Abstract: A machine, and method, for tumbling objects or parts, generally of plastic material, to remove thin flange-like projections left along mold mating lines and frequently referred to as "flash". An advancing belt-like conveyor has a portion disposed to define an object-supporting surface so upwardly sloped in the direction of conveyor advance, as to cause tumbling and consequent deflashing of a mass of objects supported on said surface. The conveyor is also movable between two positions in which the objects are, respectively, loaded upon and automatically discharged from the conveyor. In the illustrated apparatus these are upper and lower positions. Tumbling occurs in the upper position, and discharge takes place in the lower position, under the influence of the advancing movement of the conveyor. The system includes mechanism for effecting additional cleaning of the objects, while tumbling on the conveyor, by subjecting them to a blast of impact cleaning media.