Modification of tool influence function of bonnet polishing based on interfacial friction coefficient

- The interfacial friction coefficient between bonnet tool and workpiece is calculated based on the collected polishing forces.
- The friction coefficient is changed with the variety of tool rotational speed, which impacts the tool influence function.
- Modification of tool influence function model based on the interfacial friction coefficient is proposed and validated.

Aimed to improve the modeling accuracy of tool influence function (TIF) of bonnet polishing, a theoretical and experimental study is presented. This paper starts with the affecting mechanism of key parameters on the material removal of workpiece. It is indicated that the interfacial friction coefficient between tool and workpiece is changed with the variety of the tool rotational speed, which impacts the TIF but has not been taken into account in most current TIF models. Consequently, modification of TIF model based on the interfacial friction coefficient is proposed and then experimentally validated. The results show that, for the experimental groups in which the spot size is 15 mm, the difference between the maximum removal depth of the TIF predicted with the pre-modified model and that of the experimental TIF is −0.204 to 1.244λ (λ = 632.8 nm), which is obviously larger than that between the TIF predicted with the modified model and the experimental TIF −0.187 to 0.168λ. Moreover, for the experimental groups in which the spot size is 20 mm, the difference between the maximum removal depth of the TIF predicted with the pre-modified model and that of the experimental TIF is −0.135 to 2.235λ, while that between the TIF predicted with the modified model and the experimental TIF is −0.046 to 0.571λ. The experimental results indicated that the TIF predicted by the modified model is much closer to the experimental TIF, which proves the effectiveness and correctness of the modification.