CUTTING FLUIDS IN MICROMACHINING Machinery's Handbook, 31st Edition
1184
8
6
Adhesion > Centrifugal force
4
Adhesion < Centrifugal force
2
0
0
50 100 Tool Surface Speed (m/min)
150
Fig. 25. Adhesion Threshold of Microdroplets on a Rotating Tool. CL2210EP lubricant, Ø1 mm uncoated carbide tool at different speeds. Note: 1 pm = 1 picometer = 10 − 12 meter.
Simulation using computational fluid dynamics is used to study the 2D flow of microdroplets near a rotating cutting tool. Fig. 26a shows the velocity field of microdroplets moving from left to right and around a counter-clockwise rotating cylinder. A stagnant location with zero microdroplet speed is found near the top of the cylinder (cutting tool). When micromilling in MQL condition, a workpiece should not be positioned at such a stagnant location since it would receive no lubrication. Practical setups are suggested in Fig. 26b.
Microdroplets Stagnant
Tool
Uniform Micromist
Fig. 26a. Computational Fluid Dynamic Simulation of Microdroplet Dynamics.
Stagnant mist
Workpiece
Micromist
Micromill
Micromist
Micromill
Workpiece
Stagnant mist Fig. 26b. Practical Machining Setups of Tool and Workpiece to Avoid Stagnant Zone. Case Studies.— Many researchers have applied micromist in their micro and macro ma- chining studies. An example of each is given in this section. Use of Micromist in Micromilling of 316L Stainless Steel: Micromilling using Ø1 mm WC tool, 10 m m/tooth chip load, 0.348 mm axial depth, 0.558 mm radial depth were performed on 316L stainless steel with different coolants. Using the cumulative tool life models (see Tool Life on page 1166), tool life of micromilling tools are plotted and
Copyright 2020, Industrial Press, Inc.
ebooks.industrialpress.com
Made with FlippingBook - Share PDF online