Cost-effective Machining Process Research Articles

Unveiling the effect of crystal orientation on gallium nitride cutting through MD simulation

Gallium nitride (GaN) is a hard and brittle single crystal and shaping it into thin substrates for semiconductor applications is challenging. The quality of the machined surface can vary depending on the cutting orientation, primarily due to the hexagonal lattice structure of GaN. Therefore, understanding how crystallite orientation affects the cutting performance is crucial before developing a cost-effective machining process for GaN. This study used molecular dynamics (MD) simulation to investigate the cutting of GaN along different crystal orientations. Single grit cutting was performed to validate the simulation results. The simulation revealed distinct outcomes for different cutting directions. When cutting on a-plane or along the [-2110] direction on m-plane, removal efficiency was enhanced due to lower cutting resistance, and more dislocations were generated in the subsurface compared to other cutting directions. However, less phase transition and amorphization were induced, indicating lower energy consumption and smaller forces or stresses involved. Conversely, the cutting on c-plane or along the [0001] direction on m-plane showed the potential for achieving better surface integrity. This study provided valuable insights into the effect of crystallite orientation on the cutting performance of GaN and demonstrated that appropriate selection of cutting directions could result in improved surface quality, which are valuable for developing cost-effective machining technologies for GaN single crystals.

Multi-criteria optimization of micro-hole on glass using developed µ-abrasive jet machine set-up

In non-traditional machining, micro-abrasive jet machining (MAJM) is a cost-effective machining process. MAJM has been used for fabricating electronic devices and microfluidic channels. This work has made an effort to utilize MAJM for glass. A new design and fabrication of the Laval type of nozzle have been proposed to improve machining accuracy. A nozzle is conceived to ensure specific characteristics of the mixture (compressed air and abrasive particles) pass through it. The abrasive particle force is converted to kinetic energy, increasing the mixture’s velocity. The cross-sectional area of the nozzle can be circular, rectangular, square, or oval. A circular cross-sectional nozzle has been developed for high velocity, precise etching, and patterning on difficult-to-machine materials such as steel alloys. A circular cross-sectional micro-nozzle with a large aspect ratio is proposed, and the flow characteristics and cutting performance are examined precisely by the experiment. Efforts are being made to make machining processes sustainable, productive, and efficient. Here, the Taguchi-grey relational analysis integration approach has been used to analyze the machining parameters such as air pressure, stand-off distance, and abrasive mesh size (AMS). The top hole diameter, bottom hole diameter, material removal rate, and radial overcut are the response variables in this investigation. Analysis of variance (ANOVA) results showed that the AMS was the most efficient parameter, which followed the processing condition on the total input of the multi-purpose function. The reported optimized process parameters are air pressure of 8 bar, stand-off distance of 2 mm, and AMS mix (50%+100%) micron, which significantly affects the top and bottom micro-hole diameters.

Coaxiality error analysis and optimization of cylindrical parts of CNC turning process

High precision rotary shafts with precise geometrical tolerances are generally mounted with a micron level clearance between the gears and casing during operation in industrial applications. Dynamics cyclic loads are inevitable in most of these applications which has an adverse effect on the fatigue life of the critical parts. Ensuring close dimensional tolerances and coaxiality during machining is highly desirable, as it affects the rotary characteristics in many applications. Thus, control of coaxiality error plays a vital role in rotating shafts and high precision machine tools. However, use of high precision machining would drastically increase the cost of manufacturing. Thus, a cost-effective machining process that could potentially reduce the coaxiality error is of high industrial importance. The present research efforts made an attempt to achieve minimum coaxiality error on cylindrical machined parts by optimizing parameters (cutting speed, feed rate, depth of cut and cutting tool nose radius). Experiments are planned, viz. central composite design matrix and statistical analysis determine the influence of machine parameters on coaxiality error of high-strength Al 7075 alloy by applying response surface methodology. Feed rate and depth of cut factors showed significant effect on coaxiality error. All machining parameters showed a non-linear effect on coaxiality error, which defines the strong interaction factor effects. The empirical equations derived were used to minimize coaxiality error by determining a set of machining parameters, viz. applying Big-Bang and Big Crunch and Rao (Rao-1, Rao-2 and Rao-3) algorithms. Rao algorithms outperform the Big-Bang and Big Crunch algorithm both in computation effort and solution accuracy. The results of Rao algorithms are experimentally verified, which resulted in reduced coaxiality error equal to 1.013 µm and resulted in 72.6% improvement compared to CCD experiments.

Performance of Minimum Quantity Lubrication (MQL) and its effect on Dry Machining with the addition of Nano-particle with the biodegradable base fluids: A review

In any machining, cutting fluid plays a distinct role which affects both the overall machining surface as well as tool characteristics. By lubricate the job-tool interface with removal of chips it reduces the cutting forces, temperature in cutting zone, tool wear rate as well as friction co-efficient. However, due to unwanted and misuse of cutting fluids with improper disposal it affects the human health and the environment badly. Hence researchers focused their studies on various techniques available on the application of coolants to stick with the stricter environmental regulations to provide a healthy workspace to work. Among various techniques Dry machining/Minimum Quantity Lubrication (MQL) helps to optimize the use of coolants instead of conventional flood cooling. In addition to safety, MQL (Minimum Quantity Lubrication) has proved itself with remarkable progress on overall efficiency while compared with conventional coolant. This present paper review some of these research works which is based on MQL composed of biodegradable oil and/or with various Nano-particles. The review shows the improved performance of Nano-particles and/or biodegradable oil based MQL with significant better surface finish, low power consumptions, fewer tools wear. This synergistic combination of improved performance has been achieved in machining practice to lead a cost-effective machining process with cleaner technology. Such benefits led to a greater substitute for the conventional flood coolant and becoming the futuristic model by the addition of better heat transfer to get better tribological property.

A COMPREHENSIVE REVIEW ON EVALUATION OF ENVIRONMENTAL FRIENDLY MACHINABILITY, CUTTING FLUIDS AND TECHNIQUES IN METAL CUTTING OPERATION

Todays, due to the environmental concerns, growing contamination and pollution regulations, the demand for renewable and biodegradable cutting fluids is increasing day by day. Environmental friendly machining is one of the latest approach which is economical and also eco-friendly that improve the machinability. Different types of environmental friendly machining techniques are available e.g. MQL machining, cryogenic machining, dry machining and high pressure cooling approach. In this article, an attempt is made regarding environmental friendly machining processing, including different types of cutting fluids and machining techniques. The Knowledge of cutting fluid and its processing conditions is of critically importance to maximize the efficiency of cutting fluids in any machining process. In general, the generation of heat in the cutting zone due to friction at the tool-chip interface and the friction between the safety surface of the tool and the work piece is always the deciding factor on the quality of the work piece surface. In any manufacturing industries or company two factors play important role in machinability and productivity e.g. surface quality and tool wear. The main objective of this review article that analysis the different environmental friendly machining techniques and encourages the cooling approach in metal cutting operation. So finally, after the literature survey found that environmental friendly machining approach is cost effective machining process and also eco-friendly machining process.

Computer aided Genetic Algorithm based Optimization of Electrical Discharge Drilling in Titanium alloy (Grade-5) Sheet

Abstract Precise and micro holes in the different advanced materials such as Ti and their alloys is a very challenging task due to unfavourable characteristics of these materials by conventional machining. These problems may be minimised upto some extent by using new class of machining processes such as advanced machining processes. In the category of advanced machining processes, the electrical discharge drilling is the efficient and cost effective machining process for the machining of these materials. But some quality characteristics such as hole circularity, hole taper and hole dilation are the main problem associated during the machining of these materials by using electrical discharge machining. These may be minimized by selecting the optimum process parameter levels. In this study, the experiments have been conducted by using L27 orthogonal array. The discharge current, pulse on time, pulse off time and dielectric pressure have been selected as input process parameters and hole circularity, hole taper and hole dilation as output parameters. The multi regression models for hole circularity, hole dilation and hole taper have been developed by using the experimental data. The statistical analysis for the developed models shows that the models are reliable and adequate and may be used for predicting these quality characteristics satisfactorily. These quality characteristics have been optimized by using computer aided genetic algorithm based optimization method. For the optimization, the multi regression models for circularity, dilation and taper have been considered as objective function. The multi-objective optimization result obtained by computer aided genetic algorithm based optimization method, show improvements in all of the quality characteristics.

Study of the current signal and material removal during ultrasonic-assisted electrochemical discharge machining

Electrochemical discharge machining (ECDM) is a cost-effective machining process used to shape non-conductive materials such as glass and ceramics. The process can overcome poor machinability of hard and brittle materials. Different types of physical phenomena can be added to the ECDM components to improve the machining efficiency. As the main target of this paper, ultrasonic vibration was integrated to the cathode of the ECDM process (UAECDM), which resulted in vibration concentration only to the machining zone. In order to design the experimental configuration, modal analysis was used. Machining speed was the main output of this investigation. Gas film and electric discharge were two main physical phenomena during ECDM. The thickness of gas film, location, and pattern of discharges were determined, experimentally. Also, current signal was a useful tool that could record significant details of involved mechanisms and phenomena during machining. Images of gas film showed that the application of ultrasonic vibration decreased the thickness of gas film by 65%. In addition, the vibration amplitude of 10 μm created the most uniform current signal, which had a considerable effect on the material removal rate (MRR). Results showed that all levels of vibration amplitude increased the machining speed during discharge and hydrodynamic regimes of the machining process.

Sequential procedure for selecting the ranges of process parameters in rotary ultrasonic machining

Nickel-based alloys have numerous potential engineering applications. However, their widespread applications have been hindered by the elevated machining cost. There is a crucial need for commercial and cost effective machining processes for Ni-based super alloys. Rotary ultrasonic machining (RUM) is a hybrid machining process that combines the material removal mechanisms through diamond grinding and ultrasonic vibration (USM), resulting in higher machining rate than those obtained by conventional USM. Before going to the production run, it is necessary to conduct performance analysis followed by pilot experimentation for newer material. Relationships between desired outcome and the controllable machining parameters have been deducing. However, the relationships have been studied by screening the experiments. In this paper, a three-factor two-level factorial design followed by steepest ascent is utilised to find conditions for final experimentation. [Received 16 September 2016; Accepted 12 March 2017]

Effect of Deep Cryogenic Treatment on Machinability of Titanium Alloy (Ti-6246) in Electric Discharge Drilling

Currently there is a vital need for cost effective machining processes for titanium alloys. Electrical discharge machining (EDM) is used quite extensively in machining titanium alloys due to its favorable features and advantages. This paper investigates the effect of deep cryogenic treatment (DCT) on machinability of Ti 6246 alloy in electric discharge drilling (EDD) by conducting experimental investigations on the production of 10 mm diameter blind holes with electrolytic copper tool. An attempt has also been made to compare the production accuracy of holes drilled in deep cryogenically treated Ti 6246 (DCT Ti 6246) alloy and nontreated Ti 6246 alloy in terms of surface roughness and overcut. The result of study reveals the higher material removal rate (MRR) and wear ratio (WR), lower tool wear rate (TWR) in case of EDD of DCT Ti 6246 alloy workpiece as compared with nontreated Ti 6246 alloy workpiece. Also superior production accuracy of holes is reported while EDD of DCT workpiece.

Metal working fluids: finding green in the manufacturing process

PurposeThe purpose of this paper is to provide a practical review of metal working fluids and their implications to the machining practice. Despite their widespread use and applications, there are several scientific and economic factors that call for an investigation of current practices and development of new approaches.Design/methodology/approachThere are numerous methods that diverge from traditional “wet” machining, which move towards an environmentally friendly and cost effective machining process. This includes looking at both minimum quantity lubrication and dry machining as methods to reduce recurring costs, lower health care premiums associated to metalworking fluid exposure, and to minimize the environmental footprint attributed to machining.FindingsTraditional machine lubrication techniques are in use today despite a lack of scientific or economic evidence that they function efficiently. Depending on the machine type and material used, there are several possible methods that can minimize or eliminate metalworking fluids from the machining process.Practical implicationsThis paper provides a practical assessment of current industrial practices and offers opportunities for improvement from both an economic and an environmental perspective.Originality/valueThis paper provides an overview of previously conducted research to suggest areas of improvement in manufacturing processes utilizing metalworking fluids.

Taguchi technique for modeling material removal rate in ultrasonic machining of titanium

Titanium and its alloys have many potential engineering applications for manufacturing industry. Now day's there is a critical need for cost-effective machining processes for this material. Not much work hither to been reported for machining of titanium with ultrasonic machining process. In this paper, a Taguchi approach to model the material removal rate during ultrasonic machining of titanium and its alloys has been proposed and applied. Relationships between material removal rate and other controllable machining parameters (power rating; tool type; slurry concentration; slurry type; slurry temperature and slurry size) have been deduced by using Taguchi technique. The Taguchi design results suggested that Ultrasonic power rating significantly improves the material removal rate with contribution of 28%, followed by type of tool with contribution of 24.6%. The third significant factor was type of slurry with contribution of 13.3%. The comparison with experimental results will also serve as future validation of the model.

Macromodel for Ultrasonic Machining of Titanium and its Alloys: Designed Experiments

Titanium and its alloys have many potential engineering applications. There has been a critical need for cost-effective machining processes for titanium and its alloys. Not much work hitherto has been reported on the machining of tough materials like titanium by the ultrasonic machining process. An approach to macromodelling of the material removal rate, the tool wear rate, and surface roughness during ultrasonic machining of titanium and its alloys has been proposed and applied. Relationships between material removal rate (MMR), tool wear rate (TWR), surface roughness (SR), and other controllable machining parameters have been deduced by using Taguchi technique L18 orthogonal arrays. The comparison with experimental results will also serve as future validation of the model.

Plasma Assisted Milling of Heat-Resistant Superalloys

The term Thermal Enhanced Machining refers to a conventional cutting process in which an external energy source is used to enhance the chip-generation mechanism. The work presented here analyzes the basic aspects and the experimental results obtained when applying an assisting plasma jet to the milling process. This process, known as PAM (Plasma Assisted Milling) has been applied to the machining of three very low machinability materials: a Ni-base alloy (Inconel 718), a Co-base alloy (Haynes 25), (both belonging to the group of the heat-resistant alloys) and the Ti-base alloy Ti6Al4V. The study focuses on two major topics. First, the efficiency of the milling operation in terms of cutting speed, feed, axial and radial depths of cut and the plasma operating parameters has been addressed. Second, a study on the alterations of the metallurgical structure and the properties of materials after the PAM has also been performed. The process conditions for the above-mentioned Ni-base and Co-base alloys are detailed. The study under these conditions has shown an excellent performance of the whisker reinforced ceramic tools. In fact, cutting speeds as high as 970 m/min and large radial and axial depths of cuts are possible, driving to a cost-effective machining process. The absence of changes in the metallurgical structure of the alloys after applying the PAM process is also addressed. Therefore, it can be stated that this is a feasible approach to the optimization of the machining process of heat-resistant alloys. Finally, the results obtained in the PAM of Ti6Al4V are detailed. In this experimentation, a certain level of degradation was observed in the microstructure of the alloy when undergoing the PAM process, therefore the use of this technique is not recommended for this material.

Modeling of material removal rate in rotary ultrasonic machining: designed experiments

Advanced ceramic materials have many potential engineering applications. However, their widespread applications have been hindered by the high machining cost. There is a critical need for cost-effective machining processes for advanced ceramics. Rotary ultrasonic machining (RUM) is a hybrid machining process that combines the material removal mechanisms of diamond grinding and ultrasonic machining (USM), resulting in higher material removal rates (MRR) than those obtained by either diamond grinding or USM. An approach to modeling the MRR during RUM of ceramics has been proposed and applied to predicting the MRR for the case of magnesia stabilized zirconia. Relationships between MRR and the controllable machining parameters have been deduced. These relationships agreed well with the trends observed by experimental observations made by other investigators. However, the relationships have been studied by changing one variable at a time. Therefore, the interactions between these variables have not been revealed. In this paper a five-factor two-level factorial design is used to study the relationships between MRR and the controllable machining parameters. This study will provide the main effects of these variables, and two-factor interactions and three-factor interactions among these variables. The results will shed more light on the material removal mechanism in RUM. The comparison with experimental results will also serve as further validation of the model.