Pete asks,
We have been working with several different perf styles to provide ease of opening for retail ready PDQ style trays. There is a variety of different sizes and the majority of the items are earmarked for Walmart stores. While our execution has been successful we do not have an effective process to measure the force required to open the boxes to ensure consistency. Are there any tests to can recommend or any laboratories capable of testing the variables we are trying to measure?
Very good question Pete! You might review TAPPI T-813 which discusses the tensile test for the manufacturer’s joint. There are also jigs for compression testers that will measure the force necessary to bend a crease through a certain distance, usually to a 90 degree angle. Also check TAPPI 577 and 829 for ideas.
Another option may be to use a burst test at the point of the perf. TAPPI T-810 describes the burst testing method. The question would be whether conventional equipment would have a satisfactory range of operation/measure or would the bursting strength of the perforation be below the recommended operating range of the equipment.
Now let’s toss this one out to our readers to see what their thoughts and experience may be. Has anyone done this type of testing, or is anyone aware of a specific method for testing the force necessary to break a perf?
– Ralph
askralph 
April 10, 2019 at 3:13 pm
I have had a customer come to us with exactly the same question. He had thought that the burst test might be a solution to his measurement challenge. We have both modern automated burst testers and an old museum piece with a lazy hand gage that is manually operated. We experimented using the manually operated burst tester to burst through the perf. We found that the burst test devices are designed to measure peak force. The perf would tear, and then the corrugated would tear next to it almost creating an “H” shaped failure. The secondary tearing was measured as the peak force rather than the initial separation of the perf.
We tried using a calibrated eyeball to interrupt the test as soon as the perf tore but there was so much variability in the measure that it proved to be a very poor option.
Using a burst test to measure the force required to tear a perf is a bad idea.
It is my opinion that a Universal tensile type test device is the best instrument to perform this type of measurement. I went looking for other existing TAPPI test methods that could potentially be used to evaluate this property. One that I found, but do not have the ability to do, was Elmendorf Tear Test device, TAPPI T 414. Maybe someone who has that instrument could comment on its applicability for this use.
April 10, 2019 at 3:33 pm
Thank you for your comment Tom. Great input, thank you so much for sharing your experience. Anyone else have any experience in testing perfs?