Hybridization of mechanical microtextures on the cutting tools and a minimal amount of nano-green cutting fluids improves the tribological performance between tool-chip interface, reduces machining forces, cutting temperature, workpiece surface roughness, tool-chip contact length and tool wear. In this study, mechanical microtextures are fabricated on the cutting surface of the cutting tool.
TRIBOLOGICAL PERFORMANCE OF MECHANICAL MICRO-TEXTURED PINS
MACHINING PERFORMANCE OF MECHANICAL MICRO- TEXTURED CUTTING TOOLS
COMPARATIVE HARD MACHINING PERFORMANCE OF VARIOUS MECHANICAL MICRO-TEXTURED CUTTING
SYNTHESIS OF GREEN CUTTING FLUID AND ITS COMPARATIVE STUDY WITH COMMERCIAL BIO
MINIMUM QUANTITY ENVIRONMENTAL FRIENDLY CUTTING FLUIDS IN HARD MACHINING
PERFORMANCE OF MOLYBDENUM DISULPHIDE AND CALCIUM FLOURIDE BASED NANO-GREEN GREEN
HARD MACHINING PERFORMANCE WITH HYBRID MECHANICAL MICRO-TEXTURED CUTTING TOOLS
CONCLUSION AND SCOPE FOR FUTURE WORK 192-204
LIST OF TABLES
A2-M Surface Density Pin with 2% MoS2 Filled Texture A4-M Surface Density Pin with Texture Filled with 4% MoS2 A6-M Surface Density Pin with Texture Filled with 6% MoS2 A8-M Pin for surface density with texture filled with 8% MoS2 A10-M 10% MoS2 Surface density pin with filled texture A12-M Surface density pin with 12% MoS2 A14-M Surface density pin with 14% MoS2 filled texture BCF Biological cutting fluid. MµT Mechanical Microtexture MWCNT Multiwalled Carbon Nano Tube Nano-GCF Nano Green Cutting Fluid.
Notations
INTRODUCTION AND LITERATURE REVIEW
Introduction 1.2 Turning process
Environmental aspects in turning 1.8 Literature review
Objectives of the present work 1.10 Organization of the thesis
Introduction
In light of its importance, this thesis examines the turning process from a sustainability point of view in a green production environment. This chapter covers an introduction on turning process, cutting tool, cutting fluid, environmental aspects in turning process.
Turning process
Important performance parameters are tool-chip interface temperature, cutting force, feed force, coefficient of friction, workpiece surface roughness and tool wear. Cutting force, feed force, cutting fluid and cutting fluid application technique have a direct impact on workpiece surface roughness and tool wear.
Basics of turning
The friction in the secondary deformation zone further influences the chip formation at the shear zone. The shear angle affects the force required to shear the chip, as shown in the following equation, where Fs, Ff and Fc are the shear, feed and cutting forces.
Hard turning
Friction in turning
It can cause catastrophic failure of the cutting tool as it can lead to breakage of the tool tip if much material is worn away. Furthermore, unevenness in contact can stick to the cutting tool and subsequently break the removal of bits of the cutting tool and hardened chips.
Friction reduction
- Coatings
- Cutting fluids
During the turning process, the friction force opposes the movement of the chip on the tool rake surface, which accounts for about 25% of the specific cutting energy [2]. Adhesion also occurs at the tool-chip interface due to the high pressure and temperature at the intersections of the contacting asperities.
Environmental aspects in turning
Dimensional accuracy of the workpiece and tool hardness is maintained by removing the heat generated during the process. Various diseases caused due to prolonged exposure of the petroleum-based cutting fluids: (a) oil acne [9], (b) skin cancer [10], (c) mild bronchiectasis [11] and (d).
Literature review
- Dry machining
- Environmental friendly cutting fluids
- Near-dry machining
- Minimum quantity nano-cutting fluids
- Gaps in the literature
Gradually, the compositions of the cutting fluids became more complex as the cutting operations became more difficult. Canola-based cutting fluids appear to be the best compared to all three, including sunflower oil-based cutting fluids.
Objectives of the present work
Organization of the thesis
Objective 4
Objective 3
In Chapter 7, MoS2 and CaF2 based nano-green cutting fluids with varying concentrations are developed. The effect of the nano-solid lubricant (MoS2 nanoplatelets and CaF2 nanoparticles) on improved cutting fluids is studied by conducting absorption tests, dynamic viscosity tests, thermal conductivity tests, volumetric specific heat tests and wettability tests. For hard machining, the combination of the micro-textured mechanical cutting tool and an in-house manufactured minimum cutting fluid using in-house developed nano-green cutting fluid is used.
The results of the present work in the form of various journal articles, book chapters and conferences are reported.
TRIBOLOGICAL PERFORMANCE OF MECHANICAL MICRO- TEXTURED PINS
- Introduction to the tribological aspects of micro-textured cutting tools in machining 2.2 Experimental details
- Results and discussion
- Introduction to the tribological aspects of micro-textured cutting tools in machining
- Experimental details
- Fabrication of mechanical micro-textured pins and coating with solid lubricant Pins for friction and wear test were fabricated using wire cut electrical discharge machining
- Friction coefficient of the test material
- Surface temperature of the test material
- Wear, weight loss and wear rate of the test material
- Wear morphology and elemental composition of the test material
- Findings from the research work
As the texture areal density further increased from 2% to 10% of MoS2-filled textured pins, the COF further decreased. Due to this, COF reduction is observed with MoS2-filled textured pin. a) Untextured pin (b) Textured pin filled with MoS2 and (c) lubricant film formation between sliding interfaces. B, (e) surface morphology of the MoS2-filled textured pin micro-weave and (f) elemental composition of the MoS2-filled textured pin micro-weave in the corresponding area C after sliding.
Friction and wear tests were performed using untextured, unfilled textured, and MoS2 filled textured pins with varying texture surface density.
MACHINING PERFORMANCE OF MECHANICAL MICRO- TEXTURED CUTTING TOOLS
Introduction to machining with micro-textured cutting tools 3.2 Experimental details
Results and discussion
Findings from the research work
Introduction to machining with micro-textured cutting tools
Surface texture on the surface of cutting tools has emerged for stable machining for further improvements in the last decade. Various techniques such as laser micro-EDM [172], wet etching, photolithography and sputtering [39] are used to create micro-texture on the surface of the cutting tool. Micro-textures were fabricated on the raked surface of the cutting tool using a femtosecond laser by irradiating the DLC-coated tool surface.
In this work, a structural analysis was performed on the cutting tool using an ANSYS® workbench to evaluate the effect of microtextures on stress generation at the cutting edge of the tool.
Experimental details
- Materials
- Preliminary experimentation
- Experimental design
- Machining experiments
- Effect of mechanical micro-textures on the cutting tool strength
- Feed forces
- Tool-chip interface coefficient of friction
Therefore, it can be considered that the mechanical strength of the tools does not have as much influence as expected due to the presence of mechanical micro-textures on the tool rake surface. It may be possible to reduce tool-chip interface temperatures by micro-texturing the tool rake surface, due to the reduced contact area between the tool-chip interfaces over the rake surface of micro-machined tools. - texture. Also, the friction between the tool-chip interface is higher, which results in higher Ra of the UT workpiece.
Also, the presence of mechanical micro-textures on the rake surface of the tool had much less influence on the mechanical strength of the cutting tool.
COMPARATIVE HARD MACHINING PERFORMANCE OF VARIOUS MECHANICAL MICRO-TEXTURED CUTTING TOOLS
Introduction
Experimental details .1 Materials
Findings from the research work
Schematic diagram of the tool-chip interface in (a) untextured cutting tool, (b) microtextured coated cutting tool, (c) worn tool (tungsten grains are removed), (d) MoS2 with microtextured lubrication cutting tool , (e) formation of MoS2- and (f) formation of iron-. In this study, MµTs were fabricated on the rake surface of tungsten carbide cutting tool insert using a Vickers hardness tester and scratch tester. Due to the lubricating properties of MoS2 than tungsten carbide, the tool-chip interface temperature, cutting force and feed force will be lower.
After the experiments, the surface morphology, elemental composition analysis and elemental mapping of the cutting tool are analyzed using a scanning electron microscope and energy dispersive spectroscopy.
Experimental details
- Materials
- Selection of texturing area
- Fabrication of various mechanical micro-textures on the rake surface of the tungsten carbide cutting tool
- Experimental design
- Machining experiments
The adhesion and wear area on the ripping surface of the non-textured cutting tool is identified (Figure 4.4 a). Surface morphology of the rake surface of non-textured cutting tool showing (a) adhesion and wear area, (b) tool-chip contact length area, (c) notch formation. The MµT cutting tool with micro-indentations on its ripping surface is named VT (Figure 4.6 a).
Cutting tools with MµTs parallel to the main cutting edge are named as PT (Figure 4.6 b).
Result and discussion
- Effect of various mechanical textures on the cutting tool strength
- Tool-chip interface coefficient of friction
- Surface morphology of cutting tool rake surface
- Chip morphology
ANOVA for Tool and Chip Threshold Temperature of a MoS2 Coated Microtextured Rectangular Mechanical Cutting Tool. In the case of VT-M, PT-M and PDT-M cutting tools, the contact of the tool with chips is reduced due to the presence of numerous micro channels on the inclined surface of the cutting tool, which causes less heat generation. The back side of the chip carries MoS2 particles and creates a lubricating film on the inclined surface of the cutting tool.
It is observed that the tool-chip interface contact area of PDT-M cutting tool is slightly different from PT-M cutting tool wear track.
SYNTHESIS OF GREEN CUTTING FLUID AND ITS COMPARATIVE STUDY WITH COMMERCIAL BIO-CUTTING FLUID AND MINERAL
Introduction to environmental friendly cutting fluids 5.2 Experimental details
SYNTHESIS OF GREEN CUTTING FLUID AND ITS COMPARATIVE STUDY WITH COMMERCIAL BIO CUTTING FLUID AND MINERAL.
Findings from the research work
Introduction to environmental friendly cutting fluids
Availability of mineral oil (MO) based cutting fluids is limited as they are a limited and declining resource, while vegetable based cutting fluids are stable. Vegetable oils are evolving as metalworking fluids due to their higher biodegradability and ability to minimize waste treatment costs. For reasons mentioned above, vegetable oils as metalworking fluids are environmentally friendly and are also better lubricants compared to others [75].
Also, the potential biodegradable, thermal, rheological, apparent activation energy, anti-corrosion and deposition stability characteristics of all cutting fluids were investigated and compared.
Experimental details
- Synthesis of green cutting fluid
- Materials
- Physical and chemical properties of the cutting fluids
- Biodegradation study
- Thermal gravimetric analysis study
- Rheological study
- Determination of apparent activation energy
- Storage stability of the cutting fluids
The flow and behavior of the cutting fluid lubricant depends on its shear stress and viscosity. Therefore, the shear stress and the viscosities of the cutting fluids are measured as a function of the shear rate using a rheometer (Make: ANTON PAAR®, Model: MCR-101) with a coaxial cylinder master tool (Figure 5.2). ASTM D4627 defined the cutoff point as the weakest concentration of cutting fluid tested that shows no rust stains on the glass fiber filter paper.
Cutting fluids are used in the form of an emulsion to reduce heat generated and friction during machining.
Results and discussion
- Biodegradability of the cutting fluids
- Thermal stability of the cutting fluids
- Shear stress and viscosity of the cutting fluids
- Apparent activation energy of the cutting fluids
- Anti-corrosion properties of the cutting fluids
- Storage stability of the cutting fluids
The thermal stability of cutting fluids is determined by the mass loss relative to the thermal decomposition temperature (T). The results show that the amount of rusting decreases with an increase in the concentration of the cutting fluids. It confirms that GCF has better anti-corrosion properties compared to BCF and MO-based cutting fluids.
But in case of GCF, the amount of separated oil is less compared to BCF and MO.
MINIMUM QUANTITY ENVIRONMENTAL FRIENDLY CUTTING FLUIDS IN HARD MACHINING
Introduction to minimum quantity cutting fluids 6.2 Experimental details
Findings from the research work
Introduction to minimum quantity cutting fluids
Near-dry machining (NDM) or MQL or micro-lubrication, also known as minimum quantity cutting fluid (MQCF), is an alternative solution for reducing harmful environmental effects and improving machining performance [101−103]. MQCF reduces occupational hazards, addresses environmental issues and produces economic benefits by reducing fluid costs. MQCF is an accepted environmentally friendly machining method that can improve workpiece surface finish and reduce tool wear and cutting forces compared to dry machining [106, 107].
This chapter also compares the efficiency of GCF, BCF and MO using MQCF with dry tillage (DM).
Experimental details
- Materials
- Selection of optimum cutting fluid emulsion concentration, nozzle standoff distance and nozzle spray angle position
- Experimental design
- Machining experiments
In order to achieve a better cooling and lubricating effect of the cutting fluid emulsion, mix the optimal amount of cutting fluid and water. It causes the mist to diverge, resulting in less force applied by the cutting fluid emulsion mist in the machining area. A systematic study of different types of cutting fluid and nozzle positions in FC and MQL is carried out.
All experiments are performed with FC and MQCF using MO and BCF cutting fluid emulsions (Total experiments of each experiment repeated three times)).
Results and discussion
- Selection of cutting fluid concentration in the emulsion
- Selection of nozzle standoff distance
- Selection of nozzle spray angular position
- Machining performance .1 Cutting forces
In case DM, more severe crater wear is observed on the cutting tool rake surface (Figure 6.18 a). For machining with MQCF, only adhesion and abrasive wear occurs at the tool rake surface (Figure 6.18 b-d). Under cutting tool rake surface after machining with MQCF with three different cutting fluids, the maximum abrasive wear is observed in the case of MO, which is a symptom of high friction coefficient (Figure 6.18 b).
Elemental composition of the excavation surface of the cutting tool at the location of the attached material (corresponding to point A; Figure 6.19 d).
Performance of Molybdenum Disulphide and Calcium Fluoride based Nano-Green Cutting Fluids
- Introduction to nano-cutting fluids
- Nano-solid lubricant enhanced green cutting fluids .1 Preparation of nano-green cutting fluids
- Introduction about nano-cutting fluid
- Nano-solid lubricant enhanced green cutting fluids
- Preparation of nano-green cutting fluids
- Characterization of nano-green cutting fluids .1 Dispersion test
- Wetting angle measurement
- Materials and machining experiments
- Results and discussion
- Dispersion stability of the nano-green cutting fluids
- Thermal conductivity and specific volumetric heat capacity of the nano-green cutting fluids
- Viscosity of the nano-green cutting fluids
- Surface wettability by water and cutting fluids
- Machining experiments
Its wetting angle evaluates the wetting ability of cutting fluids on the surface of the cutting tool. It shows proper dispersion of nanoparticles up to saturation point in cutting fluids. Effect of concentration of nano-green cutting fluids based on solid lubricants on (a) thermal conductivity and (b) volumetric specific heat capacity.
Effect of nanoparticle concentration on the dynamic viscosity of nano-green cutting fluids with (a) MoS2 and (b) CaF2.
