In the case of pellet distributor, the problem with static charge turned out to be notorious. Most stages of the material compounding process can induce it: the cooling channel by triboelectric effect due to the air sprayed over the filament; the pelletizer by contact with the rollers or the casing; and even the robot tube itself once the pellets are cut, since they slide over the plastic surface. This causes problems since it causes two negative effects: the pellets tend to get stuck in the tube due to attraction to the walls; and, once a cup reaches a certain fill level, the charged pellets within it act as an electric repellent for oncoming pellets, pushing them away from falling into the cup, and in some instances making them fly out of the cup, as shown in Figure .