Dry Machining Conditions Research Articles

Dry machining of metal using an engraving cutter coated with a droplet-free ta-C film prepared via a T-shape filtered arc deposition

Abstract Tetrahedral amorphous carbon (ta-C) films were prepared on cutters which are used for engraving. Engraving tests were performed on metal plates using non-coated and ta-C-coated cutters, under dry machining conditions, without oil. Generally, the metal plate is engraved using a cemented carbide (WC-Co) cutter, which uses oil for the cutting process, to fabricate a nameplate. The oil causes a high environmental load and complicates the machining process. Therefore, from an industrial viewpoint, there is a need for a dry machining process. The ta-C film is a hydrogen-free diamond-like carbon film with a high mechanical hardness. In this study, droplet-free ta-C films were prepared on WC-Co cutters using a T-shape filtered arc deposition method. The work materials used in the engraving tests were aluminum, copper, and brass. The results of the engraving tests demonstrated suppression of metal adhesion to the cutting edge, prevention of chipping of the cutting edge, and a decrease in cutting resistance during engraving when a ta-C film had been coated onto the cutting edge. In addition, burr and residue on engraved grooves were also suppressed by using a ta-C-coated cutter. The ta-C film coating offered a remarkable improvement in the engraving performance of a WC-Co cutter in the dry machining process.

Influence of B4C particle reinforcement on mechanical and machining properties of Al6061/B4C composites

Abstract This study investigates the mechanical and machinability properties of the aluminum 6061 reinforced with boron carbide (B4C). Four aluminum 6061 composite specimens reinforced with 5 wt%, 10 wt%, 15 wt%, and 20 wt% B4C were fabricated using a powder metallurgy and hot-extrusion method. The composite samples were investigated to elucidate the influence of different weight fractions of B4C reinforcement content on the hardness, fracture toughness, tensile strength, transverse rupture strength (TRS) and milling properties of the resulting composites. The milling tests were performed based on the Taguchi mixed-orthogonal-array for experiments, L16 (44 × 21), to determine the effect of B4C content on surface quality and energy consumption for different cutting parameters under dry- and compressed-air cooling and using an uncoated carbide insert. The results reveal that the B4C particles are uniformly distributed in the matrix and that the fracture toughness decreases and the hardness increases as the weight fraction of the reinforcement increases. The highest tensile and transverse rupture strength are for Al6061/5 wt% B4C and Al6061 reinforced with 10 wt% B4C composite material has the best fracture toughness from among the specimens measured. At higher milling speed and lower cutting feed and under dry machining conditions, an excellent surface quality is obtained after milling all composites materials and the surface finish improves with increasing B4C content in the matrix. The power consumption and surface roughness increases when cooling with compressed air.

Ultra-Low-Frequency Vibration Assisted Machining of Ti-6Al-4V Alloy

As titanium alloys such as Ti-6Al-4V provide several benefits, including high-temperature strength and high corrosion resistance, the demand for such materials has rapidly increased, particularly in the aircraft industries. On the other hand, they are known to be among the most difficult-to-cut materials due to their mechanical and chemical properties, which make tool life extremely short. In order to solve this problem, this paper proposes a new cutting method employing ultra-low-frequency (ULF) vibration. ULF vibration ranges from less than 1 Hz to approximately 10 Hz and is generated by using a numerically-controlled machine tool axis and an NC program. The results of turning experiments showed that the developed method significantly reduces crater wear in the machining of Ti-6Al-4V, even under dry machining conditions. Moreover, the mechanism that ULF vibration affects and the effect of actual cutting time and non-cutting time in each individual vibration period on the amount of crater wear were investigated. As a result, it was found that the developed process is a promising method for achieving high performance dry machining of titanium alloys.

Study on Machining Parameters for Thrust Force and Torque in Milling AA7039 Composites Reinforced with Al2O3/B4C/SiC Particles

Metal matrix composites are used in many industrial fields such as automobile, military and aerospace applications due to their superior mechanical properties. In the present study, three aluminum 7039 metal matrix composite (MMCs) samples reinforced with 10 wt.% particulates of aluminum oxide (Al 2 O 3 ), 10 wt.% boron carbide (B 4 C), and 10 wt.% silicon carbide (SiC) were successfully fabricated using a powder metallurgy and hot extrusion method. The influences of cutting parameters on the thrust cutting force and torque during milling of the three MMCs were investigated under dry machining conditions. The milling tests were performed based on the Taguchi orthogonal -array design of experiments, for different machining parameters such as cutting speed, feed and depth of cut. The effect of reinforcement contents on cutting force and torque were specified by utilizing analysis of variance (ANOVA). Mathematical models have been generated for the thrust force and torque through regression method. The results indicated that the minimal thrust force and torque were obtained in the machining of the Al 2 O 3 reinforced specimen. The cutting force was directly influenced by the cutting feed and the axial cutting depth was the most effective machining parameter affecting milling torque in the machining of three composite specimens. The experimental results were modeled using regression analysis and artificial neural networks (ANN) to predict the thrust force and torque. The thrust force and torque were predicted with a mean squared error equal to 5.85% and 5.12% respectively using ANN models.

Modelling and Optimization of Tool Chip Interface Temperature and Surface Roughness in CNC Dry Turning of EN 24 Steel

Abstract. Kinetic energy of a machining process is converted into heat energy. The generated heat at cutting tool and work piece interface has substantial impact on cutting tool life and quality of the work piece. On the other hand, development of advanced cutting tool materials, coatings and designs, along with a variety of strategies for lubrication, cooling and chip removal, make it possible to achieve the same or better surface quality with dry or Minimum Quantity Lubrication (MQL) machining than traditional wet machining. In addition, dry and MQL machining is more economical and environment friendly. In this work, 20 no. of experiments were carried out under dry machining conditions with different combinations of cutting speed, feed rate and depth of cut and corresponding cutting temperature and surface roughness are measured. The no. of experiments is determined through Design of Experiments (DOE). Nonlinear regression methodology is used to model the process using Response Surface Methodology (RSM). Multi-objective optimization is carried using Genetic Algorithm which ensures high productivity with good product quality.

Hole diameter variation and roundness in dry orbital drilling of CFRP/Ti stacks

The inevitable problem of machining accuracy that follows accelerated tool wear deters severely the drilling of carbon fiber reinforced plastics/titanium (CFRP/Ti) stacks and is attributed to the cutting mechanism inherent to drilling and drill geometry. This paper develops orbital drilling of this stacked material by use of a special cutter under a dry machining condition and analyzes the characteristics of the variation in hole diameter and roundness. The influence of spindle speed for both CFRP and Ti alloy segments, and the bore and tool diameter ratio on these indexes with progressive tool wear is further studied. The experimental results show that the hole diameter at the CFRP exit always maintained the maximum value; spindle speed when machining different segments can improve or decrease these hole accuracy indexes, and the ratio of bore and tool diameter has greater influence on the roundness of the CFRP layer than that of the Ti alloy layer.

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].

Hole-making and its Impact on the Fatigue Response of Ti-6AL-4V Alloy

In this work, the impact of conventional drilling and helical milling processes on the fatigue response Ti-6Al-4 V (grade 5 titanium alloy) has been presented. Results show that the work pieces produced by helical milling has a 119% longer fatigue life compared with the drilled pieces under dry machining condition, and a 96% longer fatigue life for helical milled piece under lubricated condition. The use of cutting fluid has led to longer fatigue lives – 15% longer for drilling and 3% longer for helical milling. Other results such as the machined surface roughness, alloy surface and sub-surface microstructures have also been studied in details.

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.

Effects of drilling parameters and aspect ratios on delamination and surface roughness of lignocellulosic HFRP composite laminates

ABSTRACTHemp fibre‐reinforced polycaprolactone (HFRP) composite has inherent good mechanical properties and benefits which include remarkably high specific strength and modulus, low density, and renewability. No doubt, these properties have attracted wider applications of HFRP composite in engineering applications. This paper presents an investigation on the influence of drilling parameters and fibre aspect ratios, AR (0, 19, 26, 30, and 38) on delamination damage factor and surface roughness of HFRP composite laminates utilising high speed steel twist drills under dry machining condition. Taguchi's technique was used in the design of experiment. The results obtained show that increase in cutting speed reduces delamination factor and surface roughness of drilled holes, whereas increase in feed rate causes increase in both delamination factor and surface roughness. Feed rate and cutting speed had the greatest influence on delamination and surface roughness respectively when compared with aspect ratio, while an increase in fibre aspect ratios leads to a significant increase in both delamination factor and surface roughness. The optimum results occurred at cutting speed and feed rate (drilling parameters) of 20 mm/min and 0.10 mm/rev, respectively, when drilling sample of AR 19. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 42879.

Study on optimized principles of process parameters for environmentally friendly machining austenitic stainless steel with high efficiency and little energy consumption

Green manufacturing is one of the important development directions for advanced manufacturing technology. In this paper, the orthogonal turning experiment of multiple factors with the minimal quantity lubrication (MQL), dry machining, and wet machining is designed to contrast the machinability for austenitic stainless steel in order to realize environmentally friendly machining with high efficiency, excellent surface quality, energy conservation, and little consumption for austenitic stainless steel. On the basis of the experiment results, in which the conditions of MQL or dry machining instead of wet machining are given, the optimized principle of process parameters for high surface quality and environmentally friendly machining austenitic stainless steel with high machining efficiency and little energy consumption is found and proposed by the comprehensive evaluation of the integrated mechanism of the process parameters with relative cutting-specific energy, unit cutting force, surface roughness, and process condition of MQL and dry machining. The research conclusions have theoretical and practical importance for production and process to give the relevant optimized principle of process parameters for machined hardening stainless steels by studying the integrated mechanism of the process parameters especially on the basis of the orthogonal experiment of multiple factors with little experiment consumption and cost.

Graphene oxide colloidal suspensions mitigate carbon diffusion during diamond turning of steel

Diamond-based cutting tools are preferred by the manufacturing community to machine high-value, hard-to-cut materials, especially for applications with stringent surface roughness requirements. However, these tools are not an economically viable option to machine any of the transition metals or their alloys. This is due to the extreme rates of tool wear caused by chemical diffusion of carbon from the diamond tool into the transition metal/alloy workpiece. In this paper we report the use of carbon-rich, graphene oxide colloidal suspensions, as a cutting fluid, to address this critical diamond tool wear issue. Our machining tests conducted on a low-carbon steel alloy reveal that the use of graphene oxide colloidal suspension results in a ∼74% reduction in the tool wear over that seen under the dry machining condition. It also results in a ∼50% reduction in the cutting temperatures and a ∼20 to 30% reduction in the cutting forces, when compared against the dry machining condition. The trends seen in the cutting temperatures, cutting forces and the X-ray photoelectron spectroscopy (XPS) data collectively point to the possibility of the graphene oxide platelets serving as a barrier to the carbon diffusion reaction. These findings have the potential to make diamond a cost-effective tool material for machining transition metal-based materials such as ferrous and titanium alloys that have wide-spread engineering applications.

Evaluation of correlation between vibration signal features and three-dimensional finite element simulations to predict cutting tool wear in turning operation

This article presents the correlation of vibration signal feature, that is, displacement due to vibration (microns) during the machining and three-dimensional finite element simulations in tool wear monitoring of a metal turning operation. Machining of AISI 1040 has been carried on using an uncoated inserts and online vibration signals acquired using a laser Doppler vibrometer. The measured tool wear forms correlate to features in the vibration signals in frequency domains. Analyses of the results suggested that the vibration signals’ features are effective for use in cutting tool wear monitoring and wear qualification. Present work demonstrates the three-dimensional finite element analysis to predict the workpiece displacements in feed direction and corresponding tool wear with the help of induced vibrations in face turning under dry machining conditions. Vibration-assisted turning model is developed and validated by comparing the simulation results with experimental results. In this research, three-dimensional finite element modelling and simulation issues for vibration-assisted turning are explored in detail. Machine dynamic effects are taken into account to predict the outcomes such as tool wear displacements and chip formation. The model can be implemented in an online tool wear monitoring system which predicts the actual state of tool wear in real time by correlating displacement variations during the machining. The correlation between the displacement due to vibration and flank wear has been evaluated through three-dimensional finite element modelling and simulation. Comparisons of simulations with experimental results demonstrate their predictive capability. From the results, useful conclusions may be drawn, and it can be stated that the proposed models can be used for industrial application.

Analysis of thrust force in drilling B4C-reinforced aluminium alloy using genetic learning algorithm

This paper presents an analysis for the prediction of thrust force in drilling of aluminium-based composites, reinforced with boron-carbide B4C produced with the powder-metallurgy (PM) technique. The formulation was derived on experimental bases. The experiments were conducted with various cutting tools and parameters on conditions of dry machining in a computer numerical control (CNC) vertical machining centre. The thrust forces were obtained by measuring the forces between the drill bit and the work pieces during the experiments. In the experiments, particle fraction, feed rate, spindle speed and drill bit type were used as input parameters, and thrust force was the output data for the gene expression programming (GEP) software. Customizing for formulation in order to describe the problem was generated by GEP, and it was analysed from different perspectives and verified the reliability of equation.

Experimental investigation on surface finish during intermittent turning of UNS M11917 magnesium alloy under dry and near dry machining conditions

In the last decades, light materials, such as magnesium, are increasing their use in a wide range of industrial applications. The growing use of magnesium encourages the study of its use under different production processes. In this sense, the present study shows an experimental investigation in intermittent turning of UNS M11917 magnesium alloy, analysing different machining conditions: cutting speed, depth of cut and feed rate, along with the use of dry machining and minimum quantity lubrication (MQL) system. To evaluate intermittent turning process, continuous bars and slotted bars were used. The process is evaluated taking as response variable the surface roughness. Full factorial experimental designs are used and their results are analysed using the Analysis of Variance (ANOVA). Main results of the statistical analysis include the identification of feed rate as the main significant factor for all the tests, explaining the most part of the variability analysed. By contrast, cutting speed and type of interruption were not found to be significant sources of variability when analysed in isolation. Moreover, more dispersion of surface roughness values, in terms of Ra, was identified when machining at low feed rates which can difficult its prediction. In addition, when analysing depth of cut, this factor and its interaction with feed rate are also found to be significant sources of variability for Ra. Finally, the influence of the environment used in the machining process is also studied, finding that the use of the MQL system can lead to slightly worse surface roughness (Ra) results at the higher feed rates tested.

Experimental investigation on removing cutting fluid from turning of Inconel 725 with coated carbide tools

Abstract The aim of this study is to investigate the feasibility of removing cutting fluids from turning process of Inconel 725. For this purpose, the effects of machining parameters such as cutting speed, feed rate and depth of cut on machining forces were investigated. These forces include feed force, thrust force and cutting force. In addition, surface roughness was examined in both conditions of dry machining with coated tool and wet machining with uncoated tool. Results showed that in contrast with conventional machining processes, cutting speed and coating of tool are the most important parameters in removing cutting fluids. The data obtained from the tests indicated that in machining with coated tool with special ranges of parameters, cutting fluid could be completely removed from machining process. Furthermore, for both of dry and wet machining, the optimum ranges of parameters were presented in order to reach a green manufacturing process.

Hard Broaching of Case Hardened SAE 5120

To achieve knowledge of the effects of broaching to the component and the influence on subsequent process steps such as heat treatment and hard machining, broaching experiments were performed on plates made of normalized case hardening steel SAE 5120 in [1]. To investigate the effect of heat treatment, five broaching variants of [1] were chosen and hardened with two different case hardening depths, which were observed for effects generated from the surface layer carbon fraction. The hardened variants were analyzed for distortion generated through the hardening step and the specimen subsequently underwent a hard broaching stage in dry machining conditions. The cutting forces were monitored in-process, and the residual stress of the machined surface was determined using X-ray diffraction after the experiment. Surface roughness measurements also complemented the results. The results indicated that the cutting forces depend on existing distortion and therefore the volume material removed. It can also be seen that there is little influence on cutting forces with rising cutting speeds. Compressive residual stresses were present after heat treatment, but turned into tensile residual stress states after hard broaching. Effects from different case hardening depths and cutting speeds in the formation of surface roughness and residual stress could not be detected.

Effect of Machining Parameters on the Surface Roughness while Turning Particulate Composites

Metal matrix composites being used in automobile, aviation, naval, space and other structural applications because of their unique balance of physical and mechanical properties. The metal matrix composites are produced using diverse technologies in order to meet the market demand such as lower density, higher wear resistance, thermal stability at lower cost per component. Composite materials replace almost all the monolithic material while posing challenges for machining hence are graded as difficult to machine materials. The hetrogeneous structure of the composite materials leads to the failure of cutting tool during machining composites are mainly attributed for the presence of hard particles which leads to higher surface roughness value. Thus, present paper presents the results on surface roughness values of K10 grade carbide and Poly Crystaline Diamond (PCD) inserts while turning Al6061-flyash composites containing 0% to 15% fly ash in step of 5%. Parametric studies have been carried out as per ISO3685 standards following dry machining condition. The machining parameters are cutting speeds of 300m/min to 600m/min in step of 100m/min, feed of 0.06mm/revolution to 0.24mm/revolution in step of 0.06mm/revolution using a constant depth of cut of 1.2mm which is equal to three times to the nose radius of the cutting tool. The results revealed that PCD inserts exhibits lower surface roughness while turning composites containing 10% filler material when compared with that of K10 grade tungsten carbide insert.

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.

Tool-wear analysis in cryogenic machining of NiTi shape memory alloys: A comparison of tool-wear performance with dry and MQL machining

Extremely high tool-wear rate in machining of NiTi shape memory alloys (SMAs) is one of the major reasons for limiting the use of conventional machining processes on NiTi. The present study begins to address this issue by examining the effects of cryogenic cooling on tool-wear rate and progressive tool-wear by comparing the new findings from cryogenic machining with results obtained from minimum quantity lubrication (MQL) and dry machining conditions. Flank wear at the nose region, notch wear at the depth of cut boundary, and resulting machining performance criteria such as force components and surface quality of machined samples were studied. The findings from this research demonstrate that cryogenic cooling has a profound effect on controlling tool-wear rate and that the progressive tool-wear in machining of NiTi shape memory alloys can be significantly reduced by cryogenic machining.