Redesigning protective packaging buffers from the failure modes derived from crack characteristics

Abstract

Protective packaging buffers are commonly used for the purpose of containment, protection, communication, and marketing of consumer products. Because the use of protective packaging is expected to increase markedly in the years ahead, it is imperative that their designs be cost-effective. Much of the known design heuristics have been encapsulated in design methodologies and procedures, except for one aspect, that is, the failure modes of the buffers upon impact with the ground after being dropped from a height. All packaging designs are subjected to a series of confirmatory impact tests, before design deficiencies are rectified through iterative cycles of redesign and retest. Because of the heuristic nature of packaging design, many cycles of redesign are necessary before a satisfactory design solution is found. This article discusses how, from the nature and severity of the cracks, the probable causes of failure and corrective redesign measures may be estimated. Based on the value of the crack ratio (i.e., the ratio of the depth of the crack to the buffer's bearing thickness), three distinct modes of failure can be identified: marginal, critical, and catastrophic. The variation of G-value with crack ratios was studied for varying drop heights. By comparing the measured G-value to the failure mode, the conditions contributing to the failure—viz. height of drop, direction of impact, the location of the centroid, the type of fit, and degree of contact between the buffer and the product—may be estimated. Redesign guidelines to avert catastrophic buffer failure are also discussed. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 721–731, 1999