Behavior of paper on a high speed conveyor subjected to air jet impingement: a method for estimating bending stiffness

Stiffness based sorting of mixed paper waste at high speed is desirable for sorting board, cardstock, and paper from each other for efficient recycling. We propose a quick, non-contact method for measuring the relative stiffness of paper samples moving on a conveyor at high speeds. The method consists of impinging an air jet on a moving paper sample while it is crossing a gap during transfer from one conveyor belt to another. The deflection caused by the impinging air jet can be measured and used to categorize different grades of paper. In this paper, we report results from a simulation of the proposed method using a finite element model. Influence of conveyor speed, sample orientation and nozzle pressure is studied using the model. Results indicate that the stiffness estimation has sufficient resolution to distinguish between board and paper grades at high conveyor speeds.