Arrius®: Groundbreaking grinding system

18 January 20216 min reading

Nicholas Trounce

Nicholas Trounce Head of Product Management Milling Solutions Wheat & Rye Bühler AG in Uzwil / Switzerland

Lower energy consumption, faster installation, maximum food safety, highest operating reliability, and best grinding performance: Arrius, the integrated grinding system from Bühler, offers an impressive array of innovations and tangible benefits for customers.

One look at Arrius and it is clear – this is not just a facelift for an existing roller mill but a fundamentally new development. And from the very beginning, the needs of millers were the focus of attention. They were involved in the development project from day one and their input has made Arrius what it is today - a machine that is both revolutionary and familiar to millers.


Arrius is not just a roller mill but the first integrated grinding system. That might sound like a marketing slogan, but it makes total sense when you take a close look. Arrius is fully integrated, meaning the switch cabinet, the drive and gearbox, and the web server, which provides the link to digital services, are all built in. These are all components that are separate in a conventional roller mill. Integrating them brings significant advantages. It makes Arrius remarkably energy efficient, for example. The novel drive reduces energy consumption by up to 10% compared to conventional belt drives. Furthermore, the integrated drive unit together with the direct suction means it is possible to save an entire floor when building a new mill.

The innovative design also allows the Arrius grinding system to be delivered to its destination as a ready-to-install module and to be flexibly positioned within the plant. Just connect three cables, compressed air, and product inlet and outlet - and the grinding system is ready for operation. This plug-and-play system considerably reduces installation and commissioning time. By using power busbars for the electric power distribution, installation time can be reduced by a factor of three.


Bühler roller packs have stood out for their stability and precision for decades. In spite of – or perhaps precisely because of this – the company has continued to carry out intensive research in this area. The roller pack with integrated grinding force measurement ensures outstanding grinding performance. Thanks to the pre-stressed rollers, up to 10% higher starch damage can be achieved compared to conventional roller mills. The new gearbox enables parallel grinding force adjustment, which ensures uniform grinding over the entire length of the grinding gap. Moreover, by pre-stressing the rollers the gap remains stable over time. The grinding result can be adjusted directly and with ease.

grinding system

Brushless scraper bars for corrugated rolls and self-adjusting scraper blades for smooth rolls contribute to perfect grinding with low maintenance requirements. An important aspect in grinding is also the feeding of the product to be ground. The patented feeding module with asymmetrical inlet, product-independent level control and product distribution enables an even product distribution over the entire grinding gap. The complete inlet area of the feeding module is accessible for cleaning by opening the chamber door, taking hygiene to a new level. A greatly simplified grinding chamber design and improved aspiration reduce product deposits, which further increases food safety. Also unique is the support on hygienic leveling feet, which allows easy cleaning under the machine. It goes without saying that all product-contacting surfaces on the Arrius are made of stainless steel or other food-compatible materials.


On the subject of cleanliness, swinging up the product chamber cover enables easy access to the entire grinding chamber. This not only simplifies cleaning but also maintenance work. Rolls can be changed in less than 45 minutes thanks to the easy access, the slidable roller pack, and quick plug-in connections. With Arrius this can now also be carried out while grinding continues on the opposite passage - a unique feature in flour milling. The intuitive touch-screen operating unit allows easy monitoring and control of the grinding system. Thanks to the integrated web server, Arrius can be operated via smartphone, tablet or PC within the mill. The user interface is extremely intuitive and can be understood within a very short time by personnel with milling experience. Arrius also sets new standards in personal safety. The product chamber cover with electronic locking device completely closes off the grinding chamber and can only be opened when the rollers are completely stationary. In addition, the grinding chamber doors are each fitted with a hand guard to ensure safe sampling.


The Arrius grinding system is equipped with numerous sensors that continuously monitor the operating status. The sensors in the inlet of the feeding module detect product variations and the automatic feed control immediately compensates for fluctuations. This ensures that the feed is always constant and that the ground material is distributed evenly across the entire grinding gap. The novel force measurement of the roller pack enables close monitoring of the grinding process. Should deviations occur in the absolute grinding force or between the measurements on each side, an error message is issued. This contributes to maintaining optimum grinding conditions in the individual grinding systems and thus ensures an efficient overall process. The optional monitoring package includes additional sensors for monitoring the operating status including monitoring of the rollers, the product level in the inlet and the grinding gap position. The insights generated by these devices provide a solid foundation for future digital services under the umbrella of the SmartMill program.


The new grinding system Arrius is available as a four-roller and eight-roller integrated grinding system. For both models, roller lengths of 1000, 1250 and 1500 millimeters and diameters of 250 millimeters are available. The following options are also available: roller temperature monitoring, bearing temperature monitoring, inlet monitoring, and grinding gap force measurement.

Arrius The first integrated grinding system Arrius MRRA from Bühler.

Summary As with the Mill E3, Arrius improves efficiency in the areas of energy, building investment and installation time. The direct drive reduces energy consumption by up to 10%. Energy recovery is achieved mechanically via the gear unit specially developed for Arrius. The integrated drive saves an entire floor structurally, which reduces investment costs. The integrated design allows Arrius to be wired and tested ready for operation in the Bühler assembly plant. Thanks to this plug-and-play system, the time required for installation and start-up is significantly reduced.

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