Juri B. Saedon

Selective Laser Melting (SLM) of Ti6Al4V titanium alloy offers enhanced mechanical properties and design flexibility, making it attractive for biomedical and aerospace applications. However, its poor machinability, especially during milling, presents a significant challenge. Despite previous efforts, limited studies have addressed process optimization for improved surface quality in SLM-manufactured Ti6Al4V. This study aims to enhance machinability by optimizing surface roughness using the Taguchi method. An L9 orthogonal array was implemented to assess the effects of spindle speed, feed rate, and depth of cut. Analysis using Signal-to-Noise (S/N) ratios and ANOVA identified spindle speed as the most influential factor, accounting for 83.67% of the surface roughness variation. The optimized parameters led to a significant reduction in surface roughness. This research provides a systematic approach for improving the milling of additively manufactured Ti6Al4V and contributes novel insights into machining strategies for SLM components.

Friction stir spot welding (FSSW) as the solid-state welding has been expanded to be used in various materials and many applications. The significant issue in FSSW is the existence of porosity or wormholes, leads to welding failure. One reason is due to imperfect heat generation leads to temperature distribution during FSSW effect to uncertain weldment formation. This is mainly influenced by improper parameters selection. In this study, the temperature distribution in the weld zones is investigated using finite element analysis via computer numerical simulation of Altair Hyperworks software with respect to parameters i.e. spindle speed, tool plunge depth, and tool dwell time. In the simulation, tool plunge depth and tool dwell time is set constant, but spindle speed was varied from 1400, 1500, and 1600 rpm respectively. Based on the results found that at a spindle speed of 1400 rpm was produced max temperature in the weld zone at 540 °C. Meanwhile, at 1500 rpm increased the temperature at 596 °C. At 1600 rpm reached its highest temperature at 650 °C. The results show that increasing tool rotational speed, at a constant tool plunge depth and constant tool dwell time will increase the amount of temperature distribution in the weld-zones. It is concluded that the suitable temperature distribution required in FSSW is 540 °C represented the solid-state joining process provided by spindle speed of 1400 rpm.

Facing the issue of cost and efficiency in experiments and tests in determining the properties of the welded structure is a challenge in friction stir spot welding (FSSW) optimization. Employing the machine learning technique of artificial neural network (ANNs) to develop a prediction model with fewer experiments and tests is a gentle solution to forecast the properties of the spot weld structures. In this study, the extended full factorial design with respect to thetool speed, plunge depth, anddwell time are applied to the FSSW specimens of aluminium A5052-H122 of 2mm thick through 27 experiments and evaluated via tensile shearing load testing. The multilayer neural network of feed-forward and back-propagation (FFBP) algorithm was engaged to learn and train the neural network iteratively with a set of weights and bias of 27 variations of inputs to fit the predicted tensile shear loads of the spot weld structures. Based on the resulted of regression plot, it is shown that the correlation coefficient (R) is perfect for training with the value of 0.999 and for testing the correlation coefficient (R) is reached to 0.958. However, the correlation coefficient is relatively good for validation with R equal to 0.921. For all data sets, the correlation coefficient is good with R of 0.833. It can be seen that the ANNs prediction model is relatively good since the correlation coefficient relatively close to 1.

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.

Wire electrical discharge machining is a material removal process of electrically conductive materials by the thermo-electric source of energy. This kind of machining extensively used in machining of materials with highly precision productivity. This work presents the machining of titanium alloy (TI-6AL-4V) using wire electro-discharge machining with brass wire diameter 0.5mm.The objective of this work is to study the influence of three machining parameters namely peak current, pulse off time and wire tension to kerf width followed by suggesting the best operating parameters towards good machining characteristics. A full factorial experimental design was used with variation of peak current, feed rate and wire tension, with results evaluated using analysis of variance techniques (ANOVA). The test array was further extended to allow for the implementation of Response Surface Methodology (RSM) analysis in order to develop first and second order models for the prediction of kerf width response. The results showed that average percentage error between the predicted and experimental value for kerf width models was less than 2%.

The dental restorations by the usage of implants have been one of the most favourable treatment. However, the existing dense dental implant causes overloading towards the human bone that triggers ‘stress shielding effect’ and also implant loosening. This paper focused on the development of highly porous Ti-6Al-4V dental implant by metal injection molding with palm stearin binder system with an addition of sodium chloride as space holder which has been established in the fabrication of porous Ti-6Al-4V. The evaluated compositions consist of the powder volume fraction of 63vol% and 65vol%. SEM analysis shows that highly porous Ti-6Al-4V dental implant were obtained. The average density is 3.325g/cm³ for 63vol% sample and 3.915g/cm³ for 65vol% sample. While for the Vickers hardness are 113.68HV and 162.8HV for 63vol% and 65vol% respectively.

Wire electrical discharge machining is a material removal process of electrically conductive materials by the thermo-electric source of energy. This kind of machining extensively used in machining of materials with highly precision productivity. This work presents the machining of titanium alloy (TI-6AL-4V) using wire electro-discharge machining with brass wire diameter 0.5mm.The objective of this work is to study the influence of three machining parameters namely peak current, pulse off time and wire tension to cutting rate, material removal rate, surface roughness and kerf width followed by suggesting the best operating parameters towards good machining characteristics. A full factorial experimental design was used with variation of peak current, feed rate and wire tension, with results evaluated using analysis of variance techniques. Parameter levels were chosen based on best practice and results from preliminary testing. Main effects plots and percentage contribution ratios are included for the main factors and their interactions.

This paper presents an investigation on influences and multiple optimizations of wire-electrical discharge (WEDM) machining performances such as cutting rate, material removal, surface roughness and kerf width processed on titanium alloy material. The experimental studies were conducted under varying machining parameters namely pulse-off time, peak current, wire tension and wire feed. The experimental works were designed base on Taguchi design of experiment. The optimum multi-objective performance characteristics was determined using analysis of variance (ANOVA) coupled with grey relational analysis (GRA). ANOVA was used to study the significance of process parameters on grey relational grade which showed the most significant factor. The grey relational grade obtained from GRA was used to optimize the wire-electrical discharge machining process. To validate the findings, confirmation experiment had been carried out using the optimal parameters and the predicted results were found in good agreements with experimental finding. Improved machining performance in the wire electrical machining process has been achieved by using this approach.

Early stage of engine valvetrain noise improvement involves the implementation of Design of Experiment (DOE) specifically the Taguchi methodology to identify the optimum valvetrain parameters which resulted in significant noise improvement. The parameters are consist of seven controlled factors such as cylinder head tappet bore diameter, mechanical tappet diameter, valve spring load, camshaft exhaust and intake waviness together with tappet exhaust and intake clearance. The confirmation run which was previously completed yields the valvetrain noise level at 67.07db SPL by 1 meter distance in completed vehicle during idling condition. In order to satisfy the final quality of the optimal valvetrain, a test is carried out to validate the performance curve on a dynamometer according to benchmark specification. The objective of the test is to validate the optimal valvetrain based on the experimental result which minimum manufacturing target shall be achieved to indicate that the engine is operated within its intended design. The performance test was conducted at the manufacturing plant on an eddy current dynamometer which runs for 11 hours. As results, the performance are within the standard with approximate increased by 6.9% as compared with baseline valvetrain and confirmed by several follow-up tests made on the improved valvetrain. In order to verify and address the main engine output of the optimal valvetrain, brake specific fuel consumption (BSFC) and emissions test results are then presented at the end of this paper.

Hollow ceramic product is fabricated generally using slip casting technique. The conventional processes produce slip and mould waste which require for disposal schedule. A rotary moulding technique is a feasible process for producing hollow shape ceramic product and eliminates the waste. This paper focuses formulation of the slip and process parameters of the rotary moulding for hollow ceramic product fabrication. The formulated ceramic slip is poured inside the mould rotated at 2-axis system inside a controlled chamber with specific temperature, speed and time for producing green body hollow ceramic product. This process uses minimum amount of ceramic slip and long lasting mould material which will reduce ceramic waste to environment and simplify the manufacturing process for mass production. Using small amount of polymer based dispersant and coagulant agents, experimental analysis resulted the green hollow porcelain product which was successfully removed during de-moulding process without any breaks. The hollow product produces homogeneous forms of ceramic structure after firing procedure and 1.9 MPa green strength with addition of small amount of binder.