Clean Designs Promote Clean Lines

As well as the obvious aesthetics that clean lines can deliver, they also play a role in hygienic design solutions, which are so vital to so many industries. Heiko Luckhaupt at RS Components looks at what designers have to consider when designing for the food, beverage, pharmaceutical and healthcare markets.

Hygienic design is a pre-requisite of many industries and is often heavily legislated on a national and international basis; as well as being subject to extremely rigorous end user in-company standards and procedures.

For machine designers, experience plays a huge part in the design process along with an in-depth knowledge of the end application and the rigours the machines will face. But help is also available from component, ancillary and module suppliers who can help complement sleek machine designs with their own clean-lined solutions.

The concept of hygienic design covers a multitude of definitions and procedures when it comes to designing equipment for sterile, non-contaminating and wash down environments or indeed combinations of all three. Arguably the most important step is to define the materials that will be used, which must be non-toxic, smooth and non-porous, with the obvious contenders – as can be seen in virtually any sterile environment – being stainless steel and multiple inert polymer variants. Designers also need to think about lubricants, seals and insulation materials to ensure that they too do not present a contamination issue.

 

 

After the correct (or most suitable) material has been chosen the physical design must be considered. With metal constructions the primary issue is sharp corners, trap points and seams, which can create perfect recesses for bacteria to grow or for product to get caught and then released back into fresh mixes. For this reason, completely welded seams are the norm along with components such as bowls and troughs, created using metal drawing techniques, which eliminate joins all together. The same is true for plastic components, which cannot exhibit crevices or trap points in which product can be trapped and bacteria can thrive.

Complete trap- and splatter-free design is next to impossible, which is why these industries have such rigorous decontamination and cleaning procedures. In the food industry in particular, the use of scalding, high pressure water, mixed with caustic cleaning agents is widespread and for this reason machine designers have to make sure their machines are up to the extremes faced through regular cleaning. Machines will typically feature both design extremes, depending on the function of the equipment or modules, in the first instance control cabinets or IO panels will have a completely sealed design, while the remainder of the machine will have a very open and ‘approachable’ architecture which will allow operatives to access all areas with cleaning equipment. It must also feature effective draining and no horizontal surfaces. Indeed all surfaces should ideally slope to one side away from the product processing area.

 

With regards to the sealed modules, the standard industry-wide IP classification has been enhanced to include the IP69K rating for high-pressure, high-temperature wash-down applications. As well as being dust tight (IP6X), enclosures with the IP69K rating must also be able to withstand high-pressure and steam cleaning. Initially developed for road vehicles, especially those that need regular intensive cleaning, IP69K now sees widespread adoption in many other industries, including food and pharmaceutical.

Once the major structural and architectural elements of the design have been finalised, the finer details can be refined, including the specification of control equipment, sensors and cabinets. Looking at the major ancillaries such as cabinets, Rittal offers us an interesting insight into how a specialist approaches these designs. Simple features such as enclosed internal hinges, blue-coloured silicone seals, open-style mounting brackets and an all-round surface tilt all contribute to the overall hygienic feature set.

When it comes to components, machine designers are spoilt for choice, with a remarkably wide range of high-IP-rated products – including those that are IP69K-rated – from an equally wide range of suppliers. Sensors, including proximity sensors, photoelectric sensors and light/contrast sensors can be found from Telemecanique, Pepperl+Fuchs, Omron, Turck Banner, Sick and Baumer. Pushbutton switches add ABB and Eaton in to the mix and Schmersal for emergency stop pushbuttons. All of these products have to be connected somewhere down the line, so cabinet access points and conduits, trunking and routing hardware also need to be considered. In this instance WISKA, Adaptaflex and PMA have a wide choice of solutions.

For drive equipment such as motors and motor gearbox combinations, IP69K rating is not really feasible, which is why they are made “as resistant as possible” using stainless steel construction and specialist cable entry and electrical panels. They do have relatively high IP ratings, but they cannot be subject to the same aggressive cleaning regimens as their IP69K-rated peers – this must be considered in the design.

As mentioned above, not all components need to be IP69K rated; they just need to be made from materials that are best suited to being near wash down areas. For this reason stainless steel components are widely available for simple things such as latches and gates, through conveyor systems, all the way up to human machine interface screens and industrial PC enclosures. Although not directly in need of wash down, they need to be sited nearby and therefore have a modicum of resilience to what can be a hostile environment.

Hygiene and its related safety factors are covered by a huge amount of national and international legislation, and this legislation often offers a good starting point and guidelines on the primary requirements. Designers have a glut of standards and directives to consider, including EN 1672-2:2005 Food machinery/General design principles/Part 2: Hygiene requirements, EN ISO 14 159 2004 Safety of machinery – Hygiene requirements for the design of machinery and Document 13 EHEDG guideline on the hygienic design of apparatus for open processes, prepared in collaboration with 3-A and NSF International. EU regulations include 852/2004 on the hygiene of foodstuffs, 853/2004 specific hygiene rules for food of animal origin and 1935/2004 on materials and articles intended to come into contact with food.

Designing for hygienic environments may seem like a bit of a black art but in many cases the obvious solutions can boil down to simple common sense, coupled to an appreciation of water and particulate flow. Admittedly, a lot of the best and most effective designs are the result of years of experience, but even those new to the market can make serious inroads thanks to the help and availability of suitable products from a very wide range of suppliers. Most of them will also have background documentation available, which detail special considerations and concepts and even industry-specific foibles and unique demands.