A nanofluid minimum quantity lubrication with addition of one kind of nanoparticle has several limitations, such as grinding of difficult-to-cutting materials Hybrid nanoparticles integrate the properties of two or more kinds of nanoparticles, thus having better lubrication and heat transfer performances than single nanoparticle additives However, the use of hybrid nanoparticles in nanofluid minimum quantity lubrication grinding has not been reported This study aims to determine whether hybrid nanoparticles have better lubrication performance than pure nanoparticle A hybrid nanofluid consisting of MoS2 nanoparticles with good lubrication effect and CNTs with high heat conductivity coefficient is investigated The effects of the hybrid nanofluid on grinding force, coefficient of friction, and workpiece surface quality for Ni-based alloy grinding are analyzed Results show that the MoS2/CNT hybrid nanoparticles achieve better lubrication effect than single nanoparticles The optimal MoS2/CNT mixing ratio and nanofluid concentration are 2:1 and 6 wt%, respectively

Experimental Evaluation of the Lubrication Performance of MoS2/CNT Nanofluid for Minimal Quantity Lubrication in Ni-based Alloy Grinding

This study investigates the critical maximum undeformed equivalent chip thickness for ductile-brittle transition (DBhmax-e) of zirconia ceramics under different lubrication conditions. A DBhmax-e model is developed through geometry and kinematics analyses of ductile-mode grinding. Result shows that DBhmax-e decreases with increasing friction coefficient (μ). An experimental investigation is then conducted to validate the model and determine the effect of dry lubrication, minimum quantity lubrication (MQL), and nanoparticle jet minimum quantity lubrication (NJMQL) conditions on DBhmax-e. According to different formation mechanisms of debris, the grinding behavior of zirconia ceramics is categorized into elastic sliding friction, plastic removal, powder removal, and brittle removal. Grinding forces per unit undeformed chip thickness (Fn/h and Ft/h) are obtained. The lubrication condition affects the normal force and ultimately influences the resultant force on workpiece. In comparison with dry grinding (DBhmax-e = 0.8 μm), MQL and NJMQL grinding processes increase DBhmax-e by 0.99 and 1.79 μm respectively; this finding is similar to model result. The theoretical model is then assessed by different volume fractions of nanofluids under NJMQL condition with an average percentage error of less than 8.6%.

Maximum undeformed equivalent chip thickness for ductile-brittle transition of zirconia ceramics under different lubrication conditions

Dispersing mechanism and tribological performance of vegetable oil-based CNT nanofluids with different surfactants

Effects of Minimum Quantity Lubrication (MQL) in machining processes using conventional and nanofluid based cutting fluids: A comprehensive review

Experimental evaluation of the lubrication performance of mixtures of castor oil with other vegetable oils in MQL grinding of nickel-based alloy

Experimental evaluation of MoS2 nanoparticles in jet MQL grinding with different types of vegetable oil as base oil

Nanoparticles are solid nanoscale particles with features such as antiwear, antifriction, and high load-carrying capacity. This research applied nanoparticles in the cooling lubrication of grinding and theoretically analyzed the impact of cooling lubrication on the grinding surface through the energy ratio coefficient and specific grinding energy. First, the workpiece surface temperature was measured using a thermal infrared imager. A three-dimensional dynamometer was used to identify the tangential grinding force during grinding. Results showed that, with different cooling lubrication approaches, the grinding surface was distributed to workpiece, grinding wheel, grinding fluid, and abrasive debris according to different energy ratio coefficients. The calculation demonstrated that the energy ratio coefficient of dry grinding reached 64.3 %. However, the energy ratio coefficient of flood lubrication, minimal quantities of lubricant (MQL), and nanoparticle jet MQL was 36.8, 52.1, and 41.4 %, respectively. These findings indicated that nanoparticle jet MQL realized a cooling effect close to that of flood lubrication. The specific grinding energy of nanoparticle jet MQL was 35 J/mm3, which was close to that of flood lubrication at 29.8 J/mm3. This finding indicated that the lubrication effects of nanoparticle jet MQL were also similar to those of flood lubrication. Moreover, molybdenum disulfide, carbon nanotube (CNT), and zirconium oxide nanoparticles were added in the grinding fluid to conduct the grinding experiment with nanoparticle jet MQL. The comparison of energy ratio coefficients showed that the cooling performance of CNT nanoparticles was satisfactory. CNT nanoparticles were subsequently added into the grinding fluid at the volume concentrations of 1, 2, and 3 % for the grinding experiment. The results showed that the best cooling effects occurred under the 2 % volume concentration of CNT nanoparticles. Through rounds of selections and optimizations, our research acquired the nanoparticle types and volume concentration that had satisfactory cooling effects and should therefore be added in the grinding fluid.

Experimental research on the energy ratio coefficient and specific grinding energy in nanoparticle jet MQL grinding

Specific grinding energy and surface roughness of nanoparticle jet minimum quantity lubrication in grinding

In our experiment, K-P36 precision numerical control surface grinder was used for dry grinding, minimum quantity lubrication (MQL) grinding, nanoparticle jet MQL grinding, and traditional flood grinding of hardened 45 steel. A three-dimensional dynamometer was used to measure grinding force in the experiment. In this research, experiments were conducted to measure and calculate specific tangential grinding force, frictional coefficient, and specific grinding energy, thus verifying the lubrication performance of nanoparticles in surface grinding. Findings present that compared with dry grinding, the specific tangential grinding force of MQL grinding, nanoparticle jet MQL grinding, and flood grinding decreased by 45.88, 62.34, and 69.33 %, respectively. Their frictional coefficient was reduced by 11.22, 29.21, and 32.18 %, and the specific grinding energy declined by 45.89, 62.34, and 69.45 %, respectively. Nanoparticle jet MQL presented ideal lubrication effectiveness, which was attributed to the friction oil film with strong antifriction and anti-wear features formed by nanoparticles on the grinding wheel/workpiece interface. Moreover, lubricating properties of nanoparticles of the same size (50 nm) but different types were verified through experimentation. In our experiment, ZrO2 nanoparticles, polycrystal diamond (PCD) nanoparticles, and MoS2 nanoparticles were used in the comparison of nanoparticle jet MQL grinding. The experimental results manifest that MoS2 nanoparticles exhibited the optimal lubricating effectiveness, followed by PCD nanoparticles. Our research also integrated the properties of different nanoparticles to analyze the lubrication mechanisms of different nanoparticles. The experiment further verified the impact of nanoparticle concentration on the effectiveness of nanoparticle jet MQL in grinding. The experimental results demonstrate that when the nanoparticle mass fraction was 6 %, the minimum specific tangential grinding force, frictional coefficient, and specific grinding energy were 1.285 N/mm, 0.382, and 57.825 J/mm3, respectively. When nanoparticle mass fraction was smaller than 6 %, lubrication effects of nanoparticle jet MQL increased with the rising nanoparticle mass fraction. When nanoparticle mass fraction was larger than 6 %, lubrication effects of nanoparticle jet MQL decreased with the rising nanoparticle mass fraction.

Dongkun Zhang

Papers

Experimental Evaluation of the Lubrication Performance of MoS2/CNT Nanofluid for Minimal Quantity Lubrication in Ni-based Alloy Grinding

Experimental evaluation of MoS2 nanoparticles in jet MQL grinding with different types of vegetable oil as base oil

Experimental research on the energy ratio coefficient and specific grinding energy in nanoparticle jet MQL grinding

Specific grinding energy and surface roughness of nanoparticle jet minimum quantity lubrication in grinding

Experimental verification of nanoparticle jet minimum quantity lubrication effectiveness in grinding