The Effect of Various Factors on the CoF of Pallets

Duration: Spring 2019

Students: Dianjin Xu and Logan Tallman

Faculty Advisors: Dr. Laszlo Horvath and Dr. John Bouldin

Coefficient of Friction (CoF) tests are designed to observe and quantify how the factors between a C-flute corrugated sheet and a quarter-sized pallet affect the CoF of the quarter pallet. The factors examined include rates of loading, the orientation between corrugated fiber direction and deck board width of the test pallet, and the face of the pallet (equal spaced deck board versus single piece panel deck board). The quarter-sized pallets were pulled from the length side and the width side throughout the entirety of the testing, and data were collected for both orientations.

In order to determine the most conservative CoF value for a southern yellow pine pallet interacting with corrugated board, a test setup for an MTS machine was designed. This allowed for the testing of a quarter-sized pallet being pulled on a sheet of C-flute corrugated. The pallet had both a single panel deck and a spaced deck board side. The corrugated could be placed in a parallel direction to the pull of the pallet or oriented so that it was perpendicular to the pull.

To conduct the CoF testing, the wooden platform is loaded onto the back of the MTS machine and attached to the hooks on the back wall. This serves as a level base for the corrugated and pallet to be placed on. The weight box is then placed on top of the test pallet. The pallet is centered on the corrugated board with the desired testing weight, and the rate of loading profile is selected from the MTS machine software. The test is run with the string pulling the pallet across the corrugated toward the front of the MTS machine. The operator watches the load curve on the software, looking for the pallet to reach the peak load and then decrease. This means that the pallet has lost friction with the corrugated, and the repetition is complete.

After each set was finished, the set-up would then change for one or more of these variables until all combinations of the weight, flute orientation, and rate of loading profile were completed with 10 repetitions for each. In order to further understand the material properties of the southern yellow pine pallet interacting with a corrugated sample, a Technical Association for the Pulp and Paper Industry (TAPPI) Coefficient of Static Friction incline plane method test was also performed.

Data analysis was run on all sets of data to determine which factors in the coefficient of friction testing were significant. It was found that the weight, rate of loading, flute orientation, and pallet face all have significant impacts on the coefficient of friction value. The levels tested in each factor were significantly different. A significant difference was seen between the 1 inch per minute and 12 inch per minute rate of loading. Additionally, the 25 lbs. and 75 lbs. weight levels were significantly different. The panel deck face of the pallet showed a higher coefficient of friction value versus the spaced deck board side. The orientation of the corrugated board also showed a significant difference between the parallel and perpendicular orientations.

In the scope of this testing, it was found that the conditions that give the lowest coefficient of friction values were a 1 inch per minute rate of loading, under a 25 lbs. load, with the corrugated flute orientation running perpendicular to the direction of the pull, when the spaced top deck boards were in contact with the corrugated board, and the pallet was being pulled from the width side.