The demand for metallic micro-molds that can be used for inexpensive mass production of polymeric microfluidic chips is increasing. Existing manufacturing techniques such as soft-lithography and photolithography can require multiple time-consuming steps, especially when the aim is to create three-dimensional features. In this study, the feasibility of using abrasive water jet machining (AWJM) and abrasive slurry jet machining (ASJM) to fabricate such micro-molds in Al6061-T6 and SS316 was studied. Jet raster scans under various combinations of process parameters were used in order to machine micro-pockets containing free-standing structures, representing molds for casting microfluidic chips with channel networks. As expected, for both materials and using both ASJM and AWJM, the pocket roughness decreased as the distance between adjacent raster scans (step size) decreased, but the lowest waviness occurred at an intermediate step size. The best quality pockets were achieved on SS316 using ASJM with the intermediate step size and the highest possible slurry mass flow rate. Unmasked machining could not be used to fabricate molds with sharp-edged intersecting features, and a novel hybrid AWJM/ASJM masked machining technique was thus introduced. An undercut and an undesirable erosion near the edges of the mask formed if the position of the last raster scan closest to the mask was not carefully controlled. Possible reasons for these phenomena were discussed in terms of the likelihood of jet deflection off the machining kerf and mask, and the resulting erosion due to secondary slurry flow. By careful selection of the process parameters, it was demonstrated that high quality molds with both single and intersecting free-standing structures at multiple heights could be fabricated, thus making three-dimensional microfluidic chip mold fabrication feasible.

可用于廉价的聚合物微流体芯片的大量生产的金属微模具的需求正在增加。现有的制造技术（例如软光刻和光刻）可能需要多个耗时的步骤，尤其是当目标是创建三维特征时。在这项研究中，研究了使用磨料射流加工（AWJM）和磨料浆喷射加工（ASJM）在Al6061-T6和SS316中制造此类微模具的可行性。为了对包含独立结构的微腔进行加工，使用了在各种工艺参数组合下进行的喷射光栅扫描，这些微腔代表了用于铸造具有通道网络的微流控芯片的模具。不出所料，对于两种材料以及同时使用ASJM和AWJM的材料，袋状粗糙度随相邻光栅扫描之间的距离（步长）的减小而减小，但最低的波纹度出现在中间步长上。使用ASJM在SS316上获得了最佳质量的囊袋，具有中等步距和最高的浆料质量流速。未掩膜加工不能用于制造具有锋利相交特征的模具，​​因此引入了一种新颖的混合AWJM / ASJM掩膜加工技术。如果没有仔细控制最后一个光栅扫描最靠近掩模的位置，则会在掩模的边缘附近形成底切和不希望的腐蚀。关于这些现象的可能原因，从射流偏转离开加工切缝和掩模的可能性以及由于二次浆料流动而导致的腐蚀方面进行了讨论。