WE THINK DIFFERENT. Shrink vs. Stretch: How to Select a Pallet Packaging Method for Superior Business Outcomes. At a Glance

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Thomas Alexander
5 years ago
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professionals, the choice of pallet packaging method may not immediately surface as a critical success factor when designing, upgrading or refurbishing a production line or distribution center.

1 white paper august 2012 WE THINK DIFFERENT Shrink vs. Stretch: How to Select a Pallet Packaging Method for Superior Business Outcomes CHOICE OF PALLET PACKING METHODOLOGY CAN AFFECT ACQUISITION COST, OWNERSHIP COST AND ROI For many end-of-line packaging professionals, the choice of pallet packaging method may not immediately surface as a critical success factor when designing, upgrading or refurbishing a production line or distribution center. As this article explains, however, there are many aspects that should be considered when choosing a pallet packaging method, as the choice can significantly impact overall profitability and distribution chain performance. There are three recognized methods available for pallet packaging: conventional spiral stretch-wrapping, heat shrink-hooding and stretchhooding. Each method has its advantages and disadvantages depending on the specific application. Spiral Stretch-Wrapping Spiral stretch-wrapping is the most common method for pallet packaging, with literally hundreds of thousands of machines in operation world-wide. Spiral stretch-wrapping equipment has been around since the early 1970 s and provides a low-cost method for securing pallet loads for shipping. The equipment uses cast or blown linear low-density stretch film, which is pre-stretched 60% to 400%, depending on equipment type, before being wrapped around the pallet load. However, pre-stretching more than 250% provides little extra yield as the film will be stretched to a narrower band. There are many manufacturers of spiral stretch-wrapping equipment, and both equipment and film are readily available through a large number of distributors, some of which also provide after-sales service. At a Glance AT A GLANCE: The choice of pallet packaging methodology can impact a distributor s bottom line in ways that go beyond initial equipment acquisition costs. Labor cost, film cost, productivity and material requirements must be considered as well. CHALLENGES: While spiral stretch-wrapping equipment is cost-effective for some applications, it provides little stability or protection from the elements. Heat shrinkhooding, the oldest form of pallet packaging, can provide good load protection and stability, but operating costs are high. Stretch-hooding can require greater initial investment but lower operating costs and superior load integrity. BEUMER SOLUTION: Stretch-hooding makes up for higher initial acquisition cost through superior value in terms of operating costs, speed, reliability and performance. Stretch hooding provides: > Optimized use of material (film yields) > Strength and protection for the load, with tampering immediately evident > Increased production line efficiency > Reduced labor costs Choosing a pallet packaging method means considering many factors that influence both daily operating costs and overall, long-term distribution chain performance.

2 The stretch-wrap film can be applied in a variety of patterns depending on the load stability and protection required. A myriad of models are available, from turn-table models where the operator manually cuts the film and attaches the film tail to the pallet load to fully automatic rotary-arm, or satellite, models with top sheet dispenser, automatic film roll change, and speeds up to around 100 pallet loads per hour. The latest developments in spiral stretch-wrapping technology are aimed at reducing the risk of film breakage and at shortening the time required to feed the film into the machine. While spiral stretch-wrapping technology offers a cost-effective pallet packaging solution in some applications, there are drawbacks. Because the film is applied with multiple layers of a relatively narrow overlapping film band, for example, spiral stretch-wrapping provides little stability when compared to a hood style method, as there is insubstantial vertical holding force unitizing the pallet and the load. For protection against the elements, a top sheet is often applied to the pallet load. This provides nominal protection, but is practically insufficient for outdoor storage and shipping on open flatbeds in inclement weather. Accordingly, the cost of building additional warehouse storage capacity, as well as that of protective tarpaulins for flatbed shipping, must be considered when comparing spiral stretch-wrapping with a hood type method such as heat shrink-hooding or stretch-hooding. The physical properties of stretch-wrap film present challenges that should be considered when evaluating different pallet packaging methods. Among other things, the overlapping layers of stretch-wrap film tend to trap moisture, and the cling additive in the film attracts dirt and dust. Moreover, relatively low-volume film rolls mean shorter film change intervals, thus reducing machine availability and increasing operating costs. Accurately forecasting and controlling the cost of consumables (stretch-wrap film, in particular) can also be difficult, as adjustments to pre-stretch percentage and the number of film layers to be applied are often determined by individual operators on the basis of personal preference. With a hood type method, however, the packaging cost per pallet is constant allowing for more accurate budgeting and inventory planning, and helping to improve working capital turns. Heat Shrink-hooding Introduced in the 1960 s, heat shrink-hooding is the oldest form of pallet packaging by means of polyethylene film. Until the advent of stretch-hooding, heat shrink-hooding was the preferred method for optimal stability and pallet load protection. Heat shrink-hooding equipment uses gusseted tubing which is cut and sealed to form a bag. The oversized bag is applied over the pallet load and shrunk by means of heat. The most common heat sources for shrink-hooding are natural gas or LPG (liquid propane gas), but other heating methods, such as infrared or electrical hair dryer-style heaters, are also used. There are various types of heat shrinkhooding equipment available. Early versions of heat shrink-hooding equipment employed a bell/oven type principle. By contrast, most contemporary approaches to heat shrink-hooding are of the ring type, which allows for a much more controlled heat application and provides the all-important bottom shrink that ensures proper pallet and load unitizing. The heat shrink-hooding method provides very good pallet load stability and protection; it works particularly well with loads that have a substantially smaller foot-print than the pallet load as the film will shrink tightly around the contours of the pallet and load. In practice, however, such applications are rare. The operating costs of a heat shrink-hooding system are much higher than those of both spiral stretch-wrapping and stretch-hooding. This is due to several factors. Because the film bag is shrunk (as opposed to stretched), it must have a larger pre-shrink circumference than the perimeter of the pallet load so that the equipment can apply the bag over the pallet load prior to the application of heat requiring substantially more film than stretch-hooding. Requiring significant energy consumption for heating, the heat shrink-hooding method also carries the risk of fire, which can often mean higher insurance premiums to protect against potential losses. Additionally, heat shrink-hooding equipment is fairly maintenance-intensive compared to the other two methods.

The fact that most of the performance advantages offered by heat shrink-hooding (i.e., pallet load stability and protection) are available with the more cost-effective stretch hood technology has all but made heat shrink-hooding obsolete.

Stretch-hooding Introduced in the late 1980 s, the stretch-hooding method of pallet packaging has, over the past decade, gained significant market share at the expense of heat shrink-hooding and

The primary reason for this is that stretch-hooding provides superior value with respect to operating costs, speed, reliability and distribution chain performance.

3 The fact that most of the performance advantages offered by heat shrink-hooding (i.e., pallet load stability and protection) are available with the more cost-effective stretch hood technology has all but made heat shrink-hooding obsolete. Consequently, the number of shrink-hood equipment manufacturers has steadily declined over the past decade. Stretch-hooding Introduced in the late 1980 s, the stretch-hooding method of pallet packaging has, over the past decade, gained significant market share at the expense of heat shrink-hooding and spiral stretch-wrapping not only for bagged products, but also for products in Octabins, cases, pails, and other similar primary packaging formats. The primary reason for this is that stretch-hooding provides superior value with respect to operating costs, speed, reliability and distribution chain performance. The quality of today s domestically available co-extruded stretch hood films allows for pre-stretch percentages exceeding 80%, providing materially improved film yields than were possible even a few years ago. This performance, combined with film thickness reduction down to 1.6 mils, means that the per-pallet film cost with stretch-hooding is extremely competitive with that of spiral stretch-wrapping. And the stretch-hood equipment can be programmed to allow for application-specific selection of a non-sealed sleeve (for lowest possible film consumption) or a closed hood (for optimal protection and stability). The hood is formed from gusseted tubing, and the height of the pallet load is measured automatically as the pallet enters the machine ensuring that only the amount of film required for the application is precisely dispensed. Among other operating benefits, energy consumption is very low since the film is not heated, and available servo drive technology further reduces energy and maintenance costs while helping to drop noise levels, as well. The high quality of today s films means that a single film hood format can, within certain limitations, be used to stretch-hood multiple pallet sizes. However, it is important to analyze the net financial benefit of a one-size-fits-all approach, as the total film cost will be lower if each pallet size has a dedicated film hood format. An analysis is done by dividing the additional cost for equipment with a double film head by the savings per pallet achieved with dedicated film hood sizes. This will show what volume of the smaller of the two pallet loads is needed to pay for the additional film head. Stretch-hood film rolls can be up to 39-inches in diameter. Outdoor storage of pallet loads with stretch-hood. Unlike spiral stretch-wrapping, stretch-hooding provides ready evidence of tampering, as it is not possible to remove a product from the pallet without tearing the film. The smooth film surface provides for easier loading and unloading of trailers. With spiral stretch-wrapping, the friction between the films on two pallet loads can cause tears and film tails to come undone, compromising the integrity of the pallet load.

For products sold at retail outlets, such as home centers, the clear, one-layer stretch-hood film provides much better product recognition at point-of-sale than multi-layer spiral stretch-wrap film

And stretch-hood film allows for easy barcode scanning, virtually eliminating misreads and associated remedial costs.

Recent advancements in stretch-hood technology have reduced film cost per pallet load, while simultaneously offering more intuitive user interfaces, reduced energy consumption, smaller machine

4 For products sold at retail outlets, such as home centers, the clear, one-layer stretch-hood film provides much better product recognition at point-of-sale than multi-layer spiral stretch-wrap film does. It is also possible to print advertising or handling instructions on the stretch-hood film. And stretch-hood film allows for easy barcode scanning, virtually eliminating misreads and associated remedial costs. Consistently maintaining its tension, stretch-hood film is particularly well suited to products that, due to their physical properties, tend to settle after being bagged and palletized. Recent advancements in stretch-hood technology have reduced film cost per pallet load, while simultaneously offering more intuitive user interfaces, reduced energy consumption, smaller machine footprints, and throughputs exceeding 150 pallet loads per hour. Modular designs allow for faster and less costly installation. Decentralized motion control systems and bus technology reduce cabling, simplify and accelerate troubleshooting, and increase the precision in the film application process. Today s manufacturing industries deploy an increasingly transient labor force in an environment of growing sophistication in automation. Variations in experience levels, high rates of labor turnover, and cultural and linguistic diversity demand an intuitive graphic user interface for ease of operation and trouble-shooting. One manufacturer, BEUMER, has taken intuitive operation a step further by implementing features that allow the operator to switch between HMI languages with the touch of a flag icon. Furthermore, the operator can select metric or US units. Cost of Ownership Properly evaluating the choice of pallet packaging method goes far beyond comparing equipment acquisition costs. Several factors can significantly impact the cost of ownership and, consequently, the return on investment. Equipment cost. Spiral stretch-wrapping equipment is available in multiple speed ranges and varying degrees of automation. With prices ranging from below $10,000 for semi-automatic low-speed models to $120,000+ for high-speed rotary-arm, or satellite models, there generally is a spiral stretch-wrapping model for every budget.

5 Heat shrink-hooding equipment also comes in both semi- and fully-automatic models. The price range is generally between $50,000 for semi-automatic models (where the operator applies a pre-made shrink bag over the pallet load) and $200,000+ for fully-automatic, high-speed models. The price of stretch-hooding equipment has come down somewhat over the past couple of years due to the increased competition and the development of simpler equipment. Prices range from roughly $140,000 for single-format equipment to $200,000+ for multi-format equipment. For high-output facilities it is important to realize that one single stretch-hood machine can replace multiple spiral stretch-wrap machines due to the higher speeds achievable. Film cost. If protection and stability are secondary, the film cost for spiral stretch-wrapping a pallet load can be very low because of minimal film thickness and comparatively high pre-stretch percentage. Where protection and stability are critical, however, multiple layers of stretch-wrap film must be applied for stability, and a top-sheet added for protection. This can greatly increase film cost per pallet. Heat shrink-hooding is significantly more expensive in film cost per pallet than either of the other two methods. This is because the film hood must be oversized in order to apply it over the pallet load prior to shrinking. The film cost per pallet for shrink-hooding can easily exceed that of stretch-hooding by 40% or more. And substantial energy costs associated with heat shrink-hooding add to the cost-disadvantage of this method. Recent stretch-hood film developments have enabled the use of much thinner films with significantly higher pre-stretch percentages than was previously possible. This makes stretch-hooding competitive with spiral stretch-wrapping also in terms of film cost per pallet load for applications where a moderate measure of load stability and protection is required. Labor cost. Spiral stretch-wrapping equipment is fairly simple to operate and maintain. Semi-automatic models, in particular, require little training for operation. Maintenance costs, however, tend to the high side because of the quantity of moving components. The drawback of spiral stretch-wrap equipment is that the relatively low-volume film rolls require replacement fairly often at higher throughputs. Some manufacturers do offer an automatic film change option. However, this is a fairly expensive option and one that adds to the complexity of the equipment. Having to replace the film roll at short intervals reduces line availability and increases direct labor costs. As noted earlier, open shipping and outdoor storage require the application of tarpaulins over pallet loads. The resulting costs can be significant and must be included in an overall cost-of-ownership analysis. Safety also must be taken into consideration. Heat shrink-hooding equipment is moderately maintenance-intensive in comparison with spiral stretch-wrapping and stretch-hooding, as heat shrink-hooding involves more wear parts that require replacement at regular intervals. The least labor-intensive method of pallet packaging is stretch-hooding. The film roll can be up to 39 in diameter, easily allowing for 10 times longer film change intervals and increasing line availability. The film roll is handled by forklift, but the roll change is a very simple procedure where the tail of the old film is simply spliced together with the beginning of the new film typically taking no more than 10 minutes to return the machine to production. Unlike stretch-wrapping, adjustments to machine settings are rarely necessary, thus ensuring consistently high quality packaging results. Moreover, with fewer wear parts than stretch-wrap machines, stretch-hooding equipment requires very little maintenance, and five-sided protection eliminates the need for tarping. Making the Choice Making the right choice of pallet packaging method involves a thorough analysis of many parameters that influence not only the daily operating costs, but also the entire distribution chain performance. When product leaves the production facility, it is at its highest value-added state and should arrive at the customer s facility in the same condition. As pioneers in the development of innovative stretch-hood technology, BEUMER understands the pallet packaging issues that directly impact end-of-line productivity and profitability. For low-throughput applications, where stability and protection

6 are secondary to initial acquisition cost, spiral stretch-wrapping still provides an attractive alternative. However, if production line efficiency, protection against the elements, superior stability and product recognition at point-of-sale are important criteria, then stretch-hooding is the preferred solution as it offers the best combination of packaging performance and total value of ownership. The BEUMER Stretch Hood System Designed for superior user friendliness and optimum total value of ownership, the BEUMER stretch hood system provides the solution for a broad range of pallet packaging challenges and requirements. The BEUMER stretch hood i system presents a unique new concept in pallet packaging, where the stretched film hood is sealed and uniformly drawn down over the load in one movement. This improves load stability and safety while providing complete protection against contamination and the elements. Due to its compact modular design, the stretch hood i utilizes up to 30 percent less floor space compared to other pallet packaging systems. It supports a wide range of pallet sizes, and is engineered for energy efficiency, using 30 percent less compressed air and 80 percent less electricity than comparable systems. The stretch hood i is a cost-effective and environmentally sustainable approach to transport packaging. A benchmark in packaging machinery performance, the stretch hood system from BEUMER Group offers the best possible pallet packaging solution for superior business outcomes. BEUMER Corporation 800 Apgar Drive Somerset, NJ Phone: Fax: Marketing.americas@beumer.com For more information, visit beumer-nowterm.com BEUMER reserves the right to make modifications that serve technical progress.

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