Safety is a key issue in most manufacturing and industrial processes, but when it comes to food and drink, safety concerns go far beyond just staff, covering the safety of every aspect of the food item, with contamination prevention being a top priority.
The good news is that contamination can be controlled by proper cleaning and sanitisation so, for processing plants, ensuring machinery is not a potential cause of contamination is a must. Here, we look at some of the challenges bearings face in the food and drink industry and how factors such as the design of bearings should be chosen carefully to avoid giving places for microorganisms to grow.
When it comes to the food and drink sector, bearings have a core mechanical role, but they also have a significant part to play when it comes to complying with strict regulations and hygiene standards, which have recently been put in the spotlight following a spate of food safety scares that have dominated the headlines.
Food safety hazards
Food product recalls are a real concern for businesses and consumers alike. Last year, the UK’s Food Standards Agency (FSA) reported around 150 food recalls for reasons including undeclared allergens, metal contamination, and the presence of harmful pathogens. More recently, Salmonella contamination sparked concern.
Food safety hazards typically fall under three categories: chemical, physical, and biological contamination, with the latter involving microorganisms such as viruses and bacteria which can cause “food poisoning” and pose a threat to human health. With possible disease hazards including Salmonella, E.coli, Clostridium botulinum and Listeria monocytogenes, to name but a few, prevention of biological contamination is essential to limit food-borne diseases which can be a threat to human health and brand reputation.
Researching the key issues
To get closer to the key issues surrounding bearing contamination SKF, a key bearings supplier to the food and drink sector, recently undertook an extensive test that involved investigating behind and round mounted bearing units in a typical food processing setting.
This was to identify levels of contaminants and where they are typically found. Results revealed contaminant levels to be high, even after washdown; in some cases, contaminant levels increased after washdown. Similar results were found in bearing end covers. The independent test results revealed food residue trapped behind the bearing mounted unit and inside the cavity through the shaft gap during processing and pressure cleaning; as it doesn’t fully dry post cleaning, it can foster the growth of bacteria. These bacteria can spread in multiple ways, lingering in the air for several hours and then settling on equipment post disinfectant stage; getting stuck in the bearings grease; and, worryingly, actually distributed by the washing process itself.
Preventing contamination
All bearings need lubrication but with that comes potential risk. Lubrication contamination can occur regardless of facility size, operating procedures, and the training and experience of maintenance staff on-site. All it takes is one microorganism particle to penetrate the bearing lubricant. This makes the margin of error for preventing lubrication contamination very small. However, there are some steps to minimise the risk.
When it comes to bearings, the main source of concern in terms of contamination lies in the lubricant used within. To address this issue, high-quality food-safe lubricants, that are NSF, Halal, Kosher and CFUA approved, should be used. Greases that are free from allergens as listed by the EC are also very important. Where there is potential for incidental food contact, NSF category H1 lubricants are essential. Applying the correct amount of lubrication, at the right time, is also a major consideration; you want to ensure the bearing is lubricated sufficiently to perform to its best capacity, but not so much that it risks contaminating the product or dripping on the floor and becoming a slip hazard.
To combat these issues, there are options other than manual lubrication available. The use of an automatic lubrication system can deliver accurate lubricant quantities for increased HACCP (Hazard Analysis and Critical Control Points) compliance. However, for the ultimate safety solution, relubrication-free bearings dramatically reduce the risk of potential food contamination both from the lubricant itself and from the bacteria growing on the lubricant. SKF Food Line Blue Range bearings, for example, are lubricated for life and are designed to withstand the use of penetrative caustic-based cleaning fluids and high-pressure rinsing which can force itself through traditional bearing seals, which can result in grease breakdown, leakage, and food contamination.
Another issue to address relates to possible contamination from behind and around mounted bearing units and in end covers, which washdowns are not always able to remove. Here, prevention is better than cure, so a unit that has been designed with hygienic geometry of the housings can help to reduce potential contamination traps. The back seal should seal statically against the housing and dynamically against the shaft, and the end cover should fully seal against the housing on the front side, preventing process material from entering the bearing. In terms of materials used, high-grade stainless-steel bearing rings, cage, rolling elements, and seal backing plates are ideal for the food and drink sector, along with ceramic rolling elements.
Bearing seals are also another consideration. Bearing seals prevent contaminants from entering the bearing unit, reducing bearing life expectancy, whilst keeping lubricants from leaking out. No matter how well made a component is, ultimately it will start to suffer from wear and tear. The risk here is if pieces of the rubber seal break off a moving part, they can migrate through the system and into the product, which could result in a costly and time-consuming process requiring x-ray equipment, manual observation, and an extensive maintenance programme. However, failure to locate missing parts can have an even costlier outcome! To avoid this and comply with FDA and EC recommendations, seals should be manufactured from food-safe sealing materials and, where possible, coloured blue for optical detectability.
Conclusion
Bearings have an endless list of challenges to contend with. Alongside the obvious challenges that include extreme temperatures, excessive moisture due to continuous cleaning, and exposure to chemicals, food manufacturers and processors also need to adhere to stringent hygiene standards and regulations as contamination is an extremely serious issue, both in terms of consumer health and brand reputation. Given that the food and drink industry is the UK’s largest manufacturing sector, with no signs of slowing down, selecting the right bearing technology is key when it comes to achieving maximum effectiveness in preventing contamination without compromising on production efficiency.
Rubix is Europe’s largest supplier of industrial maintenance, repair and overhaul products and services, and is Europe’s leading authorised bearings distributor, selling over 100 million bearings annually from the largest, most comprehensive bearings range and stock.
uk.rubix.com
By
Alan Stewart, Rubix Bearing Product Manager – SKF Products
