Three-dimensional dynamic model of wire sawing for saw marks control

In wire sawing, the dynamic bending of flexible wire influences the sawing process and the sawn surface formation. Prediction and effective improvement of the sawn surface quality remain challenging because existing models cannot fully describe the spatio-temporal interactions between the wire and the workpiece. This study established a three-dimensional dynamic model of wire sawing considering the workpiece-wire geometrical and mechanical relationships. The model was used to simulate the spatial sawing trajectory of the wire during the sawing of a 4-inch sapphire wafer and predict the sawn surface morphology. The simulation results were validated by comparing the cross-sectional shape, wavelength, and peak-to-valley value (PV) of the saw marks generated from wire sawing experiments. It was found that the distribution of wavelength and PV of saw marks on the sawn surface was non-uniform in the feed direction, that the PV varied within 10 similar to 24 mu m and wavelengths varied within 0.32 similar to 1 mm. Moreover, force analysis confirmed that the non-uniformity of wavelengths and PV was primarily influenced by the time-varying unit contact length feed force and lateral force. A saw marks control strategy based on varying wire reciprocation periods was proposed. Compared to the primitive process, the improved process reduced the maximum PV by 50 % and the maximum wavelength by 47 %, while the distribution uniformities of both on the sawn surface were also significantly improved. This study not only provides a new approach to improving sawn surfaces but also offers a practical analytical tool for understanding the evolution of the macroscopic sawing behavior of the flexible wire during the sawing process.