Experimental Verification of McKee Formula

Abstract

Seventy RSC single-wall 200# corrugated boxes, of seven different sizes from the same manufacturer, were compressed. Actual box compression strengths were compared with those computed using the McKee formula. The ratios of side-loading to top-loading box compression strengths for 3”x3”x3”, 5”x5”x5”, and 7”x7”x7” were found to be 30%, 46%, and 62% below those derived from the formula, while the box compression strengths (top loading) were 18%, 45%, and 63% higher. Bigger boxes yielded wider discrepancy between the actual compression strength value and that predicted by the McKee formula. A similar conclusion was made with three other box sizes with the same height (4”x4”x12”, 5”x5”x12”, and 6”x6”x12”). The effect of box height (which is not included in McKee formula) on its compression strength was also investigated using three box sizes, 5”x5”x5”, 5”x5”x12”, and 5”x5”x48”. As expected, the box became weaker as the height increased due to the wall buckling. The compression strength dropped 62% from the 5” to 48” box heights. Overall, the box compression strengths (BCT) predicted by the McKee formula were off anywhere from 50.48% overestimate for the 5”x5”x48” box size to 69.36% underestimate for the 6”x6”x12” box size.