A grinding wheel is mounted at a distal end of a spindle and grinds a wafer held on a holding table. The grinding wheel includes: an annular base having a mounting surface to be mounted on the distal end of the spindle; and a plurality of segment grindstones that are fixedly attached annularly to a surface opposite to the mounting surface of the annular base and that are equidistantly spaced apart from each other. The annular base has a plurality of slits formed therein. Each of the slits represents a gap that is formed between two adjacent segment grindstones and that is extended toward a side of the annular base such that the slit has a width of the gap.

Abrasive preforms include a frame having first and second opposed parallel major surfaces. The first major surface has a plurality of first cavities formed therein. The second major surface optionally has a plurality of second cavities formed therein. The frame comprises a binder precursor material. Abrasive particles are disposed in at least a portion of the plurality of first cavities and optional plurality of second cavities. Methods of making abrasive articles using the abrasive preforms and bonded abrasive articles preparable thereby are also disclosed.

Abrasive preforms include a frame having first and second opposed parallel major surfaces. The first major surface has a plurality of first cavities formed therein. The second major surface optionally has a plurality of second cavities formed therein. The frame comprises a binder precursor material. Abrasive particles are disposed in at least a portion of the plurality of first cavities and optional plurality of second cavities. Methods of making abrasive articles using the abrasive preforms and bonded abrasive articles preparable thereby are also disclosed.

A floor polishing or grinding pad assembly is provided. In one aspect, a polishing or grinding pad assembly employs a fibrous pad, a reinforcement layer or ring, and multiple floor-contacting disks. In another aspect, the reinforcement layer includes a central hole through which the fibrous pad is accessible and the fibrous pad at the hole has a linear dimension (x) greater than a linear dimension (y) of one side of the adjacent reinforcement layer. In yet another aspect, at least one of the floor-contacting disks has an angle () offset from that of a base surface of the disk, the fibrous pad and/or the reinforcement layer. A further aspect employs a smaller set of disks alternating between and/or offset from a larger set of the disks. In another aspect, the reinforcement layer includes a wavy or undulating internal edge shape.

A grouting pan assembly includes a reinforcement ring. In another aspect, a grouting pan includes a substantially planar bottom surface and a curved sidewall surrounding the bottom surface. In a further embodiment, a grouting pan assembly includes a grouting pan having a post or mechanical fastener extending from a backside thereof for attachment to a reinforcing ring or layer.

An adapter clip to be used to mate an abrasive support plate to the drive plate of a floor finishing machine used to grind and/or polish concrete and stone flooring is designed with an internal aperture shaped to conform to and clip onto a protuberance on an upper surface of an abrasive support plate and an external shape to mate with a mounting recess formed on the machine's drive plate.

A method produces wafers from a cylindrical ingot of semiconductor material having an axis and an indexing notch in an outer surface of the cylindrical ingot and parallel to the axis. The method includes, in the order specified: (a) simultaneous removal of a multiplicity of sliced wafers from the cylindrical ingot by multi-wire slicing in the presence of a cutting agent; (b) etching of the sliced wafers with an alkaline etchant in an etching bath at a temperature of 20? C. to 50? C. and for a residence time, such that the material removed from each of the sliced wafers is less than 5/1000 of an initial wafer thickness; and (c) grinding of the etched wafers by simultaneous double-disk grinding using an annular abrasive covering.

A method produces wafers from a cylindrical ingot of semiconductor material having an axis and an indexing notch in an outer surface of the cylindrical ingot and parallel to the axis. The method includes, in the order specified: (a) simultaneous removal of a multiplicity of sliced wafers from the cylindrical ingot by multi-wire slicing in the presence of a cutting agent; (b) etching of the sliced wafers with an alkaline etchant in an etching bath at a temperature of 20? C. to 50? C. and for a residence time, such that the material removed from each of the sliced wafers is less than 5/1000 of an initial wafer thickness; and (c) grinding of the etched wafers by simultaneous double-disk grinding using an annular abrasive covering.

A tool for a floor machine. The tool includes a base having a plurality of slots, and a cleaning element provided in each of the slots. The cleaning elements are oriented along a secant or chord of the base. The cleaning elements have abrasive portions with abrasive grit thereon, and may be non-planar at least at a portion of the abrasive portion.

A grinding wheel includes a plurality of grinding stone groups arranged in an annular array, each of the grinding stone groups including at least three grinding stone segments having different thicknesses which include a smallest thickness, an intermediate thickness, and a largest thickness. The grinding stone segments in each of the grinding stone groups are successively arranged in the order of the grinding stone segment having the smallest thickness, the grinding stone segment having the intermediate thickness, and the grinding stone segment having the largest thickness, with uniform gaps left therebetween. The grinding stone segments in the grinding stone groups have respective radially inner edges aligned with each other in an annular shape.