Numerous field studies conducted by many parties, have shown that the probability of a “design drop height” event during distribution is very small, on the order of 5% or less during any particular shipment. Yet the majority of laboratory package drop test procedures typically call for 10 impacts from the design drop height on different faces, edges, or corners of the package system. Does this not
constitute a substantial over-test? This paper will examine the nature of package drop testing, why it evolved in its current format, and the significance on package performance and optimization.
When studying the distribution environment to determine typical package drop heights, it becomes apparent very quickly that the vast majority of the data is rather boring in that most impacts are at a relatively low level. For a very few number of impacts, however, the drop height can be significant, certainly significant enough to cause potential damage to a packaged product. But these less than 5% of the total recorded impacts most of the time, the vast majority of studies report only one impact from this “higher” drop height. In fact, most environmental data recorders, so called “ride recorders”, are often set up to reject data below a certain drop height because the amount of data collected would be very difficult to analyze based on the large number of very minor impacts. Thus, from a statistical standpoint, it’s very difficult to even determine the percentage of “total” drops simply because much of the data from lower drop heights is not even collected.
ConclusionIt has been shown that the nature of the package test specifications, especially in terms of the orientations and number of impacts, is conservative by its nature and will likely lead to more expensive and over-designed package systems from a shock mitigation standpoint. Where multiple impacts on a product-package system are desired for a package drop test sequence (and the authors certainly believe that that is the case), perhaps these additional impacts should be conducted using a fresh package system for each orientation. It may also be feasible to use one package for several drop orientations where a crushable package system, for example, will still offer adequate protection. In this manner, a fresh package impact orientation could be maintained with as little as 3 or 4 package prototypes during the test protocol in the laboratory.
Substantial improvement in package optimization and reduction in package cost – along with better sustainability overall – can be anticipated if and when this topic comes under more scrutiny by package test specification writers.
BibliographyForest Products Laboratory, "An Assessment of the Common Carrier Shipping Environment," General Technical Report FPL 22, U.S. Department of Agriculture, Madison WI, 1979
Kipp, Bill and Russell, Paul, “European Express Shipping Drop/Impact Study” ISTA Dimensions.06
