ISTC Reports Illinois Sustainable Technology Center Transiently Stable Emulsions for Metalworking Fluids Peter Bittorf Shiv G. Kapoor Richard E. DeVor Department of Mechanical Science and Engineering University of Illinois at Urbana-Champaign RR-119 December 2011 www.istc.illinois.edu RR-119 Transiently Stable Emulsions for Metalworking Fluids Peter Bittorf, Shiv G. Kapoor, and Richard E. DeVor Department of Mechanical Science and Engineering University of Illinois at Urbana-Champaign December 2011 Submitted to the Illinois Sustainable Technology Center Prairie Research Institute University of Illinois at Urbana-Champaign www.istc.illinois.edu The report is available on-line at: http://www.istc.illinois.edu/info/library_docs/RR/RR119.pdf Printed by the Authority of the State of Illinois Patrick J. Quinn, Governor This report is part of ISTC’s Research Report Series. Mention of trade names or commercial products does not constitute endorsement or recommendation for use. Acknowledgements The authors would like to thank the Illinois Sustainable Technology Center, a division of the Prairie Research Institute at the University of Illinois at Urbana-Champaign, for their support of the project (Grant No. HWR05191). In addition, the authors would like to thank all of the gracious and helpful staff at the Illinois Sustainable Technology Center for their assistance with data acquisition and analysis. In particular, the authors would like to thank Dr. Nandakishore Rajagopalan for his guidance and support during the project. iii iv Table of Contents Page Acknowledgements .......................................................................................................... iii List of Tables .................................................................................................................. viii List of Figures ................................................................................................................... ix Abstract ............................................................................................................................. xi Chapter 1 Introduction..................................................................................................1 1.1 Background and Motivation ................................................................................1 1.2 Research Objectives, Scope, and Tasks ...............................................................2 1.2.1 Research Objectives and Scope ...................................................................2 1.2.2 Research Tasks.............................................................................................3 1.3 Report Outline .......................................................................................................4 Chapter 2 Literature Review ........................................................................................7 2.1 Metalworking Fluid Composition ............................................................................7 2.1.1 Metalworking Fluid Classification Overview ..............................................7 2.1.2 MWF Additive Types ................................................................................10 2.2 Microfiltration .....................................................................................................12 2.2.1 Microfiltration Overview ...........................................................................12 2.2.2 Microfiltration Functionality Studies .........................................................14 2.3 MWF Lubrication Regimes ................................................................................16 2.3.1 Hydrodynamic Lubrication ........................................................................16 2.3.2 Extreme-Pressure Lubrication ...................................................................17 2.3.3 Boundary Lubrication ................................................................................18 2.4 MWF Emulsion Stability ....................................................................................19 2.4.1 Definition of Emulsion Stability ................................................................19 2.4.2 Napthenic Oils and Stability ......................................................................20 2.4.3 Destabilization of Oil Emulsions via Hardness .........................................21 2.5 MWF Performance Evaluation Methods ............................................................23 2.5.1 Tapping Torque Methodology ...................................................................23 2.5.2 Drilling-Based Methodology .....................................................................25 v 2.5.3 Comparison between Tapping Torque and Drilling-Based Methodology ....27 2.6 Chapter Summary ...............................................................................................28 Chapter 3 Effect of Water Phase Surface Tension and Viscosity on Metalworking Fluid Functionality ............................................................31 3.1 Experimental Design ...........................................................................................31 3.1.1 Surface Tension Experimental Fluids ........................................................31 3.1.2 Viscosity Experimental Fluids ...................................................................33 3.1.3 Test Set-Up and Procedure ........................................................................33 3.2 Experimental Results ..........................................................................................34 3.2.1 Experimental Comparison of Glycol Ether Solutions: Surface Tension Experiments ...............................................................................................34 3.2.2 Experimental Comparison of Surfactant Solutions: Surface Tension Experiments ...............................................................................................36 3.2.3 Experimental Comparison of Viscosity Solutions .....................................38 3.3 Discussion ...........................................................................................................40 3.4 Chapter Summary ...............................................................................................41 Chapter 4 Effect of Particle Size and Proportion of Oil on Metalworking Fluid Functionality ......................................................................................43 4.1 Extreme Pressure Additive Experiments ............................................................43 4.1.1 Experimental Design ..................................................................................43 4.1.2 Determination and Interpretation of Significant Variable Effects .............45 4.2 Boundary Lubricant Experiments .......................................................................50 4.2.1 Boundary Lubricant Selection ...................................................................51 4.2.2 Experimental Design ..................................................................................51 4.2.3 Determination and Interpretation of Significant Variable Effects .............52 4.2.4 Comparison of Optimal Boundary Lubricant Formulation with an Industrial Metalworking Fluid ...................................................................58 4.3 Chapter Summary ...............................................................................................59 Chapter 5 Formulation and Investigation of Custom Two-Phase Metalworking Fluids ...................................................................................61 5.1 Factor Levels for Custom Formulation ...............................................................61 5.1.1 Factor Levels for the EP Additive Regime ................................................61 5.1.2 Factor Levels for the Boundary Lubrication Regime ................................66 vi 5.2 Particle Size and Oil Separation of Custom Formulation ...................................68 5.2.1 Particle Size ...............................................................................................68 5.2.2 Oil Separation ............................................................................................70 5.3 Machining Tests of Custom Formulations ..........................................................71 5.3.1 Initial Machining Tests ..............................................................................71 5.3.2 Reformulation and Functionality Testing ..................................................73 5.4 Chapter Summary ...............................................................................................76 Chapter 6 Conclusions and Recommendations ......................................................77 6.1 Conclusions .........................................................................................................77 6.1.1 Effect of Water Phase Surface Tension and Viscosity on Metalworking Fluid Functionality .....................................................................................77 6.1.2 Effect of Particle Size and Proportion of Oil on Metalworking Fluid Functionality ..............................................................................................78 6.1.3 Formulation and Investigation of Custom Two-Phase Metalworking Fluids..........................................................................................................78 6.2 Recommendations for Future Work ....................................................................79