Design And Development Of A Micromilling Machine Tool And Experimental Study On Micromilling Of The Typical Hard And Brittle Material

Micromilling is an ultra-precision machining technique which is capable of realizingthe fabrication of three-dimensional and complicated geometrical features. The CNCmicromilling machine tool with excellent motion performances is the prerequisite formicromilling techniques. In order to conduct micromilling studies, the design anddevelopment of a CNC micromilling machine tool is introduced in the study firstly.Experimental evaluations are conducted for the developed desktop micromilling machinetool. Furthermore, the micromilling process has been conducted for the typical hard andbrittle material.Considering the fact that features to be created in micromilling are usually small-sized,the CNC micromilling machine tool is designed as a desktop one. The miniaturizeddesktop machine tool not only saves space and energy, but also has the ability to improvethe accuracy theoretically. Open architecture CNC system is applied to the developedmachine tool. The controller uses the UMAC motion card from Delta Tau which hasintegrated I/O and power supply. It also has high-speed USB, Ethernet, Macrocommunication system to communicate with IPC to satisfy the performance expansions.Direct drive linear motors are used to avoid the transmission errors brought byconventional ball screws. Linear encoders with the graduation of5nm are used forfeedback to construct the closed-loop control. After the construction of the desktopmicromilling machine tool, PID debugging, calibration and compensation by laserinterferometer are conducted to realize the sub-micron positioning accuracy.Based on the minimum chip thickness theory in micromachining, experimental studiesare conducted on the typical ductile material copper. The effect of the feed and axial depthof cut on surface roughness has been studied. The developed machine tool also has beenverified by the experiments.The physical properties of single-crystalline silicon have been analyzed to select themicromilling cutter and cutting fluid. Experimental studies have been conducted on thedeveloped machine tool. The federate and the cutting fluid supply method have beenselected as the experimental factors. Based on the federate identified in previous studies,the two-factor and whole-level experiments have been conducted. The surface roughnesshas been analyzed by white-light interferometer.Variance analysis has been used to study the effects of the experimental factors on thesurface roughness and the sequence of importance has been identified. It shows that thelarger the federate, the worse the surface roughness is. The cutting fluid is very importantin micromilling of single-crystalline silicon. The cutting fluid has more effects on thesurface roughness than that of the federate. Brittle-ductile transmissions (ductile-modemicromachining) can be realized in a certain micromilling conditions. The experimentalstudy found the basis for further studies on micromilling of hard and brittle materials.