Cooling and anti-friction effects of vortex tube cryogenic minimum quantity lubrication in milling of 3D printed iron-nickel alloy

3D printed iron-nickel alloy is a promising engineering material with superior properties, which is widely applied in aerospace, nuclear and petrochemical industries. However, it is rather a difficult-to-cut material due to the insufficient cooling and lubrication, and the cost of tool usage is extremely high even with TiAlN coated or TiCN coated tools. Although some scholars have attempted to conduct the eco-friendly VT-cMQL (Vortex Tubecryogenic Minimum Quantity Lubrication) system for machining iron-nickel alloy, this outdated VT-cMQL in Parallel mode still has huge shortcomings in terms of lubrication and anti-friction effects, energy consumption, and minimum hardware requirements. To solve this problem, this work proposed a new series VT-cMQL system in forms of Tandem I and Tandem II. The results show that the structure of new VT-cMQL system in Tandem I mode is simple, that only requires 1 air filter, 1 air compressor, 2 sections of pipe, and no T-joint is needed. The lowest cold flow temperature is -4.7 degrees C when the spray pressure, spraying distance, pipe length, and oil supply are 1.5 bar, 10 mm, 30 cm, and 45 ml/h, respectively. The cooling and anti-friction effect of VT-cMQL has little impact on milling tool's adhesion or oxidation, the main contribution is to further reduce abrasive wear. From the perspective of iron-nickel alloy industrial production, the new proposed VT-cMQL system can significantly reduce hardware configuration and improve the utilization of cryogenic compressed air.