Three forms of sawdust can be formed by longitudinal cutting，including ribbon-shaped chip，plate-shaped chip and spiral chip．Based on the basic law of deformation，the forming mechanism of the ribbon-shaped chip is analyzed by using the beam bending model．Based on the principle of motion synthesis and decomposition，the shear stress model is used to explain the formation of spiral chip．The research content originates from the physical problems in production and life，and its research method is conducive to breaking through the influence of the thinking set in the teaching and learning of college physics，which is bounded by books and classroom．It can also provide valuable references for the scientific innovation training of college students majored in physics．