Our day life is characterized by the use of vending machines. We are used to get cans, bottles, snacks, coffee from a big variety of vending machines spread out everywhere. From an engineering point of view what is inside a vending machine is an incredible mess of mechanical and electrical components working together, cooperating, heating, cooling in a lot of different external and internal conditions. This means that the design of a vending machine and of its components has to be robust, reliable and affordable. N&W, as market leader in vending sector (EU and a strong presence WW) and with a 70 people R&D Dep., has faced many problems related to sliding plastic/rubber components in presence of friction issues due to moisture, sugar powder (micro and macro), heat transients and pressure. To do that a testing campaign has been performed in order to achieve all the data needed to characterize friction coefficients relevant for the numerical activities. Two different systems will be presented in the paper:

• sugar dispenser sliding system
• tea infusion sliding piston

All the activities have been performed using HyperMesh, OptiStruct, MotionView and RADIOSS mo-dules. The mechanical systems, characterized by a low speed dynamic behavior, have been investigated using both explicit and implicit techniques and taking into account all the environmental conditions. The results of the numerical activities have been used to drive the design activities to more robust and reliable complex innovative systems in terms of (as shown in the paper):

• new design criteria
• coupling tolerances
• robustness
• reliability
• quality


The Author

Matteo Adobati
CAE Engineer
N&W Global Vending S.p.a.