Lightweighting, Milk bottle case study

Milk bottles are an item of packaging that most people interact with on a daily basis. In the UK alone we buy over 5.2 billion litres of milk per year, the majority of which, at 45%, is sold in a 4 pint container. Over the years the traditional, pint sized, glass milk bottle, delivered by the milk man, has evolved into a lightweight HDPE bottle which is most commonly purchased in supermarkets. In fact, more than 80% of milk is now packaged in plastic rather than glass bottles or cartons.

This shift is in part because the environmental and economical savings of transporting plastic rather than glass are significant. To benefit further from these savings manufacturers have been light weighting plastic bottles. There are multiple ways this can be done, for example, removing (or reducing) handles from smaller bottles and increasing the uniformity of wall thicknesses. Structural design is also key – the Infini milk bottle for example, achieves weight reduction by utilising an octagonal structure which increases the bottles strength: weight ratio.

The benefits of this are simple and as follows:

The first tier on the waste hierarchy pyramid is waste reduction. Since preventing packaging waste is the most desirable step, light weighting bottles is extremely advantageous from an environmental standpoint. Through light weighting, fewer raw materials are used and less energy is often required in processing and transportation. Consumers are becoming increasingly concerned with the environmental impact of the products and packaging they purchase and hence proactively improving your packaging from an eco standpoint can be an excellent marketing technique, giving your pack an edge over competitor products.

As in all businesses, cost savings are a key driver. The benefits stated above can not only lead to environmental savings but also economical savings. With legislation only getting stricter regarding producer responsibility obligations, there is a significant motivation for businesses to reduce the amount of waste they produce in order to save on costs.

However, along with the benefits, there are of course challenges of light weighting.

It is vital that packs remain fit for purpose and that light weighting doesn’t negatively impact the integrity of the bottle. A vital function of the pack is product protection – this is because the product is more valuable in terms of energy and resources than the packaging. If excessive light weighting causes an increase in damaged packs and spilt product then, no matter how great the packaging resource savings are, this is not successful.
Any pack redesign concept must consider the entire packaging solution covering primary, secondary and tertiary packaging required. This is because of the limit to the amount of material which can be removed from a primary pack without requiring an increase in secondary packaging to counteract the reduced strength. Because of this, the structural elements of the pack solution must be considered in detail, again, the octagonal Infini bottle is a great example of this.

The final key challenge is to fully understand how any changes will affect the rest of the supply chain. Even minute changes to the shape or weight can have a huge affect on the filling line for example. Fortunately, iDi Pac not only are specialists in packaging but also we have expertise within the supply chain so you can be sure nothing is left unconsidered.

Want to know more about Lightweighting Packaging? Give us a call to see how we may help you…


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