Why hygienic bearing design is critical to food safety

Hygienic design issues for food machinery play an important role in controlling food safety. However, if the hygienic design of equipment components is not considered and the concept is only applied in general, there is a risk of bacterial growth and spread in bearings, said Davide Zanghi, head of SKF's Hygienic Design Office.
Hygienic design considers the adverse effects of specific factors (such as corrosion, lubricant leakage, cleaning and automatic drying) on ​​food safety and applies appropriate design principles to solve the problems. In essence, it is a concept of designing with specific principles. Just as ergonomic design focuses on the physiological needs of users, hygienic design focuses on preventing food contamination.
The European Hygienic Engineering and Design Group (EHEDG) aims to promote the safe food production capabilities of its members (including equipment manufacturers, food companies and research institutions) by improving hygienic engineering design standards. SKF has been a member of EHEDG since 2006. In November 2016, the group held its biennial world congress in Denmark, where SKF once again highlighted its long tradition of applying these design principles.
Design principles - take bearing components seriously
Generally, EHEDG guidelines consider bearings to be a potential breeding ground for bacteria, as they can easily trap food particles and water. The general recommendation is to keep bearings away from food contact areas.
This recommendation fits in well with the latest guidelines for the hygienic design of belt conveyors for the food industry, where EHEDG focuses on two major challenges in safe food production: how to avoid food contamination due to poorly designed processing equipment, and how to improve food safety without increasing operating costs for clean production and hygiene. In fact, the main focus in the hygienic design of the entire system is on the system and the main components (such as belts); bearings and bearing units are often not given enough attention.
However, even if bearings are not in direct contact with the food area, they are often in the vicinity of the food and have high-pressure water or dry cleaning systems. This way, if bacteria are present, they can become airborne and contaminate the food.
In order to minimize the risk of contamination, hygienic design principles should be taken into account when designing bearings. One of the most important principles that constitute hygienic design is the ability to be cleaned effectively. This is actually easy to understand, but in practice it is often not easy for bearings and bearing units. Firstly, the product should be made of non-corrosive and non-porous materials (such as stainless steel) or composite materials, and the shape should be easy to clean and the retained water can be drained automatically. The bearing unit should have a filled seat to avoid leaving gaps for bacteria to grow.
In general, the use of materials such as elastomers, composites and greases should comply with food safety directives and regulations. In all cases, grease leakage into the food during operation should be avoided as much as possible.
The best approach is to equip the bearing unit with an effective end cover to prevent contaminants and cleaning liquids from entering the bearing cavity, while allowing frequent visual inspection.
Other relevant areas include:
Avoid metal-to-metal contact between unit components and attached surfaces
Relubrication should be avoided as much as possible
Achieve long service life under very demanding operation and cleaning systems
Hygienic design is fully applicable to food production and packaging machinery. However, the bearing is only one of many problem components, and solving the bearing problem is only the first step in improving the overall risk strategy.