Maintenance-free operation in a fully automated street barista system

• What was needed: Storage for the output unit
• Requirements: Maintenance-free, permanently low breakaway torque, jerk-free, hygienic and no corrosion, suitable for the food industry
• Area of application: vending machinery

In collaboration with Rothweiler Feinwerkmechanik, MyAppCafé has developed a fully automatic coffee robot that prepares customised coffee creations in a matter of seconds. Thanks to a special milk system, 650 coffee portions can be prepared without the need for refilling. Customers can place their orders on site using the touchscreen or simply via the app: they can select the desired creation, top it off with their own milk foam design and pay directly without cash. When you arrive at the vending machine, you hold your smartphone up to a reader unit and a few seconds later you are served the coffee you have created yourself. You can also send your own creation as a code to partners and friends via Messenger.
The first machine has been installed in the Postgalerie Karlsruhe since August 2020, with another in Sindelfingen, and there have been numerous enquiries, including international ones. In future, it will certainly also be found on the street, at the railway station and at the airport.

In addition to the interface problems, the dispensing systems and their storage posed a particular challenge during the construction of the system. One of the two most important selection criteria for the bearing: freedom from maintenance, because "we cannot completely rule out the possibility of liquids, coffee grounds or other substances reaching the bearing over the years. Hot/cold changes, possible condensation or vapour formation can also affect the bearing. The concept is also suitable for dispensing other foods. With a standard ball bearing, we don't know how it will react at some point. That's why we were looking for a solution that would reliably cover all scenarios", says Dirk G. Rothweiler. The second decisive requirement for the bearing: a permanently low breakaway torque. "This is particularly important at low speeds when moving off. Our servomotors start up extremely slowly, increase the speed slightly and carefully brake again until they come to a standstill." The bearing should implement the rotary movement with as little loss of force as possible.

Ready-to-install iglide® slewing ring bearings of the 04 series are ideal for this application. Their design is based on dry-running, maintenance-free sliding elements made of iglide® J material in combination with rings made of anodized aluminum. The sliding elements of this series are preloaded, thus achieving haptic freedom from playover the entire service life. The iglidur® J material is characterised by the lowest coefficient of friction in dry operation and its very low stick-slip tendency. It is also resistant to common cleaning agents in the food industry and has low moisture absorption, which allows it to be used in wet or humid environments.

The bearings have a long service life. Thanks to extensive tests in the igus® test laboratory, with load figures in the millions and precisely tailored to the customer's operating conditions, it can be precisely calculated in the online tool.