... alumina, and diamond grinding dust. The hot melts from the above are extruded to form abrasive filaments ... alumina, and diamond grinding dust. The hot melts from the above are extruded to form abrasive ... alumina, and diamond grinding dust. The hot melts from the above are extruded to form abrasive ... alumina, and diamond grinding dust. The hot melts from the above are extruded to form abrasive ...