Inconel 718 is widely used in components under harsh conditions. The abrasiveness of the carbide particles, poor heat conductivity and built-up edge (BUE) formation are common issues which warrant further investigation. In this work, the failure mode of a TiAlN/AlCrN-coated tungsten carbide (WC) tool during milling of Inconel 718 using different lubrication strategies, namely pulsating lubrication (PLS) and flood-coolant (FC), were compared. The effects of the pulsating water stream at 2000 pulse/min, when applying lubrication pressures at 8 bar, were discussed. Reduction of BUE at the tool tip was observed. The study revealed that this approach is better in delaying pitting, notch wear formation and flaking damage. Hence, the service life of a cutting tool can be extended when compared to the flood-coolant strategy.

ABSTRACT In this study, surface roughness of material Ti-6Al-4V that is the micro-cylindrical workpieces is analyze involving the wire electrical discharge turning (WEDT). The effects of pulse intensity, voltage, wire tension, and rotational spindle speed are investigate and optimize using the response surface methodology (RSM). Based on the results, the surface of the machined workpieces deteriorates according to the violent energy density generate by a high pulse intensity and voltage along with a low electrode wire tension and spindle speed. The optimal surface roughness obtains experimentally through the desirability approach is 4.0143 μm with a relative error at 5.9% compared to prediction.

Many lubrication strategies have been applied in cutting processes. The main purpose is to reduce heat generated and to lower friction on the cutting tool thus improving the surface quality of the workpiece. However, the quality of indoor air has become a major health and safety issue. This study explains the effects of cooling, lubrication strategies and cutting parameters on particulate matter emission. The experiments involved the use of TiCN CVD coated carbide with varying cutting speeds (Vc), feed rates (fz), and cooling-lubrication strategies (dry, chilled air, chilled MQL, MQL, flood-coolant and pulsating lubrication) for both Aluminium alloy 6061 and Inconel 718. Design of experiment and analysis of variance (ANOVA) were used to examine the effects of the input parameters on the PM2.5 value. Based on ANOVA, it was found that the chilled MQL and MQL exhibited high PM2.5 readings, while the other coolant strategies yielded results which were within an acceptable exposure limit.

This paper presents an investigation on cooling effect and flow structure of the spherical dimple configuration during air flow on the Aluminium surface. It is prominently known that applying dimples profile causes an enhancement in heat transfer over a plain surface. A three level of Box-Behnken response surface methodology was performed to find the correlation between the input and output variables. A total of 17 different combinations of these inputs were performed throughout the experiment. The variable inputs to be investigated namely: dimple diameter of 10 - 14 mm, dimple orientation angle of 60°- 90°, and airflow velocity of 16 - 18 m/s to observe the response on the cooling time. The Aluminium block was heated to 60°C and cooled down by air flow at room temperature. The ANOVA was used to identify the significant effect of each parameter. CFD software was used as a simulation tool to analyze the flow structure and Reynolds number that associate with the heat transfer rate to support the statistical findings. Based on the result, all the input parameters are found to be significantly dominated by air flow velocity. Staggered arrangement dimple profile surface improves cooling effect by 63% over the plain flat surface. The increment in Reynolds number will increase the heat transfer which then shortening the cooling time.

The aim of this research is to elucidate the effects of the standoff distance (SOD) in abrasive water jet machining (AWJ) on mild steel. Nine different standoff distances (z) of 5, 8, 10, 11, 15, 18, 20 and 25mm AISI 1090 steel samples were used in this study. Following the test, the kerf width and kerf taper ratio were measured. The surface morphology characteristics of the machined surface were investigated using a scanning electron microscope (SEM). The results revealed that the ratio of kerf taper increased as the standoff distance and kerf width increased. Compared to the 15mm standoff distance, 8 mm at the jet entry and exit exhibited more uniformity in kerf appearance. Both 8 and 15mm standoff distances showed that the surface roughness gradually became rougher towards the jet exit.

Nowadays, wire spark erosion of machining process has the capability to cut cylindrical shapes components by integrating rotary spindle on the machine worktable. However, this process has disadvantages in terms of low cutting rate due to the disruption of pulses caused by the rotating workpiece. This drawback become the point of study by researchers to apply ultrasonic vibration to this process. Therefore, this paper presents a comprehensive review of ultrasonic vibrations for wire spark erosion machining for fabricating cylindrical shapes parts. This review paper has been carried out in terms of current state of the process, ultrasonic excitement targets, effect of ultrasonic vibration and its parameters along with the potential research gap in this area.

Tool wear is one of the important criteria during the cutting process. It is mostly caused by the machining parameters, namely; cutting speed, feed rate, depth of cut, cooling condition, etc. This paper presents the behaviour of cutting tool during dry and chilled air condition of face mill with the cutting speed of 20 to 40 m/min, the feed rate of 0.1 to 0.2 mm/tooth and axial depth of 0.1 mm. The analysis of variance (ANOVA) is applied to identify the significance of these factors effect on tool performance, later the mathematical model for the tool life prediction was developed. The investigation revealed that the cutting speed, feed rate dominating wear rate whilst the chilled air found to be marginally significant. Finally, the optimum condition for machining parameter for greater tool life can be obtained by the combination cutting speed of 20 m/min, the feed rate of 0.1 mm/tooth under chilled air condition. Implementation of chilled air contributed 7% improvement with 45 min compared to a dry condition. The study exhibited the round type insert of dry face milling is more prone to rapid flank wear than chilled air with no BUE appearance on the tool cutting edge.

This paper reported on the effect of ambient temperature, layer thickness, and part angle on the surface roughness and dimensional accuracy. The response surface methodology (RSM) was employed by using historical data in the experiment to determine the significant factors and their interactions on the fused deposition modelling (FDM) performance. Three controllable variables namely ambient temperature (30 °C, 45 °C, 60 °C), layer thickness (0.178 mm, 0.267 mm, 0.356 mm) and part angle (22.5°, 45°, 67.5°) have been studied. A total of 29 numbers of experiments had been conducted, including two replications at the center point. The results showed that all the parameter variables have significant effects on the part surface roughness and dimensional accuracy. Layer thickness is the most dominant factors affecting surface roughness. Meanwhile, the ambient temperature was the most dominant in determining part dimensional accuracy. The responses of various factors had been illustrated in the cross-sectional sample analysis. The optimum parameter required for minimum surface roughness and dimensional accuracy was at ambient temperature 30 °C, layer thickness 0.18 mm and part angle 67.38°. The optimization has produced maximum productivity with RaH 3.21 μm, RaV 11.78 μm, and RaS 12.79 μm. Meanwhile, dimensional accuracy height eror 3.21%, width error 3.70% and angle 0.38°.

The requirement of drilling process of Carbon Fibre Reinforced Plastic (CFRP) is vital in order to fulfil final assembly specifications. Despite the excellent mechanical properties of composites, they are hard to be machined due to its toughness. The damages such as peel-up and push-out delamination usually occur during its machining. To provide drilling induced delamination is a priority to reduce parts rejection and lead to waste in time and money. In this work, a comparative study of three geometries under different cutting conditions is presented. Application Taguchi’s design of experiments for this experimental works increase the analysis reliability. Various penetration angle drilling also studied to determine the effect of thrust force and delamination. Thrust force was monitored during drilling tests, and delamination extension was quantified using image processing software. Results are processed using analysis of variance (ANOVA) then further presented by response surface graph showed that the best drill geometry, spindle speed and feed rate selection is fundamental to reduce delamination. The result obtained from the analysis shown delamination both for peel-up and push-out spread worse with increasing of drilling angle. Delamination factors are directly proportional with thrust force generated during drilling and increasing of thrust force will worsening the delamination damages. Straight flute drill is the best drill that generates lower thrust force thus reducing delamination effect compared with twist and dagger drill which on optimum feed rate and spindle speed parameter is 0.05 mm/rev and 4000 rpm, respectively. Index Term-cfrp; one-shot drilling; delamination; thrust

The accuracy of the hardness test depends on the effects of variations of the loading force and the number of indentations. The purpose of this study was to compare the micro hardness data of these factors. Aged Inconel 718 with a hardness of 450 HV was used as the specimen in this test. The investigation was carried out by observing the amount of dispersion in a set of hardness data at different loads and number of indentations. The applied loading force ranged from 0.05 to 0.3 Kgf, while the number of indentations was set from 10 to 30. From the result, it was found that increasing the applied load brought the hardness value close to the standard hardness of the material. However, an increase in the number of indentations failed to produce an accurate value.

This paper presents the result of pulsating lubrication strategy (PLS), an alternative metalworking fluids approach to improve machining performance. The formation of built-up edge (BUE) and built-up layer (BUL) is among the problems encountered during the machining of aluminum alloy, which degrades cutting performance and thus affects the machined surface quality. This study focuses on chip removal effectiveness by jetting a coolant intermittently of PLS on the cutting tool to create a hydraulic shock. The water stream coolant was set to pulsate at 2000 pulse/min with the pressure of 0.76 MPa. Applying this method improves chip evacuation. Hence, minimizing the formation of BUE and BUL more effectively than dry cutting.

Inconel 718 known as hard-to-cut material due to its superior mechanical properties; high creep resistance, high fatigue strength, and able to withstand at elevated temperature which remains as challenge to possesses a lower surface roughness (Ra) during machining. The surface topology indicates the integrity of the machined parts. The quality of the Inconel 718 surface during end milling process was investigated. The experiments involved the use of PVD coated with TiAlN/ AlCrN ball nose tungsten carbide with varying of cutting speeds (Vc) ranging between 100 and 140 m/min, a feed rate (fz) of 0.1-0.2 mm/tooth, and an axial depth of cut (DoC) of 0.5-1.0 mm. The effects of the width of cut (WoC) between 0.2 and 1.8 mm were carried out. Due to the profile of the milled surface is complex; some variations in gap distance on the spiral profile were detected. The cutting path area to be found that, the new cut is overlapped which generate a new surface roughness by eliminating the previous cut thus the non-uniform feed marks being created on the machined surface. The surface roughness measured in feed direction was found to be lowered than pick a direction. Furthermore it was found that the WoC are causes the variation in Ra. During machining at low feed rates, the phenomenon of carbide particles was observed which results third body abrasion of machined surface. The particles are then trapped between the fragments and tear surface of the workpiece, thus increases the surface roughness. Based on the interaction effect of WoC and fz, it can be concluded that the feed rate effects on the quality of machined surface whilst WoC controls Ra variation.

This present paper deals with the chip segmentation in ball nose end milling process of Inconel 718 for turbine blades. It deals with characterizing the chip morphologies and microstructure investigations under minimum quantity lubrication (MQL) condition. In this study, the effects of cutting speed (Vc), radial depth of cut (WoC), and axial depth of cut (DoC) on chip segmentation are presented. The study proved that chip dimensional values were dominantly affected by the Vc, WoC, and DoC, while the frequency of dislodged chips was affected by notch wear. It was observed that the star anise-like chips formed are associated with the tool failure.

Drilling is one of the major machining operations in manufacturing. The application of robots in machining is the alternative technique to produce new products of the future. However, the performance of the robot always been a challenge in production. This paper presents the investigation on the effect of arm robot itinerary, holes orientation and materials type on holes accuracy and toolpath angularity of Aluminum Alloy 6061 (Al 6061) and High-density polyethene (HDPE). A series of drilling experiments by using COMAU robot with 24 runs were conducted at difference combination parameters. The measurement on hole accuracy and toolpath angularity were done by CMM machine. Response surface methodology (RSM) was used as a design of experiment (DOE) for optimization. Evaluation by ANOVA showing that the interaction between arm robot itinerary and material type found to be significant factor for the hole accuracy whilst the orientation of the hole dominant factor affecting the toolpath angularity. Optimization results show that the best accuracy and angularity of the drilling hole when the arm robot itineraries of 971.82 mm (vertical direction) and 1120.65 mm (horizontal direction) for Al 6061 and HDPE respectively.

Taguchi design was utilized to determine the significant impact of ultrasonic assisted milling cutting parameter performance on Inconel 718 material. An experiment using Taguchi orthogonal array, L9 with parameters namely ultrasonic frequency, feed rate cutting speed and at various cutting condition types was conducted. The cutting condition consist of a new approach of pulsating coolant to be compared with dry and normal flooded. An orthogonal array, Pareto analysis of variance (ANOVA) and signal-to-noise (S/N) ratio were evaluated to ascertain these machining parameters effects. The obtained results indicated that the most significant parameter on the surface roughness was the cooling strategies, followed by ultrasonic frequency, cutting speed and feed rate.

In the present study, 8 experiments were conducted in dry cutting and compressed air using full factorial design. The controlled parameters are the cutting speed (20-40 m/min), the feed rate (0.1-0.2 mm/tooth) and the fixed depth of cut (0.1 mm), respectively. The result depicted that the duration of tool life can be extended up 46.3 min with lowest Ra value of 0.8 mu m by adopting the compressed air. Besides, the optimum cutting force is 5.32 N.

The main aim of the present work is to study the effect of heat enhancement method on the cooling process of a spherical dimple profile. It was prominently known that introducing dimples configuration causes an enhancement in heat transfer over a surface. In this project, an experimental investigation was carried out to examine the cooling effect of the spherical dimple profile during steady laminar flow in a wind tunnel. Seventeen different sets of parameters related to dimple diameter (mm), dimple orientation (angle) and air stream velocity (m/s) were studied. The Box-Behnken of Response Surface Methodology (RSM) was used as design of experiments (DoE) tool to evaluate these parameters on cooling time. This work deals with the analysis of variance (ANOVA) in order to establish the significant effect of input parameters. The result reveals that an increase in dimple diameter and air stream velocity increase heat dissipation. The shortest cooling time of 7 minutes can be achieved when the dimple diameter is 12 mm; the dimple orientation is 60° and air flow velocity at 18 m/s. The mathematical model has been rendered where the model has been experimentally validated with the average error of 6%.

This study involves conducting finite element (FE) analysis on face milling of Inconel 718 and investigating the effect of cutting parameters to resultant force and tool temperature. The cutting parameters considered include cutting speed in the range of 20 to 40 m/min, feed rate in the range of 0.10 to 0.20 mm/tooth and depth of cut in the range of 0.1 to 0.2 mm. The experimental approach is carried out using Analysis of Variance (ANOVA) and Response Surface Methodology (RSM). According to the results, the significant factors that affect the resultant force are feed rate and depth of cut. On the other hand, cutting speed has no significant impact on the resultant force. The interaction between feed rate and depth of cut has the most influence on the resultant force. Meanwhile, all cutting parameters considered significantly affect the tool temperature. Through the RSM method, the obtained optimal setting of the parameters is 23.13 m/min, 0.10 mm/tooth and 0.10 mm for cutting speed, feed rate and depth of cut, respectively. The simulated results are then validated by an experiment. It is found that the percentage of relative error between the FE simulation and the actual experiment for resultant force and tool temperature is 10% and 31%, respectively. Considering all possible errors, the overall trend of the simulated results is reasonably in a good agreement with the experimental results.

Inconel 718 has been widely used in aerospace because of its excellent mechanical properties such as good corrosion resistance, strong creep resistance and high fatigue strength. However, these excellent properties also lead to heavy tool damage and high cutting force in the milling process. There is no reported investigation on ultrasonic assisted machining (UAM) of Inconel 718 parts. In this paper, UAM is proposed as the potential technique to reduce tool damage and the cutting force of Inconel 718 parts. This review paper provides an overview of UAM to investigate the relationship between the tool wear and the cutting force with ultrasonic vibration compared to without ultrasonic vibration assisted. Throughout the study, the UAM scopes are related to the tool life of coated carbide insert, the force generated during the cutting process and also the final surface finish of the workpiece by using various parameters during the machining activity.