3D printing for fully automated coffee machines - long service life for an automated cup tray adjustment

• What was needed: Components for the mechanics of an automatic cup table adjustment on a fully automatic coffee machine
• Manufacturing process: selective laser sintering
• Requirements: Food conformity, stability, strength, good running properties, dimensional accuracy
• Material: iglidur® i6
• Industry: vending machinery
• Success through cooperation: high abrasion resistance, toughness and service life

The application at a glance:
Until now, the cup table of fully automatic coffee machines was adjusted to the cup size by hand. The project team at the Ansbach School of Mechanical Engineering developed a motorised, movable cup table with sensor-controlled height adjustment for fully automated adjustment of this table. A motor, a 3D-printed traverse and a 3D-printed spindle were used for the mechanics of the height adjustment. The 3D-printed components made of the high-performance plastic iglidur® i6 have very good running properties as well as high strength and service life.

The height of the cup table of a fully automatic coffee machine was previously only ever adjusted manually to the cup size, which is why an automatic solution for the adjustment was sought. A team from the Ansbach School of Mechanical Engineering developed a motorised mechanism for a height adjustment system controlled by sensors, for which the appropriate materials still had to be found for the "traverse - spindle" concept. The requirements for the concept were very good running properties between the traverse and spindle as well as reliable dimensional accuracy in order to maintain the dimensions within the fully automatic coffee machine. At the same time, the materials had to be designed for food contact and the total weight of the cup(s).

The project team found the perfect partner in igus® GmbH from Cologne. In collaboration with additive manufacturing conductor Tom Krause, the team initially succeeded in producing a prototype for the mechanical concept using 3D printing. The high-performance polymer iglidur® i6 developed by igus® specifically for laser sintering was used, which impressed the team in particular due to its high strength, dimensional accuracy and running properties. After revising and improving the concept, all of the components were ordered via the 3D printing service. In addition to the specifications already mentioned, the mechanics also impressed with their high abrasion resistance and attention to detail. It was also particularly helpful that no tools are required for the laser sintering process and that the components can be manufactured efficiently with no minimum order quantity.

The term fully automatic coffee machine mainly refers to the fully automated process of coffee preparation. The problem that different cup sizes require different height settings for the integrated cup table has so far been solved manually. A project team from the Ansbach School of Mechanical Engineering has developed an automatic and convenient cup table adjustment system to ensure that the fully automatic coffee machine lives up to its name. This uses sensors to determine the height adjustment, which then sets a motorised mechanism consisting of a 3D-printed spindle and crossbeam attached to the cup table linkage in motion. The sensors measure the travel distance between the upper edge of the cup and the lower edge of the beverage spout and recognise the height of transparent and opaque cups. Software is then used to control the motor until the specified distance is reached.

The tribologically optimised and very abrasion-resistant iglidur i6 plastic was used for the mechanism. The spindle-shaft end support operating characteristics were a decisive factor prompting the team to choose this material. The igus materials are very important, especially for vending machinery. Integrated solid lubricants make external lubrication unnecessary. This allows a hygienic operation, among other things. The material, which was specifically developed for laser sintering, has a much longer service life than conventional plastics.