Wear properties of coated ceramic tools in high speed machining of gray cast iron

Abstract

The toughness of ceramic cutting tools made of silicon nitride (Si 3 N 4 ) is improving in recent years. The nose of tool, however, wears out when cutting is performed at high speed condition, and consequently the life of the tool comes to an end. In order to reduce nose wear, the effects of coating with hard materials on the resistance of the Si 3 N 4 ceramic tool to wear were investigated. Coating the Si 3 N 4 tool with TiN+TiC+Al (ON) using the chemical vapor deposition (CVD) method proved effective for reducing nose wear as compared to when it was not coated and coated with Al 2 O 3 . The nose wear of the TiN+TiC+Al (ON) -coated Si 3 N 4 tool was reduced most effectively when applied with 6-layer coating. The nose wear in the coated Si 3 N 4 tool was found to be determined by the coating in the tool land and wear end of tool. Based on the obtained knowledge described above, a novel coating method was developed in which 3-layer coating was applied to the land part of the tool, and 6-layer coating to the other part.