Effect of friction properties of TiN and CrN coated tool edges on cutting ability of austenitic spheroidal graphite cast Iron containing 35% Nickel

Abstract

The purpose of this paper is to examine which coating material on tool edges is best for cutting spheroidal graphite cast iron containing 35% Nickel (Ni) and to understand the relation between friction properties of the coatings and cutting ability. Heat-resistant alloy materials, such as Ni-based alloy steels and Ni-based alloy cast irons containing a large amount of Ni, are known as difficult-to-cut materials due to high high-temperature strength, low thermal conductivity, and work hardening. In this study, austenitic spheroidal graphite cast iron containing 35% Nickel (FCDA-Ni35) was used as a work material, and shaper machining tests were performed for evaluating cutting abilities of TiN and CrN-coated tools. Furthermore, the friction properties of each coating were compared and evaluated by a ball-on-plate test. It was found that the ploughing force component of the CrN-coat was smaller, and the chip thickness was thinner than that of the TiN-coat, so the cutting ability was good. As a result, the CrN-coated tool has smaller cutting resistance and ploughing force component than the TiN-coated tool, and the friction coefficient of the rake face is smaller. Furthermore, the CrN-coated tool has stable chip formation, thin chip thickness, and good cutting ability on cutting for FCDA-Ni35.

Keywords

• titanium nitride
• chromium nitride
• austenite spheroidal graphite cast iron
• shaper cutting
• tribology