3D printed lead screws for automatically adjustable tray in coffee machines

Application Overview:

• What was needed: Components for the mechanism of an automatic cup tray adjustment for a fully automatic coffee machine
• Manufacturing method: Selective laser sintering
• Requirements: Food conformity, strength, stability, good operation properties, dimensional accuracy
• Material: iglide i6
• Industry: Vending machinery
• Success from the collaboration: High abrasion resistance, toughness, and long service life, food conformity according to FDA and EU 10/2011

Up to now, the height of the fully automated coffee machine's cup tray was adjusted to the cup size by hand, which is why an automatic solution was required. A team from the mechanical engineering school Ansbach developed a motorised mechanism for a sensor-driven height adjustment. The suitable materials for this concept "shaft end support - spindle" still had to be found. The concept had to have excellent operating specifications between shaft end support and spindle, and a reliable dimensional accuracy to adhere to the dimensions in the coffee machine's interior. At the same time, the materials had to be suitable for food contact and the entire weight of the cup(s).

The project team found the perfect partner in igus GmbH from Cologne. By working together with the Head of Additive Manufacturing Tom Krause, the team first succeeded in producing a prototype for the mechanical concept via 3D printing. Here, the high-performance polymer iglidur i6 was used, which igus had specifically developed for laser sintering. It convinced the team in particular with its high stability, dimensional accuracy and operating characteristics. After revising and improving the concept, all components were ordered using the 3D printing service. In addition to the specifications mentioned above, the mechanics impressed with their high abrasion resistance, level of detail and food conformity according to FDA and EU 10/2011. It was also very helpful that no tools are necessary for the laser sintering process, and parts can be produced efficiently with no minimum order quantity.

How the automatic cup tray adjustment works
The term fully automatic coffee machine mainly refers to the fully automated process of coffee preparation. Up to now, the height of the cup tray has been adjusted by hand to accommodate the different cup sizes. To make sure the fully automated coffee machine is worthy of its name, a project team from the Ansbach mechanical engineering school, developed an automatic and useful cup tray adjustment. This uses sensors to determine the height adjustment, which then sets the motorised mechanism attached to the lever arms in motion, which consists of a 3D printed spindle and shaft end support. The sensors measure the travel between the upper rim of the cup and the bottom edge of the drink outlet, and recognise both transparent and opaque cups. By using software, the motor is then controlled until the defined distance is reached.

iglide i6 - food-compliant high-performance polymer
For the mechanics, the tribologically optimised polymer iglidur i6 was used, which is very abrasion-resistant. The running behaviour between spindle and shaft end support was one of the decisive aspects that made the project team opt for this material. Especially for vending machinery, the igus materials are very significant. Thanks to the integrated solid lubricants, no external lubrication is required. Amongst other things, this allows for hygienic operation and food contact according to FDA and EU 10/2011. The material - which has been specifically developed for laser sintering - has a significantly longer service life than conventional plastics.