We have a long question here, so please forgive me for breaking format and starting with the answer.
Ryan is creating a ‘transit packaging guide’ and ‘shipping certification process’ for his customers and has inquired about testing and testing methods. (Page down to see Ryan’s full question)
I would suggest a Denver IR dryer so that you can bone dry the samples, test and then adjust up to 7% moisture. I believe the tables are included with the instrument. www.sartorius.us
The best layman’s guide to corrugated is the FBA Handbook which give testing guidelines and manufacturing tolerances. You may also be interested in the ECT brochure. These are available at www.fibrebox.org.
At AICC we have a resource called Understanding Box Performance. You can click here to purchase it on our online store.
Also, caliper is a very poor analytical tool as board can be crushed as much as 35 thousands and yet the medium will spring back the combined board sample to near the original pre-converting thickness. I much prefer the Chalmers DST as a measurement of board quality. This transverse shear testing would also take into account the quality of the adhesive bonds. If you move forward with individual pin adhesion testing look for values around 55 pounds per linear foot of glue line. www.korutest.com
Finally ECTs are always minimum values, which means they are to be maintained after the converting operations. For example 32 is the lower limit, not 27 as you have discussed.
Here’s Ryan’s original question. Thought proviking. If anyone else has any information or thoughts they would like contribute, please do. I especially like the first sentence.
I came across your blog while researching topics for my latest project – what a great resource!
We are creating a transit packaging guide and a master shipping carton/corrugated material certification process to provide our customers with verification that their finished goods meet the specifications approved and materials purchased.
I am trying to reference industry standards wherever possible, but also need to keep the testing/evaluation process as simple/efficient as possible.
We are only evaluating corrugated master shipping carton materials and are only including two material types in our guide:
SW C-flute, 32 ECT (27 ECT unconditioned); thickness: 5/32″ / 4.0mm BW BC-flute, 48 ECT (43 ECT unconditioned); thickness: 1/4″ / 6.5mm
My question to you is, could you recommend on “off-the-shelf’ set of QC/test standard reporting methods to determine if the materials are in or out of spec? Would you be able to share any details on these so that we could incorporate what industry and corrugators use to add as part of our evaluation tools? TAPPI gives great direction on how to conduct the evaluations, but not much insight on how to interpret or use the data, which is the part I am struggling with most.
* Main caveat, our samples will be unconditioned due to timing/inability to control test environments. Testing is to be done at global offices based on regional production (China, India, etc.) and in US for domestic production.
The material attributes to be evaluated:
1. Material dimensions: Is there an industry tolerance standard for CAD/dieline file to production corrugated material blank size? I have seen +/- 5%; is this common, or are 1/16” score-score or overall tolerance more common?
2. Caliper/thickness: Planned to reference TAPPI T411, but only requiring 9 test specimens (we are requiring 3 sets of production materials for another certification process, we would then take 3 test specimens from each of 3 production sets) and only requiring 1 measurement on each test specimen. I have seen a +/- 5% tolerance standard, is this recommended? Is this based on each test specimen measurement or an average of the 10 TAPPI measurements?
3. ECT: Planned to reference TAPPI T839 (mention T811) but only requiring 9 test specimens. I don’t see an industry consensus on how to evaluate the test data, but do see that NMFC Item 222/UFC Rule 41 has a requirement that 6 of the 10 specimens must meet minimum ECT specification, if 2 or more are below, a retest of 24 specimens is required. They also state a requirement that no test sample can test more than 10% below the minimum specification value. I would like to establish a simplified process for our team, but would also like to be close to an industry standard. Also, my initial thought is that our “in-compliance” range for C-flute would be 32-27 ECT, 26 ECT would be accepted with 1 point deducted from vendor performance scoring and below 26 ECT would fail as a critical violation and 2 points deducted for performance/non-compliance. Can you give any guidance here?
4. Pin Adhesion: Planned to reference TAPPI 821, but only requiring 9 test specimens. I’m not clear on what percentage/measurement tolerance is acceptable, or if this should be based on each test specimen measurement or an average of the 10 measurements. Plan is to use 400 N/M as target for both B & BC, 360 N/M would be accepted with 1 point deducted from vendor performance scoring and below 360 N/M would fail as a critical violation and 2 points deducted for performance/non-compliance. Can you give any guidance here?
5. Scoring/grading – do you have any experience with vendor performance grading or scoring? It seems some material attributes should be pass/fail, while other results should be graded to gauge production performance and drive continuous improvement. I would like to establish a straight-forward grading system to be able to track vendor/supplier performance (caliper is always low, ECT is always close to min. spec, etc.) rather than pass/fail, any suggestions?
askralph 