Comparison of machining Inconel 718 with conventional and sustainable coolant

The use of super-alloys, most of them Ni- or Ti-based, has significantly increased during the last decade. 

Industries such as the aerospace, energy or transport, use these kinds of materials due to their excellent properties that combine hardness, high temperature strength and thermal shock and corrosion resistance. These desirable material properties make these alloys extremely difficult to machine, since high values of temperature and shear forces are easily achieved and a quick cutting tool wear turns out to be an important process constraint.

Thus, with the objective to overcome this phenomenon, several methods can be used; the most common one is to add large amounts of water-based or oil-based cutting fluids directly into the cutting zone. However, nowadays other less conventional fluids are also being studied with the aim of achieving a more ecological and efficient process in the machining of these difficult-to-cut materials. Examples of this are vortex cold air or cryogenic cooling, among others.

In this study a comparison between different cooling methods in turning of Inconel 718 is presented, which is the most commonly used nickel based alloy in the industry. Tool life and workpiece surface finish has been analyzed in each case, searching the pros and cons of each cooling technique. The results reveal the possibility of replacing traditional pollutant cooling fluids by other more ecologically friendly alternatives.