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创建三维微机械、微光学和微流体装置。目前使用高速主轴的微铣削技术受到主轴和刀具跳动的困扰，这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，该刀架可以以高达5000 Hz的频率（相当于300,000 rpm）以平面运动移动金刚石刀头。通过改变激励电压的幅度、频率和相位，两个线性执行器被驱动成非相位，从而形成一条刀具路径，该路径可以从线性变为椭圆形再变为圆形。目标是通过将最小特征尺寸从25um推到1um，特征公差从2um推到小于200nm，同时在各种材料中生产光学质量的表面光加工，从而显着提高机械加工的能力。微机电系统（MEMS）为设计人员提供了在芯片上创建微型机械振荡器、光网络组件和生物实验室的能力，但是使用商业半导体制造设施创建此类设备所需的高成本和长交付周期一直是其广泛接受的障碍。半导体技术是为使用标准CMOS处理的大批量电路而设计的，而许多MEMS器件需要较小的体积，具有更复杂的结构（如移动三维微镜阵列）并且需要硅以外的材料。过去的MEMS加工研究强调高速主轴，而这项工作引入了一种新技术，避免了旋转主轴固有的跳动问题，从而创造出更小、更精确的特征。与普通金刚石车削相比，由此产生的切屑几何形状可以降低加工力，减少刀具/工件接触时间，从而延长刀具寿命，扩大工件材料（塑料，金属和陶瓷）的范围。实验旨在研究小切削深度下的材料流动，确定工艺极限，并确定不同工件材料的最佳切削条件。原型装置的制造将展示机械、光学和流体结构在3D中的集成。

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.