Wet Machining Conditions Research Articles

Investigating tool wear mechanisms in machining of Ti-6Al-4V in flood coolant, dry and MQL conditions

The objective of this study is to identify and explain tool wear mechanisms that dominate during machining of titanium alloy Ti-6Al-4V in dry, flood coolant, and minimum quantity lubrication (MQL) conditions. A series of experiments were conducted using end milling of Ti-6Al-4V by varying feed rate and depth of cut, while the cutting speed was kept constant at comparatively higher cutting speed. Both uncoated and titanium aluminum nitride (TiAlN)-coated carbide tools were used for machining Ti-6Al-4V at the same settings of parameters. It was observed that abrasion was the most dominant tool wear mechanism for all dry, flood coolant and MQL machining conditions. Edge chipping and tool nose wear were the next dominating tool wear mechanisms in conventional flood coolant machining, which may be associated with the thermal fatigue caused by the periodic cooling of tool tip from the high temperature generated during machining. On the other hand, adhesion was the second most dominant tool wear mechanism in the dry machining. Both the edge chipping and adhesion of chips to the cutting tools were reduced significantly in MQL machining. The delamination of coating film was observed when TiAlN-coated carbide tools were used for machining Ti-6Al-4V. The delamination was more significant in wet and MQL machining compared to dry machining, indicating the effectiveness of coated tools in dry machining condition compared to wet and MQL machining conditions. Among three conditions, MQL provided the least occurrences of tool wear, indicating suitability of MQL in productive machining of titanium alloys.

Tribological and Wear Performance of Carbide Tools with TiB2 PVD Coating under Varying Machining Conditions of TiAl6V4 Aerospace Alloy

Tribological phenomena and tool wear mechanisms during machining of hard-to-cut TiAl6V4 aerospace alloy have been investigated in detail. Since cutting tool wear is directly affected by tribological phenomena occurring between the surfaces of the workpiece and the cutting tool, the performance of the cutting tool is strongly associated with the conditions of the machining process. The present work shows the effect of different machining conditions on the tribological and wear performance of TiB2-coated cutting tools compared to uncoated carbide tools. FEM modeling of the temperature profile on the friction surface was performed for wet machining conditions under varying cutting parameters. Comprehensive characterization of the TiB2 coated vs. uncoated cutting tool wear performance was made using optical 3D imaging, SEM/EDX and XPS methods respectively. The results obtained were linked to the FEM modeling. The studies carried out show that during machining of the TiAl6V4 alloy, the efficiency of the TiB2 coating application for carbide cutting tools strongly depends on cutting conditions. The TiB2 coating is very efficient under roughing at low speeds (with strong buildup edge formation). In contrast, it shows similar wear performance to the uncoated tool under finishing operations at higher cutting speeds when cratering wear predominates.

Comparative evaluations of machining performance during turning of 17-4 PH stainless steel under cryogenic and wet machining conditions

ABSTRACTProductivity in machining of 17-4 PH stainless steel is adversely affected by the premature failure of tool and poor surface finish as a consequence of high cutting temperatures. Conventional cutting fluids not only create environmental and health problems but also fail to overcome the high cutting temperatures during machining. Cryogenic cooling is an environmentally clean cooling technology for attractive management of machining zone temperatures. The present study investigates the effect of cryogenic liquid nitrogen (LN2 at −196°C) on cutting temperatures, cutting forces (main cutting force, feed force), surface roughness, tool flank wear and chip morphology in turning of 17-4 PH stainless steel with AlTiN PVD-coated tungsten-coated carbide inserts and results were compared to wet machining. In overall, cryogenic machining reduces the cutting temperature, cutting forces, surface roughness and tool flank wear to a maximum of 73.4, 17.62, 44.29 and 55.55%, respectively. Improved chip breakability was found in cryogenic machining.

Machinability studies on 17-4 PH stainless steel under cryogenic cooling environment

ABSTRACTUnder higher cutting conditions, machining of 17-4 precipitation hardenable stainless steel (PH SS) is a difficult task due to the high cutting temperatures as well as accumulation of chips at the machining zone, which causes tool damage and impairment of machined surface finish. Cryogenic machining is an efficient, eco-friendly manufacturing process. In the current work, cutting temperature, tool wear (flank wear (Vb) and rake wear), chip morphology, and surface integrity (surface topography, surface finish (Ra), white layer thickness (WLT)) were considered as investigative machinability characteristics under the cryogenic (liquid nitrogen), minimum quantity lubrication (MQL), wet and dry environments at varying cutting velocities while machining 17-4 PH SS. The results show that the maximum cutting temperature drop found in cryogenic machining was 72%, 62%, and 61%, respectively, in contrast to dry, wet, and MQL machining conditions. Similarly, the maximum tool wear reduction was found to be 60%, 55%, and 50% in cryogenic machining over the dry, wet, and MQL machining conditions, respectively. Among all the machining environments, better surface integrity was obtained by cryogenic machining, which could produce the functionally superior products.

Machinability enhancement of stir cast Al-TiCp composites under cryogenic condition

ABSTRACTThe current research work makes an attempt to develop a methodology in order to produce high-quality Al-TiCp composites by using systemized inert atmospheric stir casting facility. The quality of produced composites was characterized using microstructural, Energy-dispersive X-ray spectroscopy (EDX), and machinability studies. Atomized-Cryogenic-Liquid (ACL) spray machining technique was developed and used to enhance the machinability of composite. The results of microstructural analysis reveal that TiCp refines Al grain structure to 50 times lesser than non-reinforced Al grains along the full length of the casting. Energy-dispersive X-ray analysis confirms that no metallic reaction takes place. Machining studies reveal that atomized cryogenic liquid-spray machining significantly improves the quality of machined surface and reduces the progressive wear occurring on tool during turning of Al-TiCp composites in comparison with cryogenically chilled argon, wet, and dry machining conditions, respectively. The scientific methodology highlighted in this study helps to improve the productivity and reduces the manufacturing cost in various industrial applications.

Effect of machining parameters on surface finish of Inconel 718 in end milling

Surface finish is an important criteria in machining process and selection of proper machining parameters is important to obtain good surface finish. In the present work effects of the machining parameters in end milling of Inconel 718 were investigated. Central composite design was used to design the total number of experiments. A Mathematical model for surface roughness has been developed using response surface methodology. In this study, the influence of cutting parameters such as cutting speed, feed rate and depth of cut on surface roughness was analyzed. The study includes individual effect of cutting parameters on surface roughness as well as their interaction. The analysis of variance (ANOVA) was employed to find the validity of the developed model. The results show that depth of cut mostly affected the surface roughness. It is also observed that surface roughness values are comparable in both dry and wet machining conditions.

THE IMPACT OF BIODEGRADABLE CUTTING FLUID ON THE TRIBOLOGICAL PROPERTIES OF THE FRICTION PAIRS

This paper discusses the results of wear tests performed with a T-01 M tribometer for a ball-on-disc configuration in sliding contact. The tests were carried out for HS6-5-2C steel discs with and without a TiAlN coating deposited by physical vapour deposition (PVD), which were in contact with 100Cr6 steel balls. The tests were conducted under dry friction conditions and under lubricated friction conditions with a cutting fluid containing zinc aspartate. The coating structure was observed using a JSM - 7100F scanning electron microscope. The surface texture of the discs and the balls was analysed as well as good adhesion to the substrate. Coated tools can operate under dry and wet machining conditions, and they improve the operating parameters of the element. Such coatings can be produced by chemical vapour deposition (CVD), physical vapour deposition (PVD), or similar techniques [L. 8, 4, 13].

Machining of Carbon Fibre: Optical Surface Damage Characterisation and Tool Wear Study

Better control of fibre composites machining requires reliable surface roughness and damage characterisation measurements. The performance and tool wear rate of three different state of the art CVD and PCD cutting tools manufactured for carbon fibre machining were compared in wet and dry conditions. Machined surfaces were characterised by areal surface roughness parameters using a novel focus variation optical system. The tool wear and cutting forces were recorded up to 50 linear meters of machining or until tool failure. Results showed that wet machining conditions reduced tool failure; and that the CVD tool in wet conditions machined the greatest distance of 26m before reaching an average roughness limit of 3μm. The tool type was found to be the most significant parameter on the surface quality. The optical system was found to be a useful tool for measuring roughness of individual plies and characterising machining induced surface damage.

Application of Taguchi Method for Cutting Force Optimization in Metal Machining

To evaluate and optimize the cutting process from the effective, qualitative and economic point of view, the detailed knowledge about size, direction and orientation of cutting forces is necessary. Cutting forces are an important indicator of machining performance. It helps to understand every single action which occurs during the machining process. In this study, the influence of selected cutting parameters (cutting speed and feed rate) on the behavior of cutting force components were experimentally investigated. AlMgSi1 aluminum alloy (EN AW 6082) was milled in dry and wet machining conditions utilizing uncoated sintered carbide end mills with a different helix angle. Cutting force components were measured and statistically analyzed with using of ANOVA.

A comparison of laser beam machining of micro-channels under dry and wet mediums

Micro-channels have been fabricated in nickel-based superalloy (Inconel 718) through laser beam machining (LBM). Two machining mediums are employed: dry and wet medium. Under the dry medium, laser beam passes through air prior to strike with target surface while under wet medium, the laser beam first travels through a layer of distilled water and reaches the substrate after. For both the machining environments, effects of laser power, pulse repetition rate, and laser scan speed on machined channels’ width, depth, and taperness are investigated. A comparison of parametric effects on machined channels’ profiles has been carried out for the said machining conditions. The results reveal that LBM under distilled water is more productive than LBM under air environment. In one step, wet machining conditions allow to generate a set of two micro-channels, and dry conditions generate one micro-channel. Further, to achieve the optimum dimensions of micro-channels, the appropriate level of each of the investigated laser parameter is proposed.

Experimental investigation and optimization of cutting parameters in dry and wet machining of aluminum alloy 5083 in order to remove cutting fluid

Abstract Many problems such as health and environment issues are identified with the use of flood cutting fluids in machining processes. Considerable attention has been given to reduce or completely omit the cutting fluids, and meet the demands for environment-friendly cutting processes. In this study, the effects of cutting speed and undeformed chip thickness on cutting and feed force components and tool tip temperature were experimentally investigated in order to remove cutting fluid. AA5083-O wrought alloy with a high Mg content (4.5%) was machined in dry and wet machining conditions utilizing coated carbide tool. Two-factor (cutting speed and undeformed chip thickness) and five-level fractional experiment designs completed with a statistical analysis of variance (ANOVA) were performed. Mathematical models for cutting and feed force components and tool tip temperature were developed using the Response Surface Methodology (RSM). Results show that the output variables are significantly affected by the undeformed chip thickness. On the other hand, in the high cutting speed and low undeformed chip thickness, AA5083 can be machined without cutting fluid. Also, both cutting speed and undeformed chip thickness have statistical significance on the cutting and feed force components in dry and wet machining. Finally, the appropriate ranges for the optimal turning conditions were proposed for industrial production.

Experimental comparison of carbon-dioxide and liquid nitrogen cryogenic coolants in turning of AISI 1045 steel

This experimental work is carried out to investigate the performance and influence of cryogenic coolants such as CO2 (carbon dioxide) and LN2 (liquid nitrogen) on cutting temperature, cutting force, tool wear, surface finish and chip morphology in machining of AISI 1045 steel compared to wet machining. The results proved that the application of cryogenic coolants reduced the cutting temperature drastically which resulted in appreciable improvement in surface finish of the product and reduced tool wear. The use of cryogenic LN2 reduced the cutting temperature about 3–17% when compared to CO2 coolant. Application of CO2 reduced the cutting forces and improved the surface finish of the machined part to an extent about 2–12% and 2–14% respectively when compared to the use of cryogenic LN2 coolant. Tool wear was found to be less on the application of CO2 compared to the wet and LN2 machining conditions.

A Comparison of Dry and Wet Machining of SiC Particle-Reinforced Aluminum Metal Matrix Composites

This paper explains and demonstrates the machinability of dry and wet machining of SiC particle-reinforced aluminum metal matrix composites based on the experiments. The plunge surface experiments with mill-grinding method under wheel peripheral speed of up to 14.13m/s, feed rate 80mm/min and depth of cutting 50μm were carried out on a vertical CNC milling machine. The comparisons of dry and wet machining on the force composites and surface roughness (Ra) versus material removal volume were studied. The material removal volume was gained with the same machining parameters after an equal period of time. In most cases, the tangential mill-grinding force values are greater in wet machining condition than that in dry condition. But for normal mill-grinding force, the Fn values are much greater in dry machining condition than that in wet condition. And the normal mill-grinding force in wet machining increased quickly with increasing material removal volume. A better surface finish can be produced in dry machining than that produced by wet machining. The surface roughness decreased slowly with the increasing material removal volume and the surface roughness shows an insignificant decreasing trend in wet machining.

Experimental study of high-speed milling of SiCp/Al composites with PCD tools

In this paper, high-speed milling experiments on silicon carbide particle reinforced aluminum matrix (SiCp/Al) composites with higher volume fraction and larger particles were carried out using polycrystalline diamond (PCD) tools at dry and wet machining conditions. For comparison, a TiC-based cermet tool was also used in milling the same workpiece material at very low speed. Worn PCD and cermet tools were measured and extensively characterized by scanning electron microscopy at different machining conditions. Furthermore, the effect of cutting distance on milling force and surface roughness were also investigated. The results showed that the main tool wear mechanism in machining of this type of material was abrasion on the flank face, and it was verified that the TiC-based cermet tool was not suitable for machining SiCp/Al composites with higher volume fraction and larger particles due to the heavy abrasive nature of reinforcement.

Machining of Titanium Alloys with and without Coolant

Machining titanium is challenging due to its low thermal conductivity which results in very high temperatures at the tool/workpiece interface and in addition there is a tendency for titanium to react with most cutting materials, resulting in surface and subsurface deformation in the workpiece. This paper investigates the relationship between vibration and surface deformation that occurs while machining commercially pure titanium and Ti6Al4V alloy materials under both wet and dry machining conditions. The results have demonstrated that vibration monitoring (normalised peak frequency amplitude) can be used as a predictive tool for optimising the surface quality of the machined workpiece. Twinning plays a prominent role in the subsurface of the machined Grade 2 material.

Effect of Machining Parameters on Surface Roughness During Wet and DryWire-EDM of Stainless Steel

Surface integrity of Machined parts is one of the major machining characteristics that play an important role in determining the quality of engineering components. It is well-known fact that good quality surfaces improve the fatigue strength, corrosion and wear resistance of workpiece. The purpose of this study was to investigate the effects of Wire-Electrical Discharge Machining (WEDM) variables on surface topography of stainless steel. In the present work, the effects of pulse current and gap voltage on surface topography during wet and dry WEDM of stainless steel were investigated. It was evident that as the two process parameters increase the surface topography of workpiece becomes worse. The effect of both dry and wet machining conditions on surface topography is also reported in this paper.

Diamond tools wear and their applicability when ultra-precision turning of SiCp/2009Al matrix composite

Abstract The wear pattern and its mechanisms of single crystal diamond (SCD) and polycrystalline diamond (PCD) tools have been investigated experimentally and theoretically during ultra-precision turning of SiC particle-reinforced 2009 aluminum matrix composite under wet machining conditions. The results showed that microwear, chipping, cleavage, abrasive wear and chemical wear were the dominating wear patterns of SCD tools, and PCD tools mainly suffered from abrasive wear on the rake face and adhesive wear on the flank face. The local temperature increase in the workpiece material adjacent to the contact surface of SCD tool was approximately as high as 505 °C. The combined effects of abrasive wear of SiC particles and catalysis of copper in the aluminum matrix caused the severe graphitization of SCD tool with (rake face 1 1 0-flank 1 1 0) crystal orientation. The adhesive wear on PCD tool was induced by the intermittent growth and breaking off behavior of build-up-edge. SCD tool with the crystal orientation of (rake face 1 1 0-flank 1 0 0) had the best cutting performance among the three types of tools, by which the machined surface roughness Ra was less than 49 nm after cutting for over 9 km. PCD tool had a steady and favorable cutting performance and could produce acceptable surface quality when the cutting distance was less than 6 km, during which the value of Ra was less than 46 nm and varied in the range of 12–15 nm. For this tool, adhesive wear on the rake face and abrasive wear on the flank increased gradually with the increase of cutting distance. The flank wear value of PCD was only 50 μm which was slightly higher than that of straight-nose SCD (40 μm) when cutting for 6.22 km. For all the three types of tools, with the increase of cutting distance, the machining induced defects such as craters and scratches increased too. Especially, when cutting distance was long enough to cause severe tool wear, material swelling on the machined surface was severe due to the plastic side flow. The chips formed by PCD tool were more discontinuous and fragmentary than that for straight-nose SCD tool.

Enhancement of Wet- and MQL-Based Machining of Automotive Alloys Using Cutting Tools with DLC/Polymer Surface Treatments

Machining experiments using tooling prepared with thin perfluoropolyether (PFPE) lubricant films, which were applied to diamond-like carbon (DLC) PVD coatings, were compared to traditional tooling used in wet-machining conditions for the drilling of a cast aluminum-silicon B319 alloy. Multi-layered DLC + PFPE coatings show promise under minimum quantity lubrication (MQL) machining conditions of aluminum alloys. The positive impact on performance of this surface treatment is compared to wet machining by studying tool life, wear behavior and chip formation using coated cemented carbide drill bits. Cutting torque was measured in situ together with the characteristics of the chips. Also the chip cross-section micro-structure was evaluated using a scanning electron microscope (SEM).

The Influence of Process Parameters during Machining of Ti6Al4V Alloy

Ti6Al4V alloys are considered difficult materials to machine, especially at high cutting speeds due to their low thermal conductivity and specific heat which causes high localized cutting temperatures at the tool-workpiece interface. For these reasons machining titanium alloys usually results in excessive tool wear and its low modulus promotes chatter. This regenerative vibration or chatter is a significant problem. In the investigation reported here, vibration monitoring has been used to optimise machining processes by correlating machining process parameters with vibration severity. Machining experiments were carried out under wet and dry machining conditions while vibrations were measured and analysed. The results have demonstrated that the application of a vibration monitoring system can be an important tool to increase machining speed.