Why do flame-retardant conveyor belts drift during operation? While belt drift can sometimes be caused by the conveyor itself—which we won’t elaborate on here—the main causes related to the belt itself are as follows: 1. Uneven tension during the braiding process of the belt core, resulting in one side being loose and the other tight. 2. Uneven thickness on both sides of the belt, with one side being thicker and the other thinner.