Abstract: The present invention relates to a cutting tool insert of a generally polygonal shape provided with a ceramic tip in a recess in at least one of its corners with a bottom surface and at least one side surface. At least the bottom surface of the recess is provided with rails with a height h being from about 50 to about 100 ?m, width w being from about 100 to about 200 ?m and spaced at distance 1 from about 0.75 to about 1.25 mm. The invention also relates to a method of making such an insert using a grinding wheel of a suitable profile before or after sintering or in the pressing operation.

Abstract: A method of making a whisker-reinforced ceramic body by hot pressing a preform to a disc, cutting the disc into blanks and grinding the blanks to bodies of desired shape and dimension is disclosed. The preform is prepared by dispersing 10-60% by volume of a ceramic powder mixture containing conventional sintering aids and/or grain growth inhibitors in water or an organic solvent adding 1-15 wt-% starch to the dispersion; pouring the dispersion into a mold with desired shape; heating the suspension to 50°-100° C. for 2-4 hours while covering the mold to avoid water evaporation to form a preform; removing the preform from the mold; and presintering the preform in air for 10 h at a maximum temperature of about 600° C.