A method of inverting workpieces in a mass production process includes: advancing an end effector in electronic synchronization with advancement of a carrier to synchronize arrival of the carrier at a stop position with arrival of the end effector at an unloading position, in which the end effector is in alignment with a workpiece held by the carrier for engaging the workpiece; while the end effector is in engagement with the workpiece, retracting the end effector away from the carrier to unload the workpiece from the carrier and advancing the end effector back toward the carrier to load the workpiece back into the carrier; and rotating the end effector relative to the carrier to invert the workpiece in electronic synchronization with the retracting and advancing of the end effector for loading the workpiece back into the carrier when inverted.