Modern Machining Research Articles

A new approach for local cutting force modeling enabling the transfer between different milling conditions and tool geometries

The modeling of modern high performance machining with intermittent cut and varying effective cutting parameters requires a flexible local cutting force prediction. Due to complex tool geometries and varying cutting conditions without a rigid reference system new approaches for the local cutting force decomposition are applied, investigated and compared. The force decompositions are based on the separation of the effective cutting speed into normal and tangential components to adequately consider the locally acting mechanisms. Regression models based on the effective cutting parameters are defined to compare and validate the local force decomposition. A high feed peripheral milling experiment with specific cutting force measurement is presented to develop the regression models. An extensive cutting force database for AISI 5115 is created by tool geometry and process control variable variations. The effective cutting conditions are calculated through geometric penetration simulation. Considering the tool deflection in the simulation achieves a high regression accuracy even with low chip thicknesses. This is especially important for the cutting force prediction of finishing processes. The resulting regression cutting force models and force decompositions are rated based on the applicability to different tool geometries, like a ball end mill.

Examination and prediction of process parameters for Surface roughness and MRR in VMC-five axis machining of D3 steel by using RSM and MTLBO

VMC five-axis is modern machining method, used for milling operations that focus on rotary cutters to extract surplus material from a work piece. To achieve machining economics in VMC-5-axis machining, choice of optimum process variables is crucial. Surface roughness and material removal rate are significant response variables, and analyzing and optimizing both the responses combinedly is an important research area in milling. Current research is planned to analyze, model and predict the optimum milling parametric condition of VMC-5-axis machining of D3 tool steel to anticipate surface roughness and MRR simultaneously by applying response surface methodology and multi-objective teaching learning-based optimization (MTLBO). The experiments had been planned as per Box-Behnken design of response surface methodology. Statistical analysis of variance (ANOVA) is applied to determine the significances of milling conditions on milling performance characteristics. ANOVA results revels that milling processing conditions are more significant for MRR as compared to surface roughness. Modeling of responses is made by RSM. Contour plots are drawn from developed mathematical models for visualizing the direct and combined effects of milling conditions on both the responses. Multi-responses are solved by MTLBO technique. Predicted milling condition is verified by confirmatory test. The concluding remarks have been drawn from the study. From the present research work, it is found that milling responses are improved at predicted condition obtained by hybrid RSM and MTLBO approach.

Optimization of machining parameters in wire cut electrical discharge machining Inconel 600 using untreated brass wire

Abstract WEDM is one of the precise and modern machining path leading in obtaining the efficient manufacturing techniques. In view of machining nickel–chromium alloy, one of the hard-to-cut materials, present paper deals with electro-machining of Inconel 600 using un-treated brass wire. Experiment has been conducted with varying in current, pulse on and pulse off time at constant voltage and di-electric fluid flushing rate. To minimize the experiments and material, a design of experiments was employed based on the L9 orthogonal array was selected. In WEDM pulse rating plays a critical role on surface roughness and material removal rate. Therefore the investigation was carried out to correlate best optimum conditions favouring for lower surface finish and higher material removal rate. Mathematical regression is carried out at alpha of 0.5. Anova analysis was carries out and found that for surface roughness and material removal rate current is most contributing parameter. A mathematical models has been generated in co-relation with input parameters and found that for surface roughness Rsq is 93.32 and for material removal rate Rsq is 92.37.

Application of Type-2 Fuzzy AHP-ARAS for Selecting Optimal WEDM Parameters

Machining of the nickel-based alloy is very demanding due to its extreme mechanical properties, for example, higher fatigue strength, better corrosion and creep resistance feature, substantial work hardening capability, and appreciable tensile and shear strength. Owing to these properties, the selection of machining parameters is a major challenge for modern machining industries. Therefore, the present experimental work is carried out to select the best parametric combination of the wire electrical discharge machining (WEDM) machine for reducing machining cost and human effort. The Trapezoidal Interval Type-2 fuzzy number (T2FS) integrated Analytical Hierarchy Process (AHP)-based Additive Ratio Assessment (ARAS) method is used for selecting the best WEDM process parameters of Inconel-800 superalloy. Finally, the results were compared with some existing multi-criteria decision-making methods to confirm the validity of the adopted method. The comparison shows that Type-2 Fuzzy AHP-ARAS synergy can help to formulate the problem and facilitate the assessment and ranking of WEDM process parameters when multiple criteria are jointly considered.

Special Issue on “Machining Dynamics and Parameters Process Optimization”

In 1907, F.W Taylor—the father of production engineering—exposed the fundamentals of modern machining and defined chatter as the most obscure and delicate of all problems facing the machinist [...]

Oil mist concentration and machining characteristics of SiO2 water-based nano-lubricants in electrostatic minimum quantity lubrication-EMQL milling

• SiO 2 nano-lubricant droplets presented better chargeability and more likely to be affected by electrostatic force to adsorb and deposit. • SiO 2 nano-lubricant showed higher penetrability after charging compared with vegetable oil. • The adsorption quantities of the charged SiO2 nano-lubricant droplets were larger than those of the charged vegetable oil droplets. • SiO 2 nano-lubricant EMQL showed much lower oil mist concentration and alternative machining performance of traditional oil-based MQL. Minimum quantity lubrication (MQL) machining is an advanced near dry cutting technology in modern machining field. However, the cutting oil mist produced during the process of oil-based MQL affected the ambient air quality and endangered the health of employees. To avoid this drawback, a novel lubrication/cooling method called electrostatic minimum quantity lubrication (EMQL) which used SiO 2 water-based nano-lubricant as cutting fluid was proposed. The charge mass ratio, surface tension and contact angle of SiO 2 water-based nano-lubricant and vegetable oil with different charging voltages were compared, and the penetration performance of these two lubricants was analysed using capillary dynamics equation. The adsorption and deposition properties of oil mist produced by different lubrication methods were investigated, and revealed the adsorption and deposition mechanisms of the charged droplet. The influences of the charging voltage, flow rate, air pressure, spindle speed and cutting depth on PM10 and PM2.5 concentrations under different lubrication conditions were revealed. Finally, the milling performance of SiO 2 water-based nano-lubricant EMQL of stainless steels was evaluated comparatively. The results showed that SiO 2 water-based nano-lubricant presented better chargeability compared with vegetable oil, and thus displayed stronger penetrability, adsorption and deposition capacity. SiO 2 water-based nano-lubricant EMQL with -4 kV showed the lowest oil mist concentration and similar machining performances compared with the vegetable oil MQL, and the concentration values were close to the standards set by the National Institute for Occupational Safety and Health (NOISH). The charged SiO 2 water-based nano-lubricant droplets with excellent charging performance presented better adsorbability and penetrability, so that the charged droplets were prone to be electrostatic adsorbed in the machine tool and penetrated into the cutting region, which reduced the oil mist content in the machining environment and presented alternative cutting performance.

Effect of WEDM parameters on material removal rate and kerf’s width of cobalt chromium molybdenum using full factorials design

ABSTRACT The use of non-conventional process for machining superalloys provides a better alternative compared to conventional machining. Conventional tool oriented processes like CNC machining demands higher manufacturing cost resulted from higher tool wear rate. In contrast, modern machining processes like Wire Electro-Discharge Machining (WEDM) eliminates such cost by offering contactless machining. This research investigated the effect of WEDM machining parameters, namely pulse-on-time (Ton ; 2 µs – 6 µs), pulse-of-time (Toff ; 10 µs – 30 µs), and peak current (Ip ; 10A – 14A) on the material removal rate (MRR), kerf’s width and surface integrity when machining cobalt chromium molybdenum (CoCrMo). Design of Experiment (DOE) with experimental runs of 11 full factorials design was deployed to determine the optimum parameter interaction. The result was analysed using analysis of variance (ANOVA) and mathematical models were developed to determine the relationship between the machining parameters and process performance (MRR and kerf’s width). Confirmation tests were then performed to ensure the adequacy of the result. It was found that the most significant parameter that affected both MRR and kerf’s width was pulse-on-time (Ton ). The optimum result could be achieved when pulse-on-time (Ton ) was set at a high level (6 µs) for MRR and low level (2 µs) for kerf’s width.

Preparation and analysis of micro-holes in C/SiC composites and ablation with a continuous wave laser

Pulsed lasers and continuous wave (CW) lasers play an important role in modern machining technology, especially in machining materials with high hardness, such as C/SiC ceramic composites. However, for pulse lasers, the high costs have been a huge obstacle to their application in machining C/SiC composites. In this work, a CW laser was used to machine micro-holes with less than 1 mm diameter, and the effects of different laser output powers to micro-holes quality and the methods which are used to clean residue were examined. One can conclude that, when the power output is 50 W, the micro-hole surface morphology is better than that of the holes formed with two other output power values. During laser machining, the SiC matrix will be ablated and removed from a carbon fiber layer-by-layer. After cleaning with distilled water and HF, oxide residues can be removed and the expected micro-holes would be successfully constructed.

A multi-sensor integrated smart tool holder for cutting process monitoring

As two of the most significant parameters reflecting the cutting process, cutting force, and vibration are often adopted for tool condition monitoring (TCM) which is especially important in modern machining. Hence, various methods and sensors for detecting these two signals have been proposed and developed. In this study, an innovative multi-sensor integrated smart tool holder is designed, constructed, and tested, which is capable of measuring triaxial cutting force, torque, and cutting vibration simultaneously and wirelessly in milling operations. A standard commercial tool holder is firstly modified to integrate six capacitive sensors and an acceleration sensor. All the sensors and other electronics, like data acquisition and transmitting unit, are incorporated into the tool holder as a whole system. The characteristics of the device are then determined by a series of tests. Besides, an effective TCM model is built by fusing the features of cutting force and vibration. Experimental results showed good performance of the proposed system which could support wide and flexible application scenarios.

Design, preparation and cutting performance of bionic cutting tools based on head microstructures of dung beetle

Abstract Metal cutting plays an important role in modern machining industry, but the cutting tool wear strictly restricts the processing efficiency and tool lifetime. Some billions of years of evolutionary natural creatures have the anti-friction function that scientists are eager to have in their cutting tools. Thus, two kinds of bionic cutting tools were designed based on the surface structure of dung beetle head in this article. Moreover, such tools were fabricated with laser processing based on YS8 cemented carbide cutting inserts. Ti6Al4V dry cutting experiment was carried out at CA6136 turning machine by bionic cutting tool (ap = 0.3 mm, f = 0.1 mm/r). The main cutting force of Tool1 decreased 30.41 % than the non-microstructure tool when the cutting speed vc is 20 m/min, and the average friction coefficient at the tool-chip interface of Tool2 decreased by 14.53 % at 60 m/min.

Influence of process parameters on dimensional accuracy of machined Titanium (Ti-6Al-4V) alloy in Laser Beam Machining Process

The process enhancement plays a vital role in the modern machining techniques during machining of newer materials such as titanium alloys. In the present work, a research endeavor was made to examine the effects of process parameters in laser beam machining process while drilling holes over Titanium (Ti-6Al-4V) alloy under Taguchi approach of experiments. Nozzle distance, power, focal length and gas pressure were chosen as the input process parameters to assess the dimensional accuracy quality measures such as roundness and ovality in laser beam machining process. It was found that power has the most significant impact on determining the dimensional accuracy. 1.2 mm (ND), 2 mm (L), 4 bar (GP) and 2 kW (J) has been chosen as optimal process parameters combination for obtaining better dimensional accuracy among the selected process parameters. It was also observed that the machinability could be highly influenced with lower peak power.

Multi-response optimization of WEDM process parameters during the fabrication of microchannels for industrial applications

The dissipation of heat from integrated circuits and other electronic devices are transfer by devices known as microchannels. Microchannels can be fabricated by various traditional and modern machining methods. Among the traditional and modern machining methods, the wire electrical discharge machining (WEDM) has been recently explored as a good alternative machining process. WEDM has tremendous potential on account of the versatility of its applications. In this study, the effect of WEDM parameters such as peak current (Ip), pulse on time (Ton) and pulse off time (Toff) on the surface roughness (Ra) and material removal rate (MRR) is evaluated during the fabrication of microchannels. Response surface methodology orthogonal array has been used to carry out the experimental runs using brass wire (diameter 0.25 mm) as electrode. Single-response optimization through Genetic algorithm (GA) for maximum MRR = 7.0964261800mm3/min and minimum Ra = 3.35966619 µm have found for fabrication of brass microchannel are Ip = 200.104A, Ton = 118.4 µs, Toff = 51.81 µs, and Ip = 200.36A, Ton = 118.4 µs, Toff = 45.003 µs respectively. The confirmation results show the goodness of the developed models. A set of non-dominated preto-optimal solutions has been generated for multi-response optimization through GA. The best solution has been found for maximum MRR and minimum Ra are Ip = 178.3805A, Ton = 108.8105 µs, and Toff = 44.9989 µs. It is the multi-objective optimal solution to the fabrication of brass microchannel.

Influence of modern machining processes on the surface integrity of high-entropy alloys

High Entropy Alloys (HEAs) are a recent class of materials. In contrast to conventional alloys, HEAs consist of five alloying elements in equiatomic equilibrium. The high entropy effect is due, among other things, to the increased configuration entropy, which promotes solid solution formation. Many HEAs have enormous application potential due to excellent structural property combinations from very low to high temperatures. For the introduction of HEAs in real components, however, the question of the applicability of machining production technologies for component manufacture is of central importance. This has so far received little attention in global materials research. Reliable and safe processing is essential for the demand of economical component production for potential areas of application, e.g. in power plant technology. For metals, milling is the standard machining process. This article presents the results of machining analyses. It focuses on the surface integrity resulting from the milling process on a Co20Cr20Fe20Mn20Ni20-HEA. For this purpose, investigations were carried out using ball nose end milling tools for conventional milling process in comparison to an innovative hybrid process available at BAM Berlin, Ultrasonic-Assisted Milling (USAM). USAM promises a lower degradation of the surface properties due to lower loads on the workpiece surface during machining. For this purpose, basic milling parameters (cutting speed and tooth feed) were systematically varied and cutting forces were measured during the milling experiments. The subsequent analysis of these forces allows an understanding of the mechanical loads acting on the tool and component surface. These loads cause topographical, mechanical and microstructural influences on the surface and consequently on the surface integrity. For their characterization, light and scanning electron microscopy were used, and the roughness and residual stresses via X-ray diffraction were measured. The results indicate significant advantages using USAM, especially due to reduced cutting forces compared to the conventional milling process. This causes lower mechanical loads on the tool and surface, combined with lower tensile residual stresses on and below the surface, and ultimately results in a significantly enhanced surface integrity.

CAD-CAM технології проєктування та виготовлення деталей на верстатах з ЧПК

The paper investigates the use of CAD-CAM technologies for the design and manufacture of parts on machines with numerical program control (CNC). These technologies allow designing technological routes of processing of surfaces of details of various complexity and making them on modern processing centers with CNC, and their use in the conditions of small-scale, single productions is justified and economically rational.Many operating enterprises in various industries have long been using technological equipment that is morally and physically obsolete. As a rule, wear parts (spare parts) are no longer produced for them. Replacement of obsolete technological equipment in the existing technological schemes of the production process of the enterprise requires significant material and financial costs, and its repair is complicated by the lack of spare parts. Therefore the question of manufacturing by the individual order of the enterprise of a small amount of worn out details for increase of maintainability of the operating technological equipment is actual.The article is devoted to the study of the possibilities of using CAD-CAM software systems «Autodesk Inventor», «ESPRIT» and «Creo Parametric» for the manufacture of custom worn impeller centrifugal electric pump KM 65-50-220, installed in the water treatment system of the food process .The step-by-step sequence of designing and manufacturing of a new improved (modernized) part instead of worn-out, possibilities and advantages of modern CAD-CAM software complexes, technological possibilities of CNC equipment is investigated. It is shown that the use of CAD-CAM systems «Autodesk Inventor», «Esprit» and «Creo Parametric» and a modern machining center Haas UMC-750 with CNC for the manufacture of a new improved design of the impeller of the electric pump, in single production, has significantly reduced technological time, preparation for the manufacture and replacement of worn parts, to improve the quality, reliability, durability and maintainability of the equipment operating at the enterprise.

A Short Review on Machining With Ultrasonic MQL Method

Cutting fluids are required in huge amount in the modern machining methods. Cutting fluids are needed for providing lubrication as well as cooling the workpiece during machining. Cutting fluids are made of mineral oils and have many drawbacks including many health hazards and environment impact. Various other methods of cutting fluid delivery are being tested in order to reduce the effects of cutting fluids in machining. One such method is minimum quantity lubrication. Many researchers have shown the effectiveness of MQL over the conventional flood method. However the MQL method has drawbacks in terms of heat carrying capacity. In order to increase the effectiveness of the MQL method many advanced methods are being tested for improving the cooling efficiency of the MQL method. One of the methods is ultrasonic method. This method is currently in nascent stages and is being researched upon as a viable alternative to the conventional MQL method. This paper describes this hybrid delivery method in machining.

Abrasive Jet Drilling Of Glass using Normal-bed and Fluidized-bed AJM Setup

Abrasive Jet Machining (AJM) is a promising unconventional modern machining process used to machine hard and brittle materials. This paper focuses on machining of borosilicate-glass work piece with various grits of zircon abrasives using normal and fluidised bed mixing chamber based AJM setups.The normal AJM setup is first designed and fabricated to conduct the experiments according to the Box-Behnken design of response surface methodology. Again, some modifications are made in the existing normal mixed chamber to fabricate the fluidized bed mixing chamber based AJM setup and experiments are carried out with the same input parameters on both the AJM setups. The SEM micrograph analysis is performed to study the impact-mechanism and crack-propagation due to AJM.

Experimental Study on Abrasive Flow Machining (AFM): New Approach for Investigation on Nano-SiC in the Improvement of Material Removal and Surface Finishing

The latest improvement in the usage of good strength, hard, and high-temperature-resistant materials in manufacturing required the advancement of modern machining methods. The AFM (abrasive flow machining) is a non-conventional finishing technique within which an abrasive viscoelastic polymer is pressed around the surface area of the workpiece. An AFM experimental arrangement is manufactured and designed along with highly generated media in order to finish the internal cylindrical surface areas of Al7075/SiC NMMCs. Work pieces are made by means of lathe operation soon after stir casting metal matrix nanocomposites, 25 mm diameter crossbar of 1%, 2%, 3%, and 4% nano-SiC (50 nm) by weight. The effect of abrasive flow machining process parameters, namely, extrusion pressure, abrasive mesh size, and the number of cycles on surface roughness (ΔRa) and material removal (MR) was evaluated. The mechanical properties such as hardness, tensile strength, and density are calculated. The scanning electron microscopy (SEM), OM, EDS, and XRD analysis additionally show the enhancement in the surface finish of these NMMCs.

Multi-response Optimization and Surface Texture Characterization for CNC Milling of Inconel 718 Alloy

The objectives of any modern machining process are to continuously enhance both volume and rate of production with best utilization of the resources. Attempts are always made to innovate, explore, plan and use resources such that the machining work becomes more and more effective, efficient, economically viable and environment-friendly. This requires knowledge or awareness of the factors which govern machining economy. In this research work, a fuzzy-based desirability function analysis has been considered for selection of input parameters of a CNC milling process, which will simultaneously optimize the responses like surface roughness, axial cutting force and material removal rate for decision making. A multi-response optimization for CNC milling of Inconel 718 alloy has been performed. The results showed that observation 12 has the highest value of multi-performance characteristic index (MPCI) and optimum combination of machining parameters is speed (3500 rpm), feed (100 mm/rev) and depth of cut (0.25 mm). In addition, most influencing factors for highest value of MPCI are feed rate. Digital image processing technique is used to measure the pixel count within two successive scratches. This technique illustrates that maximum and minimum distances between two successive scratches are 45.3 mm and 3.74 mm, respectively.

An outlook on the sustainable machining aspects of minimum quantity lubrication during processing of difficult to cut materials

Modern machining scenario is facing intense pressure to adopt sustainable machining to fulfill the demand of future energy need without compromising the reserve of conventional energy resources. The water crisis, energy deficit, global warming and profitability have generated the need of handsome debate on sustainable manufacturing in present scenario of industry 4.0. The technological development have raised the comfort level of living being with context to transportation, telecommunication and medical facilities as a result of processing harder grade materials utilizing conventional and modern machining operations. However, during processing of aforementioned materials the advanced level of process parameters require higher energy, consequently, resulted into elevated cutting temperature leading to poor product quality as well as uneconomical machining. Hence to lower the excessive cutting temperature the metal working fluids are utilized to absorb the heat evolved at different zones of machining operation. Consequently, the temperature get reduced, but raises the scarcity of negative effects such as skin rashes, itching, asthma, water pollution, soil pollution, mist generation and sometimes unprofitable conditions. So, to bridge the gap between the limitations of dry machining and conventional flood lubrication, the concept of minimum quantity lubrication has been exercised to achieve the challenges and goals of sustainable machining. In this papers, the sustainable machining aspects of minimum quantity lubrication has been while processing the titanium, Inconel, magnesium and other ferrous alloys which are widely used. The Investigation indicated that the sustainable machining is dominant in present era of machining employing minimum quantity lubrication, cryogenic cooling and other hybrid cooling methodologies. Furthermore, several technological advancements, such as UAG, ECT, UAM and LAM have been reported to ease conventional machining operations during processing of harder grades materials.

FEM-Design & fabrication of a micro-milling tool by tangential laser machining

Due to the progressive miniaturization of components, micro-cutting is gaining in importance. The fabrication of micro-cutting tools by USP laser processing provides an alternative solution to grinding. It enables high geometric flexibility in the tool design and a very low rejection rate. In this paper, the cutting tool geometry is optimized using FEM simulations. These self-designed tool geometries with a diameter of 0.2 mm are produced on a modern 8-axis laser machining center and analyzed by 3D-confocal microscopy and SEM. Finally, the tools are successfully tested in chipping copper and compared to conventional tools.