Analysis of Droplet Spreading on a Rotating Surface and the Prediction of Cooling and Lubrication Performance of an Atomization-Based Cutting Fluid System

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
Isha Ghai ◽  
Johnson Samuel ◽  
Richard E. DeVor ◽  
Shiv G. Kapoor
Keyword(s):  
Surface Tension ◽  
High Viscosity ◽  
Cutting Fluid ◽  
Droplet Spreading ◽  
Shape Information ◽  
3D Shape ◽  
Spreading Model ◽  
Lubrication Performance ◽  
Rotating Surface ◽  
Cooling And Lubrication

Droplet spreading on a rotating surface has been modeled with an aim to design an efficient atomization-based cutting fluid (ACF) system for micromachining processes. To this end, single-droplet impingement experiments are conducted on a rotating surface to capture the 3D shape of a droplet upon impingement. A parameterization scheme is then developed to mathematically define the 3D shape of droplet upon impingement. The shape information is used to develop an energy-based model for droplet spreading. The droplet spreading model captures the experimental results within 10% accuracy. The spreading model is then used to predict the cooling and lubrication for an ACF-based microturning process. The model captures the cooling and lubrication trends observed in microturning experiments. A parametric study is conducted to identify the significant factors affecting the performance of an ACF system. Droplet speed is found to have a dominant effect on both cooling and lubrication performance, particularly, with a low surface tension fluid for cooling and a low surface tension and high viscosity fluid for lubrication.

Graphene Oxide Colloidal Suspensions as Cutting Fluids for Micromachining: Part 1 — Fabrication and Performance Evaluation

2015 ◽  
Author(s):  
Bryan Chu ◽  
Eklavya Singh ◽  
Johnson Samuel ◽  
Nikhil Koratkar
Keyword(s):  
Graphene Oxide ◽  
Cutting Temperature ◽  
Colloidal Suspensions ◽  
Cutting Fluid ◽  
Droplet Spreading ◽  
Bulk Fluid ◽  
Graphene Layers ◽  
Lubrication Performance ◽  
Cooling And Lubrication ◽  
Lateral Length

This paper is aimed at investigating the effects of graphene oxide platelet (GOP) geometry (i.e., lateral size and thickness) and oxygen functionalization on the cooling and lubrication performance of GOP colloidal suspensions. The techniques of thermal reduction and ultrasonic exfoliation were used to manufacture three different types of GOPs. For each of these three types of GOPs, colloidal solutions with GOP concentrations varying between 0.1–1 wt% were evaluated for their dynamic viscosity, thermal conductivity and micromachining performance. The ultrasonically-exfoliated GOPs (with 2–3 graphene layers and lowest in-solution characteristic lateral length of 120 nm) appear to be the most favorable for micromachining applications. Even at the lowest concentration of 0.1 wt%, they are capable of providing a 51% reduction in the cutting temperature and a 25% reduction in the surface roughness value over that of the baseline semi-synthetic cutting fluid. For the thermally-reduced GOPs (with 4–8 graphene layers and in-solution characteristic lateral length of 562–2780 nm), a concentration of 0.2 wt% appears to be optimal. The findings suggest that the differences seen between the colloidal suspensions in terms of their droplet spreading, evaporation and the subsequent GOP film-formation characteristics may be better indicators of their machining performance, as opposed to their bulk fluid properties.

Droplet Behavior on a Rotating Surface for Atomization-Based Cutting Fluid Application in Micromachining

2010 ◽  
Vol 132 (1) ◽  
Author(s):  
Isha Ghai ◽  
John Wentz ◽  
Richard E. DeVor ◽  
Shiv G. Kapoor ◽  
Johnson Samuel
Keyword(s):  
Surface Tension ◽  
Evaporation Rate ◽  
High Viscosity ◽  
Cutting Fluid ◽  
Fluid Viscosity ◽  
Droplet Shape ◽  
Low Viscosity ◽  
Droplet Behavior ◽  
Rotating Surface ◽  
Cutting Zone

The droplet behavior on a rotating surface has been studied to better understand the physics underlying atomized cutting fluid application. To this end, microturning experiments are carried out and the cutting performance evaluated for varying cutting fluids and at different droplet speeds. Microturning experiments indicate that a cutting fluid with low surface tension and low viscosity generates lower cutting temperatures, whereas a fluid with low surface tension and high viscosity generates lower cutting forces. Single-droplet impingement experiments are also conducted on a rotating surface using fluids with different surface tension and viscosity values. Upon impact, the droplet shape is observed to be a function of both the droplet speed and the surface speed. The spreading increases with increased surface speed owing to the tangential momentum added by the rotating surface. Spreading is observed to also increase with a decrease in fluid surface tension and does not change with the fluid viscosity. The evaporation rate is observed to increase for a rotating surface owing to convective heat transfer. Low surface tension and low viscosity are observed to increase the evaporation rate. It is concluded that a fluid with low surface tension and low viscosity is an effective coolant of the cutting zone, whereas a fluid with low surface tension and high viscosity is effective for lubrication.

Graphene Oxide Colloidal Suspensions as Cutting Fluids for Micromachining—Part I: Fabrication and Performance Evaluation

2015 ◽  
Vol 3 (4) ◽  
Author(s):  
Bryan Chu ◽  
Eklavya Singh ◽  
Johnson Samuel ◽  
Nikhil Koratkar
Keyword(s):  
Graphene Oxide ◽  
Cutting Temperature ◽  
Colloidal Suspensions ◽  
Cutting Fluid ◽  
Droplet Spreading ◽  
Bulk Fluid ◽  
Graphene Layers ◽  
Lubrication Performance ◽  
Cooling And Lubrication ◽  
Lateral Length

This paper is aimed at investigating the effects of graphene oxide platelet (GOP) geometry (i.e., lateral size and thickness) and oxygen functionalization on the cooling and lubrication performance of GOP colloidal suspensions. The techniques of thermal reduction and ultrasonic exfoliation were used to manufacture three different types of GOPs. For each of these three types of GOPs, colloidal solutions with GOP concentrations varying between 0.1 and 1 wt.% were evaluated for their dynamic viscosity, thermal conductivity, and micromachining performance. The ultrasonically exfoliated GOPs (with 2–3 graphene layers and lowest in-solution characteristic lateral length of 120 nm) appear to be the most favorable for micromachining applications. Even at the lowest concentration of 0.1 wt.%, they are capable of providing a 51% reduction in the cutting temperature and a 25% reduction in the surface roughness value over that of the baseline semisynthetic cutting fluid. For the thermally reduced GOPs (TR GOPs) (with 4–8 graphene layers and in-solution characteristic lateral length of 562–2780 nm), a concentration of 0.2 wt.% appears to be optimal. The findings suggest that the differences seen between the colloidal suspensions in terms of their droplet spreading, evaporation, and the subsequent GOP film-formation characteristics may be better indicators of their machining performance, as opposed to their bulk fluid properties.

Experiments on the breakup of drop-impact crowns by Marangoni holes

2018 ◽  
Vol 844 ◽  
pp. 162-186 ◽  
Author(s):  
Abdulrahman B. Aljedaani ◽  
Chunliang Wang ◽  
Aditya Jetly ◽  
S. T. Thoroddsen
Keyword(s):  
Surface Tension ◽  
Lower Surface ◽  
High Viscosity ◽  
Solid Substrate ◽  
Immiscible Liquid ◽  
Hole Formation ◽  
Low Viscosity ◽  
Stress Changes ◽  
Lower Surface Tension ◽  
The Impact

We investigate experimentally the breakup of the Edgerton crown due to Marangoni instability when a highly viscous drop impacts on a thin film of lower-viscosity liquid, which also has different surface tension than the drop liquid. The presence of this low-viscosity film modifies the boundary condition, giving effective slip to the drop along the solid substrate. This allows the high-viscosity drop to form a regular bowl-shaped crown, which rises vertically away from the solid and subsequently breaks up through the formation of a multitude of Marangoni holes. Previous experiments have proposed that the breakup of the crown results from a spray of fine droplets ejected from the thin low-viscosity film on the solid, e.g. Thoroddsen et al. (J. Fluid Mech., vol. 557, 2006, pp. 63–72). These droplets can hit the inner side of the crown forming spots with lower surface tension, which drives a thinning patch leading to the hole formation. We test the validity of this assumption with close-up imaging to identify individual spray droplets, to show how they hit the crown and their lower surface tension drive the hole formation. The experiments indicate that every Marangoni-driven patch/hole is promoted by the impact of such a microdroplet. Surprisingly, in experiments with pools of higher surface tension, we also see hole formation. Here the Marangoni stress changes direction and the hole formation looks qualitatively different, with holes and ruptures forming in a repeatable fashion at the centre of each spray droplet impact. Impacts onto films of the same liquid, or onto an immiscible liquid, do not in general form holes. We furthermore characterize the effects of drop viscosity and substrate-film thickness on the overall evolution of the crown. We also measure the three characteristic velocities associated with the hole formation: i.e. the Marangoni-driven growth of the thinning patches, the rupture speed of the resulting thin films inside these patches and finally the growth rate of the fully formed holes in the crown wall.

scholarly journals Droplet spreading and permeating on the hybrid-wettability porous substrates: a lattice Boltzmann method study

Open Physics ◽  
2016 ◽  
Vol 14 (1) ◽  
pp. 483-491 ◽  
Author(s):  
Wen-Kai Ge ◽  
Gui Lu ◽  
Xin Xu ◽  
Xiao-Dong Wang
Keyword(s):  
Surface Tension ◽  
Contact Angle ◽  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Droplet Spreading ◽  
Small Surface ◽  
Pore Sizes ◽  
Fluid Properties ◽  
Boltzmann Method ◽  
Porous Substrates

AbstractThe spreading and permeation of droplets on porous substrates is a fundamental process in a variety of applications, such as coating, dyeing, and printing. The spreading and permeating usually occur synchronously but play different roles in the practical applications. The mechanisms of the competition between spreading and permeation is significant but still unclear. A lattice Boltzmann method is used to study the spreading and permeation of droplets on hybrid-wettability porous substrates, with different wettability on the surface and the inside pores. The competition between the spreading and the permeation processes is studied in this work from the effects of the substrate and the fluid properties, including the substrate wettability, the porous parameters, as well as the fluid surface tension and viscosity. The results show that increasing the surfacewettability and the porosity contact angle both inhibit the spreading and the permeation processes. When the inside porosity contact angle is larger than 90° (hydrophobic), the permeation process does not occur. The droplets suspend on substrates with Cassie state. The droplets are more easily to permeate into substrates with a small inside porosity contact angle (hydrophilic), as well as large pore sizes. Otherwise, the droplets are more easily to spread on substrate surfaces with small surface contact angle (hydrophilic) and smaller pore sizes. The competition between droplet spreading and permeation is also related to the fluid properties. The permeation process is enhanced by increasing of surface tension, leading to a smaller droplet lifetime. The goals of this study are to provide methods to manipulate the spreading and permeation separately, which are of practical interest in many industrial applications.

Characterization of Fluid Film Produced by an Atomization–Based Cutting Fluid (ACF) Spray System During Machining

2013 ◽  
Author(s):  
Alexander C. Hoyne ◽  
Chandra Nath ◽  
Shiv G. Kapoor
Keyword(s):  
Flow Characteristics ◽  
Fluid Film ◽  
Cutting Fluid ◽  
Spray Parameters ◽  
Film Model ◽  
Thin Fluid ◽  
Spray System ◽  
Thin Fluid Film ◽  
Film Development ◽  
Cooling And Lubrication

The atomization–based cutting fluid (ACF) spray system has recently been proposed as a cooling and lubrication solution for machining hard to machine materials (e.g. titanium alloys). On the tool rake face, the ACF spray system forms a thin film from cutting fluid that penetrates into the tool–chip interface to improve tool life. The objective of this work is to characterize this thin fluid film in terms of thickness and velocity for sets of ACF spray parameters. ACF spray experiments are performed by varying impingement angle in order to observe the nature of the spreading film, and to determine the film thickness at different locations after impingement of the droplets. It is observed that the film spreads radially outward producing three fluid film development zones (i.e. impingement, steady, unsteady). The steady zone is found to be between 3 and 7 mm from the focus (impingement point) of the ACF spray for the set of parameters investigated. An analytical 3D thin fluid film model for the ACF spray system has also been developed based on the equations for continuity of mass and momentum. The model requires a unique treatment of the cross–film velocity profile, droplet impingement and pressure distributions, as well as a strong gas–liquid shear interaction. The thickness profiles predicted by the analytical film model have been validated. Moreover, the model predictions of film velocity and chip flow characteristics during a titanium turning experiment reveal that the fluid film can easily penetrate into the entire tool–chip interface with the use of the ACF spray system.

Cutting Mechanism Study on Technology in Near-Dry Deep-Hole Drilling

2010 ◽  
Vol 455 ◽  
pp. 251-256
Author(s):  
Peng Hai ◽  
H.X. Wei
Keyword(s):  
Cutting Fluid ◽  
Hole Drilling ◽  
Deep Hole ◽  
Mechanism Study ◽  
Cutting Mechanism ◽  
Dry Cutting ◽  
Two Phase ◽  
Deep Hole Drilling ◽  
Mathematical Mode ◽  
Cooling And Lubrication

Near-dry deep hole processing technology is a kind of technology which dry cutting technology is applied to deep hole processing to save energy and decrease environmental pollution. In this paper, the structure and work principle of near-dry deep-hole drilling system were introduced and the cutting mechanism of near-dry deep-hole drilling was analyzed which include the mechanism of cutting fluid atomization and flow, the mechanism of atomized cutting fluid cool and lubricate, and the mechanism of separating chips into short pieces and discharge chips by air stream, etc. The mathematical mode of gas-liquid two-phase flow of atomized cutting fluid in drilling shaft and the cooling and lubrication mechanism of the capillary in cutting zone were introduced. It is found that near-dry deep hole processing has better cooling and lubrication effect through experiments.

Shielding Nozzle Design and Analysis for Atomization-Based Cutting Fluid Systems in Micromachining

2015 ◽  
Vol 3 (2) ◽  
Author(s):  
Andressa Lunardelli ◽  
John E. Wentz ◽  
John P. Abraham ◽  
Brian D. Plourde
Keyword(s):  
Fluid Dynamic ◽  
Continuous Phase ◽  
Computational Fluid Dynamic Model ◽  
Parameter Analysis ◽  
Cutting Fluid ◽  
Nozzle Design ◽  
Fluid Systems ◽  
Cutting Surface ◽  
Droplet Tracking ◽  
Cooling And Lubrication

Atomization-based cutting fluid systems (ACFs) are increasingly being used in micromachining applications to provide cooling and lubrication to the tool–chip interface. In this research, a shielding nozzle design is presented. A computational fluid dynamic model is developed to perform parameter analysis of the design. The numerical simulations were accomplished using the Eulerian approach to the continuous phase and a Lagrangian approach for droplet tracking. Based on the results of the simulations it is determined that the shielding nozzle is effective at providing droplets to the cutting surface at an appropriate speed and size to create a lubricating microfilm.

Interactions Between High-Viscosity Droplets Deposited on a Surface: Experiments and Simulations

2012 ◽  
Author(s):  
J. Esmaeelpanah ◽  
A. Dalili ◽  
S. Chandra ◽  
J. Mostaghimi ◽  
H. C. Fan ◽  
...  
Keyword(s):  
Surface Tension ◽  
Free Surface ◽  
Piecewise Linear ◽  
Three Dimensional ◽  
Surface Force ◽  
Line Length ◽  
High Viscosity ◽  
Droplet Shape ◽  
Viscous Liquids ◽  
Straight Lines

A combined numerical and experimental investigation of coalescence of droplets of highly viscous liquids dropped on a surface has been carried out. Droplets of 87 wt% glycerin-in-water solutions with viscosity 110 centistokes were deposited sequentially in straight lines onto a flat, solid steel plate and droplet impact photographed. Impacting droplets spread on the surface until liquid surface tension and viscosity overcame inertial forces and the droplets recoiled, eventually reaching equilibrium. Droplet center-to-center distance was varied and droplet line length was measured from photographs. As droplet spacing was increased there was less interaction between the droplets. A three dimensional parallel code has been developed to simulate fluid flow and free surface interaction by solving the continuity, momentum and volume-of-fluid (VOF) equations. The two-step projection method was employed to solve the governing equations for the whole domain including both liquid and air phases. The continuum-surface-force (CSF) scheme was applied to model surface tension and the piecewise-linear-interface-construction (PLIC) technique used to reconstruct the free surface. Computer generated images of impacting droplets modeled droplet shape evolution correctly and compared well with photographs taken during experiments. Accurate predictions were obtained for droplet line length during spreading and at equilibrium.

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