Metalised Film: Time To Act

Monday, September 18th, 2017

Kyle Thomas, strategic business unit (SBU) manager at Eagle Product Inspection, looks at the rising popularity of metalised film as a packaging format and the increased need for x-ray inspection as a result.

Trends in the food manufacturing industry are driven by retailers’ needs to improve both sustainability and marketability. Consumers are demanding more and more in terms of green credentials and it falls to food and beverage manufacturers to find ways to respond in order to stay aligned.

There is thus a growing need for a packaging format with the ability to increase shelf sustainability, yet provides an attractive platform for brand messaging. One solution for this came clearly in the form of metalised film coated polymers.

Conventionally, films used for food and beverage packaging such as regular clear barrier packaging are susceptible to light. It is exactly this, as well as the moisture and oxygen content within the packaging, that leads to premature staling.

Metalised films however, create an effective light barrier, thereby keeping ultra violet (UV) and visible light from attacking the oils within the product itself, which would otherwise cause them to turn rancid at an accelerated rate. Oxygen and moisture are also dealt with far more effectively with metalised films as they are a much harder barrier to penetrate. Metalised packaging can therefore extend the shelf-life of food and beverage products, and in doing so, contributes to the sustainability of food as retailer’s stocks and consumer purchases can stay on shelves for longer.

Increasingly, these metalised films are used as stand-up pouches, a popular packaging format within the snacks sector—for items such as cookies, nuts and dried fruits—but also in the wider food and beverage industry in other formats for products, such as for cereal items like granola and muesli, stir-in sauces, or even ready-to-drink beverages.

These pouches therefore open up a wider range of innovative decoration options for branding purposes, making them highly desirable amongst product marketers.

Challenges To Manufacturers

For consumers and retailers, metalised pouches are a fantastic prospect, as we have seen from the advantages above, but for manufacturers they pose a different challenge—that of product inspection.

A large number of manufacturers—including many small contract operations—have historically relied on metal detection as a means of inspection. With the rising demand for products packaged within metalised, film-coated pouches, it is challenging for metal detection systems to meet the specifications required by retailers for this format.

Vision inspection is not a possibility, as the packages are not clear, leaving x-ray as the most viable solution. Manufacturers looking to continue to supply major retailers, including the smaller contractors who collectively make up a large section of the industry, must therefore prepare to move towards this technology or face lost revenue through simply being unable to meet the required specifications.

The Advantages Of X-Ray

Contaminants in chocolate chips.

Metalised film poses no challenges for x-ray inspection systems in any size or format. As the films themselves have very little absorbance value, the x-ray is not affected by the packaging, meaning retailers’ specifications can be met and surpassed with ease. Metal detectors use magnetic field displacement, so the packaging actually works against the detection specification.

When compared with metal detectors, x-ray has a number of benefits over and above its ability to offer superior detection. X-ray, in addition to metal, is also capable of detecting several other physical contaminants, such as glass, stones, dense plastic and rubber components as well as calcified bone. These systems also have the capability to perform quality checks on the production line, making total cost of ownership and return on investment figures more attractive than single function systems, as they have the ability to detect gross under or overfills, or missing components for example.

In addition, having an x-ray inspection system would allow manufacturers to deal with both food and beverage products at the same time. While metal detection systems can be used for beverage products since inspection takes place before packaging, they cannot be used for food products where the inspection process succeeds packaging. This two-in-one benefit of x-ray systems place it a level higher than metal detection systems.

Further, while it is never ideal to be told by retailers that you must invest in a technology, the fact remains that they are highly likely to walk away from companies who simply cannot meet their specifications. A nut manufacturer in the US, for example, said that they do not have a choice about investing in x-ray, as a retailer refused to use them unless they did so, and this stance continues all the way down to the smaller contract manufacturers.

This hard-line policy is driven, in part, by the fierce safeguarding of brand reputation by retailers, who would be in the line of fire should a contaminated product reach a consumer via their outlet. Social media channels have made it much easier for both positive and negative stories to circulate worldwide, and in some cases such an event could also have litigious consequences.

As a result of this, retailers have strict policies when it comes to contaminant detection and the trend for more stringent specifications looks set to continue as greater focus is being placed on preventing product recalls. The ability to meet and exceed retailers’ expectations is essential for contract wins and retention. For manufacturers, peace of mind can be achieved through investing in a technology such as x-ray, which not only ensures continued compliance with evolving specifications through its capabilities, but also adds several layers of benefit to production lines and overall productivity.

Foil or metalised film packaging has many advantages for manufacturers: it allows them to make an effort toward green manufacturing, it prolongs the shelf-life of the product within, and it can be applied innovatively to a large range of food and beverage product applications. Though the material cannot be used with metal detection equipment or traditional inspection systems, manufacturers can easily use x-ray inspection to penetrate through low-density foil or metalised film to obtain a better view of contaminants in food products and ensure the standard of food safety is upheld.

How X-Ray Works

X-rays are invisible. Like light or radio waves, they’re a form of electromagnetic radiation. Because their wavelength is short, x-rays can pass through materials that are opaque to visible light. However, they do not pass through all materials with the same ease. The transparency of a material to x-rays is broadly related to its density, which is why x-ray inspection is so useful in the food, beverage, and pharmaceutical industries. The denser the material, the fewer x-rays that pass through. Hidden foreign bodies, like glass and metal, show up under x-ray inspection because they absorb more x-rays than the surrounding product.

An x-ray system is essentially a scanning device. When a product passes through the unit, it captures a grey-scale image of it. The software within the x-ray system analyses the grey-scale image and compares it to a predetermined acceptance standard. On the basis of the comparison, it accepts or rejects the image. In the case of a rejection, the software sends a signal to an automatic reject system which removes the product from the production line.

By exploiting simple density differences and analysing the resulting grey-scale x-ray images, x-ray inspection equipment has moved beyond product safety into other areas of quality control. In addition to detecting foreign bodies, modern x-ray systems are multi-tasking defenders of product and brand quality. In a single pass at high line speeds, x-ray systems can perform several inspection tasks simultaneously, including:

  • Measuring product weight, width, area, and volume
  • Identifying missing or broken products
  • Monitoring fill levels
  • Measuring mass
  • Inspecting for compromised seals while still catching contaminants