Dry Machining Conditions Research Articles

Experimental investigation on hard turning of AISI 4340 steel using cemented coated carbide insert

Hard turning is a developing technology that offers many potential advantages compared to grinding, which remains the standard finishing process for critical hardened surfaces. In this work, an attempt has been made to experimentally investigate hard turning of AISI 4340 steel under wet and dry condition using cemented coated carbide insert. Hardness of the workpiece material is tested using Brinell and Rockwell hardness testers. CNC LATHE and cemented coated carbide inserts of designation CNMG 120408 are used for conducting experimental trials. Significant cutting parameters like cutting speed, feed rate and depth of cut are considered as controllable input parameters and surface roughness (Ra), tool wear are considered as output response parameters. Design of experiments is carried out with the help of Taguchi’s L9 orthogonal array. Results of response parameters like surface roughness and tool wear under wet and dry condition are analysed. It is found that surface roughness and tool wear are higher under dry machining condition when compared to wet machining condition. Feed rate significantly influences the surface roughness followed by cutting speed. Depth of cut significantly influences the tool wear followed by cutting speed.

Control of tribofilm formation in dry machining of hardened AISI D2 steel by tuning the cutting speed

This study is focused on the investigation of nano-scale tribological effects formed during the machining of hardened material. Tribofilm formation was associated with the transfer of workpiece material to the cutting tool surface with further tribo-oxidation occurring through interaction with the environment. In addition to wear evaluation studies, a number of advanced surface analytical techniques were used to characterize surface phenomena, including X-ray photoelectron spectroscopy (XPS) and Auger Electron Spectroscopy (AES) (including AES imaging). This was combined with Scanning Electron Microscopy / Energy Dispersive X-Ray Spectroscopy (SEM/EDX) studies. Wear performance of uncoated ceramic (mixed alumina and TiCN) tools was studied in detail at different constant cutting speeds (50; 80; 100 and 120 m/min) and tuned through two-step and three-step cutting speed adjustments (120–100 and 120–100–80 m/min) during hard dry turning of AISI D2 tool steel. The tuning of the cutting speed was performed in order to enhance the generation of favourable tribofilms and obtain an extended tool life. As a result of these tuned cutting approaches, tool life was increased by 36% at 120–100 m/min and improved 99% at 120–100–80 m/min when tested separately. Both the two-step and three step speed adjustment involved enhanced formation of beneficial tribofilms on the tool surface under a higher cutting speed, with a subsequent lower speed preventing the wearing out of these films and thus sustaining the improved tribological conditions. This research provides a novel strategy to enhancing the efficiency of machining processes which operate under extreme tribological conditions of dry machining of hardened tool steels.

Machining and Machinability of Tool Steels: Effects of Lubrication and Machining Conditions on Tool Wear and Tool Life Data

The machinability of materials depends on various factors including the workpiece materials and condition, the cutting tool data and the machining conditions (wet or dry). Most tool life data found in literature are established using dry machining conditions. This makes it difficult to make suitable comparison with wet machining conditions, to compute cost effective machining conditions or to simulate the machining processes, especially for newly developed alloys. In the present paper, the machinability of tool steels is investigated using dry and wet milling process. Tools steels with different compositions and hardness were milled using carbide inserts and the tool wear/tool life performance studied. The coefficients of the Taylor model of tool life were established for each steel and then used to compute the economically speeds and the maximum productivity speeds. It was found that the dry milling is more advantageous for the tested steels, especially for roughing operations, but the tool life data in dry machining conditions was very sensitive to materials compositions and hardness compared to wet machining conditions.

An Experimental Study of Surface Roughness Variation in End Milling of Super Duplex 2507 Stainless Steel

This study focuses on surface roughness evaluation of SUPER DUPLEX 2507 stainless steel in dry and wet machining condition. Dryand wet milling experiments were conducted with three levels of cutting speed, feed rate and constant axial depth of cut. The effects of these cutting parameters on the surface roughness in dry and wet machining condition are evaluated. The multiple regression analysis has been applied to find the relationship between surface roughness and cutting parameters. The regression equation revealed that the feed rate is the most dominant factor that influences the surface roughness followed by the cutting speed. It is also concluded that surface finish obtained in wet machining is much better compared to dry machining.

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.

Experimental Investigations on the Machinability of Inconel 625 under Dry Cutting Environment

The main objective of present work is to experimentally investigate the machinability of Inconel 625 superalloy under dry machining conditions using a coated carbide insert (KCU10). The machining studies were performed in a CNC lathe. The cutting conditions were selected as per the preliminary experiments and inserts manufacturer catalogue. The parameters such as cutting speed and feed are chosen as variable parameters with three levels and depth of cut was maintained constant for all the experiments. The machinability indices such as tangential force, axial force, specific cutting pressure, surface roughness and tool wear were investigated for the chosen process parameters and the results are presented here.

Taguchi optimization of surface roughness and flank wear during the turning of DIN 1.2344 tool steel

Abstract In this study, a turning operation was applied to DIN 1.2344 hot work tool steel under dry machining conditions. The optimum machining conditions were determined by investigating the surface roughness (Ra) and the flank wear (Vb) depending on the machining parameters. Experiments were performed according to the Taguchi L9 orthogonal array and signal/noise (S/N) ratios were used in the evaluation of the test results. Optimum Ra and Vb values were determined by Taguchi optimization. The effects of the machining parameters on Ra and Vb were found with the help of analysis of variance (ANOVA). According to the ANOVA results, the most important parameter affecting Ra and Vb was feed rate. Two different multiple regression analyses (linear and quadratic) were conducted for the experimental results. A higher correlation coefficient (R2) was obtained with the quadratic regression model, which showed a value of 0.99 for both Ra and Vb. Finally, confirmation tests were performed and showed that the optimization has been successfully implemented. By the Taguchi analysis the optimum results for both surface roughness and flank wear were found to be a cutting speed of 120 m × min−1, a feed rate of 0.15 mm × rev−1 and a depth of cut of 0.5 mm. The results of the calculations and the confirmation tests for Ra were 0.84 μm and 0.80 μm, and for Vb, 0.0892 mm and 0.0824 mm, respectively.

ANN surface roughness prediction of AZ91D magnesium alloys in the turning process

Abstract This contribution presents an approach for the modeling and prediction of surface roughness in the turning of AZ91D magnesium alloys using an artificial neural network. The experiments were conducted with CCGT, DCGT and VCGT cutting tools under minimum quantity lubrication and dry machining conditions. AZ91D alloys were machined at different cutting speeds and feed rates, and the depth of cut was kept constant. 15 out of 18 experimental data points were used for the training of the artificial neural network model and the remaining 3 were used for the testing process. The average percentage error was calculated as 0.000815 % and 0.663 % for training and testing, respectively. The model and target results were found to have extremely low error rates.

Investigation of ionic liquids as additives to canola oil in minimum quantity lubrication milling of plain medium carbon steel

Minimum quantity lubrication (MQL) machining has been widely explored as an alternative to cutting fluids, which are known to be major sources of operator health hazards and environmental pollution. However, the lubricants employed in MQL machining have limitations and quest for a more sustainable and effective lubricant continues. Ionic liquids, which have been explored for many engineering applications including tribology, can be strong candidates as environmentally friendly lubricants for sustainable machining applications due to their eco-friendly nature and flexible physical as well as chemical properties. This study aims to investigate the feasibility and effectiveness of ionic liquids as lubricants in MQL machining, and to study their action mechanism as lubricants in extremely demanding conditions encountered in metal cutting. This paper presents the results of a pioneering study conducted to investigate the effects of three representative ionic liquids on the tribology of machining when applied as additives to vegetable oil (Canola) in MQL milling of a plain medium carbon steel. The results demonstrate that the presence of even small quantities of ionic liquids significantly affects the tribological conditions of the machining process, has a great potential to be applied to metalworking fluids in near dry machining conditions, and can be considered as a potential way to reduce forces during machining, thus reducing energy usage and achieving sustainable 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.

Sliding wear behavior of SPS processed TaC-containing Ti(CN)-WC-Ni/Co cermets against Silicon Carbide

Dense (>98.5%) TiCN-WC-Ni/Co cermets with or without TaC are prepared by spark plasma sintering technique at 1400°C and 70MPa pressure for 3min and their friction and wear properties are investigated against commercially available hard counterbody silicon carbide ball at 5, 10 or 20N load. Core-rim morphology is observed in SEM images of sintered samples which results due to dissolution and reprecipitation process. Vickers Hardness and fracture toughness varied from 15–17GPa and 8.79 to 9.51MPam1/2. Nano hardness of core-rim-binder phases of cermets lie between 11.14–26.01GPa. Maximum hardness and fracture toughness were obtained for Ti(CN)-5WC-10Ni-10Co-5TaC (in wt%) cermet. With change in the cermet composition and sliding load, coefficient of friction varied from 0.3 to 1.1. Wear rate of cermets varied from 4.7×10−7mm3/Nm to 2.2×10−6mm3/Nm and of worn SiC ball from 4.4×10−7mm3/Nm to 1.5×10−6mm3/Nm. Hard debris oxides are responsible for higher COF at low load of 5N and their compaction leads to the formation of tribolayer at high load of 20N. The worn surfaces of cermets are characterized by microcracking, tribolayer formation and spalling. The addition of TaC in TiCN-WC-Ni/Co cermets led to the refined carbide size having lowest contiguity of ceramic phase and attributed to reduced wear. Present research contributes in context of dry machining conditions and is conducted to explore the potential of new cermet material in severe wear conditions against hard material.

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.

High temperature oxidation resistance of CrN/(Ti, Al, Zr, Cr)N bilayer films deposited by multi-arc ion plating

CrN/(Ti, Al, Zr, Cr) N bilayer films were successfully deposited on cemented carbide (WC-8%Co) substrates by multi-arc ion plating process using two Ti-Al-Zr alloy targets and one pure Cr target. As a result of bilayered structure and addition of alloying elements (e. g. Al and Cr), the films exhibited excellent high temperature oxidation resistance under both short-term isothermal (up to 800 °C) and long-term cyclic (up to 600 °C) exposure conditions. Combined with pre-established outstanding tribological properties (e. g. maximum hardness of 4000 HV0.01 and maximum adhesion strength over 200 N), these observations make such films quite a promising candidate to extend the cutting tool life span and boost the performance in high-productivity, high-speed and high-feed cutting or in dry machining conditions.

Parametric optimisation for surface roughness of AISI 4340 steel during turning under near dry machining condition

The objective of this investigation is to find the best feasible machining parameters in order to obtain better surface quality. The turning operation is carried out with TiN coated carbide insert on AISI 4340 steel under near dry machining condition. The machining parameters, namely cutting velocity, feed rate and depth of cut are chosen for the conduct of experiments based on L9(33) orthogonal array. The surface roughness of the machined work piece is measured by using surface roughness tester. A mathematical model representing average surface roughness is developed using nonlinear regression analysis with the help of MINITAB software. The optimum machining conditions for minimum surface roughness are determined through Taguchi's technique and genetic algorithm and verified with confirmation experiments.

Effects of different cutting conditions on the surface roughness parameters of iron-copper-carbon powder metallurgy composites

Metal matrix composites gained higher importance in the last decades. Due to the porous structure and the wide range of material compositions, the secondary machining of these materials poses several difficulties for the manufacturers. In this work, the effect of cutting parameters such as cutting speed, feed rate, depth of cut, directions of cut and different cooling types were investigated during the face milling of iron-based sintered metals made by powder metallurgy. A full factorial design was selected for the reliable experiments. Main effect analyses have been carried out to know the significance of the input parameters. Surface roughness parameters (Ra and Rz) were selected as response parameters. The applicability of simple models for predicting the surface roughness parameters based on the measured data were also investigated. The investigations revealed that dry machining conditions and high cutting speeds resulted in better surface roughness values.

Optimization of Machining Parameters for surface roughness on turning of Niobium alloy C-103 by using RSM

The focus of this research work is to study the effect of cutting parameters – speed, feed and depth of cut on the machinability of Niobium C-103 under dry machining condition using response surface methodology1 (RSM). Niobium based superalloys are an unusual class of metallic materials with an exceptional combination of high temperature strength, toughness, and resistance to degradation in corrosive or oxidizing environments2. In present study various machinability models were developed. This machinability models defined a functional relationship between cutting variables and responseof surface roughness. Cutting levels for experimentation was selected based on the cutting insert manufacturer recommendations. The Analysis shows that Feed is the most evident factor for Surface Roughness.

Technical, Economic and Environmental Review of the Lubrication/Cooling Systems Used in Machining Processes

The use of cutting fluids in machining processes is a serious concern because their cost, and environmental and health effects. In the last decades, efforts have been developed to come up with alternatives to overcome their main drawbacks. The ultimate goal is the complete suppression of cutting fluids. However, because of the demanding requirements of the machining processes, in some cases it is not possible to use dry machining conditions. Reasons can be found in the excessive heat generated in the process, the increase of the friction between the tool and the workpiece or the need to evacuate the chips generated. The pull for sustainable products is also encouraging the developing of new cutting fluid formulations. In the present paper, a comprehensive analysis of the use of cutting fluids and main alternatives in machining is carried out. Particularly, the analysis was done focusing on the economic, environmental and technical points.

Parametric optimisation for surface roughness of AISI 4340 steel during turning under near dry machining condition

Parametric optimisation for surface roughness of AISI 4340 steel during turning under near dry machining condition

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.

Comprehensive study on machinability of sustainable and conventional fibre reinforced polymer composites

The conventional homogeneous materials can no longer effectively satisfy the growing demands on product capabilities and performance, due to the advancement in products design and materials engineering. Therefore, the fibre reinforced composites (FRCs) with better properties and desirable applications emerged. These enhanced qualities of the FRCs have emphasized the need for analysing their machinability for further improvement of performance. Hence, this paper presents a comprehensive investigation on the machinability effects of drilling parameters (feed rate, cutting speed and thrust force), drill diameters and chips formation mainly on delamination and surface roughness of hemp fibre reinforced polymer (19/HFRP) and carbon fibre reinforced polymer (MTM 44-1/CFRP) composite laminates, using high speed steel (HSS) drills under dry machining condition. The results obtained depict that an increase in feed rate and thrust force caused an increase in delamination and surface roughness of both samples, different from cutting speed. Also, increased drill diameter and types of chips formation caused an increase in both delamination and surface roughness of both samples, as the material removal rate (MRR) increased. Evidently, the minimum surface roughness and delamination factor of the two samples for an optimal drilling are associated with feed rates of 0.05–0.10mm/rev and cutting speed of 30m/min.