Non-conventional Machining Process Research Articles

Recent advancements in ice jet machining process as an alternative of AWJM

Currently, sustainability has the utmost significance in manufacturing sector. Also, the manufacturers are constrained to keep an eye on the inflexible environment conventions which reassure for reduction of varied industrial risks inherent in any industrialized process while exploiting the newfangled prospects that get up from refining methods and products. There are many forms of non-conventional machining processes has been developed over the century. They are either consuming natural resources or they are very expensive to maintain and operate. Ice jet machining is an imperative ecological variation of abrasive water jet machining i.e. AWJM which has been developed over the years. It warrants the environmental friendly machining of materials. It varies from AWJM since abrasive particles are replaced by ice particles for machining which also ensures lesser cost, well machining competence, recycling, waste management thereby inclusive sustainability. This study presents ice jet machining technology where its mechanism, process parameters and working principle has been discussed. Its significant benefits over other conventional processes as well as some recent advancement in this technology are also discussed. Finally, a cost analysis has been done for finding overall operational cost of Ice-jet machining.

Critical Analysis of the Selection of Non-Conventional Machining Processes

Non-Convectional Machining (NCM) processes are used widely to produce accurate and intricate material shape such as titanium, stainless steels and resistant alloy that are of high strength, fiber-based composite, refractories and ceramics. The production of more complex shapes of materials using convectional machining processes is considered to be challenging. This research paper focusses on the section of the most effective NCM process. The ‘choice’ of the most considerable NCM process for a particular application could be seen as a multi-technique for making proper choices for diverse or conflicting approaches. To aid the process of choosing, various NCM techniques have been proposed in this research. This contribution focuses on the usage of unexplored NCM and Multi-Feature Decision-Making (MFDM) ‘choice’ issues.

EXPERIMENTAL INVESTIGATION OF SURFACE TOPOGRAPHY OF AL7075-T6 ALLOY MACHINED BY EDM

Electrical discharge machining is one of the most important non-conventional machining processes for removing material from electrically conductive materials by the use of controlled electric discharges. EDM is a non-contact machining process, therefore, is free from mechanical stresses. This paper investigates the machining Al7075-T6 alloy by EDM using a copper electrode. Al7075-T6 alloy was selected, because of its growing use in a lot of engineering applications. The effect of electrical parameters, peak current and pulse-on time, on the surface integrity, was studied. Area surface roughness parameters (arithmetical mean height, Sa, and maximum height, Sz) were measured on all samples and 3D surface characterization has been carried out with confocal laser scanning microscopy. The experimental results showed that the surface roughness is mainly affected by the pulse-on time.

EXPERIMENTAL ANALYSIS OF CUT QUALITY ON SS347 MATERIAL USING CO2 ASSISTED LASER BEAM CUTTING AND PARAMETRIC OPTIMIZATION USING GENETIC ALGORITHM

Laser Beam cutting is a type of non-conventional machining process in which the removal of materials takes place due to the melting and vaporization of material when the laser beam comes in contact with it. This work examines the impact of the cut quality characteristics of the SS347 material and to find reduced surface roughness, machining time and heat affected zone by laser beam cutting. The cutting process was assisted by CO2 gas pressure. Power, standoff distance, speed and CO2 gas pressure are the cutting parameters considered for this study and the output parameters measured are machining time, heat affected zone and surface roughness. In accordance with L-9 orthogonal arrays, the experiments were planned. Analysis of Variance has been used to study how input functions influence output functions which revealed that speed (59.75% and 89.75%) is the significant factor for machining time and surface roughness while power (91.27%) was the dominant factor for heat affected zone. Gas pressure did not have much influence in the output parameters. The mathematical expressions of the output are used as input for the multi-objective function of the genetic algorithm. Optimal solutions are compared to hybrid and without-hybrid functions. It is found that the hybrid function shows a higher performance compared to the without hybrid function.

Machining performance evaluation under recently developed sustainable HAJM process of zirconia ceramic using hot SiC abrasives: An experimental and simulation approach

The proposed research work accomplishes the experimental study and computational fluid dynamics (CFD) technique for erosive footprint prediction extent in hot abrasive jet machining (HAJMing) constraints on target surface erosion rate, surface roughness of intricately shaped tapered holes generation. The CFD-obtained footprints were in superior agreement with experimentally measured data. HAJMing process uses a relatively high speed air-hot abrasive stream to produce both high accuracy micro-channels and tapered holes. HAJM also defines itself phenomenal competence over all advanced manufacturing techniques due to its growing demands for better surface reliability with defects (mostly stress, heat) free surfaces. Zirconia is widely accepted and associated in the non-conventional machining processes and industries with the years of track on record of proven performance in a vast number of brittle materials. Most perceptible act in this research is the selection of abrasive particle to achieve the appropriate intricate shaped holes on zirconia ceramic with hot silicon carbide (SiC) abrasives. Machining of these features are done with varying the abrasive temperature. Optical microscopic view was considered for the generation of machined holes during HAJMing. All the experimental data were presented to study the effect of machining constraints on target surface erosion rate and surface roughness using HAJMing. Single impact experiments were executed to measure the target surface erosion due to impact of individual hot silicon carbide abrasive particles. An experimental setup has been designed to conduct the machining trials using Box-Behnken design of experiments. It is also shown that the generated workpiece surface contour and erosion rate are the function of machining constraints which have a negligible influence on air-abrasive flow characteristics. This research work also deals with the sustainability assessment under environmental-friendly hot abrasive-assisted machining conditions.

Review on Effects of Electrode in Electrical Discharge Machining Process

Electrical Discharge Machining is one of the non-conventional machining processes used for electrically conductive material. It is widely used for manufacturing complicated parts which are tough to be produced by conventional manufacturing processes. It is based on thermoelectric energy between workpiece and electrode. Metal is removed by melting and vaporizing because of spark occurs in the gap between electrode and workpiece. Workpiece and electrode must have electrically conductive to generate a spark. The performance of the EDM process is largely depends on the electrode. Electrode is considered as tool in EDM process. Selection of the electrode material plays vital role in the EDM process. Different electrode materials have different properties. Hence, the performance of the EDM process changes with different materials. Researchers have used different materials as electrode to investigate the effects of materials and to improve the performance of EDM process. This paper reviews the research work carried out in the field of materials and manufacturing methods for electrodes in EDM process. Keywords: [EDM, Electrodes, Materials, Manufacturing Process].

A study on Electrical Discharge Machining of Titanium Grade2 with experimental and theoretical analysis

Titanium alloys, due to their unique properties, are utilized in numerous modern high-end applications. Electrical Discharge Machining (EDM) is a non-conventional machining process, commonly used in machining of hard-to-cut materials. The current paper, presents an experimental study regarding the machining of Titanium Grade2 with EDM, coupled with the development of a simulation model. The machining performance indexes of Material Removal Rate, Tool Wear Ratio, and Average White Layer Thickness were measured and calculated for different pulse-on currents and pulse-on times. Moreover, the developed model that integrates a heat transfer analysis with deformed geometry, allows to estimate the power distribution between the electrode and the workpiece, as well as the Plasma Flushing Efficiency, giving an insight view of the process. Finally, by employing the Response Surface Methodology, educed regression models that correlate the machining parameters with the corresponding results, while for all the aforementioned indexes, ANOVA was performed.

Analysis of Sub-processes Specific to Hybrid Non-conventional Machining Methods

In principle, all non-conventional machining processes can be viewed as the sum of various sub-processes, the separate analysis of which influences the effectiveness of this machining process. The first question to answer is the criteria by which these sub-processes can analyzed. Since the non-conventional processes work exclusively based on electrical energy, voltage and current determine the character of the sub-process. The second focus is the time constant with which voltage and current influence the process, from which the measurement of the corresponding parameters result. The third group of influencing parameters is the working medium and its change due to the main removal process. In the summary, these three groups are consider with regard to a process model with which a process control (technology), a process regulation (process stability) and a safety control (limit value exceeded) are guide.

Multi-scale characterization of material and surface integrity of Inconel 718 when milling by Abrasive Water Jet process: Context of repair application

Inconel 718 (IN718) is a precipitation hardened nickel-base super-alloy exhibiting poor machinability and used in the hot section of aircraft engines. These components are subjected to severe thermo-mechanical loads in a highly corrosive environment, limiting their service life due to cracks and wear. Due to their high added-value, repair of damaged IN718 components is an interesting alternative instead their replacement. Repair process involves material removal of the damaged zone and subsequent cavity refill. Nevertheless, material removal of IN718 by conventional methods is a challenging task. Abrasive Water Jet (AWJ), a non-conventional machining process, offers a potential alternative to mitigate IN718 machining problems. However, research on the impact of AWJ process parameters during IN718 milling on the surface and material integrity is limited in the literature. Furthermore, in repair context, no study proposes AWJ machining as material removal process. The present work focuses on a multi-scale characterization of the influence of AWJ process parameters (pressure, traverse speed, step-over distance and abrasive size) on surface roughness, depth of cut, abrasive embedment and residual stress, during milling of untreated IN718. Surface integrity characterization on the milled surfaces was conducted through 3D optical microscopy, profilometry and SEM techniques. Residual stress measurements were performed in longitudinal and transverse directions with respect to the machining path using XRD technique. The results showed that all milled surfaces presented abrasive embedment and a compressive residual stress state with similar values in both directions. Up to 15% of the area of a milled surface consisted of abrasive embedment. The tool path has not influenced the residual stresses. Furthermore, surface roughness is dependent on pressure and traverse speed; depth of cut is influenced by pressure, traverse speed and grit size; abrasive embedment depends on pressure, step-over distance and grit size; whilst, residual stresses are influenced by traverse speed and grit size.

Significance of Taguchi Design compared to Response Surface Methodology in predicting optimal machining conditions for PCM process

Photochemical Machining (PCM) is a non-conventional machining process which produces stress free complex flat metal components. Optimization of process parameters for Photochemical machining of SS316L steel is done using Taguchi method and the results are compared with results obtained through Response surface methodology (RSM) available in literature. The objective of this work is to predict the optimal machining conditions of PCM to achieve minimum undercut for SS316L steel. The Factors affecting the response of the model are: Etching Time (Ti), Temperature (T) and Etchant Concentration (C) in PCM. This work shows that Taguchi method is faster compared to RSM in predicting the optimal conditions for minimizing defects in PCM process. Taguchi method requires only 9 experiments for finding optimal conditions whereas RSM requires 20 experiments saving about 55% of time and effort.

Completion detection and efficiency improvement for breakout stage of fast EDM drilling

Electrical discharge machining (EDM) is a non-conventional machining process that removes material by consecutive electrical sparks. Fast EDM drilling is one of such processes, which employs rotary tubular electrodes and inner flushing to enhance the machining efficiency and stability. It is widely used to produce small holes on various kinds of products. The breakout event occurs when the electrode just penetrates the workpiece during the drilling process, which marks the start of the breakout stage of the process. At this moment, the outlet of the hole is smaller than the desired due to severe radial tool wear, and the hole is not completed. As a result, further feeding is needed before the electrode fully penetrates the workpiece. To avoid back-strikes, the hole completion detection is crucial. However, the uncertainty of longitudinal and radial tool wear makes it difficult. This paper proposes a novel method to detect the hole completion by analyzing the discharge signals in the breakout stage. Besides, for the machining efficiency to become much lower in the breakout stage, the control strategy is also proposed to improve it by adjusting the reference voltage and gain factor of the servo controller. The optimal parameters were found by a full-factorial experiment. Experiments were conducted to validate the proposed methods by drilling holes at various inclinations. The results show that the proposed hole completion detection method could successfully sense the hole completion without misjudgments. And the electrode was fed at most 1.81 mm out of the hole outlet when the detection was made. Besides, the proposed control strategy improved the machining efficiency by up to 56.2% in the breakout stage in the experiments.

Modeling and analysis of a novel rotational magnetorheological abrasive flow finishing process

The present work proposes a new non-conventional machining process. The proposed method is a combination of magneto-rheological finishing and rotational abrasive flow finishing process. The modeling of the new process was done on the brass workpiece at different magnetic field strengths and at different rotational speeds to observe its effect on final surface roughness and volumetric material removal. From the results, it was inferred that the value of surface roughness decreases with the increase in rotational speed and magnetic field for the constant number of cycles. This decrease in surface roughness value authenticates the active participation of the centrifugal force and rheological behavior of polishing fluid. The present study shows that with the rotation of magneto-rheological polishing fluid, an extra component of centrifugal force adds up to the resultant force which increases the volumetric removal rate and surface finish as compared to other finishing processes.

On machining Ti6Al4V ELI with EDM by using copper and graphite electrodes: a comparison study

Electrical Discharge Machining (EDM) is a non-conventional machining process, in which, the material removal occurs by repetitive sparks. By utilizing EDM, conductive materials can be machined in complex shapes and geometries, with high dimensional accuracy, regardless of their mechanical properties. Titanium alloys, due to their unique inherent properties, find extensive use in the modern industrial environment. Nevertheless, they are still classified as hard-to-cut materials, facing significant difficulties in their machining with conventional methods. The current paper presents a comparative study regarding the machining of Ti6Al4V ELI with EDM, by using copper and graphite electrodes. The control parameters were the pulse-on current and time, while the machining performance was estimated in terms of Material Removal Rate (MRR) and Tool Wear Ratio (TWR). Additionally, the surface roughness was evaluated according to the Ra. For the aforementioned indexes, Analysis Of Variance (ANOVA) was performed.

Model Prediction and Experimental Study of Material Removal Rate in Micro ECDM Process on Borosilicate Glass

Miniaturization of products has become a major technological challenge in production industries. Material removal in microscopic and sub-microscopic level has become a demand for producing such products. Electro-Chemical Discharge Machining (ECDM) is one of the hybrid non-conventional machining processes to machine materials that are electrically conductive and non-conductive at a micro-level utilizing the principles of Electro Discharge Machining (EDM) and Electro-Chemical Machining (ECM). The most common nonconductive materials machined with this process are various types of glasses, ceramics, composites, etc. In the current paper, a Finite Element Model (FEM) of the ECDM process is carried out in the discharge regime (less than 300 μm) with pulsed DC in a 2D domain to characterize the Material Removal Rate (MRR) as a process output response in borosilcate glass machining. From the model and experiements the value of MRR is found to be 0.373 mg/ min and 0.414 mg/min. It can be considered that there is almost negligible difference in MRR between experimental and model values with 9.9% error variation. Hence the results are validated with experimentation, and there is a good agreement observed between the results.

A Comprehensive Study on Processing Ti-6Al-4V ELI with High Power EDM.

Electrical Discharge Machining (EDM) consists of a non-conventional machining process, which is widely used in modern industry, and especially in machining hard-to-cut materials. By employing EDM, complex shapes and geometries can be produced, with high dimensional accuracy. Titanium alloys, due to their unique inherent properties, are extensively utilized in high end applications. Nevertheless, they suffer from poor machinability, and thus, EDM is commonly employed for their machining. The current study presents an experimental investigation regarding the process of Ti–6Al–4V ELI with high power EDM, using a graphite electrode. Control parameters were the pulse-on current (Ip) and time (Ton), while Machining performances were estimated in terms of Material Removal Rate (MRR), Tool Material Removal Rate (TMRR), and Tool Wear Ratio (TWR). The machined Surface Roughness was calculated according to the Ra and the Rt values, by following the ISO 25178-2 standards. Furthermore, the EDMed surfaces were observed under optical and SEM microscopy, while their cross sections were also studied in order the Average White Layer Thickness (AWLT) and the Heat Affected Zone (HAZ) to be measured. Finally, for the aforementioned indexes, Analysis Of Variance was performed, whilst for the MRR and TMRR, based on the Response Surface Method (RSM), semi-empirical correlations were presented. The scope of the current paper is, through a series of experiments and by employing statistical tools, to present how two main machining parameters, i.e., pulse-on current and time, affect major machining performance indexes and the surface roughness.

Multi-Response Optimization of Parameters using GRA for Abrasive Water Jet Machining of EN31 Steel

A wide variety of materials are used in the automobile industry that includes casting tools, dies, studs, nuts & bolts, bearings, and punches, etc. These require high hardenability, great toughness, more strength, and good resistance to thermal shocks. Among various grades of steel, the EN31 fulfills all these qualities efficiently. But, due to its high hardness and strength, conventional machining of EN31 is not economical. Among various non-conventional machining processes, abrasive water jet machining is employed when there is a necessity for high surface finishing & fast cutting. This paper includes the machining of EN31 steel with an Abrasive Water Jet Machine. In this work, Pressure, Abrasive Mass Flow Rate, Standoff Distance & Traverse Speed (Quality) are considered as parameters, and hence their effects on the responses like Machining Time, Surface Roughness & Hardness are studied. With Grey Relational Analysis, all the selected parameters are optimized for; minimum machining time, minimum surface roughness & maximum hardness. The approach is used to obtain Grey Relational Grade (GRG) and hence the optimal solution is obtained.

Enhancement of material removal rate in Electric Discharge Machining of Inconel 718 using cryo-treated graphite electrodes

Recent advancements witnessed the growth of many Nickel based super alloys like Inconel 718 which has very high strength and corrosion resistance. However, non-conventional machining processes are required for these super alloys due to its poor machinability. Electric Discharge Machining (EDM) is one such non-conventional machining operation where we can machine the materials irrespective of their hardness & strength. One of the limitations of EDM is the low Material Removal Rate (MRR). This paper discusses the effects of cryogenically (cryo) treated graphite electrodes on the MRR of Inconel 718 during EDM operation. Experimental results showed that MRR is improved by using the cryo-treated graphite electrodes.

Wire electrical discharge machining of AA6063/B4C composite fabricated by stir-casting process

Owing to high strength, high rigidity, damping power, lower density, increased abrasion and wear resistance capacity, aluminium-based metal matrix composites (AMC) are attaining considerable popularity in various engineering fields. Because of the reinforcement's abrasive nature, the materials' machining is challenging with the conventionally available processes. Therefore, non-conventional machining processes are being employed for better machining performance. To achieve these objectives AA6063/B4C composites with different weight fractions (5% & 10% by wt.) were fabricated by using economic and simple stir casting technique. Thereafter, microstructure of the prepared composites was analyzed under WSEM equipped with EDX. Furthermore, mechanical property like hardness test were performed on fabricated composites using Brinell hardness testing machine. Machining was performed using wire electrical discharge machine (WEDM) to investigate the effects of process parameters pulse on time (Ton), pulse off time (Toff), current (I) and table feed (S) and weight fraction (5 and 10%) of the reinforcement Boron Carbide (B4C) on the machining responses, namely material removal rate (MRR), cutting rate (CR), and kerf width (KW) of the prepared composites. The result shows that with the increase in Ton, I, S except Toff increases MRR. The cutting rate shows an increasing trend with increasing in S, and the Kerf width increases with the increase in Ton and I. The developed composite's morphological study reveals a uniform distribution of B4C particles in the aluminium matrix phase. To satisfy the different criterion like high MRR and high CR and less KW, the overall evaluation criterion (OEC) giving equal weightage was formulated.

Parametric optimization of hole geometry in laser drilled Inconel 825 by grey based response surface methodology

Laser micro drilling is a non-conventional machining process which uses thermal energy to remove material from the workpiece. This paper presents the parametric study on Nd:YAG laser micro drilling of 2 mm thickness INCONEL 825 plate a Nickel based super alloy which have found purpose in nuclear, aerospace, and production industries due its high strength and resistant to oxidation at high temperature. The present work is to improve the geometrical characteristic like hole taper and hole circularity. Integrated grey Taguchi based Response surface methodology (GT-RSM) was used to predict optimal cutting condition . The effect of process parameters such as air pressure, trepanning speed, frequency and lamp current on the output response hole circularity at entry and hole taper is studied by grey based response surface methodology. Lamp current and air pressure is determined most influential parameter on hole circularity and hole taper.

Review on optimized process parameters of electrochemical machining and its variants

The electrochemical machining (ECM) is a non-conventional machining process which has the competency to fabricate microchannel, micro holes, cavity, and difficult to cut materials. There are lots of research papers on ECM and micro-ECM. The objective of this review is to summarize some of the significant processing parameters of electrochemical machining. This review article aims to discuss process capability and research development of ECM and its variant, considering the knowledge of both applied and basic research fields. It also provides new sights into the technological understanding of ECM and micro-ECM, which will be helpful in future engineering developments of this technology.