Material Removal Mechanisms in Vortex Machining

该奖项的研究目标是了解一种新的纳米级表面去除工艺，该工艺利用抛光浆的局部诱导涡流。这些涡流是由一根微米级的振荡光纤浸入待加工表面附近的流体中产生的，涡流相对于探头是静止的。不同直径的探头（7 μ m至400 μ m），在高频下振荡(超过100 Hz至10？会产生不同大小和量级的局部漩涡，导致横向尺寸小于一毫米的材料去除足迹。加工足迹的大小将由驱动振荡的幅度和频率以及探头相对于工件的方向来控制。分析模型将用于分离产生不同涡旋模式和速度剖面所需的纤维尺寸和驱动频率。内部实验装置将实现预测的涡流动力学和实际过程材料去除足迹之间的相关性。影响材料去除率和表面质量的实际机制（工艺参数和浆液成分）也将进行研究。如果成功，该项目将实现成本相对较低的技术，具有以下特点和能力：1)控制尺寸的亚毫米尺寸的工具，3)从高度局部区域去除材料而不会对工件造成损伤的能力，4)完成传统上具有挑战性的几何形状的能力，如微流体通道和再入特征，以及5)消除当前使用更大工具的子孔径工艺所带来的中频误差的能力。这将伴随着分析模型的实验验证，这将有助于方便地隔离最佳工艺参数。参与的本科生和研究生将获得与美国制造业相关的核心技术能力，如微制造、精密设计、计量和化学。示范模块将通过夏令营项目促进科学和工程学科的发展，并在研究生水平的机械工程、光学和纳米科学项目中突出精密工程的跨学科性质。

The research objective of this award is to obtain an understanding of a new, nanometer level, surface removal process that utilizes locally induced vortices of polishing slurry. These vortices are produced by a micrometer scale oscillating fiber immersed in the fluid near to the surface to be machined, the vortices being stationary relative to the probe. Probes of varied diameters (7 µm to 400 µm), oscillating at high frequencies (over 100 Hz to 10?s of kHz) will produce localized vortices of varying size and magnitude resulting in material removal footprints with lateral dimensions of less than a millimeter. The size of the process footprint will be controlled by the amplitude and frequency of the driving oscillations and the orientation of the probe with respect to the workpiece. An analytical model will be used to isolate the fiber sizes and drive frequencies required to produce differing vortex patterns and velocity profiles. An in-house experimental set-up will enable correlations between the predicted vortex dynamics and the actual process material removal footprints. Actual mechanisms (process parameters and slurry composition) contributing to material removal rates and surface quality will also be investigated.If successful this project will realize a relatively low cost technology with the following features and capabilities; 1) sub millimeter sized tooling of controllable size, 3) the ability to remove material from highly localized regions without imparting damage into the workpiece, 4) the ability to finish traditionally challenging geometries such as micro fluidic channels and re-entrant features, and 5) the ability to remove mid spatial frequency errors imparted by current subaperture processes that use larger tooling. This will be accompanied by experimental verification of analytical models which will facilitate expedient isolation of optimal process parameters. The undergraduate and graduate students involved will gain competency in core technologies relevant to US manufacturing such as micro-manufacturing, precision design, metrology, and chemistry Demonstration modules will be developed to promote science and engineering subjects through summer camp programs and to highlight the interdisciplinary nature of precision engineering in graduate level Mechanical Engineering, Optics and Nanoscale Science programs.