2009               
               
               
Company                                  Contact              Phone Number             Website                                            E mail
               
Advanced Packaging Technology             Tony White        847-520-4343    http://www.advanced-labs.com/                            twhite@advanced-labs.com
Advance Packaging Corporation             Tom Staal        616-949-6610    http://advancepkg.com/ISTA-testing-services/index.htm    tstaal@advancepkg.com
Cal Poly State University             Dr. Jay Singh        805-756-2129    http://calpack.calpoly.edu/packminor.html            jasingh@calpolly.edu

Pin Adhesion Targets/Expected Values

MEMBER'S QUESTION:

I am trying to get a grasp on pin adhesion.  My starch supplier gave me the following minimums and targets to shoot for:

Grade                          Min                Target
26 lin- 35 lin                40#                  45#
42 lin                            45#                  50#
56 lin – 73 lin              52#                  57#

In a previous emai lyou stated “I like to see pin adhesion values average at 55#/linear foot of glue line, while others are willing to settle for 50#, the minimum values should not drop below 45#.”

I have tested 29 ECT and the DB Bottom Pan result was 41#.  Is 41# too low for 29 ECT?  The next day I tested 275 BC and the DB Bottom Pan result was 68#.  There were no changes to the starch settings on the machine between the two days. 

My question is: Why is there so much variability in the Pin Adhesion results and is that normal?  I check B flute and C flute pin adhesion once a week and there is always a large variance from week to week. 

 

ASK!RALPH RESPONDS:

Medium as Liner

MEMBER'S QUESTION:

We use the calculations for BCT and ECT that are in the Fibre Box Handbook.  Do you know if those calculations are fairly accurate or do you have another way of calculating that information?

Also, we just tested 33/23/33med/23/33 for ECT and BCT.  The ECT result is 54 and the BCT result is 1,222 lbs.  Do you have any advice that would deter us from running 33 lb medium as the middle liner? The dimension of the box is 21.5 x 12 x 10 1/8.  The boxes are stacked 5 above the bottom box and hold 43 lbs. of material in each box.

ASKRALPH! RESPONDS:

The formulas in the FBA Handbook are the way to go!  I used a simplified version of the same formulas myself.  If you tell me the dimension of the box I can tell you if you were with the theoretical range of predicted BCT based on the components  and the ECT that you obtained after the press.

Medium as a facing is fine.  You could possibly loose a little stiffness in the side walls and a little more compression in the entire structure since moisture pickup in high RH condituions may be greater with the medium.  There are other AICC members that use three plies of medium in certain application and others that use three plies of linerboard, but for very different applications.  It’s all about the wonderful engineered design of the corrugated structure.

The theoretical range in ECT given the variation of the ring crush of the components is 40 to 58.  You were in the top quartile in ECT.  Compression potentials with that given range in ECT start at 980# top-to-bottom and goes up to 1420#.  This assumes that the board caliper was 0.260 inches. You were in the middle range in cox compression and your safety factor was 5.