A method of electro-dynamically matching a bearing assembly includes electrically separating inner and outer races from rolling elements of the bearing assembly with lubricant and rotating the inner race relative to the outer race. A voltage differential is applied across the inner and the outer races and via isolated rolling elements and the race eroded an electrical discharge event across a gap defined between the one or more of the races and rolling elements. Electro-dynamically matched bearing assemblies and reaction/momentum flywheel arrangements for artificial satellites are also described.

A method of electrodynamically finishing a plain bearing includes electrically separating a bearing housing from a journal shaft with a lubricant disposed on a bearing surface of the bearing housing. The bearing housing or the bearing housing is rotated relative to the other and a voltage differential applied across the bearing housing and the journal shaft. One or more asperities disposed on the bearing surface are eroded with electric discharge events between the journal shaft and the bearing housing. Electrodynamically finished bearing assemblies and reaction/momentum wheel arrangements having such bearing assemblies are also described.

A method for machining a part includes wire electro-discharge machining the part, and then selectively reducing a zinc content of the residual recast layer left on a surface of the part, while otherwise leaving the recast layer substantially intact.

A method for machining a part includes wire electro-discharge machining the part, and then selectively reducing a zinc content of the residual recast layer left on a surface of the part, while otherwise leaving the recast layer substantially intact.

A wire electrode is hung from an upper die guide of a wire electric discharge machine toward a workpiece, a distance from a position where the wire electrode on the top surface of the workpiece is hung down to a top end position of a machined groove formed by the electric discharge machining is calculated based on a commanded taper angle and the distance from the top surface of the workpiece to an upper die guide fulcrum position of the upper die guide, and automatic wire connection is performed by moving an upper nozzle by the calculated distance. In this way, a wire connecting operation can be performed in the vicinity of the tapered groove.

A wire electrode is hung from an upper die guide of a wire electric discharge machine toward a workpiece, a distance from a position where the wire electrode on the top surface of the workpiece is hung down to a top end position of a machined groove formed by the electric discharge machining is calculated based on a commanded taper angle and the distance from the top surface of the workpiece to an upper die guide fulcrum position of the upper die guide, and automatic wire connection is performed by moving an upper nozzle by the calculated distance. In this way, a wire connecting operation can be performed in the vicinity of the tapered groove.

A wire electric discharge machine has a function of estimating the time for replacement of a filter based on a use situation for the machine. A time Tr during which the filter is serviceable is calculated according to an equation, Tr=|(PdPn)/P|, based on a fluid pressure variation amount P, a current filter fluid pressure Pn, and a filter life pressure. A remaining available time Td for the filter which takes into account the operation rate of the machine is calculated according to an equation, Td=Tr/W.

A wire electric discharge machine has a function of estimating the time for replacement of a filter based on a use situation for the machine. A time Tr during which the filter is serviceable is calculated according to an equation, Tr=|(PdPn)/P|, based on a fluid pressure variation amount P, a current filter fluid pressure Pn, and a filter life pressure. A remaining available time Td for the filter which takes into account the operation rate of the machine is calculated according to an equation, Td=Tr/W.

A machining liquid is supplied to a predetermined level when a workpiece is on a table. A volume of the workpiece is obtained from a difference between the machining liquid amount at the predetermined level when a previous workpiece is not on the table, and the machining liquid amount when the workpiece is on the table. A weight of the workpiece is obtained from the obtained volume and a previously stored density of the workpiece. A weight of a mounting jig is obtained in the same procedure. A total volume of the jig and workpiece is obtained when the jig is on the table and the workpiece is fixed to the jig. The volume of the workpiece is obtained by a difference with respect to the volume of the jig. The weight of the workpiece fixed to the jig is obtained from the obtained volume and the previously stored density.

A machining liquid is supplied to a predetermined level when a workpiece is on a table. A volume of the workpiece is obtained from a difference between the machining liquid amount at the predetermined level when a previous workpiece is not on the table, and the machining liquid amount when the workpiece is on the table. A weight of the workpiece is obtained from the obtained volume and a previously stored density of the workpiece. A weight of a mounting jig is obtained in the same procedure. A total volume of the jig and workpiece is obtained when the jig is on the table and the workpiece is fixed to the jig. The volume of the workpiece is obtained by a difference with respect to the volume of the jig. The weight of the workpiece fixed to the jig is obtained from the obtained volume and the previously stored density.