Downgauging: Weight Loss Tips for Flexible Packaging
Manufacturers of packaged goods today are constantly challenged to reduce packaging – for cost and environmental reasons – while ensuring it still serves the primary purpose: protect the contents and help sell the product.
Polyethylene, the most widely used flexible packaging material, has come a long way and packaging engineers have capitalized on those advances by designing multilayer flexible packages that are thinner and lighter than ever.
So how do you continue to downgauge packaging without compromising its primary purpose? Here are a couple steps that can uncover additional opportunities.
Step 1. Evaluate the opportunityMillions of tons of polyethylene go into billions of flexible packages every year making a gram of weight savings significant. Consider your program. If you can cut packaging thickness in half and still maintain stiffness, how much less material will you need? How much weight could you save? How does that impact cost? The answers to these questions could offer some insight into your options of a possible downgauging opportunity.
Step 2. Seek stiffness properties outside the film itselfOne reason many people think packages and pouches cannot be downgauged further is that the thinner materials would reduce stiffness, which is essential to the package’s feel. And quite honestly, overly flexible films feel flimsy. Challenge your sealing layer in a multilayer package to play a more active role in package stiffness.
Sealants vary quite a bit in stiffness. For example, some grades of ionomer resins are up to five times stiffer than premium metallocene PE sealing materials. Demand multiple performance levels from every layer in the structure.
Step 3. Think differently about that "cost" variablePurchasing strategies aside, the lowest cost is not always related to the cheapest material. The path to a sustainable cost reduction may require an initially higher-cost specialty resin because it eliminates the need for many lower-cost resins from the structure. That, in turn, reduces the total amount of material, which delivers sustainability improvements along with cost savings.
As an example – DuPont worked to downgauge a meat packaging pouch, which resulted in a reduced thickness of 30 percent and a 4 percent reduction in cost.
Importantly, the reduction in seal layer thickness caused no loss of the structure’s stiffness and feel because the replacement film provided equivalent stiffness in a much thinner layer.
Step 4. Expect more from your polymersEach layer in a multi-structure serves a purpose – but do not let any layer get away with serving only one purpose.
While it is great that the sealing layer adds stiffness, why not also ask it to resist puncture and reduce leakers?
These options are available, and will help your polymers perform at a much higher peak.
Step 5. Consider rethinking the entire package structureLet’s take a closer look at meat packaging example DuPont worked on. This bacon package uses multilayer films for a thermoformed bottom, an unformed lid and a linear low density PE sealing layer that is 56 micron thick.
Securing significant savings required a rethink.
We ended up using a relatively stiff layer of Surlyn on the inside, which shifted the structure’s other stiff material, a PA6 barrier layer, to the outside – a construct applicable to all composite structures: stiff layers outside, flexible layers inside, as in aircraft wings.
Then, to combat moisture-induced curling of the exposed PA6 and improve its thermoformability to maintain thickness in corners, we blended amorphous polyamide, into the PA6 layer. That change permitted a reduction in thickness of the barrier layer.
Last, a low-cost LDPE core layer contributes by keeping the stiff layers, PA and Surlyn, apart. DuPont Nucrel functions as tie layers.
As a result, package thickness dropped more than 30 percent and material costs reduced 4 percent. As a secondary gain, we improved puncture resistance more than 25 percent.
Step 6. Seek adviceYou do not have to be a scientist to design a better package, but having one handy does help – especially when it comes to staying abreast of the variety and growing range of materials to improve packaging. So do online tools and models that help reduce the number of prototype iterations.
While there are many tools, we use proprietary computer software built around a sophisticated stiffness model to help identify ways to downgauge packaging and deliver performance. That helps reduce some design and prototyping iterations.
We also work extensively with software to provide life cycle analysis (LCA), a growing imperative when measuring and comparing the environmental footprint of alternative packaging materials.
While this program does not take into account the effects of downstream processing, consumer use or end-of-life scenarios, it can calculate non-renewable energy consumption and greenhouse gas emissions created during the production of different materials. Often the results are used as a means of exploring technology options.
Once we understand the material type, thickness and price point for each layer, we add it to the data we already have related to non-renewable energy consumption and greenhouse gas emissions. Output from the model includes package weight per 1000 in2 or m2, overall thickness, stiffness factor (related to bending stiffness), total material cost, total non-renewable energy (materials) and total greenhouse gas emissions (materials).
So, in short, downgauging is possible. It can help accomplish not only a cost savings, but also an environmental savings. Follow these weight loss steps and see if your materials are able to be downgauged.