skip to main content


The NSF Public Access Repository (NSF-PAR) system and access will be unavailable from 11:00 PM ET on Thursday, June 13 until 2:00 AM ET on Friday, June 14 due to maintenance. We apologize for the inconvenience.

Title: Multiphase flow distribution in mql drilling using optical intensity distribution based approach
Oil flow distribution in Minimum Quantity Lubrication (MQL) plays an important role in the efficiency of machining processes, but it remains challenging to measure experimentally. This paper presents a new method to measure the oil flow distribution in through-channel drill bits based on the reflected light intensity. Measurements were conducted from multiple angles in order to map the flow distribution across the channel cross-sectional area. The method is applied to drill bits of a circular cross-section channel and two helix angles, 0° and 30°. The results show that, for the 0° helix angle channel, the oil concentrates near the periphery of the channel, while for 30° helix angle channel, the oil concentrates towards the center of the drill point. Furthermore, Computational Fluid Dynamics (CFD) simulation was conducted to compare with the measurement results, and it was observed that the oil distribution is correlated to the velocity field. Oil flow concentration is high in low velocity regions. Though preliminary, this study has concluded that the velocity field generated using single-phase CFD is a critical indicator for oil distribution in an MQL flow.  more » « less
Award ID(s):
Author(s) / Creator(s):
; ;
Date Published:
Journal Name:
Manufacturing science and engineering
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. Mist distribution is a critical factor in through-tool minimum quantity lubrication (MQL) drilling since a small amount of lubricant is used. However, it has rarely been discussed because of the difficulty in measuring the mist flow experimentally. In this paper, an optical approach is developed to approximate the mist distribution by using high-speed images from multiple angles. Drill bits with two through-tool channel shapes (circle and triangle) and three helix angles (0°, 30°, and 45°) are 3D-printed for mist distribution analysis. Further, computational fluid dynamics (CFD) is conducted to investigate the underlying physics behind mist flow variations. The results show that, in the circular channel, the mist is concentrated near the periphery; the low concentration region shifts away from the chisel point as the helix angle increases. For the triangular channel, the mist is concentrated near three vertices but is less affected by the helix angle. Furthermore, based on the CFD solution, high mist concentration tends to be in low-velocity regions and vice versa. This study confirms a noticeable difference of mist flow distribution in different through-tool channel designs. 
    more » « less
  2. null (Ed.)

    Minimum quantity lubrication (MQL) drilling has been known for decades, but limited knowledge is available on two-channel through-tool MQL drilling due to the lack of accessibility to production systems. A common problem in MQL drilling is the absence of a rational approach to select the oil flow rate. The limited entry and exit area, and fixed energy available to the flow make the behavior complicated. This study leverages the capabilities in Ford’s manufacturing lab to abridge the research gap. Four different oil flow rates (0 ml/h, 15 ml/h, 30 ml/h and 60 ml/h) and two different drills (twist drill and straight drill) were used to find out the influence of oil flow rate on the cutting performance. Tool life, tool wear, cutting force and torque were monitored as the cutting performance indicators. It was concluded that, the common belief of higher oil flow rate providing better tool life, does not hold true for through-tool MQL drilling. The tool life for 30 ml/hr. oil flow rate appeared to be the highest compared to all the other cases for both the drills. Increasing the oil flow rate above 30 ml/hr. decreased the tool life. However, it is to be noted that the optimal oil flow rate values may be specific to the case.

    more » « less
  3. null (Ed.)
    This study characterized airborne microdroplet diameters and size distribution from two commercially available lubricants A and B for internal minimum quantity lubrication (MQL). The effects of air pressure, oil channel size, physical properties of lubricants on the resultant microdroplets and through-tool MQL drilling performance were studied. Airborne microdroplet diameters were highly sensitive to the coolant channel sizes and air pressure. Cluster method was used to divide microdroplets into smaller clusters for comparison. Experimental data show that the average airborne microdroplet of lubricant B was larger than that of lubricant A at different air pressures and channel sizes. The contact angle of lubricant A was at least 10° less than that of lubricant B when depositing on glass or aluminium. High-speed imaging showed the tendency of more viscous lubricant B sticking to the drill tip, and higher pressure and longer time was required to atomize this viscous oil. Built-up-edges were less significant when drilling A380 aluminium with lubricant A. Due to high machinability of A380 aluminium, variation of hole diameter and hole cylindricity were minimal when drilling with different lubricants. Insignificant improvement in hole quality was observed when drilling with excessive amount of MQL lubricants or high concentration of lubricant C in flood coolant. 
    more » « less
  4. Road accidents caused by heavy rain have become a frightening issue in recent years requiring investigation. In this regard, an aerodynamic comparative and experimental rain study is carried out to observe the flow phenomena change around a generic ground vehicle (Ahmed Body at a scale) and the utility truck. In this paper, a Discrete Phase Model (DPM) based computational methodology is used to estimate the effect of rain on aerodynamic performance. First, an experimental rain study of the Ahmed body at a scale that is representative of a car or light truck was conducted at the Wall of Wind (WOW) large-scale testing facility using force measurement equipment. In addition, the experiment allowed drag, lift, and side-force coefficients to be measured at yaw angles up to 55 degrees. Next, experimental results are presented for the Ahmed Body back angle of 35 degrees, then compared to validate the computational model for ground vehicle aerodynamics. Afterwards, we investigated the effect of heavy rainfall (LWC = 30 g/m3) on the external aerodynamics of the utility truck with the morphing boom equipment using the validated computational fluid dynamics method, and the external flow is presented using a computer visualization. Finally, force & moment coefficients and velocity distributions around the utility truck are computed for each case, and the results are compared. Keywords: Experimental Wind-Driven Rain Wind Tunnel Testing, Heavy Rainfall, The Ahmed Body, Utility Truck, Morphing Boom Equipment, Discrete Phase Model (DPM), Automotive Aerodynamics, Computational Fluid Dynamics (CFD) 
    more » « less
  5. Abstract

    We present simulations of two-phase flow using the Rothman and Keller colour gradient Lattice Boltzmann method to study viscous fingering when a “red fluid” invades a porous model initially filled with a “blue” fluid with different viscosity. We conducted eleven suites of 81 numerical experiments totalling 891 simulations, where each suite had a different random realization of the porous model and spanned viscosity ratios in the range$$M\in [0.01,100]$$M[0.01,100]and wetting angles in the range$$\theta _w\in [180^\circ ,0^\circ ]$$θw[180,0]to allow us to study the effect of these parameters on the fluid-displacement morphology and saturation at breakthrough (sweep). Although sweep often increased with wettability, this was not always so and the sweep phase space landscape, defined as the difference in saturation at a given wetting angle relative to saturation for the non-wetting case, had hills, ridges and valleys. At low viscosity ratios, flow at breakthrough is localized through narrow fingers that span the model. After breakthrough, the flow field continues to evolve and the saturation continues to increase albeit at a reduced rate, and eventually exceeds 90% for both non-wetting and wetting cases. The existence of a complicated sweep phase space at breakthrough, and continued post-breakthrough evolution suggests the hydrodynamics and sweep is a complicated function of wetting angle, viscosity ratio and time, which has major potential implications to Enhanced Oil Recovery by water flooding, and hence, on estimates of global oil reserves. Validation of these results via experiments is required to ensure they translate to field studies.

    more » « less