Evaluation of the convective heat transfer coefficient for minimum quantity lubrication (MQL)

Abstract

Purpose -The purpose of this paper is to evaluate the cooling ability of minimum quantity lubrication (MQL) cutting fluid. Design/methodology/approach -An experimental system is devised to find the heat transfer coefficient of MQL under simulated reaming conditions. Cooling rate of the specimen is measured with an infrared camera. The effect of air pressure and oil volume on cooling rate is tested. Metal cutting tests are performed to evaluate the effect of heat transfer coefficient on workpiece temperature. Findings -Convective heat transfer coefficient for MQL increases with increasing air pressure. Oil volume has an indeterminate effect on the heat transfer coefficient; however, it is a dominant factor for controlling temperature during reaming. Practical implications -The results of the study can provide guidance to optimize the temperature controlling ability of MQL for production. Originality/value -There is limited information available in literature regarding the heat transfer coefficient of metal working fluids, particularly for MQL. In particular, experiments designed to investigate the effect of air pressure and oil volume on the heat transfer coefficient of the mist have not been previously documented. This information may be used to improve the overall cooling ability of MQL mist, thus increasing its effectiveness at controlling tool wear and maintaining part quality. The other major contribution of this work is to separate the role of the cooling and lubrication for controlling temperature while reaming aluminum. Prior to this study, there has been relatively little research performed for the reaming metal cutting operation, and still less for reaming with MQL. The nature of how metal working fluids control temperature is not fully understood, and this work provides insight as to whether cooling or lubrication plays the dominant role for reaming.

Turning operation of AISI 4340 steel in flooded, near-dry and dry conditions: a comparative study on tool-work interface temperature

“…The amount of friction generated between tool and workpiece has an influence on the quality of machined components [8]. The aforementioned issue could be overcome by applying cutting fluids on tool-work interface [5,9]. The usage of cutting fluids are primarily: (i) to reduce the heat generated in the tool-work interface [6,10], (ii) to reduce the friction between the tool and work due to machining operation [11] and (iii) to wash away the metal chips removed during the machining operation [12].…”

Experimental Investigation on Laser Assisted Diamond Turning of Binderless Tungsten Carbide by In-Process Heating

“…There are many boundary conditions during the laser heating process, which can be divided into the laser heating effect, thermal radiation [ 19 ], and cutting fluid convection [ 20 ]. For the Gauss laser spot on the z = 0 plane, the heat flux of spiral trajectory moving laser spot can be described as where P (W) refers to the laser power, r (μm) is the laser spot radius, δ is the laser absorptivity, and the laser scanning path can be determined by the initial position ( x 0 ,0), feed rate f (μm/rev), and rotation speed n (rev/min).…”

A note on the use of the minimum quantity lubrication (MQL) system in turning

“…However, there are also some disadvantages associated to the use of the cutting fluids such as their costs, environmental impact and safety (Klocke and Eisenblätter, 1997;Kurgin et al, 2012). These drawbacks encourage the research on the development of new cutting fluids such as the bio-based cutting fluids (Ozcelik et al, 2011) and new cooling/lubricating alternatives.…”