Dry Machining Process Research Articles

Towards sustainable machining of 17-4 PH stainless steel using hybrid MQL-hot turning process

The use of a minimum quantity of lubrication (MQL) with extremely low consumption of lubricant in machining processes has been reported as a technologically and environmentally feasible alternative to conventional flood cooling. In hot machining, the external heat source is applied during machining that will assist to increase machining performance. Many external heating techniques are available and each type has advantages/disadvantages. 17-4 PH stainless steel (AISI630) is martensitic stainless steel, which is widely used in energy equipment, aerospace and petrochemical industries. The objective of the present paper is to integrate MQL technique, for the first time, with a hot turning process for finding an optimum possible hybrid technique for a particular machining process. The effects of different machining parameters on MQL turning of 17-4 PH stainless steel have been investigated in comparison with dry and wet machining processes. Experiments were also designed for machining using MQL and dry techniques to evaluate surface roughness, tool wear, machined surface morphology, chip morphology as well as chip formation mechanism under different pre-heating temperatures. The results show that applying MQL technique with online thermally enhanced turning (MQL-hot turning) increases the efficiency of machining of 17-4 PH stainless steel. The cutting parameters and pre-heating temperature are important parameters and should be selected carefully when using hybrid MQL-hot turning. In addition, machining with MQL is beneficial to the environment and machine tool operator health as lubricant consumption during operation with MQL is 7-fold lower than in the conventional system.

Evaluation of Tool Life in the Dry Machining of Inconel 718 Parts from Additive Manufacturing (AM)

The need for developing sustainable manufacturing processes are more and more increasing due to environmental regulations that are introduced worldwide. In the field of manufacturing metallic parts, the dry machining process is the effective way to reduce the costs of production and to avoid harm in environment and human health. Especially, Inconel 718 parts, which is very popular in aerospace, chemical, and nuclear industries, produced with additive manufacturing require a finishing process for quality assurance to rough and porous surfaces after printing process. Generally, machining of difficult-to cut materials such as Inconel 718 need the cutting fluids to improve the surface integrity and tool life. The present work investigates the effect of microstructure life of the Inconel 718 part produced by additive manufacturing on the tool compared with the wrought Inconel 718 part during the dry machining. The experimental findings show that the tool life of the Inconel 718 from AM is increased due to the melt pool microstructure formed by the laser irradiation though the hardness is higher than the wrought Inconel 718. Abrasive wear is strongly affected to tool life of the Inconel 718 from AM while adhesive and fracture wear is mostly found in the tool of wrought Inconel 718.

Exergy efficiency optimization model of motorized spindle system for high-speed dry hobbing

High-speed dry hobbing (HSDH) has been regarded as an environmentally benign gear machining technique. Current research on energy efficiency of machine tool focuses on the energy efficiency for workpiece material removal but rarely involves the energy consumption required to control thermal stability. Due to the fact that thermal effect dominates the machining accuracy and accuracy consistency, especially in the dry machining process, the energy consumption for thermal stability control should be taken as useful energy consumption. In view of this, by taking the motorized spindle system (MSS) as the study objective, which is a core subsystem of machine tool enabling HSDH and characterizes intensive and inefficient energy consumption, an exergy-based method is proposed to evaluate the comprehensive energy efficiency of MSS. Furthermore, an exergy efficiency optimization model is proposed to maximize total exergy efficiency and minimize average temperature of MSS. A solution method integrating Pareto Dominant-based Multi-objective Simulated Annealing (PDMOSA) and Technique for Order of Preference by Similarity to an Ideal Solution (TOPSIS) is proposed to search the best solution of the optimization model. A case study is introduced to validate the proposed model and a final optimal solution is obtained at the total exergy efficiency of 53.5% with balanced temperature of 35.4 °C. The cooling water in MSS is identified to be a dominant factor that affects total exergy destruction. The presented model can give a reference to select appropriate process parameters of MSS for green and precision machining.

Effects of continuous minimum quantity lubrication with ultrasonic vibration in turning of titanium alloy

Minimum quantity lubrication (MQL) technique has been widely used in different machining processes. However, oil mist discharged from MQL system induces negative effects for working space. In this paper, a continuous MQL system with ultrasonic vibration (U-CMQL) is proposed for near dry machining process. A valve-less micro-pump is designed to supply continuous lubrication to the cutting edge without making oil mist. Penetration mechanism of micro lubrication in ultrasonically assisted machining (UAM) process is firstly analyzed. Experiments are carried out to study the influence of dry machining, ultrasonically assisted machining, and U-CMQL machining on turning performance of Ti–6Al–4V alloy. Cutting force, tool wear, surface roughness, and chip morphology are experimentally analyzed. The results show that U-CMQL technique not only maintains neat working area but also improves the machinability characteristics to some extent. In comparison with dry machining and ultrasonically assisted machining, U-CMQL shows lower cutting force and tool wear rate due to the combined advantages of lubrication and vibration. Moreover, short tool-chip contact length, favorable chip morphology, and better surface integrity are obtained under U-CMQL machining.

Reducing deformation, stress, and tool wear during milling processes using simulation-based multiobjective optimization

This paper presents the optimization of a dry machining process where thermomechanical effects like shape deviations and a time-dependent domain are major challenges. First, the simulation model to compute finite element approximations to a general milling process is presented. The model includes a submodel (dexel model) for material removal and process forces and heat flux introduced by the machining tool. In a second part, we present a multiobjective optimization algorithm based on metamodels that serve as a tool to identify the process parameters that improve processes with different performance measures that exhibit conflicting behavior. With this metamodel-based optimization method, we avoid the use of a large number of high-fidelity computer simulations, which are commonly computationally expensive. The approach is tested on two case studies for optimizing (a) workpiece deformation and equivalent stress after milling, and (b) shape error and tool wear.

Tool life enhancement in dry diamond turning of titanium alloys using an eddy current damping and a magnetic field for sustainable manufacturing

Titanium alloys are widely applied in the aerospace, automobile, and biomedical industries for manufacturing precise components because of their excellent material properties. However, titanium alloys are regarded as difficult to cut materials due to their low thermal conductivity, the resulting serious tool wear and poor surface integrity inevitably lead to high machining cost and energy consumption. On the other hand, uses of fluid lubricant in machining processes of titanium alloys are sizable in order to provide an effective cooling media to dissipate high cutting heat generated in machining. Although the use of lubricant has been discouraged because of the drew damages to the environment and health, dry machining of titanium alloys is not practical currently as high friction force and cutting temperature induced from the dry machining environment which further accelerate and worsen tool life. Therefore, the environmental concerns cover a feasibility of dry machining of titanium alloys; In this study, a novel machining technology, a magnetic field was applied in dry single point diamond turning (SPDT) of titanium alloys to enhance diamond tool life, which aims to overcome the machining difficulties of dry machining. An eddy current damping effect reduces the machining vibration of rotating workpiece and a magnetic field enhances the thermal conductivity of tool/workpiece interface in SPDT, which help to relieve the problematic sources of tool damage in dry machining process. Under the influence of magnetic field, experimental results showed an improvement of surface integrity of machined surface, reductions of adhesive wear, flank wear and built up edge of tool as well as the machining vibration in dry SPDT. The proposed machining technology minimizes the environmental damage of wet machining, uplifting tool life and surface quality of machined components simultaneously, it offers a feasibility of environmental friendly dry SPDT of titanium alloys in practical applications, providing sustainable manufacturing for high precise products.

Penyelidikan Perilaku Interaksi Kimiawi Lapisan Diamond Film Pahat Karbida Pada Operasi Bubut Kering Bahan Al 6061

The purpose of the research was to characterize diamond-film coating which is used as carbide tool coating material, especially coating material (diamond-film CVD) and substrate material (WC/Co) in general approach interaction of chemically, This is related to the research which reported about the functional failure of carbide tool coating material, used in dry machinery process of non-ferro metal in the initial wear. The study on the characteristics of tool diamond-film coating was conducted through chemical interaction approaches which occurred between the working object and tool through dry machining process. Cutting condition was v= 350 m/min; f= 0.15 mm/put; a= 1.5 mm in Initial-wear phase (tc= 1.736 min). The result of the test was abrasive wear VB = 0.070 mm. Chemical load was tested through micro analysis using energy dispersive analysis X-Ray spectroscopy (EDAX), the result of the test was the distribution of diamond-film coating elements in aluminum 6061 testing material on the cutting conditions indicated that diamond-film coating material was still significant. The conclusion of the study was that by using chemical interaction approaches, was no coating delamination in diamond-film coating of carbide tool. The phenomenon of the three approaches was the gradual disappearing of a part of the volume of diamond-film coating material which layered substrate material as the result of abrasive-coating wear.

Measurement of burr removal rate and analysis of machining parameters in ultrasonic assisted dry EDM (US-EDM) for deburring drilled holes in CFRP composite

An ultrasonic assisted dry electrical discharge machining (US-EDM) process in a gaseous fluid medium was proposed to remove the burrs formed on the exit region of a drilled hole. In preliminary experiment, three different electrode tools (copper, brass, and aluminum) were utilized. In secondary experiment, US-EDM and dry-EDM were compared and performed using the copper tool. US-EDM parameters, such as capacitance (C), pulse-on time (TON), and vibration amplitude (Ap-p) were considered as functions of the predicted burr removal rates (BRRs) model. Based on signal to noise (S/N) ratio analysis, machining parameters C=10−2µF, TON=150µs, and Ap-p=4.919µm provided the optimal BRR. The BRR was affected the most by capacitance, followed by pulse-on time and ultrasonic vibration amplitude. The copper tool provided a higher BRR than other tools. US-EDM is considerably effective when TON is low and the performance of US-EDM is better than that of Dry-EDM. Scanning electron microscopy (SEM) analysis showed that the US-EDM method created a heat-affected zone surrounding the machined surface of the deburred exit hole in range of 200µm–500µm.

Analysis of Hard Machining of Titanium Alloy by Taguchi Method

Hard Titanium alloys have good strength to weight ratio and resistance against corrosion. Machining such hard alloys causes lot of tool wear. Hard machining is a dry machining process using a single point cutting tool for machining hardened material whose Vickers hardness number is above 45.The main advantage of hard turning is the possibility of eliminating grinding operations and it is environment friendly. The surface integrity of the work piece has to be maintained to give longer life to the machined component. The investigation was done turning titanium alloy in a CNC machine using the L9 orthogonal array as plan of experiments. The objective is to optimize the cutting parameters which is done using Taguchi method. Based on the response table obtained by DOE the optimum surface roughness and tool wear was obtained. The tool wear at different operating conditions were found using confocal microscope and the surface roughness was determined using Form Talysurf.

Machinability of Stainless Tool Steel using Nitrogen Oil-Mist coalant

For all dry machining process, temperature generated in the cutting zone is the major challenge. It causes tool failure and results in unsatisfactory surface finish. Application of flood coolant method during machining processes can significantly reduce the temperature and consequently extend the cutting tool life. However, it has serious concerns regarding environmental pollution, operator health and manufacturing cost. These issues are usually attempts to be overcame by using minimum quantity lubrication (MQL) technique. This method merges the advantages of both dry cutting and flood cooling by spraying a small amount of lubricant to the cutting zone using vegetable oil. In this paper, another technique is proposed in order to further enhance the machineability of the stainless tool steel (STAVAX ESR 48 HRC). This involves using of nitrogen gas (N 2 ) and air as cooling medium in combination with oil mist lubricant (MQL). The results show that the combination between nitrogen and oil-mist lubricant much more prolonged the tool life and improved the surface finish than the air-oil mist lubricant medium.

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.

Dry Machining Process of Milling Machine using Axiomatic Green Methodology

Most of companies know that there are strategies to become green industry, and they realize that green efforts have impacts on product quality and cost. Axiomatic Green Methodology models the relationship between green, quality, and cost. This methodology starts with determining the green improvement objective and then continues with mapping the functional, economic, and green requirements. From the mapping, variables which affect the requirements are identified. Afterwards, the effect of each variable is determined by performing experiments and regression modelling. In this research, axiomatic green methodology was implemented to dry machining of milling machine in order to reduce the amount of coolant. Dry machining will be feasible if it is not worse than the minimum required quality. As a result, dry machining is feasible without producing any defect. The proposed machining parameter is to reduce the coolant flow rate from 6.882 ml/minute to 0 ml/minute, set the depth of cut at 1.2 mm, spindle rotation speed at 500 rpm, and feed rate at 128 mm/minute. This solution is also resulted in reduction of cost for 200.48 rupiahs for each process.

Analysis of Thermal Damage in FRP Drilling

Among machining operations applied to polymeric composite materials, drilling is the more important one due to the need to implement mechanical couplings, which in most cases are not yet possible using structural adhesives. Such process is very critical because not only it causes the interruption of the fibers continuity, but also it can generate localized thermal shock in the resin, due to the presence of extremely hard and abrasive fibers and to the low thermal conductivity of the resin itself, that limits the heat dissipation. These phenomena are more severe in dry machining process, that are used in aeronautic industry. The poor FRP machinability is manifested in the induced phenomena of delamination, fragmentation and matrix thermal damage that cause negative outcomes, such as the reduction of the material fatigue strength and the consequent decay of long-term performance. The evaluation of such critical issues is possible through indirect analysis, that is through the analysis of some control parameters, such as the process forces and temperatures that assume different values depending on the combination of cutting parameters. Therefore, to acquire useful information for machining optimization is possible through process monitoring: the input data can be analyzed, processed and made available to optimize the process parameters in order to reduce critical issues such as the delamination, the fragmentation and the thermal damage.The present work deals with the problem of damage due to the high temperatures reached during the FRP dry drilling process. The temperature was measured by K type thermocouples positioned in the workpiece, near the hole surface, and it was evaluated as a function of the main process parameters in order to estimate the critical cutting conditions that lead to critical temperature overcoming.

Review on recent development in environmental-friendly EDM techniques

The electrical discharge machining (EDM) is unitary of the widely used unconventional machining because of its ability to cut very hard material engendering high dimensional accuracy as well. In thermo-electric process, control sparks generation between electrodes causes material removal; however, application of hydrocarbon oil based dielectric is an issuance of environmental disruption. To rectify this problem, replacement of dielectric is main concerns in EDM research. This paper highlights Dry-EDM, Near-Dry EDM and EDM in water, which is conceived as an environment amiable alteration in the oil EDM process. The work gives a thorough review of Dry, near-dry EDM and EDM in water as a process, where the target is to endeavor dielectric fluids that can be substituted bypassing hydrocarbon oil. It is perceived that water and gas based dielectrics could take over oil-based fluids in die sink applications. Novel technological advances in dry EDM machining processes, which deliberate the relatively advanced stage of a technology in to the area of academic and industrial research is briefly reviewed. An outline of the prospective trend of reviewing is intimate in the last fragment.

Review on Recent Development in Environmental-friendly EDM Techniques

The electrical discharge machining (EDM) is unitary of the widely used unconventional machining because of its ability to cut very hard material engendering high dimensional accuracy as well. In thermo-electric process, control sparks generation between electrodes causes material removal; however, application of hydrocarbon oil based dielectric is an issuance of environmental disruption. To rectify this problem, replacement of dielectric is main concerns in EDM research. This paper highlights Dry-EDM, Near-Dry EDM and EDM in water, which is conceived as an environment amiable alteration in the oil EDM process. The work gives a thorough review of Dry, near-dry EDM and EDM in water as a process, where the target is to endeavor dielectric fluids that can be substituted bypassing hydrocarbon oil. It is perceived that water and gas based dielectrics could take over oil-based fluids in die sink applications. Novel technological advances in dry EDM machining processes, which deliberate the relatively advanced stage of a technology in to the area of academic and industrial research is briefly reviewed. An outline of the prospective trend of reviewing is intimate in the last fragment.

Development and Validation of a Hybrid Model for the Prediction of Shape Deviations in dry Machining Processes

Dry cutting operations offer economic and ecologic advantages over conventional machining. When machining conditions are pushed towards the regime of high performance cutting, the applicability of dry cutting is limited among others by the achievable geometric accuracy. In order to comply with increasing demands in machining precision and the necessity to expand the utilisation of dry cutting, a novel hybrid model has been developed exemplary for a face milling process. It enables a predictive minimisation of size and shape deviations in machining. The model takes into account deviations due to thermal expansion during the cutting operation and due to machining induced residual stresses which are especially important in the manufacturing of thin-walled high precision components. It is therefore based on two initially separated finite element sub-models. Sub-model 1 calculates the mechanic response of the workpiece loaded with a near surface residual stress field (source stresses) resulting from plastic deformations generated during the chip formation process. Sub-model 2 calculates the local thermal expansion of the workpiece during a three-dimensional simulation of a moving heat source.In this paper the focus lies on shape deviations resulting from thermo-elastic effects (sub-model 2). It covers a face milling process of plates made from normalized 42CrMo4. Transient three dimensional temperature fields are calculated in a FEM model of a moving surface heat source. The temperature fields are used to calculate the mechanical response of the workpiece which is coupled with a kinematic simulation of the tool movement to obtain the resulting surface shape. The results are validated against measured shape deviations for varying machining parameters. In the long term, the model will be applied to evaluate and identify optimal machining strategies.

Modeling and Simulation of Machining-induced Surface Integrity Characteristicsof NiTi Alloy

NiTi shape memory alloys have gained increased interest in various industries, including biomedical and aerospace applications due to their unique properties such as shape memory effect and superelasticity. Martensitic phase transformation in NiTi significantly affects the surface integrity characteristics. This phase transformation needs to be better understood to control and enhance the shape memory and microstructural properties of NiTi shape memory alloys. This study presents results of combined experimentation and simulation of cutting-induced phase transformation in orthogonal machining of NiTi shape memory alloys. A phenomenological modeling approach was utilized to model machining-induced phase transformation. NiTi shape memory alloys alloy were in austenite phases at room temperature. The transformation during dry machining process from austenite to martensite phases, and the resulting volume fraction was successfully simulated using DEFORM 2-D software by implementing a user-defined subroutine. The developed model is capable of capturing the trend of variationsinvolume fracture and the depth of transformed layer as a function of cutting speed.

Parameter Identification for Finite Element Based Models in Dry Machining Applications

Dry machining is a challenging topic in industrial manufacturing: The absence of coolants results in ecological and economical benefits, but also in a significant increase of the occurring thermal stress. This leads to geometrical deviations of the machined workpiece impairing the functional performance of the final part. The increased thermal stress is especially important in high-precision manufacturing and requires careful process planning. To determine process parameters in order to minimize geometrical errors, optimal control is an appropriate tool. A precise partial differential equation model representing the material behavior is required. The partial differential equation contains unknown physical quantities, such as heat fluxes, which cannot be measured directly. One common method to derive these quantities is solving an inverse problem by parameter identification, i.e. determining the model parameters, such that the model matches the measurements best. We will present a simultaneous analysis and design approach which states a numerical finite element discretization of the model as constraints of the resulting nonlinear optimization problem (NLP). The proposed method takes advantage of both, direct consideration of state constraints, like temperature boundaries, and lower computational costs compared to the nested analysis and design approach. The additional implementation costs can be significantly reduced by using an external finite element library for assembling the optimization constraints and its derivatives. This approach for determining physical parameters of milling experiments is user-independent and works fully automated. It is the first step for an optimal control of dry machining processes. We will give a description of this method as well as numerical identification results of real heat flux densities by the sparse NLP solver WORHP.

Enhanced method for the evaluation of the thermal impact of dry machining processes

From today’s point of view the modelling of machining operations is a promising tool to extend the productivity and the precision of future industrial manufacturing. The importance of predictive simulation and compensation of thermally induced workpiece deformation during machining is especially important in dry machining because of the absence of cooling lubricants. Since the simulation results mainly depend on the boundary conditions of the model, a detailed knowledge of them is necessary. In this case the most important boundary condition is the intensity and possibly the distribution of the surface heat flux representing the heat flow into the workpiece resulting from the chip formation. The surface heat flux cannot be measured directly. One possible way to determine surface heat fluxes is to employ a thermal model of the machining process and match simulated and measured time and space dependent temperature fields. This procedure is time-consuming and is in most cases subjective because the congruency of temperature fields is rated manually, e.g. by the position of single isotherms. Therefore an enhanced method for the determination of surface heat fluxes is proposed in this paper. The method is based on nonlinear optimisation techniques and a simple finite difference scheme for numerical solution of the heat equation (WORHP-FDM). The procedure is objective between repeat measurements and works in a fully automated manner. The implementation is validated by the comparison to an analytical solution of the moving heat source based on the model of Carslaw and Jaeger and then applied to measured thermal images from milling experiments.

Surface Integrity Characteristics of NiTi Shape Memory Alloys Resulting from Dry and Cryogenic Machining

NiTi alloys are extensively used in many industries due to their unique properties such as super elasticity, shape memory and phase transformation. Since the NiTi alloys have temperature-dependent mechanical and material properties, this work focuses on the effects of dry and cryogenic machining processes on surface integrity characteristics of NiTi alloys. Surface quality and topography, microstructure, transformation response and phase transformation temperatures of machined specimens are measured to assess the machining-induced surface integrity characteristics of NiTi alloys. Obtained results illustrate that machining of NiTi alloys under different cutting and cooling conditions affects their resulting surface integrity characteristics. Moreover, as compared to dry machining, cryogenic machining helps to improve surface quality and has substantial effects on the phase transformation behavior of machined specimens.