Experimental Evaluation on the Effect of Nanofluids Physical Properties With Different Concentrations on Grinding Temperature

This chapter is proposed to solve the insufficient MQL cooling and heat transfer capability based on the heat transfer enhancement theory of solid. Adding nanoparticles into the base fluid can significantly elevate heat conductivity coefficient of the base fluid and enhance convective heat transfer capability of the grinding area. Researchers have carried out numerous experimental studies on nanofluids with different concentrations. However, the scientific nature of MQL cooling has not been explained. Degradable, nontoxic, low-carbon, and environmentally friendly green grinding fluid, palm oil taken as the base fluid, grinding force, grinding temperature and proportionality coefficient of energy transferred to workpiece of nanofluids with different volume fractions, are investigated in this chapter. Based on the analysis of the influence of physical characteristics of nanofluids on experimental results, cooling and heat transfer mechanism of NMQL grinding is studied. The experimental study can provide a certain technical guidance for industrial machining.

Finite Element Analysis of Grinding Temperature Field for NMQL in Nickel-Base Alloy Grinding

Temperature is not only an important parameter in machining, but also an important basis for process optimization. Accurate prediction and reasonable analysis of grinding temperature is of great and far-reaching significance to the development and promotion of nanofluid micro-lubrication. In this chapter, the mathematical model of finite element simulation of temperature field of high efficiency deep grinding under four kinds of cooling lubrication conditions is established, and the three boundary conditions and the constraints of simulation model are established, and the mesh division and time step algorithm are determined respectively. Using ABAQUS simulation platform and theoretical model to simulate grinding temperature field, the distribution characteristics of grinding temperature field under different working conditions are analyzed from different directions, different grinding depths, and different workpiece materials.

Enhanced Heat Transfer Mechanism of Nanofluids Minimum Lubrication Grinding

This chapter will discuss in detail the various aspects of nanofluids, form preparation of nanofluids, characterization and flow and energy transportation mechanisms of nanofluids. Preparation of nanofluids has been performed using various methods where one step and two step methods are widely known. These methods are discussed in detail for various nanoparticles with stabilizing agents for stable production of nanofluids. Further, the characterization techniques of various aspects of nanofluds including thermal conductivity and factors influencing the thermal conductivity of nanofluids are introduced in depth. The chapter also sheds light on the experimental analysis of flow and heat transfer of naofluids, natural convection analysis of naofluids, and boiling heat transfer of nanofluids.

Experimental Evaluation on Tribological Performance of the Wheel/Workpiece Interface in NMQL Grinding With Different Concentrations of Al2o3 Nanofluids

As a result of the growing need for environmental protection and the increasing number of health problems faced by workers, traditional lubricants are gradually being replaced. Nanofluids, which contain nanoparticles in the proper base fluid, can serve as a low carbon, “green” lubricant. Nanofluids show improved heat transfer capability and lubricating properties. Therefore, increasing lubricating effects is an effective way to improve machining performance. The tribological properties of grinding wheel/workpiece interface with different concentration of Al2O3 nanofluid micro-lubrication grinding were studied. The influences of the force ratio, viscosity and contact angle of Al2O3 nanofluids with different concentrations on the grinding force and the surface quality of workpieces are discussed. The best concentration of Al2O3 nanofluid with good lubrication performance in grinding zone was obtained.

Experimental Study of Lubricating Property at Grinding Wheel/Workpiece Interface Under NMQL Grinding

Nanofluid is the suspension formed by lubricating oil and nanoparticles with particles sizes of 1~100 nm, and common nanoparticles include metal nanoparticles (Cu, Ag, etc.), oxide nanoparticles (Al2O3, SiO2, ZrO2, etc.), carbides (CNT, diamond), and MoS2 nanoparticles, etc. Different nanoparticles exhibit various physicochemical properties (e.g., structure and shape), which can influence their tribological characteristics. In this work, six nanofluids, namely, MoS2, SiO2, diamond, carbon nanotubes (CNTs), Al2O3, and ZrO2, were used as minimum quantity lubrication grinding fluids to select the kind of nanoparticles with optimum lubrication performance in grinding nickel alloy GH4169. Experimental results concluded the following: 1) Nanoparticles with spherical or sphere-like molecular structure and nanofluids with high viscosity demonstrate superior lubrication performances. 2) The polishing effect of nanodiamond particles enhances their surface morphology. 3) The lubricating property of the six nanofluids is described in the following order: ZrO2 < CNTs < ND < MoS2 < SiO2 < Al2O3.

Experimental Evaluation of the Lubrication Properties of the Wheel/Workpiece Interface in MQL Grinding Using Vegetable Oils

Given the increasing attention to environmental and health problems caused by machining, the development of an environmentally friendly grinding fluid has become an urgent task. In this study, seven typical vegetable oils (i.e., soybean, peanut, maize, rapeseed, palm, castor, and sunflower oil) were used as the minimum quantity lubrication (MQL) base oil to conduct an experimental evaluation of the friction properties of the grinding wheel/workpiece interface. With nickel-based alloy GH4169 as workpiece material, the flood grinding and MQL grinding were selected. Experimental results indicated that castor oil MQL grinding had a friction coefficient and specific grinding energy of 0.30 and 73.47 J/mm3, which decreased by 50.1% and 49.4%, respectively, compared with flood grinding. Moreover, maize oil had the highest G-ratio of 29.15. Peanut, sunflower, and soybean oil with more saturated fatty acids, castor oil with more castor acids, and palm oil with numerous palmitic acids were suitable as lubricating fluids.

Experimental Research on Grinding Temperature With Different Workpiece Materials

The results show that the nanofluids with a volume fraction of 2% have good comprehensive properties for lubrication. However, this study only concentrates on workpiece material—nickel base alloy. Based on literature analysis, researchers have carried out a large quantity of researches on NMQL grinding of different workpiece materials including hard steel HSS, quenched steel 100Cr6, nickel base alloy, Ti-6Al-4V alloy, soft steel CK45, and cast iron. They have mainly focused on grinding force, surface roughness, etc. The heat transfer state of nanofluids is neglected, and the research on the heat transfer mechanism of grinding temperature is lacking. Therefore, grinding temperatures obtained through MQL grinding with different concentrations of vegetable oils-based nanofluids as well as their heat transfer mechanism are investigated through simulation and experiment in this chapter.

Introduction

This chapter introduces the application background and characteristics of five kinds of grinding processing methods, briefly describes the enhanced heat transfer mechanism and tribological properties of nanofluids, and points out that nanofluids minimum quantity lubrication (NMQL) solves the technical bottleneck, namely minimum quantity lubrication (MQL) heat transfer capacity is insufficient and opening a new path for application of MQL to grinding process. The current status of exploratory research on the mechanism of minimum quantity lubrication grinding using nanofluids as cooling lubricants is analyzed. The research characteristics of the new green NMQL grinding technology are described, and the chapter puts forward some key problems such as the heat transfer enhancement process of NMQL, the anti-friction and anti-wear tribological mechanism of nanoparticles, and the controlled transport strategies of minimal quantity of lubricating droplets. It will be of great scientific significance and pragmatic value to perfecting NMQL grinding technical system.

Modeling and Simulation of the Surface Topography Generation With Ordinary Grinding Wheel

In order to simulate the surface grinding process of the common grinding wheel and evaluate the surface topography of the workpiece, the mathematical model of the common grinding wheel is established by using the abrasive vibration method to realize the parameterization of the simulated grinding wheel. The grinding wheel body with random arrangement of abrasive grains is generated, and the simulation of common grinding wheel morphology is completed. Then, according to the grinding kinematics model, elastic deformation model and plastic accumulation model, the simulation of the process is realized, and the workpiece surface morphology matrix is generated. Finally, the influence of grinding parameters and grinding wheel parameters on the workpiece surface morphology and surface roughness is studied by calculating the surface roughness value.

Experimental Research on Heat Transfer Performance in MQL Grinding With Different Nanofluids

An investigation into the effect of nanofluid minimum quantity lubrication (MQL) on the temperatures in surface grinding is presented and discussed. Six types of nanoparticles, namely molybdenum disulfide (MoS2), zirconium dioxide (ZrO2), carbon nanotube (CNT), polycrystalline diamond, aluminum oxide (Al2O3), and silica dioxide (SiO2), are considered to mix individually with a pollution-free palm oil in preparing the nanofluids. A commonly used Ni-based alloy was chosen as the workpiece material. It is shown that CNT nanofluid results in the lowest grinding temperature of 110.7°C and the associated energy proportionality coefficient of 40.1%. The relevant physical properties of the nanofluids such as the coefficient of thermal conductivity, viscosity, surface tension, and the contact state between the droplets and workpiece surface (contact angle) were discussed to shine a light on their effect on the cooling performance. A mathematical model for convective heat transfer coefficient was then developed based on the boundary layer theories.