Issue link: http://cp.revolio.com/i/586959
H h h The Hewlett Packard Company (HP), like many global entities, has a worldwide presence – with manufacturing, distribution centers, and/or sales locations in all regions and virtually every country around the world. The end result is that HP products frequently are shipped thousands of miles from factories to customers, with most shipments including significant times in trucks, ocean containers, and/or rail cars, and many including air shipment routings. Like many companies, HP utilizes packaging engineers to specify packaging materials, packing and unitizing methods, and test specifications which are designed to ensure successful product deliveries to end customers. For our products which travel via very long supply chains, Box Compression Test (BCT) is the specification of choice, and the discussion in this paper is geared towards the challenges of box compression strength loss in long, environmentally dynamic supply chains. BCT specifications are set by multiplying the maximum expected top load expected in the supply chain by a "safety factor" multiple, to account for sundry variables which reduce box strength over time. This approach is mostly effective, although we see occasional boxes or shipments which have box compression damage, for reasons which are not readily apparent. The desire to eliminate these compression failures, but without increasing BCT specifications, costs, and environmental impact, has led to the investigations which are the subject of this paper. This paper seeks to change the focus from box strength when the box is new, and what environmental variables it will see during usage, to how component papers and corrugated geometric structure properties will respond when exposed to the usage environment. To do this, we will review the physical mechanisms of strength loss. Thereafter, the goal will be to use this knowledge to slow the unavoidable loss of box compression strength. This paper does not present new research, but seeks to stimulate review and reconsideration, by the corrugated industry and end users, of an existing extensive body of very good research, and to encourage additional research which will clarify best commercial practices for slowing the rate of compression strength loss in long, dynamic supply chains. At HP, we have begun a series of tests to validate a test apparatus and process, which we will then use to evaluate proposed ideas for improving long term compression performance. We will share these results in the future. The Starting Point - Establishing BCT Specifications Hewlett Packard uses a typical approach for determining BCT specifications, calculating it thus: L =((W x )+((p/units per layer) x (# of pallet loads – 1)) x F (Equation 1) Where: L = minimum required compressive strength of production box, lbf. W = weight of one individual container or shipping unit H = maximum stack height h = height of one individual container or shipping unit p = 50 lb pallet F = safety factor – Examples: • F=5 Use when the corrugated box is supporting the entire compressive load. • F=3.5 Use when the cushion/product or internal inserts add additional compressive strength. Generally, the safety factor "F" is a multiple which is applied to the maximum expected top load. It vaguely accounts for declines in compression strength over time, and seeks to ensure that boxes continue to have compression strength sufficient to support expected top loads during expected useful life. The above examples of F=5 and F=3.5 are common, rough "rules of thumb" which have been found to be useful. Such rules of thumb serve as a practical, simple proxy to cover a variety of strength reducing variables. With this in mind, there have been attempts to rationalize the safety factor. One well known example is provided in the Fibre Box Association's "Fibre Box Handbook" (Fibre Box Association; 2005). Multipliers are recommended for a number of factors – storage time under load, relative humidity and temperature under load, unitizing variables, etc. 18 ista views • October 2015 • www.ista.org Long Term Corrugated Container Compression Performance > CONTINUED FROM FRONT COVER