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Micropencil grinding tools (MPGTs) are micromachining tools that use superabrasives like diamond and cubic boron nitride (cBN) grits to manufacture complex microstructures in a broad range of hard and brittle materials. MPGTs suffer from a rather low tool life, when compared to other more established microprocessing methods. It was documented that when used on hardened steel workpieces, MPGTs suffer from a large amount of adhesions, mostly located at the pivot point of the tool. These adhesions lead to the clogging of the abrasive layer and ultimately in tool failure. Another problem this machining process suffers from is the formation of substructures (smaller channels inside the microchannels). The pivot is usually less prone to abrasive wear, has higher protrusion, and is therefore responsible for the deepest substructures. These substructures can easily take up half the depth of cut, obstructing the function of machined microchannels--it is one of the major flaws of this micromachining process. A micro-electrical discharge machining method (μEDM) can solve these issues by manufacturing a cavity at the pivot of these tools. A novel method that uses measurement probes to position the substrate above the μEDM electrode is implemented and a parameter study to determine the cavity manufacturing parameters is conducted for substrates with diameters<40μm. The goal is to demonstrate the first ever complete and reliable manufacturing process for MPGTs with a cavity and to demonstrate the advantages they provide in a machining process when compared to regular MPGTs. [ABSTRACT FROM AUTHOR]

Multi-axis electrical discharging machining (EDM) is the main manufacture method for shrouded blisks, which are key components of aero and rocket engines. Involving both linear and rotational axes, a feeding path for machining a narrow and twisted channel consists of a large number of G-code lines. Accelerations and decelerations at junctions, which connect two neighboring G-code lines, can significantly reduce the machining efficiency. In this paper, a new simplification of feeding paths in roughing EDM for shrouded blisks is proposed in order to reduce the number of junctions on a feeding path. However, deviating from the original feeding path, a simplified feeding path can bring over contour errors which can cause geometrical errors of workpieces. Contour error can thus serve as a criterion for simplifying the original path. Eight vertices of a hexahedron, which contains the electrode, are used to represent all points inside and on an electrode. Forward kinematics of a six-axis EDM machine is used to calculate the contour errors of the eight vertices when the electrode feeds along a simplified path. A simplified feeding path can be found provided that the contour error constraint is respected. Machining tests show that the use of a simplified feeding path in roughing EDM machining can reduce the average total machining time by 26.5% without significant impact on surface roughness and white layer thickness. [ABSTRACT FROM AUTHOR]