The objective is simple: Have the goods arrive at their destinations in satisfactory condition and at minimum expense. The challenge is that products can be damaged and that packaging materials, labor and shipping activities all cost money. But with understanding, analysis and appropriate designs, both safe arrival and effective cost control can be reasonably achieved.
Its important to understand the hazards of distribution. In general, there are four categories of hazards: Shock (drops, impacts), vibration (during movement or transportation), compression (packages stacked in storage or vehicles) and atmospheric (temperature, humidity, altitude, static electricity, etc.). All of these are certainly present in parcel distribution, although the special aspects of this mode, particularly automatic sorting and handling, can create unique variations and severities, which must be taken into account.
In addition to understanding the hazards, we need to know how the goods might react to these hazards. Can they break, deform, fatigue, leak, scratch, discolor, corrode or just stop working properly? What constitutes failure or unacceptability? If possible, it is best to quantify damage definitions so that all stakeholders know and agree upon the limits of product acceptance.
Then, in order to develop appropriate packages, we must know what packaging materials and configurations are available and how to best apply them. Outer containers for parcel distribution can include various constructions of boxes, bags, pails, cans, tubes or envelopes. Interior packaging can include air pillows, bubble or cellular sheeting, various paper forms, loose-fill materials, corrugated or solid fiber pads and structures, desiccants and corrosion inhibitors, foam plastic cushions, molded pulp, foam-in-place materials, plastic films, suspension elements and much more. The ideal solution is for the package to provide exactly the proper type and amount of protection needed by the product not more, not less and at the lowest possible overall cost.
Parcel Distribution Hazards
Shock: This hazard of parcel distribution can occur when packages are dropped; strike (or are struck by) other packages or by sorting mechanisms; or shift and fall during transit. In this environment, there are many shocks of relatively low severity (equivalent to drops from relatively low heights), with typically only a few impacts equivalent to drops from 30 to 40 inches or higher.
Although it is recognized that impacts predominately occur on and around the base of the package (bottom face, edges and corners), packages should be designed to protect against impacts from any direction. Base is generally defined as the bottom surface when the package is in its most stable orientation; sorting operations cannot always honor up arrows or orientation labels.
Long, slender packages may be subjected to bridging during sorting. Bridging can occur during conveyor or chute movement when a long package gets supported only by the ends. It may then be susceptible to damage from even relatively mild impacts near its center. Large, flat packages (mirrors, panels) can be more prone than other types of packages to damage from impacts on their faces.
Typically, only corrugated boxes with weights less than 70 to 75 pounds travel through the carriers automatic sorting systems. Large, heavy, non-corrugated and non-rectangular packages (or products with no packaging, such as tires or spools of wire) are handled in various ways, depending on the carrier and location, and therefore may be subjected to more severe environments.
Vibration: Potentially damaging vibration may occur during transit by road, rail or air. The severity of motion is low compared to shock, but long exposure times (hours or days) can cause abrasion and scuffing, loosening of closures and fasteners, fatigue and cumulative damage. Parcel carriers use a number of different transport modes, including trucks of various types, trailers on flatbed railcars, aircraft and others. The modes can have unique vibration characteristics, and packaged products can react differently to each.
Long-haul vehicles are loaded to utilize essentially all of the interior space. This means that package orientation within the load cannot be predetermined, and therefore, packages must be able to withstand vibration in any and all directions. Long and flat packages may not be fully supported along their lengths or faces, potentially causing increased stresses.
Compression: Warehouse storage is not generally a part of parcel distribution, but packages are stacked in the long-haul transport vehicles and the resultant compression forces are dynamic (varying due to vibration) during transit. Dynamic compression can be several times the magnitude of static compression. Since package orientation within the load cannot be predetermined, packages must be able to withstand this compression in any direction.
The average density of loads in long-haul vehicles can range to 12 or more pounds per cubic foot. Since any particular package can be at the bottom of the stack, the usual approach is to design for dynamic forces equivalent to average load densities at full vehicle heights.
The carriers local pick-up and delivery vans generally have interior shelves to hold the packages, so the compressive forces in these vehicles are much less. But the vibration signatures are different from the signatures of long-haul, so the potential for damage still exists.
Atmospheric Conditions: These conditions can affect the characteristics of both products and packages. High humidity weakens corrugated; high temperatures can weaken plastic, and low temperatures can tend to make it brittle; high altitudes can distort or damage air-containing or sealed components; static discharges can destroy electronics; and so on. Packages must be designed to protect their products under atmospheric extremes, including winter temperatures, summer temperatures plus the temperature rises in closed vehicles and containers, near 100% relative humidity, altitudes to 20,000 feet for unpressurized feeder aircraft and other conditions as appropriate.
Parcel Distribution Packaging
Protection: The ideal parcel distribution package would take into account and protect its contents from:
· A relatively large number of low-level shocks and a few severe shocks, from any direction, caused not only by flat surface impacts, but also by impacts with other packages and objects
· Vibrations caused by the modes of transport used, along any package direction, while under compressive loads equivalent to those encountered in transit vehicles
· Extremes of temperature, humidity, altitude and other atmospheric conditions, which might occur alone or in combination with the shock, vibration and compression discussed previously
Design: Obviously, every situation can be different, but there are some general guidelines which can help to ensure success in the parcel distribution environment:
· If possible, practical and economical, package in a conventional corrugated box. These packages will be sorted with the carriers automatic systems, resulting in more controlled and repeatable inputs.
· If unusual packages are used (not a corrugated box, exceptionally long or flat, heavy, awkward, etc.), account for the associated additional hazards and possibly increased hazard severities.
· The contents of corrugated boxes should generally be no more than 50% of the weight indicated on the box manufacturers certificate (BMC: the circular emblem on the bottom of the box). Gross weight limits listed on the BMC apply mostly to shipment by motor freight or rail and have been shown to be inappropriate for the parcel distribution environment.
· If possible, design for stability (no tipping or tumbling) at angles up to 40 degrees. This will help prevent damage during movement on the carriers inclined conveyors and chutes as well as during airplane climbing and banking maneuvers.
· If the product is factory-packed in a specifically designed container, consider quantifying its mechanical fragility using established methods and engineering the protection accordingly.
· If miscellaneous products are being packed into stock containers (a pick-and-pack operation), a key element of successful configurations includes the thickness and type of void fill or cushion materials. Items should be spaced away from the container walls and from each other, with greater distances for fragile objects.
Pre-shipment Testing: Before committing a packaged-product design to large-scale parcel distribution, it is prudent to test it in a laboratory and assess its performance. Testing protocols that more closely simulate the target environment can lead to more effective and cost-efficient solutions.
All of the major carriers publish packaging guidelines and testing protocols on their Web sites. International Safe Transit Associations ISTA Test Procedure 3A, Packaged Products for Parcel Delivery System Shipment, is arguably the most accurate simulation test currently available for parcel distribution. It includes various shock tests, top-loaded vibration and atmospheric conditioning. In fact, the ability to pass the rigorous ISTA 3A is one of the requirements of UPSs tariff.
Obviously, the very nature of package distribution is fraught with inherent hazards. However, by taking the time to examine both your processes and your packaging, you can save your organization time, money and headaches.
William I. Kipp is Associate Executive Director of International Safe Transit Association (ISTA), a trade group dedicated to the control of costs, damage and resources during the physical distribution of goods. He can be reached at 650-355-7211 or by e-mail at