Rulmeca: It all depends on the hygienic conditions

Many process and conveying machines and systems in the food, beverage and pharmaceutical industries need to be cleaned after each production cycle in order to make them ready for the next production cycle, clean and free from potential pathogens and cross-contamination. Clean-in-place processes are increasingly being used for this purpose. They are characterized by the fact that they are carried out on site and without dismantling the components. The aim of these cleaning methods is to establish a process through the exact definition of cleaning agents, pressures, temperatures and times, in which the desired cleaning performance can be reproduced at any time and can therefore be sustainably ensured and documented.

Using steam jets against sensitive components

In conveyor technology, clean-in-place processes are often implemented while the conveyor belt is running. And there are good reasons for this: On the one hand, it is quite time-consuming to remove and reinstall a heavy conveyor belt that extends over several meters. On the other hand, it is also the case that the links of plastic modular belts, for example, can be cleaned more easily during operation, as this is the best way to reach the gaps piece by piece where the links open the widest. But cleaning crews often take an uncompromising approach with high-pressure cleaners and steam jets. They have a clear mission: to get everything spotlessly clean as quickly as possible. No consideration is given to sensitive components.

Lean design: The PTFE seal with double lip developed and manufactured by Rulmeca is effective and efficient. Photo: Rulmeca

Conveyor components such as drum motors must therefore not only be resistant to aggressive cleaning agents and disinfectants, but must also be one hundred percent leak-proof even when cleaned several times a day with splash water and high-pressure and steam jet cleaning.

Double protection

Whether a component offers the required tightness is usually specified in IP degrees of protection. It is important that motors are equipped with double IP protection, as it makes a difference whether a system is specified for protection to IP66, IP69 or both types of protection with IP66/IP69. The higher-quality IP69 protection does not automatically include IP66 protection. With IP66 protection, a strong jet of water from a distance of 3 meters at 100 liters per minute at a pressure of 1 bar against the housing from any direction for at least 3 minutes has no harmful effects. IP69 offers protection against high-pressure or steam jet cleaning. This means that systems are protected against water jets from close proximity at high temperatures.

The stainless steel drum motors from Rulmeca have exactly this double IP66/IP69 protection level, therefore IP66/IP69-plus. This means that they are verifiably protected against pre-cleaning and subsequent rinsing with cleaning agents and disinfectants as well as microbiological cleaning with steam jet and high-pressure cleaners.

Also tested during operation

The IP 66/69-plus degree of protection offers protection against high-pressure cleaners and steam jets, even in clean-in-place applications. Photo: Rulmeca

This double protection is obviously sufficient. However, it does not quite apply to drum motors, because you need to know that the IP tests are carried out when the motor is at a standstill. But what about conveyor systems that are cleaned using the clean-in-place method while the motor is running? For such applications, drum motors would also have to have IP66/69-plus protection during operation. But how does this requirement differ? When the motor is mounted and rotating, the belt forces load the axle bearing on one side. This can result in microscopically small gaps that are not present when the motor is stationary.

These gaps can lead to the ingress of cleaning agents and water, which can reduce the service life of the motors and increase maintenance costs. Rulmeca was therefore the first company in the industry to test its drum motors during operation. And even during operation, it has been proven that the motors offer reliable protection under both IP66 and IP69 conditions.

One hundred percent tight

The critical point is the seal between the static axle journal and the rotating drum. Rulmeca has developed an extremely tight solution at this point. Competitive solutions often use a hardened bushing that is glued to the axle journal and works with a steel disk seal. Rulmeca uses a comparatively simpler friction seal made of high-quality PTFE. In the sealing area, the axle journal has been surface-tempered by roller burnishing. This makes the sealing surface harder and smoother. The PTFE microparticles on this surface ensure friction-free and long-term tight running without abrasion. The PTFE seal has a double lip seal developed in-house by Rulmeca without a micro-screw effect to ensure 100% tightness even during operation and with the additional belt tensile forces that occur here. This is because normal turned seals create very fine thread grooves through which liquids can migrate during rotation, like a pickup over a record. This effect does not occur with Rulmeca drum motors, making them safe against the entry and exit of liquids.

About Rulmeca

Rulmeca Germany GmbH is part of the Rulmeca Group based in Alme/Italy. With over 200 employees, Rulmeca Germany GmbH produces idlers, drum motors and belt drums for use in unit load and bulk material handling technology at two ISO-certified sites in Aschersleben and Leipzig. The company works together with system manufacturers, development offices and end users worldwide. In addition to the production of conveyor technology components, Rulmeca also offers its customers the calculation of conveyor belt elements for complex systems as a service.

Conclusion

The industry has long been aware of the problem that water can enter the drum motor despite IP66 or IP69 protection. Rulmeca has found a solution and now certifies to both protection classes and also extends this protection class to ongoing operation.

Andreas Flies