A method for machining ribs or grooves on a workpiece such as a shaft or an air or gas axial bearing intended to be rotated about a longitudinal axis of a centrifugal compressor. All of the ribs or grooves are obtained at once by the machining tool on a workpiece portion driven such that it rotates, by moving the workpiece or the tool holder in a longitudinal machining direction, the machining tool moving back and forth with a machining position in contact with the workpiece and a position wherein it is not in contact with the workpiece from the start to the end of the workpiece portion. The back-and-forth movements of the machining tool are synchronised with the sinusoidal program set up in the machining unit, as well as with the desired, programmed arrangement of the ribs or grooves to be produced on the workpiece portion.

A work holder includes: a first holding part having three attracting members that are arranged circumferentially apart from each other to attract an axial end face of an annular work; and a second holding part having a contacting member that is held in contact with an inner periphery or outer periphery of the work and restricts radial movement of the work.

A plain bearing sleeve includes an inner diameter, a sleeve length greater than the inner diameter, an outer diameter, and a wall thickness smaller than 8% of the inner diameter. A sleeve blank includes a longitudinal axis, an outer surface, an inner surface, a first end face, a second end face opposite the first end face, and at least three threaded holes arranged on the first end face. A method for producing the plain bearing sleeve includes clamping the outer surface at the first end face for rotation, machining the inner surface to the inner diameter, fixing the first end face at the at least three threaded holes for rotation, machining the outer surface to the outer diameter, clamping the inner surface at the second end face for rotation, and cutting a ring with the first end face and the at least three threaded holes from the sleeve blank.

A method for machining ribs or grooves on a shaft (7) with an axial bearing (24) forming part of the shaft. The ribs or grooves (32, 24a) are obtained on a workpiece portion of the shaft and of the axial bearing, by moving the shaft or at least one tool holder fitted with a machining tool in a longitudinal direction of machining, by the tool performing reciprocating motions with a position in contact and with a position not in contact with the shaft or the axial bearing from the beginning to the end of the workpiece portion or face. The reciprocating motions are synchronised with the sinusoidal programming carried out in the machining unit, along with the desired and programmed arrangement of the ribs or grooves to be produced.

A method for machining ribs or grooves on a workpiece including a shaft (7) and an air or gas axial bearing (24) attached to the shaft or forming a part of the shaft. The workpiece is rotated about a longitudinal axis of a centrifugal compressor. All of the ribs or grooves are obtained at once by the machining tool on a workpiece portion driven such that it rotates, by moving the workpiece or the tool holder in a longitudinal direction, the machining tool moving back and forth with a machining position in contact with the workpiece and a position wherein it is not in contact with the workpiece from the beginning to the end of the workpiece portion. Reciprocating motions of the machining tool are synchronised with the sinusoidal program, as well as with the desired, programmed arrangement of the ribs or grooves to be produced on the workpiece portion.

A work holder includes: a first holding part having three attracting members that are arranged circumferentially apart from each other to attract an axial end face of an annular work; and a second holding part having a contacting member that is held in contact with an inner periphery or outer periphery of the work and restricts radial movement of the work.

A plain bearing sleeve includes an inner diameter, a sleeve length greater than the inner diameter, an outer diameter, and a wall thickness smaller than 8% of the inner diameter. A sleeve blank includes a longitudinal axis, an outer surface, an inner surface, a first end face, a second end face opposite the first end face, and at least three threaded holes arranged on the first end face. A method for producing the plain bearing sleeve includes clamping the outer surface at the first end face for rotation, machining the inner surface to the inner diameter, fixing the first end face at the at least three threaded holes for rotation, machining the outer surface to the outer diameter, clamping the inner surface at the second end face for rotation, and cutting a ring with the first end face and the at least three threaded holes from the sleeve blank.

Embodiments of the present disclosure are directed to a roller-skate bearing seat truing tool comprising a plurality of spaced teeth, a first handle, and a second handle. The plurality of spaced teeth may be operable to true up a cylindrical surface of a roller-skate bearing seat and a vertical surface of the roller-skate bearing seat. The first handle may comprise a protrusion longitudinally extending from one end. The second handle may comprise a receptacle at one end configured to slidably receive the protrusion. The plurality of spaced teeth may be disposed about an upper rim of the receptacle, on an upper rim of the first handle, about the protrusion, or both.