Improved Surface Finish Research Articles

Investigations on homothetic and hybrid micro-textured tools during turning Inconel-718

ABSTRACT Amused with the blissful benefits of micro-textures, researchers consider it a promising option for improving cutting tool performance, especially during machining superalloys. Through this study, the machining performance of two homothetic and six hybrid micro-textured tungsten carbide inserts have been comparatively assessed while dry turning Inconel-718. Dimple and channel micro-textures were the two independent homothetic textures. Dimple and channel micro-textures with 0°, 45°, and 90° orientation angles and a combination of triangle, square, and dimples constituted six different hybrid micro-textures. Micro-textures were fabricated on the rake face of inserts using a Ti-sapphire fired, nanosecond pulsed, infrared fiber laser. Dimple and channel micro-textured tools at 90° texture angle on rake face performed exceptionally well. Improvements in average tool life, cutting forces, and surface finish have been reported. Adhesion and attrition were the predominant forms of tool wear. Chip morphology study revealed long helical and continuous but segmented chips.

Improvement of surface finish and accuracy utilising multi-step pulse waveforms in electrochemical micromachining

Improvement of surface finish and accuracy utilising multi-step pulse waveforms in electrochemical micromachining

Eco-friendly sustainable machining with MoS2-based solid lubricant

Machining is one of the basic and inevitable operations in the manufacturing industry. The machining performance is estimated based on various parameters like cutting forces, surface roughness, tool–chip interface temperature, and specific energy. In the traditional approach, cutting fluids are greatly utilized to dissipate the generated heat during machining, but their utilization causes a threat to nature and human being’s health. Therefore, there emerges a necessity to determine user-friendly, sustainable, and eco-friendly substitutes for traditional cutting fluids. The field of advanced tribology has proposed the usage of solid lubricants due to their inherent properties, such as excellent tribological performance, reduced machining zone temperature due to lowered friction, and enhanced tool life. Therefore, in the present study, pure MoS2 and composite MoS2–TiO2 solid lubricants have been employed in the milling process of AISI 52100 steel with HSS end mill cutter. The machining was carried out in different conditions such as uncoated tool without use of lubricant, uncoated tool with use of lubricant, coated tool without use of lubricant, and coated tool with use of lubricant that were employed to analyze their effect on machining performance. The experimental results showed substantial improvement regarding reduced cutting forces, reduced temperature at tool–chip interface, improved surface finish, and average tool wear with the application of solid lubricants. Among the various lubricating conditions, composite MoS2–TiO2-coated tool with composite MoS2–TiO2 lubricant exhibits excellent machining performance.

Small hole fabrication through additively manufactured CuCr1Zr electrode during EDM of a novel Haynes 25 superalloy

Present work proposes an extensive experimental investigation to evaluate the machinability of Haynes 25 work piece with additively manufactured CuCr1Zr (prepared through selective laser melting process), pure copper and graphite electrodes, in view of producing small holes of diameter 3 mm. Prior to machinability investigation, material characterization studies in terms of energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) analysis along with several other mechanical as well as physical properties such as density, microhardness, tensile strength, electric conductivity and thermal conductivity, are carried out for both the electrodes. Outcomes of critical process parameters viz. current (I), voltage (V), pulse on time (Ton), duty factor (τ), and flushing pressure (Fp) are studied on performance measures such as material removal rate (MRR), electrode wear ratio (EWR), specific energy consumption (SEC), surface roughness (Ra), and radial overcut (ROC). The EDMed surface is carefully analysed by a field emission scanning electron microscopy (FESEM) study. It is observed that additively manufactured CuCr1Zr electrode is proficient enough to produce parts with greater accuracy, improved surface finish with least amount specific energy consumption, thus saving cost and time during machining. The ideal level of cutting parameters are identified, validated with confirmative experiment with an average error of 2.79 percentages to produce precise accurate EDMed parts. This work delivers an energy efficient as well as cost effective machining strategy to produce precise and accurate small holes for EDMed applications, thus paving way for productivity of the process.

Enhancing MRR in face milling by varying cutting speed

The goal of the research is to use grey relational analysis to increase the material removal rate during high-speed machining of titanium alloy. By utilizing the best materials and processes, contemporary industries aim to increase the quality of their products. Achieving the desired product quality at a reasonable cost is ensured by choosing materials that are challenging to cut, like titanium, and by setting the best machining parameters. Depending on the process conditions, industries strive for increased productivity and improved surface finish in machining operations. In order to maximize the rate of material removal during high-speed machining of Ti-6Al-4 V, the process parameters of feed rate, cutting speed, stepover, and depth of cut are chosen in this research work. During the experiments, a L9 orthogonal array was used. The study reveals that the cutting speed, stepover have a direct impact on the rate of material removal. The rate of material removal was found to rise with respect to stepover, speed, and frequency for all depths of cut. A confirmation test was run, and the results were compared to what was anticipated. Inferring that it is in strong agreement with the experimental results.

Effectiveness of synthetic coolant at 0°C on machining of SS304 with PVD coated TiCN tool to evaluate and compare tool wear and surface finish with conventional machining method

ABSTRACT The work-hardening and low thermal conductivity characteristics of SS304 had always been a challenge to machine it easily with better tool life and surface finish. The type of coolant, its temperature and surface coated inserts plays a pivotal role in machining the hard materials. A number of experiments were performed with a TiCN and tungsten carbide inserts in combination with soluble/synthetic coolant at ambient temperature and at 0oC TiCN-coated cemented carbide insert with synthetic coolant at 0°C is recommended for machining as per the results obtained through this research work. It was found that TiCN-coated inserts used for machining SS304 with synthetic coolant at 0°C provide better tool life, less tool wear, improved surface finish and low heat generation. The tool life was enhanced approximately by 75%, 20% reduction in maximum temperature generation and 50% improvement in surface finish of workpiece.

The use of Preston equation to determine material removal during lap-grinding with electroplated CBN tools

Grinding executed in a lapping configuration is an alternative finishing process benefiting from both grinding and free-abrasive machining, while minimizing the heat effect impact. Electroplated tools can be effectively used in different abrasive processes, including high-speed grinding, however, the assessment of machining performance over time is a key factor in their correct use to achieve satisfactory technological results. In conventional grinding, bigger grain-coverage provides better results due to the higher bonding strength of grains. In lap-grinding, fracturing and crushing of the abrasive particles initially covered by the plating result in a suspension which is typically dosed continuously in free-abrasive machining. Due to this, the process transforms from two-body (grinding) to three-body abrasion (free abrasive machining) which may result in reduced grinding performance approaching asymptotically a specific value while improving surface finish. The main aim of the presented study is the evaluation of electroplated CBN tools used in lap-grinding of 40H alloy steel workpieces whose hardness was 54 HRC. The obtained results and observations of the working surface of CBN wheels and workpieces allowed for the identification of the wear characteristics for three nickel plating thicknesses corresponding to 35%, 50% and 65% of the nominal CBN crystal size and for specific process parameters. The surface roughness Ra parameter decreased gradually from the initial value 1.9 μm to the values below 0.7 μm for bigger B107 grains and for all plating thicknesses. For smaller B64 grains, the surface roughness and waviness parameters reached similar values to those obtained for the larger B107 grains at corresponding processing times. The lowest value of Ra parameter below 0.4 μm was obtained for B64 grains and for the thinnest plating but with a 50% reduction in material removal comparing to B107 grains. The Preston equation was employed to calculate the material removal as a function of time under variable process conditions in the machining zone due to the tool wear. This attempt extended the range of the material removal modeling, despite the fact that the electroplated wheels were subject to wearing down resulting in the gradual reduction in the efficiency, as well as in the change of the working conditions in the workpiece-tool contact zone.

State-of-the-art and perspectives of cutting edge preparation and its effect on the cutting performance of titanium alloy

Titanium alloys are commonly used in industrial applications due to their exceptional mechanical and chemical properties. However, their low thermal conductivity and high chemical reactivity pose significant challenges in machining, leading to increased cutting forces, rapid tool wear, and poor surface quality. To overcome these issues, advanced cutting edge preparation techniques have been developed to enhance the machining performance of titanium alloys. This paper provides an overview of state-of-the-art cutting edge preparation techniques for titanium alloy machining and examines their effects on machining performance. It first presents a characterization method for cutting edge geometry and explores how it affects machining performance, demonstrating that strategic cutting edge preparation can significantly enhance performance by reducing cutting forces and improving surface finish. The paper also emphasizes the underlying mechanisms of cutting edge preparation and its impact on machining performance and subsequent cutting edge erosion. Finally, it concludes by discussing future research directions in this field, highlighting the need to develop new cutting edge preparation techniques and optimize existing ones. Overall, this paper serves as a valuable resource for researchers and engineers seeking to improve the cutting performance of titanium alloys in various applications.

Experimental modelling and optimisation of electrochemical surface grinding of hybrid metal matrix composite

ABSTRACT The demand of hybrid-metal-matrix composites (HMMCs) is rising continuously in various industries such as aerospace, automobile and biomedical. Therefore, effective machining of HMMCs is essential for their productive utilisation. However, machining processes are usually not feasible for shaping this composite due to inherent properties of matrix and reinforcing material, and melting of reinforcement particles. In the present work, a hybrid Electro-Chemical Surface Grinding (ECSG) setup has been developed by combining the Electro-Chemical Machining and Mechanical Grinding action. The process applied on Al-SiC-Gr composite, which is a key member of HMMC family. It is a better alternative for many parts like piston and piston ring in automobile industries. Central composite design-based Response Surface Methodology has been used for experimental modelling, response prediction and optimisation. The effects of significant control factors such as applied voltage, electrolyte concentration, wheel speed, table speed and electrolyte flow rate on material removal rate (MRR) and surface roughness (SR) have been studied. The results revealed that electrolyte concentration and applied voltage are most significant factors for both MRR as well as SR. Genetic algorithm-based optimisation results confirm 45% and 38% improvements in MRR and surface finish.

A novel optimization algorithm based PID controller design for real-time optimization of cutting depth and surface roughness in finish hard turning processes

This paper proposes a novel method to improve surface finish in turning processes by effectively controlling the cutting depth. A metaheuristic algorithm based PID control system, in combination with a piezoelectric vibration sensor for feedback, is introduced to regulate the position of the servo motor that controls the cutting tool. The PID controller is optimized using Q-learning based Sand Cat Optimization algorithm to achieve the best performance in terms of cutting depth accuracy and surface finish quality. The piezoelectric sensor provides real-time feedback information about the cutting process and allows for precise adjustments to the cutting depth. The results demonstrate the proposed system's ability to handle variations in cutting conditions and tool's wear and tear. Compared to highly optimized standard PID control, improved robustness and stability has been achieved in experimental results by proposed framework. Experimental results demonstrate improved robustness and stability compared to standard PID control. Several materials with high hardness of 20–65 HRC including Phenolic Bakelite, Copper, Thermoplastic, and Stainless Steel (AISI-420, AA6061-T6, and AISI-316) are tested. Minimum value of Vibration amplitude achieved is 0.598 μm for cutting depth of 0.25 mm. The sustained minimum amplitude of vibration and Ra value of the surface finish is found comparable to standard models with less than 10% error.

Development and potential use of MWCNT suspended in vegetable oil as a cutting fluid in machining of Monel 400

The heat dissipation problem that arises when machining difficult to cut materials can be mitigated by using nano-cutting fluids, which have a much higher thermal conductivity value than the basic lubricants. Since the heat carrying capacity of the Minimum Quantity Lubrication (MQL) system is significantly lower than that of other coolants, a number of nano-additives are used to increase its cooling effectiveness. Therefore, this study firstly focuses on the assessment of nano-cutting fluids and theirsignificant efficacy in the machining operation of nickel-based alloys. Multi-walled carbon nanotube (MWCNT) suspended in vegetable oil is compared with distinct cooling environmental conditions namely, dry, MQL and cryogenic carbon dioxide (CO2). The novelty of this work is that the different volume fractions of 0.2 – 1 wt% of MWCNT were dispersed to study the contact angle, viscosity and thermal conductivity of the prepared molecular liquid and then, the potential of MWCNT suspended in vegetable oil is used to evaluate the outcomes of surface roughness (Ra), cutting temperature (CT) and tool wear (Vb) while machining Monel 400 alloy. The outcomes affirmed that employing nano MQL in machining operations resulted in a mean reduction of about 65% in the temperature evolved concerning no coolant condition. Additionally, the use of nanoparticles leads to an improved surface finish and abridged tool wear.

An environment-friendly sustainable machining solution to reduce tool consumption and machining time in face milling using a novel wiper insert

Machining is a high energy-consuming manufacturing process that also generates an enormous amount of waste in the form of chips and worn tools. With governments focusing on reducing the environmental footprint by switching to renewable energy sources and enforcing stricter regulations, industries have started looking for sustainable practices in machining as well. However, a detailed strategy with a multipronged approach in the product design, process, and system is required to transform machining into an eco-friendly process. In addition, developing a sustainable machining solution must be attempted without compromising the other critical performance characteristics of the tools. Hence, the article reports the development (design and manufacturing) of a new wiper milling insert and the investigations carried out to evaluate the sustainability quotient of the tool such as machining power, specific cutting energy, total machining time, and tool consumption. The study confirms that the new wiper milling insert can assist in combining the rough and finish machining steps into one without increasing the power consumption, which reduces the number of tools required for machining. In addition, a 50% reduction in machining time and a significant improvement in surface finish can be obtained simultaneously using the wiper insert.

INVESTIGATION ON PERFORMANCE OF EXTRUSION HONING PROCESS ON QUALITY OF SURFACE TEXTURE

The EH approach overcomes this limitation of conventional finishing method. The present study focus on the impact of number of passes at the specimen's entry and exit sides of the carrier media. The improvements in surface finish (Ra) on both side i.e entry and exit are evaluated as well. A dimensionless expression for Ra is also developed. The relation is implemented using Buckingham’s π theorem and comparison of developed model is performed with experimental results. SEM analysis is made to portray surface texture produced by selected process parameters such as number of passes, volume fraction and grit size of abrasive grains.

Experimental investigation on deballing and surface finishing of selective laser melted 18Ni300 steel using polymer rheological abrasive medium

Additively manufactured metallic parts compete with casted and forged parts in physical and mechanical properties. However, the presence of various surface defects, such as balling and staircase effects, lack of fusion, surface undulations, etc., hinders the direct functional application of the as-built part and demands further post-processing. Abrasive flow finishing (AFF) is an extensively employed post-processing technique to finish additively manufactured parts. This process uses polymer rheological abrasive medium (abrasive medium) to finish internal and external surfaces. Even though significant research has been carried out on the surface finishing of selective laser melted metallic parts, the mechanism of material removal and surface finish improvement is not explored much. In the present work, the mechanism of deballing and surface finish improvement on selective laser melted 18Ni300 steel using the AFF process is studied. A newly developed polysaccharide-based abrasive media with monomodal and bimodal abrasive particle distribution are employed for finishing. At an extrusion pressure of 7.5 MPa, the influence of abrasive particle distribution and the number of finishing cycles on the amount of material removed and percentage change in surface roughness (% ΔRa) is observed. It was found that the abrasive medium with bimodal abrasive particle distribution resulted in more material removal and % ΔRa than monomodal. Surface roughness reduction of up to 93% was obtained using the abrasive medium with bimodal abrasive particle distribution. It was noticed that the loosely adhered powder particles were removed within the initial 15 cycles, and the balling effect was completely eliminated within 75 cycles. After 375 cycles, the as-built side surface was free from all other surface defects, such as micro-cracks, shallow pits, material ridges etc. Based on the obtained results, a suitable material removal mechanism in selective laser melting parts using the AFF process was proposed.

Optimization of hot rolling parameters of CRNO steel with the aid of hot compression test and deformation map

Abstract Cold-rolled non-oriented (CRNO) electrical steels find a wide variety of applications in the core of electrical machines due to low core loss and high magnetic permeability. Stringent market conditions not only require CRNO steel with superior magnetic properties but also demand excellent surface conditions. CRNO steel is cold rolled to 0.5 mm in reversing mill. High hot rolled input thickness (>2.6 mm) increases the number of passes during cold rolling and adversely affects the mill productivity. It also results in surface defects such as buckling and coil break. The flow stress of this steel varies differently compared to conventional rolled steel. Thus, it becomes difficult to optimize the reduction schedule and hence safe hot rolling practice is adopted to restrict roll force within permissible limit resulting in higher thickness. A hot compression test was carried out in a Gleeble–3500 to evaluate the flow stress behaviour of this steel and a deformation map was developed to optimize the hot rolling window. The input from the hot compression test and deformation map was used to develop a mill setup model to accurately predict the roll force and optimize the reduction schedule of CRNO steel in the finishing stands of HSM. The final thickness of hot-rolled coils during industrial trials with an optimized reduction schedule was found to be in the range of 2.4–2.6 mm compared to 2.7–3.0 mm during conventional rolling. These coils were further cold rolled and finished in 4–5 passes compared to 6–7 passes with conventional rolling. Reduction in the number of passes has resulted in increased productivity during cold rolling as well as improved surface finish.

One-Step High-Speed Finish Drilling of Inconel 718 Superalloy via Novel Inserts

Inconel 718 is considered the most widely adopted nickel-based superalloy, and drilling of this alloy is always challenging for researchers. Cemented carbide twist drills have been evaluated in the drilling of this alloy by changing the cutting environment or by varying the tool geometry. In the latter case, the cutting speed has been extended from 30 m/min to 60 m/min when drills are micro-textured or ground. In this study, contrary to cemented carbide twist drills, for the first time, inserts named stepped (central) and peripheral (wiper) are evaluated in the drilling of this alloy. The central insert is designed for balanced forces, while the peripheral is a wiper insert designed for better surface finish. Drilling experiments are conducted in flood cooling conditions with a 12 mm diameter twist drill equipped with novel stepped and wiper inserts at varying cutting speeds (25, 35, and 45 m/min) and feed rates (0.04, 0.06, and 0.08 mm/rev). At a cutting speed (Vc) of 25 m/min and feed rate (f) of 0.04 mm/rev, 25 holes are drilled with roughness (Ra) values ranging from 0.40 µm to 0.60 µm, which represents a significant increase in the number of holes per drill and improved surface finish over to previous work. The new inserts showed almost three-fold longer tool life compared to a standard drill bit at a higher Vc of 45 m/min and 0.04 mm/rev f with an Ra between 0.22 µm to 0.43 µm, which is deemed acceptable for aerospace applications. In addition, minimal surface and sub-surface defects were observed, eliminating the need for a post-drilling finishing operation; therefore, a one-step drilling operation was achieved.

Cold Microdrawing of Pure Magnesium Capillary Structures for Biomedical Applications

Abstract This paper presents a study on cold microdrawing of pure magnesium for biomedical applications, where hollow sinking drawing of microtubes of 820 μm diameter and wall thickness around 100 μm was used, varying drawing speeds to achieve a significant reduction in cross-sectional area in a single pass. Results showed an improved surface finish with reduced surface roughness after drawing. The material exhibited an increase in microhardness and ultimate tensile strength by 41% due to work hardening caused by plastic deformation. The study also identified wall thickening of the tube and observed springback behavior of Mg at the die exit. Drawing forces were collected for process monitoring, and finite element (FE) simulations were conducted to assess the risk of pure Mg microtube breakage. This research contributes to advancing the state of the art in Mg microtube drawing, addressing the unique challenge of working with such small tube dimensions where limited studies currently exist.

Effect of copper nano-cutting fluids in end milling of al 6061 and its influence on work piece morphology

Due to its exceptional mechanical qualities, aluminium 6061alloy is frequently utilised at automotive and aerospace industries. During the machining process, lubricating oil is typically supplied into the cutting zone to enhance machining performance, including tool life and workpiece surface quality. However, conventional coolants perform less effectiveat higher temperatures. The introduction of Copper Nano coolant at cutting interface could sustain greater temperatures. The surface finish of work piece is improved significantly as the Nano coolants at the tool-chip interface considerably reduces friction and thermal deformation. Utilizing the Minimum Quantity Lubrication (MQL) approach could reduce the amount of lubrication oil needed, reducing pollution. Cu Nano lubricants are made in concentrations of 0.2, 0.6, and 1.0% vol. in a water–oil base lubricant in a 20:1 ratio. The size, structure, and elemental content of the Cu nanoparticles are studied using EDX and FESEM. Cutting force, temperature, and surface quality are alsomeasured. It has been noted that the use of copper Nano coolants enhanced the workpiece's surface polish and greatly decreased the cutting forces and cutting temperatures. The development of thin layer over work piece is responsible for improved surface finish and reduced cutting forces and temperatures.

Optimization of parameters for turning of OHNS steel

Present scenario of industries is to lower the production cost, time and increase the profit. For high quality production of components, hard turning is suitable process as it is having numerous advantages. It requires low cost and time, flexibility in production, improved surface finish and material removal rate (MRR). Due to its advantages, it becomes essential as grinding process. This process can be applied when the hardness of the material is above 45 HRC. The characteristics required with the machine for hard turning are hard cutting tools availability, required tool geometry, capacity of tool holding and required power supply. Surface roughness and MRR are the most important factors which are essentially considered during machining process evaluation point of view. In this proposed experimental work, the detailed study of the analysis of surface roughness and MRR during turning of oil hardened non shrinkable (OHNS) steel is to be done. For the good quality of surface finish and higher material removal rate in the industry to earn more profit, it is essential to do the optimization of the process. In this research work, the input parameters of the CNC machining of OHNS steel are optimized. The selected input parameters are spindle speed, feed rate. The output parameters are surface finish and MRR. The experiments were performed as per the Taguchi DOE and the results were analyzed. The significance of each parameter is analyzed in ANOVA and the parameters were optimized with validating the experimentation as per the regression model.

Effect of applied pneumatic pressure on the polishing spot size and the total normal force in pneumatically configurable polishing

The present study pertains to a compliant polishing technique called Pneumatically Configurable Polishing (PCP) which uses the precise inflation of a thin elastomeric diaphragm or membrane using pneumatic pressure for generating nano level surface finish on substrate surfaces. The PC polishing tool which has a cup shape is made to contact the workpiece surface such that its flexible nature can adapt itself to the macro features on the workpiece. This inflated tool-work contact leads to the entrapment of the hard abrasives preplaced in the interface zone in the form of a slurry. The rotary motion of the tool along with the relative motion between the workpiece and tool, help to generate an improved surface finish in the interface area. The area of the finishing zone is an important outcome of the polishing regime because it defines the dimensions of the area which will be affected by the tool. It also helps to estimate the time needed for polishing a large area. Also, the force transmitted to the workpiece surface is an important measure to estimate the functional life of the tool. In the current study, the variation of the spot size and total normal force are modelled mathematically in terms of the physical and geometrical properties of the tool as well as the applied fluid pressure. The Hertz theory of contact is used to model the contact conditions in the polishing interface zone. The model studies the effect of pneumatic pressure on membrane inflation and its influence on the area of the polishing spot at varying working gaps. The effect of the applied fluid pressure is studied on the normal force experienced by the workpiece, and the results obtained from the model are validated with experimental verification under identical polishing conditions. The values obtained experimentally show a close agreement with the theoretical results obtained from the model.