Coating thickness effects on diamond coated cutting tools

• Published in: Surface & coatings technology Vol. 204; no. 6; pp. 1056 - 1060
• Main Authors: Qin, F., Chou, Y.K., Nolen, D., Thompson, R.G.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 25-12-2009; Elsevier
• Subjects: Applied sciences; Coating thickness; Contact of materials. Friction. Wear; Cross-disciplinary physics: materials science; rheology; Diamond coating; Exact sciences and technology; Finite element; Machining; Materials science; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metals. Metallurgy; Nonmetallic coatings; Physics; Production techniques; Surface treatment; Surface treatments; Tool wear; Coating thickness; Diamond coating; Machining; Tool wear; Finite element; Cutting tools; Diamond tool; Diamonds; Mechanical properties; Surface treatments; Non metal coating; Layer thickness; Finite element method; Wear; Modelling; Tribology
• ISSN: 0257-8972; 1879-3347
• DOI: 10.1016/j.surfcoat.2009.06.011

Chemical vapor deposition (CVD)-grown diamond films have found applications as a hard coating for cutting tools. Even though the use of conventional diamond coatings seems to be accepted in the cutting tool industry, selections of proper coating thickness for different machining operations have not been often studied. Coating thickness affects the characteristics of diamond coated cutting tools in different perspectives that may mutually impact the tool performance in machining in a complex way.
In this study, coating thickness effects on the deposition residual stresses, particularly around a cutting edge, and on coating failure modes were numerically investigated. On the other hand, coating thickness effects on tool surface smoothness and cutting edge radii were experimentally investigated. In addition, machining Al matrix composites using diamond coated tools with varied coating thicknesses was conducted to evaluate the effects on cutting forces, part surface finish and tool wear.
The results are summarized as follows. (1) Increasing coating thickness will increase the residual stresses at the coating–substrate interface. (2) On the other hand, increasing coating thickness will generally increase the resistance of coating cracking and delamination. (3) Thicker coatings will result in larger edge radii; however, the extent of the effect on cutting forces also depends upon the machining condition. (4) For the thickness range tested, the life of diamond coated tools increases with the coating thickness because of delay of delaminations.