Effect of natural vibration of bamboo cylinder on the shape of fine bamboo fibers extracted by endmilling process for self-adhesive moldings

This study evaluates the effects of forced chatter vibration on the shape of bamboo fibers for the production of 100% bamboo molds. Considering that fiber shape variation during end milling affects the mechanical properties of the molded product, we first determined the effect of bamboo cylinder shape on natural vibration through impact testing and finite element analysis. Based on these results and the temperature at the time of cutting, cutting conditions that do not resonate with the natural frequency were examined, and it was found that a ratio of approximately 4.5 between the natural frequency and intermittent cutting frequency was appropriate. Next, we investigated the effect of the relationship between the endmill's intermittent cutting frequency and the natural frequency of bamboo on fiber shape. The results showed that when the ratio of the endmill's intermittent cutting frequency to the bamboo's first- and second-order natural frequencies was an integer multiple, resonance increased the vibration of the bamboo cylinder, which decreased the average width of the extracted fibers and increased their standard deviation. It was also shown that the effect of third-order natural frequencies was small. Further investigation of the effect of height variation confirmed that at heights below 125 mm the vibration amplitude was sufficiently small to have no effect on the mean or standard deviation of the fiber widths.