MechChem Africa July 2017

⎪ Power transmission, bearings, bushes and seals ⎪

Hygienic design of bearings is key to food safety

Bearings are easy places to trap food particles. SKF has considered this for a long time in its design principles for bearings, especially so in the case of the food safety product ranges. SKF has its own hygienic design offices and has been a member of the European Hygienic Engineering & Design Group since 2006.

A n emphasis on the hygiene element of thedesignof equipment canplay an important role in controlling the safety of manufactured food products. However, applying this too broadly without focusing specifically on the hygienic design of the components part of the system can potentially risk the spread of bacteria trapped within bearings, says Davide Zanghi, theperson responsible for thehygienicdesign office at SKF. Hygienic design considers specificallyhow problems suchas corrosion, lubricant leakage, cleaning and self-drying could adversely af- fectfoodsafety–andappliesdesignprinciples to solve the problem. In essence, it is a design philosophy applied through dedicated and specific rules. Just as ergonomic design pays close attention to the physical needs of prod- uct users, hygienic design has a laser focus on preventing issues of food contamination. In November 2016, Denmark ran its bien- nialWorldCongress atwhichSKF–amember of the European Hygienic Engineering & Design Group (EHEDG) since 2006 – high- lighted its long recordusing thesedesignprin- ciples. In general, EHEDGguidelines consider bearings an easy place to trap food particles and water and therefore these are seen as potential breeding grounds that will harbour bacteria. The best advice is to keep bearings well away from food product contact areas. This is very much the case with recent guidelines on hygienic design of belt con- veyors for the food industry, where EHEDG addresses two of themajor challenges in safe food production: how to avoid contamina- tion of food through inadequately designed processing equipment and how to improve food safety without raising operating costs for cleaning and production hygiene. Even if a great deal of attention is concentrated on systems design, major components such as belts, bearing and bearing units consistently have a low profile within the overall hygienic system design. However, even if not in direct contact with the food zone, bearings are often in the proximity of food products and, with high- pressure water or dry cleaning regimes, they

pose the risk that bacteria – if present – can become airborne and potentially contaminate the food product. In order to minimise the risk of contamination, designing bearings

with hygienic design principles in mind is a key consideration. One of the most important

Hygienic design of bearing is key to food safety.

endcoversthatpreventprocesscontaminants and cleaning fluids fromentering the bearing units’ cavities and, at the same time, allow for frequent visual inspection. Other important aspects include: • Avoiding metal-to-metal contacts in- betweenunit components and in-between units and attaching surfaces. • Avoiding re-lubrication as much as possible. • Achieving a high service life despite very demanding operating and cleaning regimes. Hygienic design applies to food production andpackagingmachinery in their entirety. But dealing specificallywithoneof themost prob- lematiccomponents–bearings–canonlyhelp to improve the overall risk strategy. q

principles underpinninghygienic design is the ability to clean effectively. For bearings and bearing units, thismay be easy to understand but it is often difficult to achieve in practice. For a start, the products shouldbemade from non-corrosive and non-porous materials, such as stainless steel, or composites, and with shapes that are cleanable and allow for self-draining. Bearing units should have filled bases, which removes cavities where germs may fester. In general, materials used such as elas- tomers, composites and grease, should be compliant with food safety directives and regulations. In all instances, any potential for grease leakage onto the food product during operation should be avoided. Ideally, bearingunits shouldhaveeffective

SKF’s hygienic design office. Hygienic design considers specifically how problems such as corrosion, lubricant leakage, cleaning and self-drying could adversely affect food safety – and applies design principles to solve the problem.

July 2017 • MechChem Africa ¦ 13