“The hygienic design rule: no right angles!”

Hygienic design is playing an increasingly important role for manufacturers and users of packaging machines. Dr Marc Mauermann from the Dresden Fraunhofer Institute for Process Engineering and Packaging explains what is important when designing machines.

What are the biggest challenges in the mechanical packaging of food?
The biggest challenge is the complexity of the production processes. More and more foods are being offered in different variants and compositions. Products are becoming more individual, batches smaller. This applies to almost all areas of food production. For this you need flexible machines. Areas which come into contact with the product are particularly affected by hygiene requirements. They must be cleaned regularly, for example when changing batches. This must be safe, reproducible and fast. A machine that meets the requirements of hygienic design does not accept right angles and is easy to clean. Anyone who has ever cleaned knows that. Machine construction always means a compromise between functionality, production, costs and hygienic design.

What is the trend?
The trend over the last ten years has been very positive! Many companies are implementing basic criteria very well, as defined by the European Hygienic Engineering & Design Group (EHEDG), among others. One of the most important aspects is accessibility: all areas of the machine must be easily accessible for automatic and manual cleaning. Experience in manual cleaning shows that the easier it is to reach critical areas, the more lilkely they are to be cleaned regularly. Areas that cannot be reached by automatic processes are not cleaned!

Are there industries where the equipment is better suited to the principles of hygienic design?
This is not easy to answer. If a greenfield investment is made somewhere and a thorough risk assessment is carried out, the latest and best equipment can be purchased with a view to hygienic design. It is more difficult to raise the level in an existing operation, because more compromises have to be made. Here, areas dealing with highly sensitive products, such as baby food, should be very well placed.

Would machines have to be redesigned from scratch?
Well, these are economic considerations that have to be considered. A new design costs a lot of money. Evolutionary developments which represent an improvement, are more economical in terms of design and detailing. The development and implementation of hygienic design for machine components are an ongoing process. Last year, we investigated the cleanability of valves, cameras, gripping elements, closing and filling parts, robot and machine elements in our test stands and were able to validate hygienic design in many cases.

Are there differences in the processing of liquid and powdery materials?
I wouldn’t say that. In processes that are cleaned wet, there is a higher microbial risk, in the dry area hygienic design focuses on accessibility for dry cleaning processes and dust control. There are rules here too, such as no gaps or right angles.

Do you have another example besides right angles?
If you have a pipeline and put a sensor there, for example, a dead space can develop at the projection. If the ratio of length to diameter of the dead space (l/d) is greater than one, then either the effort involved in cleaning increases immensely. or the dead space cannot be cleaned at all.

What other aspects play a role in hygienic design?
Attention should be paid to the easy cleanability of floor drains and gullies. The floor is clean when the gully is clean. It must be possible to drain all machines and pipes:. if product residues or water remain in the machine, this can be a breeding ground for microbial contamination. Installations directly above open products must be viewed critically. The materials used in product contact must be easy to clean and disinfect. We recommend a roughness of Ra 0.8 µm for stainless steel and welding seams, which must be of high quality.

Dr.-Ing. Marc Mauermann is Deputy Head of the Processing Technology Division at the Fraunhofer Institute for Process Engineering and Packaging (IVV) in Dresden.