Tester Tech Tips, Corrugated Series #002: Pin Adhesion Test of Board

Measuring adhesion/bond strength of the fluted medium to the liner plays a vital role in corrugated box performance. The pin adhesion test determines strength properties of the bond formed during the combining operation and is used to monitor and control adhesion strength to identify manufacturing defects such as poor adhesive penetration, spotty adhesion and containers with low bond strength.

Example of pins and the direction of the force applied to the combined board.

Pin Adhesion Fixtures

Our pin adhesion fixtures are illustrated the other side of this page. To provide a quote for a fixture we need to know flute type (A, B, or C), test type (selective or non-selective), and flute size.

Test type, selective or non-selective: Are you interested in measuring select the side, or do you want to measure the force to separate the weakest side?

Note: TAPPI T 821 uses the selective method. The PAT fixture is designed to concentrate the force on the strong side of the flute bond to liner. The non-selective method allows the failure to occur at the weak side of the flute bond to liner.

PAT fixtures are expressed as the number of flutes in one foot. To determine this measurement, we take a sample of corrugated and count out 11 glue lines. We then measure with a caliper the precise distance between glue line #1 and glue line #11. The distance is then converted to the number of flutes per foot.

How to measure flutes per foot:

Align the first flute with the 0 on the caliper/ruler.

Count the number of flutes to the measurement on the ruler that most closely aligns with a flute. An example of this is 3.1875″ measured over a distance of 10 flutes.

If we are measuring a C flute, count 11 glue lines which is 10 flutes. We determined the distance between the #1 and #11 glue line is 3.1875″, there are 10 flutes over 3.1875″.

Use the following formula to calculate:

• 10 flutes/3.1875″ =3.137
• 3.137 x 12 =37.647

There are 37.7 flutes per foot. The pin fixture you would request would be a C flute, 37.7.

Pin adhesion fixtures are designed specifically for the type of corrugated board being measured. Typically, a specimen is required to confirm the exact board dimensions.

TMI requests the customer send us a sample to determine the correct flute size. We do not require a sample if the request is for a replacement fixture and the customer already has a part number. The sample size of combined board required to determine the pin configuration and pin size should be minimum 12″ wide by 12″ long.

TMI’s pin adhesion fixtures ““ if you”™d like to receive a quote, please provide the following: flute type (A, B, or C), test type (selective or non-selective), and flute size.

Pin Adhesion Fixture & Part Numbers