Why is bearing health design critical to food safety

The hygienic design of food machinery plays an important role in the control of food safety.However, a general application of this concept without regard to the hygienic design of equipment components could pose a risk of bacterial growth and transmission in the bearings, said Davide Zanghi, head of SkF’s hygienic design office.

Sanitary design should consider the adverse effects of specific factors (such as corrosion, lubricant leakage, cleaning and automatic drying) on food safety and apply appropriate design principles to address the problem.In essence, it is an idea of design with specific principles.Just as ergonomic design focuses on the physiological needs of the user, hygienic design focuses on preventing food contamination.

The European Alliance for Sanitary Engineering and Design (EHEDG), of which SKF has been a member since 2006, aims to promote the safe food production capacity of its members, including equipment manufacturers, food companies and research institutions, by improving the standards of sanitary engineering design.In November 2016, the Alliance held its biennial World Congress in Denmark, where SKF once again highlighted its long tradition of applying these design principles.

Design Principle – Be careful with bearing assemblies

In general, the EHEDG guideline states that food particles and water can easily be trapped in bearings, so bearings are seen as a potential breeding ground for bacteria.The general advice is to ensure that bearings are kept away from food contact areas.

This recommendation is very much in line with the latest guidelines for the hygienic design of belt conveyors in the food industry, where EHEDG focuses on two major challenges in safe food production: how to avoid contamination of food by poorly designed processing equipment, and how to improve food safety without increasing the operating costs of cleaner production and hygiene.In fact, the main concern in the overall system hygiene design is the system and the main components (such as belts);And often the bearing and bearing unit attention is not enough.

However, even if the bearings are not in direct contact with the food area, they are often near the food and have high-pressure water or dry cleaning systems.As a result, bacteria, if present, could spread through the air and contaminate food.

In order to minimize the risk of contamination, hygienic design principles should be fully considered when designing bearings.And one of the most important principles that makes up sanitary design is the ability to clean effectively.This is actually easy to understand, but in practice it is often not easy for bearings and bearing units.First of all, the product should be made of non-corrosive and non-porous materials (such as stainless steel) or composite materials, and the shape is easy to clean, retaining moisture can be automatically drained.Bearing units should have a padded base 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 food during operation should be avoided as far as possible.

The best approach is that bearing units are equipped with efficient end covers that prevent contaminants and clean liquids from entering the bearing cavity while allowing frequent visual inspection.

Other relevant areas include:

Avoid metal-to-metal contact between the unit assembly and the attached surface

Supplemental lubrication should be avoided whenever possible

Long service life under very demanding operation and cleaning systems

Sanitary design is fully applicable to food production and packaging machinery.However, bearings are only one of many problematic components, and addressing bearings is only the first step in improving the overall risk strategy.）