Tribological characteristics and cutting performance of Crx%C-coated carbide tools

In this study, the tribological characteristics and cutting performance of chromium carbide (Crx%C)-coated cemented carbide tool inserts and micron-drills were investigated in dry machining condition. Crx%C coatings have been deposited with different optical emission monitoring (OEM) set values, x%, of chromium target “poisoning” by unbalanced magnetron (UBM) sputtering and OEM control. The microstructures and mechanical properties of Crx%C coatings have been characterized by the experiments of SEM, nanoindentation and adhesion. The tribological properties of the coatings have been tested against different counterbodies under dry conditions using an oscillating friction and wear tester. Indexable inserts with Crx%C coatings were applied to turning AISI 1045 steel and JIS C5191 phosphor bronze material by a lathe. Micron-drills with Crx%C coatings were adopted in ultrahigh spindle speed (105 rpm) PCB through-hole drilling test. Experimental results indicate that the coating microstructures, mechanical properties and wear resistance vary according to the chromium content. Cr10%C-coated inserts showed the best wear resistance in AISI 1045 steel turning test. Cr50%C-coated tools have performed exceptionally well in both phosphor bronze turning and PCB through-hole drilling tests. The service life of Cr50%C-coated tool is 15 times greater than that of an uncoated tool in PCB through-hole drilling test.