Circularity Error Research Articles

Damage-free hole making using microwave drilling in flax/PP composite

ABSTRACT The current study focused on the examination of hole quality in microwave drilling of microwave cured natural flax and polypropylene composites. The effect of two input parameters, i.e. microwave power and feed rate of the concentrator were investigated to evaluate HAZ, circularity error, and overcut of the hole. Stereomicroscopic images were used for examination of the response parameters. The full factorial design of the experiments was carried out with two factors and four levels. It was found that flax/PP composite drilled at 180 W of microwave power and 130 mm/min of feed rate resulted in a minimum overcut and circularity error of 9 µm and 138.5 µm, respectively. Also, 360 W of microwave power and 130 mm/min of feed rate showed a reduced HAZ of 67.5 mm2. There was no fiber delamination observed during hole formation. Regression analysis was done in order to establish a relationship among responses and process parameters. Additionally, an ANOVA was undertaken to determine the significance of the model. Over 95% of the correlation between the experimental data and the projected model outcomes was observed. Combined interaction of both the input parameters was shown through surface and contour plots.

Investigating micro-EDM machinability of Ti-35Nb-7Zr-5Ta (TNZT) alloy

ABSTRACT Titanium and its new-generation alloys are widely employed in high-end applications due to their special properties. Modern industries frequently use micro – Electro Discharge Machining (μ-EDM), a non-conventional machining technique that is especially useful for processing hard to machine materials like titanium alloys. μ-EDM can produce intricate shapes with excellent dimensional precision. The main emphasis of this work is an experimental analysis of the μ-EDM of TNZT alloy (Ti-35Nb-7Zr-5Ta) employing a tungsten carbide (WC) electrode. The results showed that with the increase in capacitance (C) 10nF to 100nF at Voltage (V) 80 V, the machining performance parameters such as material removal rate (MRR), overcut (OC), crater area, surface microhardness, and surface roughness increase by 6.38, 1.52, 4.66, 1.07, and 3.29 times, respectively. However, the circularity error of the µ-hole increases by 1.81 times. This study intends to show how the two key machining factors (C & V) influence significant machining performance parameters.

An Analysis of Chip Formation and Hole Circularity in Drilling Applications: An Aircraft Components Perspective

Drilling plays a critical role in the production of precise holes for aircraft components. However, drilling aluminum alloys poses challenges, leading to poor hole quality and potential defects in the airframe structure. This study focused on investigating chip formation, hole circularity, and drilling parameters, specifically feed rate and spindle speed. Dry drilling trials are conducted using high-speed steel drill bits and the Al6061-T6 alloy. The CIMCO MDC-MAX software is employed to monitor machine performance and accumulate comprehensive data. The study investigates the effect of varying feed rates on hole circularity, chip development, and chip thickness. Findings indicate that higher feed rates result in increased circularity error and chip thickness. The circularity graph shows inconsistencies due to workpiece vibration during drilling. Chip thickness rises with the feed rate, particularly with an increased number of drilled holes, attributed to factors such as tool rubbing and improper cutting. Additionally, the study highlights the correlation between machine performance and product quality. The CIMCO MDC-MAX data reveals that a feed rate of 0.260 mm/rev corresponds to high machine performance and low circularity. Conversely, Drill 6, operating at a feed rate of 0.230 mm/rev, exhibits poor machine performance and higher average circularity. The research enhances understanding of chip formation and hole circularity in drilling applications for aircraft components. The results emphasize the importance of optimizing drilling parameters to achieve superior hole quality. Practical implications are provided for enhancing the drilling process in aerospace manufacturing.

Impact of process parameters in drilling of glass epoxy composite with clam shell and cenosphere filler: A comparative analysis

Drilling is one of the secondary machining techniques most frequently utilised when Glass Fibre Reinforced Polymer (GFRP) materials are assembled into a structure. The present work examines the drilling GFRPs and analyses hole quality based on the different traditional parameters: feed rate, spindle speed, and drill tool diameter. However, the hybridization of glass fiber- reinforced polymers (GRPs) by incorporating fillers as secondary reinforcement in the present piece of research has introduced new challenges for hole drilling and achieving the desired surface finishes. The delamination at the hole entrance and exit, considering the drill diameter of the HSS twist drill (6, 8, 10 mm), feed rate (0.04, 0.08, 0.12 mm/rev), cutting speed (1000, 1200, 1400 rpm), and filler content (0, 10, 20 wt.%) in GFRP, are the major factors are considered. The fillers used are clamshell powder and cenosphere, which are marine waste and thermal power plant waste, respectively. The present paper aims to study the effect of these fillers on the drilling-induced damages to the holes in terms of delamination factor, surface roughness, and dimensional accuracy of the hole (taper error, circularity error) of GFRPs. The most widely preferred Taguchi experimental design has been used for optimising the process parameters to obtain minimum delamination, surface roughness, and hole error. The study also aims to develop a correlation between feed rate, cutting velocity, drill diameter, and filler content with the delamination factor, surface roughness, taper error, and circularity error in a GFRP material. The observed results show that clamshells filled GFRP shows lower delamination, surface roughness, circularity error, and taper error compared to cenosphere filled GFRP composites under the same process parameters. It indicates the positive impact of the fillers in the drilling of GFRP, where the main objective is to reduce drilling-induced defects.

Calibration strategies for enhancing accuracy in serial industrial robots for orbital milling applications

PurposeThis research paper aims to optimize the calibration process for an ABB IRB 120 robot, specifically for robotic orbital milling applications, by introducing and validating the use of the observability index and telescopic ballbar for accuracy enhancement.Design/methodology/approachThe study uses the telescopic ballbar and an observability index for the calibration of an ABB IRB 120 robot, focusing on robotic orbital milling. Comparative simulation analysis selects the O3 index. Experimental tests, both static and dynamic, evaluate the proposed calibration approach within the robot’s workspace.FindingsThe proposed calibration approach significantly reduces circularity errors, particularly in robotic orbital milling, showcasing effectiveness in both static and dynamic modes at various tool center point speeds.Research limitations/implicationsThe study focuses on a specific robot model and application (robotic orbital milling), limiting generalizability. Further research could explore diverse robot models and applications.Practical implicationsThe findings offer practical benefits by enhancing the accuracy of robotic systems, particularly in precision tasks like orbital milling, providing a valuable calibration method.Social implicationsWhile primarily technological, improved robotic precision can have social implications, potentially influencing fields where robotic applications are crucial, such as manufacturing and automation.Originality/valueThis study’s distinctiveness lies in advancing the accuracy and precision of industrial robots during circular motions, specifically tailored for orbital milling applications. The innovative approach synergistically uses the observability index and telescopic ballbar to achieve these objectives.

An experimental investigation into the influence of water column height in submerged mode of abrasive waterjet trepanning on the hole quality

Abrasive waterjet (AWJ) trepanning/drilling exhibits immense potential to realize holes of various shapes and sizes in a diverse range of materials, ranging from soft-and-ductile to hard-and-brittle, making it highly valuable for various industries. AWJ trepanning offers the advantage of not requiring tool changes to accommodate different hole shapes and sizes; adjusting the jet path can produce the desired hole geometry, proving exceptionally advantageous for mass production. However, the stochastic nature of the jet results in geometrical errors (diametric deviation, taper angle (α)), form errors (circularity error (Ce), cylindricity error (Cy)) and quality issues (damage region, edge radius (R), surface roughness (Ra), and waviness (Wa)). To address these issues, trepanning in submerged mode can be adopted as it attenuates the mist region and aggressiveness of the jet. This study analyzes the influence of the submerged mode of trepanning on the geometry, form, and quality of trepanned holes relative to the in-air mode. The study found that submerged trepanning produces a more consistent hole diametrical profile along the depth and minimizes the average Ce and α by 23.18 % and 29.20 %, respectively. The maximum Cy in in-air trepanning was reduced in submerged mode by 36.76 %. The average damage region and R reduced by 50.80 % and 35.49 %, respectively. The qualitative and quantitative analysis of the trepanned surface morphology is presented in-air and submerged mode: the results show that the Ra and Wa decrease at the hole entry and middle zone and increase at the exit zone. Finally, the process parameters level settings for achieving near-optimal trepanning responses (α, Cy, Ce, damage region, R, Ra, and Wa) suggested with the help of mean response- and parallel coordinate- plots. Micrographs of submerged trepanned surfaces show that the material removal mechanism (MRM) governs by shallower craters and grooves at the entry and middle zone of the hole, and at the exit zone, the MRM is random, in comparison to the in-air mode.

Machining efficiency and geometrical accuracy on micro-EDM drilling of titanium alloy

ABSTRACT In the current study, micro-electric discharge drilling (µEDD) is conducted on a titanium grade 2 alloy using a tungsten carbide (WC) tool electrode of 496 µm diameter. Capacitance, voltage, and feed rate are selected as machining variables to conduct the experiments based on the full factorial experimental design method. Overcut, material removal rate (MRR), circularity, and hole taper are considered as performance measures. Furthermore, overall evaluation criteria (OEC) is utilized for multiple-objective optimization by allotting varying and equal weight percentages to each response measure. The results of OECs are compared with a revolutionary heuristic multi-objective genetic algorithm (MOGA), resulting in a similar optimal parametric combination and close response measures are obtained. Micrographic investigation demonstrates that at lower capacitance and voltage levels, there is less burr formation, recast layer, and circularity error. Moreover, FESEM and EDS analyses are employed to investigate the machined surface topology and elemental composition respectively.

A comparative study of hole integrity performance in composite‐metal stacks using coated and uncoated tungsten carbide drill bits

AbstractThis study aims to develop tetrahedral amorphous carbon nanocomposite layer coated tungsten carbide drill bits for single shot drilling of composite metal stack. Different coatings were tested for hole integrity performance compared to an uncoated tool and the results were validated using process capability six‐pack analysis. The drilling process employed a 4.85 mm twist drill with a feed rate of 0.05 mm/rev and spindle speed of 2600 rev/min. The experimental results indicate that, all the coated tools produce H9 tolerance holes while uncoated tool produced H7 tolerance holes with 18 % to 35 % better results. But statistical results show that all the tools including uncoated tool require improvement to stay within the control limits. The hole circularity error obtained by all the tools were below 24 μm in both the panels and is supported by the statistical results as well. The uncoated tool exhibited 17.91 % better surface roughness in aluminium panel compared to coated tools, while coated tools produced 17.2 % to 22.3 % better surface roughness in composite panel. Statistical results suggested that, improvement is necessary when drilling aluminium panel by all the tools while dopant added coated tools produce better results in composite panel.

Hole quality evaluation for abrasive water jet drilling of GF/Al mesh reinforced epoxy hybrid composites

AbstractIn this study, neat glass (NG) fiber and hybrid GF/Al‐wire mesh composites with two different aluminum configurations (AG: with Al in the outer surface, and GA [Glass fiber/Al‐mesh]: with Al in the core) were fabricated using hand‐layup technique and then drilled via an abrasive water jet (AWJ) machine. The impact of the drilling parameters on the hole qualities; delamination , kerf angle (), and circularity error () of the holes were studied. Using Taguchi L9 orthogonal array, drilling operations were conducted. The following AWJ drilling parameters were chosen; water pressure (P), stand‐off distance (S), and traverse speed (V) with three levels each. A single‐objective optimization using Taguchi method was performed to minimize the drilling responses for the least outcome. In addition, gray relational analysis (GRA) was used as a multi‐decision technique. Analysis of variance (ANOVA) was carried out to identify the impacts of AWJ drilling parameters. The results indicated that for AG specimen, was reduced by 5.3%–10.96% and its by 10.4%–29.65%. GA had the lowest kerf angle. The most effective parameters on delamination for NG, AG, and GA were P, followed by S and V. Validation tests showed small variations between experimental and predicted values.Highlights A new GF/Al Wire Mesh Reinforced Epoxy Hybrid Composites were manufactured. AWJ drilling of the manufactured Composites was conducted. Hole quality was improved by adding Al to the outer layers (AG specimen). AWJ parameters were Controlled and optimized to reduce , , and . Process optimization was performed by single and multi‐objective optimization.

Nanoparticle Incorporation to Enhance Titanium Alloy Electric Discharge Machining Capabilities

The primary objective of this study was to examine the effects of the Powder-blended Micro Electric Discharge Machining (PMEDM) technique on micromachining applications, specifically when sea water is employed as the dielectric medium. Tiny apertures with a width of 200µm were punctured over Ti-6Al-4V plates. In the initial round of experimentation, the machining performance was evaluated by subjecting sea water to various process variables without the inclusion of any other ingredients. The effects of input variables, including electrode material, hole voltage, current, Pulse-on-time, and Duty factor, on the Material Removal Rate (MRR), Tool Wear Rate (TWR), Overcut (OC), Circularity Error (CE), and Taper Ratio (TR) were analysed by conducting tests in accordance with Taguchi's L18 plan design. The method employed to ascertain the optimal parametric configuration for multi-objective enhancement involved utilising the strategy of soliciting inclination based on similarity to an ideal arrangement. The present study aimed to investigate the effects of foreign materials on the dielectric-based miniature electrical discharge machining (EDM) process in sea water. This was achieved by utilising powders with varying weight concentrations and molecule sizes, including non-conductive (Al2O3), semi-conductive (SiC), and conductive (Al) powders. The experimental setup ensured that the variable boundaries were maintained at their ideal settings. The results indicate that the choice of tool has a notable influence on the functioning of micro EDM when sea water is employed as the dielectric, without the inclusion of extraneous particles. The performance metric of multi-objective execution in PMEDM is influenced by the conductivity of supplementary compounds. An 83.18 percent increase in Material Removal Rate (MRR) was observed when SiC added compounds were utilised in Powder Mixed Electrical Discharge Machining (PMEDM). Conversely, there was a drop in Tool Wear Rate (TWR) by 36.42 percent, Open Circuit voltage (OC) by 21.48 percent, Current Efficiency (CE) by 45.15 percent, and Tool Roughness (TR) by 22.87 percent.

An experimental examination of the dry drilling machinability features of cellular glass‐filled new‐generation metallic composite foams

AbstractOn the way to the real industrial applications of the metal matrix composite foams, the machining issue is highly critical in terms of dimensional accuracy, surface quality, and design diversity. Therefore, especially for lightweight automotive and aerospace components, the drilling machinability properties of cellular glass‐added aluminum composite foams were examined in this paper, and this is the first initiative in the literature specific to millimeter‐scale glass and aluminum‐zinc matrix combination. To comprehend the drilling properties, the outputs of thrust force, cylindricity, material removal rate, specific cutting coefficient, circularity error, damage factor, surface roughness, and chip formation were measured elaboratively. The results showed that cylindricity and damage factor of foams elevated with the increased feed rates (from 0.05 mm×rev−1 to 0.2 mm×rev−1) and cutting speeds (from 25 m×min−1 to 100 m×min−1). Maximum thrust force value reached up to 150 N for 0.2 mm×rev−1 feed and 25 m×min−1 cutting speed. Besides, specific cutting coefficient values ranged between 360 MPa and 114 MPa. The highest surface roughness of 58.3 μm was obtained with the lowest cutting speed of 25 m×min−1, and the long/continuous chip structure converted into a separate/short structure based on rising feed and cutting speeds.

Laser Beam Machining of Titanium Alloy—A Review

This study investigates the laser beam machining mechanism, surface formation mechanisms, heat-affected zone, taper formation, and the dimensional deviation of the titanium alloy, based on the information available in literature. The heat induced by the laser beam melts and vaporises titanium alloy, which is removed by a high pressure-assisted gas. The machined titanium alloy surface is expected to have craters and resolidified materials which were contributed by the low thermal conductivity of the titanium alloy. Taper and circularity error can be minimised by optimising the laser parameter, but it cannot be avoided in the laser beam machining of titanium alloy. Laser beam machining induces a non-diffusion phase transformation, which slightly changes the surface mechanical properties of the titanium alloys. Laser beam machining is gaining popularity as a way to improve the surface finish quality and properties of titanium components manufactured by additive manufacturing processes. To enhance the machining efficacy of titanium alloys, several hybrid machining processes were proposed.

Experimental study of geometric error of CNC turning machine tools based on ISO 13041-6

The product quality of machining results is greatly influenced by the accuracy and precision of CNC lathe machine tools. Regular inspection of the geometric inaccuracy of the machine tool is necessary to verify its operational viability. This research contribution focuses on conducting experimental studies to evaluate machine tool geometric error. The aim is to explore cost-effective measurement methods as alternatives to direct measurements, which often involve laser interferometers and ball bar tests. The objective of this study is to investigate the geometric inaccuracy of a CNC turning machine by conducting experimental cutting tests in accordance with ISO 13041-6:2009. The testing will utilize conventional workpiece forms and requirements, including circularity features, flatness, circular features, and maybe combination features. Several geometric errors that can be acquired with this method include circularity errors, linear positional errors, and squareness errors. The cutting test for each workpiece feature of the given shape and specification requires the use of 5 specimens. Consequently, the mean value of the geometric error may be computed. The geometric error value is derived by the analysis of measurement data collected from a Coordinate Measuring Machine (CMM) applied to a specimen of the machined workpiece. Moreover, the evaluation of the geometric error condition of machine tools is ascertained through the comparison of the average data for each category of geometric error against the permissible standard values given in ISO 10791-2, ISO 10791-4, and ISO 13041-4. The findings of the study indicate that the implementation of the object machine study is not viable for the production of machined workpieces of satisfactory quality. This is primarily due to the presence of geometric errors in CNC turning that exceed the acceptable tolerance levels. Specifically, these errors manifest as linear positional deviations along multiple coordinates along the X-axis and Z-axis, as well as squareness deviations between the X-axis and Z-axis. The maximum value of the linear positional error along the X-axis is 55.2 μm, while the maximum value of the linear positional error along the Z-axis is 25.6 μm. Additionally, the greatest observed squareness error is 37.3 μm. The X and Z machine axes exhibit deviations beyond acceptable limits in terms of unidirectional accuracy and unidirectional repeatability, as per the established norm

Optimization of drilling parameters in vertical machining centre drilling on magnesium AZ91D alloy under dry condition with Taguchi design

Drilling using a Vertical Machining Centre (VMC) remains a prevalent machining technique, even if current metal cutting processes have improved. Drilling settings on a VMC are optimized using the Taguchi technique to minimize surface roughness, hole diameter, and circularity error roundness test in this experimental investigation. In order to obtain the optimum process parameters in the VMC drilling on Magnesium AZ91D Alloys, L16 orthogonal arrays was formed by changing the four different speed, feed and end point angle. In the trials, an AZ91D alloy was employed and a variety of process factors, like drilling speed (250, 350, 450 and 550 rpm), feed rate 0.025, 0.05, 0.075 and 0.1 mm/rev), and end point angle (55, 75, 95 and 118°) were examined. Experimental results shows that a combination of slow speed (250 rpm), higher feed (0.1 mm/rev), and a medium end point angle (75°) resulted in the lowest roughness average value. It was possible to achieve the hole diameter accuracy by using the parameter at higher speed (450 rpm), higher feed (0.1 rev/min) and an end point angle of 118°. The lowest possible cylindricity error was perceived at 250 rpm speed, 0.01 mm/rev feed and 118° end point angle respectively. The lowest possible roundness error was perceived at 250 rpm speed, 0.05 mm/rev feed and 118° end point angle respectively. It was noticed from this experimental study and Taguchi technique, the surface roughness of the drilled hole is greatly affected by speed, feed and end point angle of the drill bit tool. Lower magnitude of drill tool speed and lower end point angles cause the good surface roughness values rather than the higher magnitude. The drilled hole’s diameter accuracy is significantly influenced by lower tool speed, higher feed rate and higher end point angle of the drill bit tool. The lower tool speed and higher end point angle of the drill bit tool are the two major factors, which are influenced the minimum cylindricity and roundness errors. It was observed from this experimental study, the lower drill bit tool speeds, higher tool feeds and higher end point angles are the important factors, which are significantly affected the quality of the drill holes during the machining of Magnesium AZ91D alloy in Vertical Machining Centre ((VMC) under dry conditions.

Numerical and experimental analysis of margin geometries of twist drills in deep hole machining operations

In deep hole machining operations with twist drills, whirling vibrations lead to a significant increase in hole diameter deviation and circularity error. In this article, a nonlinear physical model with special consideration of the contact area between the margins of the tool and the workpiece is developed to predict the hole circularity of drilling operations. Numerical simulations are used to study the geometry of the drilling tool to propose a new margin design. In an experimental study, it is shown that the newly developed margin geometry for twist drill tools decreases radial vibrations and leads to a significant improvement in hole diameter deviations and hole circularities.

Investigation of Abrasive Aqua Jet Hole Making (AAJHM) parameters using desirability analysis on Inconel-625 space alloy

Inconel-625 is one of the high-strength space alloys with wide applications in aerospace industries and corrosion resistance environments. The applications of Inconel-625 material require blind holes with adequate quality characteristics. In the conventional method, the hole-making on Inconel-625 is difficult due to its mechanical behaviour. The abrasive aqua jet machining process can cut hard and brittle materials among various unconventional machining processes. This work proposes to determine the ideal values of process parameters to generate quality holes on Inconel-625 space alloy by optimizing the abrasive aqua jet hole-making process parameters using a desirability analysis. Abrasive jet pressure (AJP), gap distance (Gdi), traverse speed (Tspeed), and abrasive mixture (Abrmix) of garnet and silicon carbide were identified as potential process variables. The quality hole surface is discussed through surface roughness (SR), erosion rate (Er), circularity error (CI), and cylindricity error (CY). The experimental investigation discloses that SR, CI, and CY decreased by 27.35 %, 56.23 %, and 42.56 %, and Er increased by 32.83 % when the AJP reached its higher value of 300 MPa. According to desirability analysis, the optimal level of machining parameters for numerous solutions is AJP = 300 MPa, Gdi = 1 mm, Tspeed = 96 mm/min, and Abrmix = 100%SiC (AJP-2, Gdi-2, Tspeed-1, Abrmix-2). The ANOVA investigation revealed that AJP was the most contributed parameter, trailed by Abrmix as 100%SiC. SEM and 3D images were used to analyze the surface topography of the hole surface of Inconel-625.

Experimental study on the quality of drilled holes in Sabai grass reinforced composites

Hole quality in composites plays very important role in the production of close tolerance holes in automobile parts. Through drilling experiments in Sabai Yarn reinforced composite, this study examines the impact of different input parameters like feed rate, rpm, and tool diameter. The circularity of hole was measured with the help of CMM. The circularity error was reported in the range of 0.037 to 0.1628 mm. Design of experiments and Taguchi method have been used to study the effect of process parameters. The circularity of hole mainly depends on feed rate and rpm in the drilling process of Sabai yarn composite. The circularity error and delamination are minimum in treated reinforcement in yarn (0°) and woven yarn (0°/90°) compared to the untreated reinforcement yarn (0°) and woven yarn (0°/90°). Due to strong bound strength fibres cannot pull-out its cut with tool edge so that it gives smooth machined surface in treated reinforcement. The chip formation in drilling depends on the feed rate and tool diameter. Chips are discontinuous at the higher feed rate and higher rpm.

Digital twin-driven centering process optimization for high-precision glass lens

Glass lenses are key photoelectric components of laser systems in semiconductor equipment. The circularity, surface quality, and optical axis precision of the glass lens directly affect the efficiency of a laser system. In the processing of conventional glass lenses, centering is often used to meet specification requirements. However, high-precision processing of materials with high hardness and low ductility is difficult. The process of centering a glass lens is performed according to processing parameters determined by experience, the degree of wear of the grinding wheel, and specifications of the glass lens. Circularity errors, edge cracks, and optical axis errors are common defects in lens processing; such defects must be identified through manual inspection and thus result in high scrap rates and production costs. To address this problem, a digital twin-driven (DTD) centering process optimization system for high-precision glass lenses was developed in this study. The proposed system combines an omnidirectional information model of production line manufacturing data, a virtual process model based on sensor signals, and a design of experiment–based genetic algorithm (DOE-GA). The models of the system are connected through data flow and operate simultaneously to create a high-fidelity virtual simulation of the centering process. To facilitate evaluation of the performance of the proposed DTD centering process, the process was implemented in an industrial setting. The test in the real-world production line shows that the proposed DTD system reduces the time of process development from 4 h to 1 h, decreases the inspection from full to 10% sampling inspection and improves the yield rate by 20%.

Helical Milling of CFRP/Ti6Al4V Stacks Using Nano Fluid Based Minimum Quantity Lubrication (NF-MQL): Investigations on Process Performance and Hole Integrity.

The structural components in the aeronautical industry require CFRP/Ti6Al4V stacks to be processed together, which results in poor hole integrity due to the thermal properties of the materials and challenges related to processability. These challenges include quality variation of the machined holes because of the limitations in process properties. Therefore, a novel solution through helical milling is investigated in the study using nano fluid based minimum quantity lubrication (NF-MQL). The analysis of variance shows, for Ti6Al4V, eccentricity (PCR = 28.56%), spindle speed (Ti) (PCR = 42.84%), and tangential feed (PCR = 8.61%), and for CFRP, tangential feed (PCR = 40.16%), spindle speed (PCR = 28.75%), and eccentricity (PCR = 8.41%) are the most significant parameters for diametric error. Further on, the rise in the circularity error is observed because of prolonged tool engagement at a higher value of tangential feed. Moreover, the surface roughness of Ti was reduced with an increasing percentage of MoS2 in the lubricant. The spindle speed (37.37%) and lubricant (45.76%) have a potential influence on the processing temperature, as evident in the analysis of variance. Similarly, spindle speed Ti (61.16%), tangential feed (23.37%), and lubrication (11.32%) controlled flank wear, which is critical to tool life. Moreover, the concentration of MoS2 decreased edge wear from ~105 µm (0.5% concentration) to ~70 µm (1% concentration). Thorough analyses on process performance in terms of hole accuracy, surface roughness, processing temperature, and tool wear are carried out based on the physical science of the process for cleaner production. The NF-MQL has significantly improved process performance and hole integrity.

A comprehensive parametric study on abrasive waterjet trepanning of Al-6061 alloy

ABSTRACT Abrasive waterjet (AWJ) can be used to realize holes of any size and shape in difficult-to-machine ductile materials with negligible heat-affected zone by simply changing the jet path. In this study, the influence of various process parameters, such as waterjet pressure (P), jet traverse speed (), abrasive mass flow rate (m a ) on the AWJ-trepanned hole’s geometrical features (diameter, taper angle, profile), form characteristics (circularity error, cylindricity error), quality measures (damage region, edge radius, burr formation, uncut material, surface morphology), and material removal mechanism in Al-6061 alloy is studied. The results show that higher P and m a at lower are desirable for achieving nominal geometrical features, minimal form error, burr length, and uncut material. Damage region reduces with the decrease in P and m a at higher . Edge radius reduces with the increase in P at lower and m a . The micrographs showed that the initial damage region is uniform at higher P and lower . Better surface quality is obtained at higher P and m a as lip formation and material pile-up are minimum. Material fracture and cracks in the vicinity of the burr are observed. Based on the mean response analysis, near-optimal parameters are suggested for efficient trepanning.