Provided is a method of quantitatively evaluating machined surface quality, in which quantitatively evaluating the machined surface quality is possible and a stable evaluation is obtained. The method includes the steps of: measuring the positions of cutter marks arranged in a feed direction of machining paths; calculating a difference between the positions of the cutter marks on the adjacent machining paths in a pickfeed direction; and quantitatively evaluating the surface quality using a standard deviation of the difference.

A miniaturized turbogenerator (200) to directly provide electrical propulsion (307 308, 309) to small land, air, and maritime vehicles without an intervening electricity storage battery (315). The invention comprises of a process of miniaturization (500) of a turbine engine core (100), in particular its compressors and turbines (400), by means of hyper-feed machining by linear force alone, i.e. without rotation of either the workpiece or the cutting tool (505), and a resulting apparatus of a miniaturized turbogenerator (200) that has sufficient power density to provide high-performance electrical propulsion (310) for commercially feasible automobiles, urban air mobility vehicles, and other small vehicles and vessels with greater performance than battery-electric vehicles (300).

A miniaturized turbogenerator (200) to directly provide electrical propulsion (307 308, 309) to small land, air, and maritime vehicles without an intervening electricity storage battery (315). The invention comprises of a process of miniaturization (500) of a turbine engine core (100), in particular its compressors and turbines (400), by means of hyper-feed machining by linear force alone, i.e. without rotation of either the workpiece or the cutting tool (505), and a resulting apparatus of a miniaturized turbogenerator (200) that has sufficient power density to provide high-performance electrical propulsion (310) for commercially feasible automobiles, urban air mobility vehicles, and other small vehicles and vessels with greater performance than battery-electric vehicles (300).

A tool for machining a groove of a rotation-symmetric component, preferably a piston of an internal combustion engine, is provided. The machining is carried out by a rotation of the tool around an axis of symmetry of the rotation-symmetric component to be machined. The tool includes at least one arm disposed in such a way that a circumference of the rotation-symmetric component can at least be partially enclosed. Also, a machining device for machining of the groove is provided on the at least one arm. At least one adjusting device is provided. With the help of the at least one adjusting device, a contact force on the rotation-symmetric component of the at least one machining device can be selected. Further, the tool includes an adjusting device with which the tool can be adapted to different diameters of a rotation-symmetric component.

Disclosed herein is a wafer thinning method for thinning a wafer formed from an SiC substrate having a first surface and a second surface opposite to the first surface. The wafer thinning method includes a separation start point forming step of applying the laser beam to the second surface as relatively moving the focal point and the SiC substrate to thereby form a modified layer parallel to the first surface and cracks inside the SiC substrate at the predetermined depth, thus forming a separation start point, and a wafer thinning step of applying an external force to the wafer, thereby separating the wafer into a first wafer having the first surface of the SiC substrate and a second wafer having the second surface of the SiC substrate at the separation start point.

A chamfering tool that chamfers an opening edge of a target hole formed in a work, the chamfering tool including a support shaft, a base shaft having the support shaft on a tip end side thereof and being eccentric with respect to the support shaft, and a blade portion having a rake face that is a step surface of a step protrusion portion protruded laterally from the support shaft or that is an end surface of the support shaft. The blade portion including an edge line in a shape of a curve and being bulged to a side away from a center axis of the support shaft, and the edge line being inclined with respect to an axial direction of the support shaft.

A chamfering tool that chamfers an opening edge of a target hole formed in a work, the chamfering tool including a support shaft, a base shaft having the support shaft on a tip end side thereof and being eccentric with respect to the support shaft, and a blade portion having a rake face that is a step surface of a step protrusion portion protruded laterally from the support shaft or that is an end surface of the support shaft. The blade portion including an edge line in a shape of a curve and being bulged to a side away from a center axis of the support shaft, and the edge line being inclined with respect to an axial direction of the support shaft.

A chamfering tool that chamfers an opening edge of a target hole formed in a work, the chamfering tool including a support shaft, a base shaft having the support shaft on a tip end side thereof and being eccentric with respect to the support shaft, and a blade portion having a rake face that is a step surface of a step protrusion portion protruded laterally from the support shaft or that is an end surface of the support shaft. The blade portion including an edge line in a shape of a curve and being bulged to a side away from a center axis of the support shaft, and the edge line being inclined with respect to an axial direction of the support shaft.

A fly-cut apparatus to process a work with bumps on a front surface. A fly-cut apparatus cuts an upper surface of a BG film laminated to a work including a bump region with bumps formed on a front surface and an outer peripheral region around the bump region. The fly-cut apparatus includes a fly-cut tool, a tool spindle with a lower end to which the fly-cut tool is attached, and capable of ascending and descending in a state of rotating the fly-cut tool, and a chuck which rotatably retains the work, and the fly-cut tool cuts the upper surface of the BG film from a center toward an outer perimeter.

A fly-cut apparatus to process a work with bumps on a front surface. A fly-cut apparatus cuts an upper surface of a BG film laminated to a work including a bump region with bumps formed on a front surface and an outer peripheral region around the bump region. The fly-cut apparatus includes a fly-cut tool, a tool spindle with a lower end to which the fly-cut tool is attached, and capable of ascending and descending in a state of rotating the fly-cut tool, and a chuck which rotatably retains the work, and the fly-cut tool cuts the upper surface of the BG film from a center toward an outer perimeter.