RMB/D1 ceramic grinding media is produced by mixing porcelain,
kaolin,clay, river clay together with brown alumina oxide abrasives. The
wet material is formed into desired shape (usually by extrusion and
cutting) and then fired to vitrify. Fusion bonding is used to make some
media. Such media are available in a wide range of shapes and sizes.
Also, when the engineer selects the proper grade of abrasive, the
correct proportion of abrasive to binder, and the most suitable binder,
this media will adapt to a great variety of application, and
workpieces. 

The binder acts as a burnishing surface, and this works against rapid cutting.