As a market leader based in Switzerland, Bell Food Group is one of the major processors of meat and convenience products in Europe. The company has been the exclusive meat supplier, within Switzerland, for an international fast food chain for a number of decades. A new X-ray inspection solution at Bell's Oensingen site in Switzerland checks the customer's burger patties for various foreign bodies, plus product errors and visual defects, such as patties joined together, holes, dents and product flakes.
Increased customer requirements and demands in terms of quality assurance and production capacity gave Bell the push to rethink the configuration of their production line for burger patties. Bell decided to dismantle the previous line, carry out a hall conversion and replace individual production line components as part of modernization measures.
State-of-the-Art Product Inspection
"I think X-ray inspection is currently the ultimate extra that we can offer our customers when it comes to detecting foreign bodies in the burger patties," says Niki Berger, who is responsible for the quality management of fresh goods at Bell's Oensingen site. "Along with metallic contaminants, it can detect various additional foreign bodies that are commonly found in meat, including bone and cartilage, as well as stones, high-density plastic or glass. The X39 X-ray system also provides a whole range of other options for checking the patties for product errors and visual defects."
Bell Food Group manufactures burger patties for some of the worlds most recognizable fast food chains.
Ueli Schönenberger, in charge of patty production at Bell, discusses the way in which the purchase decision was made in favour of the X39 X-ray system. "First of all, we looked all over Europe at what was available on the market and who was using what system. We were able to experience the METTLER TOLEDO X-ray inspection system in real-time and in a comparable environment at two sites – one in Ireland and the other in Germany. The exchange of system experiences with the local line managers encouraged us to contact METTLER TOLEDO."
Automated Product Integrity Checks
The X39 X-ray inspection system has been in use in Oensingen since January 2017 and underwent a successful customer audit in May 2017. It currently casts a strict x-ray eye over well above a million patties a week – most of these being the three standard products, which vary in terms of size, form and weight. "In comparison to previous product inspection technologies, we can now trace and reject foreign bodies that are half the size. A definite bonus when it comes to safety", says Niki Berger. His colleague Ueli Schönenberger also highlights the high standard of the automated product integrity checks: "We used to remove patties that were broken or had holes in them from the belt by hand or separate them manually before packaging. With the X-ray inspection system and its integrated control laser, we can now detect and visualize such faulty products automatically and reject the relevant patties without manual intervention." The line manager defines the tolerance limits for visual defects. The system will inspect for edge defects, flakes on the top or bottom of the patties, as well as holes, cracks and dents.
Detailed Error Indication
Depending on the variant of burger patty that Bell are producing the x-ray system will inspect between three and six lanes. If a visual defect is detected, the relevant patty is rejected using multi-lane air nozzles. This significantly reduces the volume of patties rejected in comparison to simpler x-ray system variants that reject the entire batch from production. "We can even differentiate between these individual rejections by product error," says Ueli Schönenberger.
"In practice, this means we can first define and save the tolerance parameters for individual reasons for rejection. Then we can get an extremely detailed picture of how many patties were rejected as the result of foreign bodies such as bone and cartilage or as the result of visual defects. We can therefore reject the patties into different disposal containers, depending on the cause of the error, e.g. separated into those containing foreign bodies and those with visual defects. An image of each individual rejected patty is saved in the image library so that we can analyse exactly where and how the problems occurred. In my opinion, the combination of all these capabilities is far more than other providers can offer."
Once the patties enter the x-ray system its integrated control laser checks if the patties have been separated properly. If the spacing between two patties falls below the minimum spacing of five millimetres, these patties are rejected through a failsafe reject flap and returned directly to the production line in preparation for rework. "We're talking here about so-called width errors where the necessary separation for the downstream detection stages is insufficient," explains Stephan Bauert, METTLER TOLEDO Business Area Manager. "We reject these patties – even though they have no detected errors – before inspection so that they can be fed back into the production line immediately from their upstream position. This minimizes product loss for the customer without losing out on any of the benefits of our product integrity check solution."
The X39 can inspect and reject non-conforming burger patties in a multi-lane format.
Meeting Audit Requirements with Complete Documentation
Standard settings for tolerance limits are saved in the X39 software for each patty product variant. "By observing and evaluating these limits, we are able to keep on narrowing error tolerances," says Niki Berger. "For additional safety measures, once an employee logs into the system any changes that they are able to make have already been pre-defined depending on their role within the business. All changes that the employee makes to the saved standard settings are documented. A further benefit which differs from our old solution is that, this data is available to us together with the inspection results data in digital form. This simplifies not only our internal processes for further process optimization, but also the quality management documentation for our customers."
The majority of product settings for each patty variant has now been validated after just over half a year and have been saved in the X39. Employees therefore only have to select a product from the product library in order to run the inspection process, based on the pre-approved product data. While employees can carry out calibrations and rectify simple defects, line managers have further access options that enable them to carry out additional settings changes on the x-ray system.
"The next step that we want to consider in terms of validating and refining the product library is the subject of glass when it comes to detecting foreign bodies," says Niki Berger. "Another subject that we still have on the agenda for this year is networked access to the data that our X-ray inspection system provides. In future, we want to archive all data collected by the X39 within a network and evaluate it. This makes it easier for us to pass on quality indicators to customers. In turn, the customers can then analyse the figures for their own quality optimization processes."
When required, reject confirmation sensors can be pulled out and cleaned, ensuring all products not meeting the pre-defined standards continue to get rejected from production.
Harsh Washdown Environment
The X39 device installed on the burger patty production line is IP69-rated and is therefore suitable to undergo intensive daily cleaning processes. The infeed and outfeed belts in the X-ray inspection system are subject to particular stresses. While the deep-frozen patties tend to slide at belt transition points, the tension of the infeed belts can slacken under the hard water jet pressure in regular washdowns, making readjustment necessary. "All in all, this purely mechanical effect has turned out to be a major challenge for us," says Ueli Schönenberger. "We are really very satisfied with the advice and support provided and the installation of the system. We have worked with METTLER TOLEDO directly on site to set up interactive fine-tuning such as the optimization of the conveyor belts and conveyor belt transition points and adapt this to the individual products and the environment.”
For us, X-ray technology brings enormous benefits in terms of quality assurance. The burger patties can be levelled out evenly and we have fewer problems with both our own and our customers’ packaging systems.
Each individual patty that goes through the system is photographed and then saved as an individual file, we can access these files at any time. We can call up each individual patty image and use various tools to take a detailed look at where there is a defect in that particular patty.
Each patty type is registered in the product library and with every product change, an employee can simply select the product using the touchscreen buttons and start the inspection process.
The X-ray technology provides us with enormous benefits in terms of quality assurance. We inspect the patties not only to check for foreign bodies, but also to ensure that the patties have no visual defects. This simplifies packaging and the customer receives a perfect-looking burger.