Safe Shipment Stacking through TOPS Pro By Jewel Vijar, Packaging Intern TOPS Software Corporation March 2011 The transportation and warehousing industry has played an important role in the advancement of trade and commerce. It has provided a link between manufacturers and consumers or retailers. Businesses contract with transportation (usually trucking) and warehousing companies to pick up, transport, store and deliver a variety of goods. Many goods are carried using intermodal transportation to save time and money. 1 Intermodal transportation involves the use of more than one mode of transport in a trip from origin to destination. These modes of transportation can be by truck, train, plane, or ship, though typically, trucks, being the most flexible, perform at least one leg of the trip. In preparing products for shipment, primary packs, sometimes consolidated in secondary packs, are contained in shipping containers to get them ready for shipping usually as unitloads (pallet loads). The shipping container may take different constructions and materials depending on the packaging expert s recommendation which may be influenced by the nature of the product being shipped and as required, sometimes limited, by government laws that may apply (e.g. when transporting hazardous materials). Another important factor is the hazards, physical and environmental, that may harm your product during the whole transportation process. Shipping containers nowadays are built in additional consideration of these hazards to provide sufficient product protection, which, yes, incurs extra packaging costs but will significantly minimize product damage costs. While these hazards or unsuitable environments are easily controlled before loading your products to a transport vehicle or after unloading them to their designated destinations, their chances are especially magnified during transportation. A lucid example would be transporting products like blood and some vaccines. These products are temperature-sensitive and may degrade or become useless if exposed to higher temperatures. While it is easy to maintain these products in on-site refrigerators, you might actually need refrigerated trucks to transfer them from a site to another. As such, climatic conditions can cause potential damage to products due to the effects of temperature (and humidity). Aside from environmental conditions which can be damaging to your product shipment, other hazards you might need to consider are shock, compression, and vibration. The impact of a shock, which occurs during handling when shipments are dropped, are struck by other packages or objects, or when they shift or fall during transit, may cause fatigue or damage to a package and its contents; vibration, which occurs when a freight package is mechanically moved or transported, may result in damage including scuffing, abrasion, loosening of fasteners and closures, freight package or freight product fatigue and failure; compression, occurs when the freight package is under load from other packages which can happen in a static or dynamic environment. 2 Altitude is another potential hazard that you might want to take note especially when you, by land, transport products from one area to another with high difference in elevation. A similar case is transporting products on a non pressurized aircraft exposing products to a much lower pressure than where the aircraft took off. Singling it out, compression, however, does not occur by accident as how shock may occur, by nature as how climatic conditions and altitude may affect your products, or by physics as how vibration may disturb your products compactness and functionality. It is the need to stack shipments for space and cube maximization that packaging experts needed to deal with compression. In order to maximize space and cube in trucks and other shipping vehicles, it will require stacking shipments, one above another, compressing the most those shipments loaded directly on the floor.
Not only is stacking applied during shipping but is also done in product storage in warehouses. Warehousing and storage facilities in the U.S. comprised 15,200 establishments in 2008. These firms take responsibility for keeping general merchandise and, sometimes, refrigerated goods secure and in good condition. Some facilities provide additional logistical services, such as labeling, inventory control management, repackaging, and transportation arrangement. 3 While kept in warehouses, products may still be exposed, but not as much during shipping, to now a rather more controlled set of physical and environmental hazards. However, while other hazards are significantly reduced (vibration, climatic conditions, unchanging air pressure), compression still appears to be a problem needing close attention since to conserve space and cube is still an apparent necessity. Shipping containers play a very important role, not only to make loading and unloading easier with unitized primary/secondary packs, but to also protect their contents from being damaged by these physical and environmental hazards. In designing ship cases, much consideration is given to anticipating the shipping environment your products are to go through. Such is necessary in order to identify the minimum protection your products require to remain undamaged when they reach the last leg of their trips. As much as possible, your ship cases should be able to give enough product protection to prevent product damages, but not too much protection that you overpay for packaging costs. There are different types of shipping containers: intermodal freight containers, corrugated box, wooden box, crate, intermediate bulk shipping container, bulk box, insulated shipping containers and a lot more. Shipping containers can be classified as reusable or non-reusable. While most of those mentioned are reusable, corrugated boxes, though some can be returned for a few more uses, are non-reusable in general. Several case studies have been conducted as to the savings incurred in using reusable shipping containers (plastic shipping containers to be specific) over corrugated boxes. However, the compatibility and results will vary on case to case basis including but not limited to the product being shipped, total cost of ownership of shipping containers, shipping frequency and even shipping distance. Aside from being economical, corrugated boards are a highly-engineered material to withstand compression during stacking. Regardless of the threat of replacement by newer solutions, corrugated boxes are still widely used. In fact, a study foresees the Global Corrugated Board Market to grow by 5% to 2015. 4 Corrugated fiberboard is a highly-engineered and a primary material in the shipping, distribution and storage of almost every product. Aside from being economical, boxes made from corrugated boards are able to withstand compression for products stacked in transit or in warehouses. Therefore, top-to-bottom box performance strength is critical in a stacking situation. It relates to its ability to survive transportation and warehousing. Going into further details, the Compression Strength, of a package is defined to be the amount of evenly distributed weight the package can support under controlled test conditions (usually referred to as the Lab Compression Strength). Compression strength is easily determined using compression tester, however the machine can cost $50,000 for small machines to over $100,000 for larger climate controlled models used to test whole pallet loads, not to mention you need to house and maintain it. There are about five ISTA (International Safe Transit Association) test labs in every state in the US that can do the testing. Safe Shipment Stacking through TOPS Pro 2
Another way of determining the Compression Strength of corrugated boxes is through the McKee formula: COMPRESSION STRENGTH = (Flute Constant) x (ECT) x (BP).4924 x (Caliper).5076 where Flute Constant = 5.87 ECT = Edge Crush Test Value BP = Box Perimeter ECT appears to be the best predictor of Compression Strength as it measures the ability of a small vertically placed sample of combined board to sustain a top-to-bottom load. The box perimeter, equal to 2L + 2W given your box stands along its height, also affects the compression strength of your boxes; so does the caliper of your corrugated. The shape, the length-to-width ratio, the amount and type of printing, and direction of the flutes are possible weakening factors that you might want to be accounted for in your box s compression strength. However, the compression strength calculated from this formula assumes that the test value is obtained under standard conditions of 72ºF and 50% RH using a compression tester. The allowable top load in actual-use conditions will always be less than the compression strength because the package will be weakened by several factors such as humidity, time, stack misalignment, pallet overhang and vibration from transportation. With these factors taken into account, the calculated value now becomes the Box Performance or the Stacking Strength. Packaging experts should make sure that the corrugated boxes meet the stacking strength requirements of your product load stacked either in a shipping vehicle or warehouse. In as early as in the package design process, it is important to be able to predict your box s stacking ability so you are able to foresee how to safely stack loads on a pallet and into a truck or warehouse. Many firms rely on technology and innovation to simplify and expedite this whole process and for that simple reason, TOPS Pro was developed. TOPS Pro is a package design program developed to assist packaging professionals in creating optimal package designs and pallet patterns. Aside from easily being able to determine optimum package sizes, superior pallet configuration, and truck placement options, you are confident that your stacking arrangement is completely safe. With TOPS Pro, you have the whole packaging process integrated into a single software, combining packaging design with pallet and shipping optimization while maintaining safe stacking. Let s do a simple shipcase-to-pallet-to-vehicle process as a stacking-strength calculation example. Suppose we have a 2-lb. 16x14x12 shipcase that you intend to load onto a GMA (Notched) Pallet and finally ship into a 40ft truck. Allowing a 2-inch overhang on the pallet, we are initially presented with solutions regarding pallet configuration and vehicle placement (see image on next page). Safe Shipment Stacking through TOPS Pro 3
Given we have picked the above solution, we are expecting to stack two unitloads during shipping. Considering that and the fact that the shipcases are column-stacked, the shipcases closest to the floor will carry the minimum weight of seven similar shipcases, that are stacked on it not including the pallet. Now we test for stacking strength to find out which board grades, preloaded in TOPS Pro, will, with a safety factor, withstand the stacking compression the solution calls for. The Stacking Strength dialog box (see image below) is where you get to put in your actual-use conditions. Two different storage/shipping conditions will affect a shipment differently. So make sure to modify these parameters. Otherwise they will take their default values which may simulate a totally different environment compared to that of your shipment. Be sure to input the number of loads we are expecting to stack. In this case we are stacking 2 unitloads. Safe Shipment Stacking through TOPS Pro 4
You will then be presented with the results (see image below). In the upper part of the TOPS Pro tells us, that at 2 loads high, bottom case must support 133.22 lbs. In the upper part of the Stacking Strength results screen is the summary of your box specifications and related parameters you have entered. TOPS Pro tells us, that at 2 loads high, bottom case must support 133.22 lbs. A list of board grades follows right below, some highlighted in blue, some not. The ones in blue are those board grades that meet the stacking requirements for this particular shipment. Now you are able to know which board grades you can safely use, and if you have their pricing, you know which will save you best without compromising stacking safety. With TOPS Pro, there is little limit of what you can do when it comes to packaging design. Not only are you able to calculate for stacking strength, but it can also create primary packs, size your cases and shippers, optimize pallet arrangements, and maximize shipment in your vehicle. For better representation of your primary packs, mix trays, and mixed pallets, TOPS Pro is seamlessly integrated with additional modules that could create realistic primary packs and trays for you (Create A Shape Yourself Module), drag-and-drop different primary packs to your trays or trays/shipcases to your pallets (MixPro Module). Also, with some firms using Radio Frequency Identification Devices (RFID) to track and manage incoming and outgoing shipments, TOPS Pro can identify the best location for placement of RFID tags. For over 20 years, TOPS Pro has been providing package design solutions and is, every now and then, updated to cater to the continually changing needs of the packaging industry in terms of package design, Safe Shipment Stacking through TOPS Pro 5
case sizing, ship case optimization and shipment planning. TOPS Pro still continues to set world standard for total optimization of packaging and distribution channels. 1 Bureau of Labor Statistics. December 19, 2009. Truck Transportation and Warehousing. Retrieved March 15, 2011 from: Bls.gov/oco/cg/cgs021.htm 2 IoPP Transport Packaging Committee. November 27, 2007. Guide to Packaging Freight Shipments. Retrieved March 15, 2011 from: iopp.org/files/public/ioppfreightshippingguidelines.pdf 3 Bureau of Labor Statistics 4 Pira International. 2010. Global Corrugated Board Market to See 5% Growth to 2015 According to Pira International. Retrieved March 15, 2001 from: http://www.pira-international.com/global-corrugated-board-market-to-see-5-percent-growth-to-2015-according-to-pirainternational.aspx Safe Shipment Stacking through TOPS Pro 6