Rotating machines vibrate due to imbalance. This vibration can cause harmful shocks, reduce reliability, and increase maintenance costs. For this reason, it is crucial to remove or reduce these unwanted vibrations. Sometimes, the unbalance varies in each round of rotation and it is necessary to balance the system with the new amount of unbalance. The washing machine is one of the tools that make the vibrations created in each working cycle different from each other due to the creation of different unbalances. Therefore, to improve the performance of the laundry, the use of an automatic balancer seems to be desirable. The automatic ball balancer, it can balance the system with variable unbalances automatically and without the need for a control system. The presence of an ABB in the washing machine reduces the steady-state acceleration by 30%. In the previous works done in this field, the collision between balls is ignored, which causes some modeling errors. In this research, a 3D mathematical modeling of a washing machine with an automatic ball balancer is presented. The model is verified with experimental tests on a Samsung H147W washing machine which has not automatic ball balancer. Then, the collision between the balls is added to the model and again the new model is validated with the experimental tests on a Samsung WW10H9600EW washing machine. Finally, some effective parameters in the function of the ABB, such as the mass and size of the balls and the viscosity of oil inside the balancer are presented . Keywords : Unbalance, Washing machine, Modeling, Suspension, Automatic ball balancer, Collision, Ball