An abrasive article can include a body including a plurality of portions including a first abrasive portion and a second abrasive portion. The first abrasive portion can include a vitreous bond material and abrasive particles contained within the bond material. The second abrasive particles can include an organic bond material and abrasive particles contained within the bond material. The body can have a burst speed of at least 65 m/s. In an embodiment, the abrasive article can include an interior portion coupled to the first and second abrasive portions. In another embodiment, the interior portion can optionally include abrasive particles or a filler material.

An abrasive article can include a body including a plurality of portions including a first abrasive portion and a second abrasive portion. The first abrasive portion can include a vitreous bond material and abrasive particles contained within the bond material. The second abrasive particles can include an organic bond material and abrasive particles contained within the bond material. The body can have a burst speed of at least 65 m/s. In an embodiment, the abrasive article can include an interior portion coupled to the first and second abrasive portions. In another embodiment, the interior portion can optionally include abrasive particles or a filler material.

A bonded abrasive article includes elongate shaped abrasive particles. The elongate shaped abrasive particles comprise an elongate shaped ceramic body having opposed first and second ends joined to each other by at least two longitudinal sidewalls. At least one of the at least two longitudinal sidewalls is concave along its length. At least one of the first and second ends is a fractured surface.

A bonded abrasive article includes elongate shaped abrasive particles. The elongate shaped abrasive particles comprise an elongate shaped ceramic body having opposed first and second ends joined to each other by at least two longitudinal sidewalls. At least one of the at least two longitudinal sidewalls is concave along its length. At least one of the first and second ends is a fractured surface.

A super-abrasive grinding wheel includes a core and a super-abrasive grain layer provided on a surface of the core, the super-abrasive grain layer including diamond abrasive grains and CBN abrasive grains, the diamond abrasive grains and the CBN abrasive grains being fixed to the core in a single layer by a binder. The diamond abrasive grains and the CBN abrasive grains have projecting tips acting on a workpiece, the projecting tips having a variation in height of 10 μm or less, the diamond abrasive grains having their projecting tips with irregularities of 0.1 μm or more in height.

A super-abrasive grinding wheel includes a core and a super-abrasive grain layer provided on a surface of the core, the super-abrasive grain layer including diamond abrasive grains and CBN abrasive grains, the diamond abrasive grains and the CBN abrasive grains being fixed to the core in a single layer by a binder. The diamond abrasive grains and the CBN abrasive grains have projecting tips acting on a workpiece, the projecting tips having a variation in height of 10 μm or less, the diamond abrasive grains having their projecting tips with irregularities of 0.1 μm or more in height.

The present invention relates to an additive manufacturing system and its methods. The system includes a material conveyor, an energy source, and a micro-forging device. The material conveyor is configured to convey material. The energy source is configured to direct an energy beam toward the material, the energy beam fuses at least a portion of the material to form a solidified portion. The micro-forging device is movable along with the material conveyor for forging the solidified portion, wherein the micro-forging device comprises a first forging hammer and a second forging hammer, the first forging hammer is configured to impact the solidified portion to generate a first deformation, and the second forging hammer is configured to impact the solidified portion to generate a second deformation greater than the first deformation.

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.

A machining apparatus machines an end face of a tapered roller with a grinding wheel. The machining apparatus includes a support mechanism configured to support the tapered roller, a wheel unit on which the grinding wheel is mounted, and a base configured to support the wheel unit so that the wheel unit is swivelable about a center line in a vertical direction. A machining point where the grinding wheel is brought into contact with the end face of the tapered roller supported by the support mechanism is located on an extension of the center line serving as a swivel center of the wheel unit.