Characterizing Mist Distribution in Through-Tool Minimum Quantity Lubrication Drills

2020 ◽  
Vol 142 (3) ◽  
Author(s):  
Jay K. Raval ◽  
Yi-Tang Kao ◽  
Bruce L. Tai
Keyword(s):  
High Speed ◽  
Minimum Quantity Lubrication ◽  
Flow Distribution ◽  
Critical Factor ◽  
Helix Angle ◽  
Distribution Analysis ◽  
Low Velocity ◽  
Minimum Quantity ◽  
Drill Bits ◽  
Mist Flow

Abstract The 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 deg, 30 deg, and 45 deg) are 3D printed for mist distribution analysis. Furthermore, 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.

Coolant Channel and Flow Characteristics of MQL Drill Bits: Experimental and Numerical Analyses

2017 ◽  
Author(s):  
Yi-Tang Kao ◽  
Behrouz Takabi ◽  
Mozheng Hu ◽  
Bruce L. Tai
Keyword(s):  
Flow Structure ◽  
High Speed ◽  
Critical Role ◽  
Flow Analysis ◽  
Flow Characteristics ◽  
Minimum Quantity Lubrication ◽  
Drill Bits ◽  
Mist Flow ◽  
Oil Concentration ◽  
Computational Analyses

In minimum quantity lubrication (MQL) machining, mist flow plays a critical role in both lubrication and cooling. This paper aims to characterize the mist flow structure of different coolant channel designs for through-tool MQL drilling. Two different channel geometries (circular and triangular cross-section) and two sizes of each channel were selected for both experimental and computational analyses. The flow structure was captured by a high-speed camera and explained using computational fluid dynamics (CFD). The results showed that, for all the channel geometries, higher oil concentration was found close to the drill center. Specifically, in the triangular channel, the flow tends to accumulate at three corners. This study also measured the airspeed, which increased with the hydraulic diameter of the channel. These results have demonstrated the effects of channel geometry and the feasibility of using CFD in mist flow analysis.

Multiphase Flow Distribution in MQL Drilling Using Optical Intensity Distribution Based Approach

2019 ◽  
Author(s):  
Jay K. Raval ◽  
Wayne N. P. Hung ◽  
Bruce L. Tai
Keyword(s):  
Velocity Field ◽  
Cfd Simulation ◽  
Circular Cross Section ◽  
Flow Distribution ◽  
Helix Angle ◽  
Machining Processes ◽  
Cross Sectional ◽  
Oil Distribution ◽  
Drill Bits ◽  
Oil Flow

Abstract 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.

A Critical Factor in Enhancement of MQL Lubricants: Platelet Thickness

2013 ◽  
Author(s):  
Trung Kien Nguyen ◽  
Patrick Y. Kwon ◽  
Kyung-Hee Park
Keyword(s):  
Tool Wear ◽  
Vegetable Oil ◽  
Ball Mill ◽  
Minimum Quantity Lubrication ◽  
Critical Factor ◽  
Solid Lubricants ◽  
Minimum Quantity ◽  
Lamellar Type

The lamellar-type solid lubricants are readily available in a form of platelets. The diameter and thickness of these platelets are typically up to tens of microns and few microns, respectively, which are classified as micro-platelets. Some of these platelets are also available as nano-platelets whose thickness is well below a micron (even to few nanometers). In the previous work, the vegetable oil mixed with nano-platelets was enormously effective for Minimum Quantity Lubrication (MQL) machining. Clearly, the micro-platelets are not as inexpensive. In addition, the mixtures with the micro-platelets are not as stable as those with the nano-platelets. This paper intends to find the effect of the thickness differential on these platelets in MQL machining. The tribometer test shows that the nano-platelets are much more effective than the micro-platelets in reducing wear without changing the friction. With the MQL ball mill experiment, the micro-platelets present in MQL oil increased the tool wear, even compared to the traditional MQL with pure oil only. Thus, the thickness of the nano-platelets holds an important characteristic to enhance MQL-based machining.

scholarly journals Feasibility Study on the Minimum Quantity Lubrication in High-Speed Helical Milling of Ti-6Al-4V

2012 ◽  
Vol 6 (7) ◽  
pp. 1222-1233 ◽  
Author(s):  
Xuda QIN ◽  
Linjing GUI ◽  
Hao LI ◽  
Bin RONG ◽  
Dongsheng WANG ◽  
...  
Keyword(s):  
Feasibility Study ◽  
High Speed ◽  
Minimum Quantity Lubrication ◽  
Helical Milling ◽  
Minimum Quantity

Effect of Cryogenic Minimum Quantity Lubrication (CMQL) on Cutting Temperature and Tool Wear in High-Speed End Milling of Titanium Alloys

2010 ◽  
Vol 34-35 ◽  
pp. 1816-1821 ◽  
Author(s):  
Yu Su ◽  
Ning He ◽  
Liang Li
Keyword(s):  
Tool Wear ◽  
Titanium Alloys ◽  
High Speed ◽  
End Milling ◽  
Cutting Temperature ◽  
Cutting Speed ◽  
Minimum Quantity Lubrication ◽  
Minimum Quantity ◽  
High Cutting Speed ◽  
Cryogenic Minimum Quantity Lubrication

Cryogenic minimum quantity lubrication (CMQL) is a kind of green cooling/lubrication technique, which consists of the application of a small amount of lubricant (6-100 ml/h), delivered in a refrigerated compressed gas stream to the cutting zone. This paper experimentally investigates the effect of CMQL on cutting temperature and tool wear in high-speed end milling of titanium alloys. Comparative experiments were conducted under different cooling/lubrication conditions, i.e. dry milling, refrigerated air cutting, and CMQL. The refrigerated gas equipment was manufactured based on composite refrigeration method to provide the refrigerated air. The experimental results show that application of CMQL resulted in drastic reduction in cutting temperature and tool wear especially when machining titanium alloys at a high cutting speed.

Investigation of Grinding Ti-6Al-4V under Minimum Quantity Lubrication (MQL) Condition

2011 ◽  
Vol 487 ◽  
pp. 84-88 ◽  
Author(s):  
Z.Q. Liu ◽  
Guo Giang Guo ◽  
Xiao Hu Zheng ◽  
Qing Long An ◽  
Ming Chen
Keyword(s):  
Surface Roughness ◽  
Flow Field ◽  
Surface Quality ◽  
Minimum Quantity Lubrication ◽  
Grinding Force ◽  
Minimum Quantity ◽  
Dry Grinding ◽  
Force Ratio ◽  
Mist Flow ◽  
Physical Changes

This paper investigates the surface grinding of Ti-6Al-4V under minimum quantity lubrication (MQL) condition. The experiment result indicated that grinding force ratio and specific energy have close related to grinding parameters. Due to the flow field of MQL mist has easy been affected by feed rate, the interaction between of MQL mist flow field and feed rates of worktable has great effect on surface roughness and surface quality. Additionally, comparing to dry grinding, MQL could help to improve surface quality by restrain chemical reactions and physical changes.

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