Achieving nano-mirror machining with CNC milling requires a combination of advanced equipment, precise tooling, and meticulous control over the machining process. While CNC milling is inherently limited in achieving true nano-level accuracy, some techniques and considerations can help come close to nano-mirror quality surfaces:
- High Precision CNC Machine: Use a high-quality CNC milling machine with superior rigidity, stability, and high precision linear motion components. The machine should have a low level of thermal expansion to minimize dimensional changes during the machining process.
- Ultra-Precision Spindles: Utilize ultra-precision spindles capable of high rotational speeds and low run-out, ensuring smooth and precise machining.
- High Precision Tooling: Select cutting tools with high geometrical accuracy and sharp cutting edges. Diamond or cubic boron nitride (CBN) tools are often used for ultra-precision machining.
- Minimal Tool Runout: Ensure that the tool runout is minimal to avoid vibration and chatter during machining, which could negatively affect surface finish.
- Control System: Implement advanced control systems with sub-micron resolution to accurately program and control the CNC milling process.
- Adaptive Control: Use adaptive control systems that can adjust cutting parameters in real-time based on feedback from sensors to compensate for any deviations during the machining process.
- Cutting Parameters: Optimize cutting parameters, including feed rates, cutting speeds, and depth of cut, to minimize tool wear and achieve the desired surface finish.
- Vibration Damping: Incorporate vibration damping techniques and mechanisms to reduce the impact of vibrations on the machined surface.
- Tool Path Strategies: Utilize specialized tool path strategies, such as spiral milling or trochoidal milling, to achieve smoother finishes and reduce tool marks.
- Workpiece Material: Choose materials with excellent machinability and low levels of internal stress, as these factors can affect the final surface quality.
- Final Polishing: Consider using additional post-machining processes, such as diamond polishing or chemical mechanical polishing (CMP), to further enhance the surface finish.
It’s important to note that achieving true nano-mirror machining using conventional CNC milling is extremely challenging due to the limitations of machine and tool accuracy. For applications requiring sub-nanometer surface finishes, specialized processes like single-point diamond turning or advanced optical polishing techniques are often employed.
Mirror machining system is used to reshape the rotating tool. Mirror machining can be realized by using the reshaped tool for machining. Muye iQ series machine tools are equipped with this system to process with ultra-high precision and ultra-high surface quality. Its finish machined surface roughness can reach Ra10nm, which greatly reduces the polishing time and avoids the distortion of optical surface caused by manual polishing in traditional processing technology. It is very suitable for optical mold processing in 3C and lamp industries.
- The mirror processing system realizes the tool shaping effect
1) Improve the accuracy of tool radial runout
Because of the runout accuracy of the tool shank and the error that is considered to be generated when installing the tool, there is a certain runout of the tool in the traditional machining. The dressing of the mirror machining system can improve the tool runout problem after actual clamping caused by the tool shank accuracy and tool accuracy.
2) Improve the shape accuracy of tools
For tools with poor tool trueness, especially those worn after machining for a period of time, mirror machining system can improve tool trueness.
3) Improve tool surface roughness
For the tool with poor surface roughness, the reshaping function can improve its surface roughness.
- Composition of mirror processing system
The mirror processing system consists of functional program, tool shaping device, calibration grinding wheel, GC reference grinding wheel, tool shaping device lubricator, high-precision workpiece automatic measuring device, and tool shape measuring device.
1) Function program: NC program to realize the coordination of tools, tool shaping devices, automatic workpiece measuring devices and tool shape measuring devices
2) Cutter shaping device: calibrating device, grinding and dressing the cutter
3) Calibrate the grinding wheel: use the dressing tool
4) GC reference grinding wheel: dressing calibration grinding wheel
5) Tool shaping device lubricator: lubricating when dressing grinding wheel and tool
6) High precision workpiece automatic measuring device: used to detect the diameter and runout of grinding wheel
7) Tool shape automatic measuring device: used to measure GC reference grinding wheel and tool
- Features of mirror processing system
The mirror machining system can improve the tool runout, true sphericity and surface roughness, and improve the surface quality of tool machining. The dressing function of the tool can realize the multiple use of the tool and greatly reduce the use cost of the tool. With Muye iQ series machine tools, high quality mirror processing can be achieved and polishing time can be reduced.