Analysis of the surface roughness and cutting tool wear using a vapor compression assisted cooling system to cool the cutting fluid in turning operation

摘要

One of the major challenges in machining is controlling the temperature in the cutting region. Cutting fluids can be used to prolong tool life because of their cooling and lubricating abilities. The properties of the cutting fluid and the manner in which it is applied will vary to prevent problems caused by thermal distortions within the parts. Temperature control during machining makes it possible to meet the tolerances for shape, size, and finish required in the parts' specifications. Among the various cooling methods used in machining, the most notable are nanofluids, cryogenic systems, and refrigerated compressed air. This study presents a vapor compression refrigeration system to cool the cutting fluid in the liquid state. This method is advantageous due to its reduced cost and ease-of-application when compared to cryogenic systems. In addition, the liquid has a higher convective coefficient than compressed air, making the thermal exchange more efficient. In this study, the vapor compression refrigeration system is used to stabilize the temperature of the cutting fluid during machining of SAE 1045 steel with a CNC lathe. Ten test bodies were machined during the study, five using the fluid temperature control system and five without. The machining parameters used in the experiment were: cutting speed =180 m/min, feed rate = 0.2 mm/rotation and depth = 1 mm. The results were evaluated by analyzing temperature evolution, surface finish through medium roughness R-a, and tool wear by means of scanning electron microscopy. Among the principal conclusions reached, it was verified that refrigerated cutting fluid presented better performance with regard to surface finish and tool wear, showing that the proposed method is an excellent alternative to cryogenic systems and those that use refrigerated compressed air.