An abrasive disk has one or more layers in which abrasive grains are embedded. Embedded in one layer is a sensor for detecting an original periphery of the abrasive disk that has been altered by wear. The sensor has at least one closed conductor loop which is arranged at a radial distance from the original periphery such that, when the original periphery is worn by more than the radial distance, the conductor loop is interrupted. A transponder emits a radio signal indicative of whether the conductor loop is closed or interrupted.

An abrasive disk has one or more layers in which abrasive grains are embedded. Embedded in one layer is a sensor for detecting an original periphery of the abrasive disk that has been altered by wear. The sensor has at least one closed conductor loop which is arranged at a radial distance from the original periphery such that, when the original periphery is worn by more than the radial distance, the conductor loop is interrupted. A transponder emits a radio signal indicative of whether the conductor loop is closed or interrupted.

A silicon carbide single crystal substrate includes a first main surface, a second main surface, and a circumferential edge portion. The second main surface is opposite to the first main surface. The circumferential edge portion connects the first main surface and the second main surface. The circumferential edge portion has a linear orientation flat portion, a first arc portion having a first radius, and a second arc portion connecting the orientation flat portion and the first arc portion and having a second radius smaller than the first radius, when viewed along a direction perpendicular to the first main surface.

A silicon carbide single crystal substrate includes a first main surface, a second main surface, and a circumferential edge portion. The second main surface is opposite to the first main surface. The circumferential edge portion connects the first main surface and the second main surface. The circumferential edge portion has a linear orientation flat portion, a first arc portion having a first radius, and a second arc portion connecting the orientation flat portion and the first arc portion and having a second radius smaller than the first radius, when viewed along a direction perpendicular to the first main surface.

A tire pre-conditioning system includes a first mandrel, a second mandrel spaced apart from the first mandrel, and a controller in communication with the first mandrel and the second mandrel. The first mandrel is fixedly attached to a first shaft and including a first tapered sidewall. The second mandrel is fixedly attached to a second shaft and including a second tapered sidewall. The controller is operable to axially move the first mandrel and the second mandrel toward one another until the first and second tapered sidewalls are opposing respective beads of a tire, and supply pressurized fluid into an internal cavity of the tire to inflate the tire. The inflating causing the beads to move relative to mandrels while contacting the opposing respective tapered sidewalls to burnish the beads of the tire.

A tire pre-conditioning system includes a first mandrel, a second mandrel spaced apart from the first mandrel, and a controller in communication with the first mandrel and the second mandrel. The first mandrel is fixedly attached to a first shaft and including a first tapered sidewall. The second mandrel is fixedly attached to a second shaft and including a second tapered sidewall. The controller is operable to axially move the first mandrel and the second mandrel toward one another until the first and second tapered sidewalls are opposing respective beads of a tire, and supply pressurized fluid into an internal cavity of the tire to inflate the tire. The inflating causing the beads to move relative to mandrels while contacting the opposing respective tapered sidewalls to burnish the beads of the tire.

An alumina sintered body including an inner layer in which alumina crystal grains contained have an average aspect ratio of 1.0 to 2.0 and an outer layer which covers at least a part of the inner layer from outside and in which alumina crystal grains contained have an average aspect ratio of more than 2.0, the alumina sintered body being free from silicon except unavoidable impurities.

An alumina sintered body including an inner layer in which alumina crystal grains contained have an average aspect ratio of 1.0 to 2.0 and an outer layer which covers at least a part of the inner layer from outside and in which alumina crystal grains contained have an average aspect ratio of more than 2.0, the alumina sintered body being free from silicon except unavoidable impurities.

To provide an alumina sintered body, abrasive grains, and a grinding wheel having high hardness and excellent wear resistance. An alumina sintered body comprising: an inner layer comprising alumina crystal grains; and an outer layer covering at least a part of the inner layer from outside, having a higher content of an alkaline earth metal than the inner layer, and comprising alumina crystal grains, wherein the content of the alkaline earth metal in the outer layer is 1.0 to 30.0 mass % in terms of oxide, the alumina sintered body being free from silicon except unavoidable impurities.

To provide an alumina sintered body, abrasive grains, and a grinding wheel having high hardness and excellent wear resistance. An alumina sintered body comprising: an inner layer comprising alumina crystal grains; and an outer layer covering at least a part of the inner layer from outside, having a higher content of an alkaline earth metal than the inner layer, and comprising alumina crystal grains, wherein the content of the alkaline earth metal in the outer layer is 1.0 to 30.0 mass % in terms of oxide, the alumina sintered body being free from silicon except unavoidable impurities.