Ultra Precision 3D Micromachining

该项目将展示一种新的微加工工艺的有效性，该工艺可用于在各种材料中制造三维微机械、微光学和微流体设备。目前使用高速主轴的微细加工技术受到主轴和刀具跳动的困扰，这些问题限制了特征尺寸和公差。其概念是用压电驱动刀架取代高速主轴，该刀架可以在高达5000赫兹的频率下以平面运动移动钻石刀尖-相当于300,000转/分钟。通过改变励磁电压的幅值、频率和相位，两个线性致动器被异相驱动以产生可从线性改变到椭圆再到圆形的刀具路径。我们的目标是通过将最小特征尺寸从25um提高到1um，将特征公差从2um提高到200 nm，显著提高机械加工的能力，同时在各种材料上产生光学质量的表面光洁度。微电子机械系统(MEMS)为设计者提供了在芯片上制造微型机械振荡器、光网络组件和生物实验室的能力，但使用商业半导体制造设施制造此类设备所需的高成本和长时间一直是它们被广泛接受的障碍。半导体技术是为使用标准CMOS工艺的大容量电路而设计的，而许多MEMS器件需要更小的体积，具有更复杂的结构(例如移动的三维微镜阵列)，并且需要硅以外的材料。过去的MEMS加工研究侧重于高速主轴，而这项工作引入了一种新技术，可以避免旋转主轴固有的跳动问题，从而创建更小、更精确的特征。与普通的金刚石车削相比，由此产生的切屑几何形状减少了加工力，减少了刀具/工件的接触时间，从而延长了刀具寿命，并扩大了工件材料(塑料、金属和陶瓷)的范围。实验的目的是研究小深度切割的材料流动，确定工艺的极限，并确定不同工件材料的最佳切割条件。原型设备的制造将在3D中展示机械、光学和流体结构的集成。

This project will demonstrate the effectiveness of a new micromachining process that can be used to create three-dimensional micro-mechanical, micro-optical and micro-fluidic devices in a wide variety of materials. Current micromilling techniques using high-speed spindles are plagued by spindle and tool runout that limit the feature size and tolerance. The concept is to replace the high-speed spindle with a piezoelectric driven tool holder that can move the diamond tool tip in a planar motion at frequencies up to 5000 Hz - the equivalent of 300,000 rpm. The two linear actuators are driven out of phase to create a tool path that can be changed from linear to elliptical to circular by varying the amplitude, frequency and phase of the excitation voltages. The goal is to significantly improve the capability of the mechanical machining by pushing the minimum feature size from 25 um to 1 um and the feature tolerance from 2 um to less than 200 nm while producing optical quality surface finish in a variety of materials. Microelectromechanical systems (MEMS) offer designers the ability to create miniature mechanical oscillators, optical network components and biological labs on a chip, but the high cost and long lead time needed to create such devices using commercial semiconductor fabrication facilities has been an impediment to their widespread acceptance. Semiconductor techniques are designed for high-volume circuits using standard CMOS processing while many MEMS devices are needed in lower volumes, have more complex structures (such as moving three-dimensional micromirrors arrays) and require materials other than silicon. Past MEMS machining research has emphasized high-speed spindles while the effort introduces a new technique that avoids the runout issues inherent with a rotating spindle allowing smaller, more accurate features to be created. The resulting chip geometry leads to reduced machining forces and reduced tool/workpiece contact time creating longer tool life and extending the range of workpiece materials (plastics, metals and ceramics) when compared to normal diamond turning. The experiments are designed to study the material flow at small depths of cut, to define the limits of the process and to identify the optimum cutting conditions for different workpiece materials. Fabrication of prototype devices will demonstrate the integration of mechanical, optical and fluidic structures in 3D.