Ensuring The Safety And Integrity Of Tall, Rigid Containers

Monday, September 18th, 2017

Daniela Verhaeg, marketing manager at Mettler Toledo safeline x-ray, looks at how x-ray technology can enable superior inspection of tall, rigid containers.

Tall, rigid containers are used frequently in the food industry and are commonly defined as containers that are taller than they are wide. Metal cans, doypacks, cartons and composite cans are commonplace containers that fall under this category, as do glass bottles and jars.

These types of applications, once filled, are routinely checked by x-ray inspection systems for contaminants such as glass, metal, dense plastic, mineral stone and calcified bone.

However, there are challenges associated with different packaging types. Different packaging materials, for example, allow x-rays to pass through them to varying degrees—with some absorbing more than others—which has a direct effect on detection sensitivity.

Factors such as product density, depth and orientation to the x-ray system are also key to consider in contaminant detection. Each type of packaging can be defined as low, medium or high density, and will determine the best machine for your operation.

Low Density

Plastic containers, composite cans and doypacks are all examples of low density packaging. Packaging materials of low density are the easiest ones to inspect, providing outstanding levels of detection sensitivity.

The dimensions of the container itself will be the only limiting factor—the larger the diameter of a container, the more detection levels will be affected due to an increased level of product within. The packaging itself presents no challenges to detection sensitivity.

Medium Density

Medium density containers such as metal cans are commonly used to package food products such as soup, pet food, fish and seafood, and fruit and vegetables. Due to the denser type of packaging, more x-rays are absorbed which can have an impact on detection sensitivity.

These packaging types, when compared to lower density containers, usually contain products of a higher density at larger diameters, which is an additional factor to take into consideration. The main challenge is to detect smaller contaminants located in detection blind spots such as the base or side walls of the cans.

High Density

Finally, high density packaging is mainly of glass construction and is commonly used across the food industry for a wide range of products. High density glass containers are the most challenging to inspect as the primary contaminant— glass—is the same material as the packaging itself. Blind spots can be created in the neck, base and sidewalls of glass jars which all have the potential to mask contaminants that are potentially dangerous.

Glass-in-glass contamination can be severe. The smallest of glass fragments has the potential to harm consumers, which in turn can lead to product recalls and damage to brand reputation—both of which will be detrimental in terms of cost.

Food Safety Is A Critical Consideration

The safety of consumers remains top on the list of priorities for the food industry and x-ray inspection systems play a major role. Glass shards, metal, calcified bone, mineral stones, and dense plastic and rubber compounds can all be identified using this technology, safeguarding consumers from potentially harmful contaminants.

For manufacturers it is paramount to remove contaminated containers from the production lines before they reach the retailers. There have been many product recalls in recent years, the result of which has been significant damage to the reputation of the affected brands and loss in consumer confidence. The financial losses incurred by these elements alone can be crippling, and that is before the cost of a recall is factored into the equation.

Social media channels available worldwide have made it incredibly easy for consumers to share experiences of individual brands with the wider population, therefore a contamination event could be in the public domain within minutes. It is this, coupled with the fact that the world is now a far more litigious place, which makes effective contaminant detection more important than ever.

Which X-Ray System Is Best Suited To The Product Density I Am Working With?

Low Density Product Inspection

For low density packaging types, an x-ray system with a single horizontal beam will be best suited as the packaging design is often of a low design complexity and the container material absorbs low amounts of x-ray. A single beam has one x-ray generator, which creates a beam that skims across the surface of the production line conveyor belt that enters into a detector on the opposite side, building an image of complete packs as they pass by. Horizontal single beam systems are able to straddle existing production conveyors, which means there is generally no disruption to operations on the line. Their overall footprint is small, and installation is fast and cost effective.

Medium Density Container Inspection

For medium density containers (metal cans), a horizontal split-beam system is preferable as it provides an increased area of inspection. From a single x-ray generator, x-ray radiation is funnelled through a duel diverging collimator, which creates two beams angled from each other. These beams then strike two separate detectors, meaning every can is imaged twice from a different viewing angle. This increases the effective coverage inside the container and, with it, the probability of detection.

The benefit of a split beam x-ray system is that if a contaminant is against the side wall on one image, it will appear nearer the centre of the pack on the second image, making it much more visible and detectable. The base coverage is also increased. It is important to remember that the spacing of products on the line is imperative as each container must be able to be inspected individually.

High Density Containers

Finally, high density containers, such as glass, have proven challenging with regard to achieving all-round inspection. However, by employing either a combination beam system or a single angled beam (through the base) system, manufacturers can detect and remove glass contaminants, for example, within glass packages at high speed without slowing down the production.

Combination beam systems can feature up to four x-ray beams (three horizontal and one vertical), which optimises detection capabilities in blind spots such as the base, sidewalls and necks of containers—the most challenging areas to inspect.

Single angled beam systems pass an x-ray beam down through the base of glass containers while simultaneously inspecting the upper part of the container. This method opens up the base and lower body of glass jars, enabling the crown to appear flat and therefore removing traditional blind spots from the inspection process. The angle used for inspection is also ideal for providing full-height fill level checking, which is accurate at high throughput speeds.

A Variety Of Benefits In A Single System

In addition to providing superior contaminant detection to food manufacturers, x-ray systems available on the market today are also capable of performing many tasks simultaneously.

For tall, rigid container applications, fill level inspection is a very common quality inspection routine. The process ensures not only regulatory compliance but also profitability through the avoidance of over-fill or under-fill.

An under-filled package can be deemed illegal in certain circumstances, whereas over-filling is essentially giving away product free of charge. X-ray systems are able to monitor and feedback information on fill levels, as well as to reject products that do not meet set parameters.

In addition, other quality checks such as product alignment, cap inspection, vacuum presence and checking for damaged packaging can all be carried out in-line without the need to slow down production speeds.

The ability to carry out these tasks in-line and simultaneously on one system is highly desirable to manufacturers. Production schedules continue to be demanding and any reduction in line speeds is likely to have an impact on profitability. X-ray systems enable continuous operations at high throughput with outstanding detection sensitivity.

Regulatory Compliance

The regulatory landscape for the food industry continues to evolve. Therefore, systems that contribute to and facilitate compliance are increasingly necessary in day-to-day operations.

HACCP requires manufacturers to identify critical control points (CCPs) on production lines and to install necessary measures to control the risks, and the US Food Safety Modernisation Act (FSMA) guidelines represent the biggest change in food regulations since the Food and Cosmetic Act was established in 1938.

Hazard Analysis Risk Based Preventative Controls (HARPC) is a part of FSMA, and has come into effect from September 2016. Under HARPC, manufacturers are required to identify food safety risks, establish controls to minimise those risks, and verify that those controls are working effectively.

Global standards are reviewed by the GFSI, which includes approved schemes like the British Retail Consortium (BRC), the International Food Standard (IFS), the Food Safety System Certification (FSSC 22000), and Safe Quality Food (SQF).

Location and operations will determine which standard manufacturers need to comply with, but one common goal can be identified easily—to ensure food safety.

X-ray systems are an increasingly popular control measure due to their superior contaminant detection and significant uptime advantages, such as the aforementioned ability to carry out multiple inspection tasks simultaneously. All product inspection systems for the food manufacturing industry are designed to withstand harsh wash-down environments, ensuring outstanding hygienic design and food safety.

For tall, rigid containers there are several challenges manufacturers face in terms of product inspection. By installing x-ray detection systems, not only can they guarantee the highest levels of contaminant detection regardless of the container they are working with, they can also realise myriad other benefits relating to increased uptime, regulatory compliance and ultimately profitability.