Titanium alloys, due to their unique properties, are utilized in numerous modern high-end applications. Electrical Discharge Machining (EDM) is a non-conventional machining process, commonly used in machining of hard-to-cut materials. The current paper, presents an experimental study regarding the machining of Titanium Grade2 with EDM, coupled with the development of a simulation model. The machining performance indexes of Material Removal Rate, Tool Wear Ratio, and Average White Layer Thickness were measured and calculated for different pulse-on currents and pulse-on times. Moreover, the developed model that integrates a heat transfer analysis with deformed geometry, allows to estimate the power distribution between the electrode and the workpiece, as well as the Plasma Flushing Efficiency, giving an insight view of the process. Finally, by employing the Response Surface Methodology, educed regression models that correlate the machining parameters with the corresponding results, while for all the aforementioned indexes, ANOVA was performed.

Electrical Discharge Machining (EDM) consists of a non-conventional machining process, which is widely used in modern industry, and especially in machining hard-to-cut materials. By employing EDM, complex shapes and geometries can be produced, with high dimensional accuracy. Titanium alloys, due to their unique inherent properties, are extensively utilized in high end applications. Nevertheless, they suffer from poor machinability, and thus, EDM is commonly employed for their machining. The current study presents an experimental investigation regarding the process of Ti–6Al–4V ELI with high power EDM, using a graphite electrode. Control parameters were the pulse-on current (I_p) and time (T_on), while Machining performances were estimated in terms of Material Removal Rate (MRR), Tool Material Removal Rate (TMRR), and Tool Wear Ratio (TWR). The machined Surface Roughness was calculated according to the Ra and the Rt values, by following the ISO 25178-2 standards. Furthermore, the EDMed surfaces were observed under optical and SEM microscopy, while their cross sections were also studied in order the Average White Layer Thickness (AWLT) and the Heat Affected Zone (HAZ) to be measured. Finally, for the aforementioned indexes, Analysis Of Variance was performed, whilst for the MRR and TMRR, based on the Response Surface Method (RSM), semi-empirical correlations were presented. The scope of the current paper is, through a series of experiments and by employing statistical tools, to present how two main machining parameters, i.e., pulse-on current and time, affect major machining performance indexes and the surface roughness.

In this study, the environmentally friendly friction stir processing (FSP) method was utilized to fabricate surface composites employing technical aluminum matrix 1050-H14 and aluminum alloy 6060-T4 reinforced with silicon carbide (SiC) particles. Microstructure analysis, employing light and scanning electron microscopy, in conjunction with comprehensive evaluations of hardness, compressive strength, and tribological properties, was conducted to elucidate significant findings. The results reveal that an augmented number of FSP passes contributes to the homogenization of microstructure, leading to the alteration of SiC particle morphology and fragmentation. Consequently, this phenomenon results in improved mechanical properties, particularly noteworthy in the case of AA6060-T4 alloy matrix composites, and enhanced wear resistance. Both AA1050-SiC and AA6060-SiC composites demonstrate notable increases in compressive strength compared to their unreinforced matrices. Particularly noteworthy is the substantial enhancement in compressive strength observed in the AA6060-SiCp composite, escalating from 249 to 331 MPa (at ε = 0.1) and from 398 to 715 MPa (at ε = 0.2) with an increase in the number of FSP passes. Additionally, FSP’s ability to precisely control process parameters such as tool rotational speed and traverse speed allows for the optimization of mechanical properties and microstructural characteristics tailored to specific application requirements. This study highlights the potential of FSP in fabricating high-performance aluminum matrix composites with superior strength and wear resistance, positioning it as a viable technique for advanced engineering applications. The environmentally friendly nature of FSP, due to its solid-state operation and reduced energy consumption, further underscores its suitability for sustainable manufacturing practices.

As a non-conventional machining technology, EDM is used extensively in modern industry, particularly in machining difficult-to-cut materials. CALMAX is a chromium-molybdenum-vanadium tool steel with exceptional toughness, ductility, and wear resistance that has a wide range of applications. Despite the fact that EDM is routinely used in CALMAX machining, the related published research is brief and limited. The current research gives a complete experimental study of CALMAX machining using EDM. A Taguchi Design of Experiment (DOE) was used, using pulse-on current, pulse-on time, and open-circuit voltage as control parameters. Material Removal Rate (MRR), Tool Material Removal Rate (TMRR), and Tool Wear Ratio (TWR) were used to evaluate machining performance, while Ra and Rz were used to estimate Surface Quality (SQ). The produced White Layer (WL) parameters were determined using optical and SEM microscopy, as well as EDX measurements and micro-hardness studies. Finally, for each of the aforementioned indexes, Analysis of Variance (ANOVA) was performed, and multi-objective optimization was based on Grey Relational Analysis (GRA). The results show that higher open-circuit voltage produces lower WL thickness, although by increasing the pulse-on time, the TWR is increased. The average hardness of the WL is increased about 400% compared to the micro-hardness of the bulk material.

The paper presents a review of the literature and authors’ research on the current achievements in the field of extrusion of aluminium alloys, magnesium alloys, powders and aluminium-based composites in particular. The microstructure transformations taking place during homogenisation of billets from the medium- and high-strength heat-treatable aluminium alloys are still an object of interest of researchers. The recently published papers are related to dissolution of soluble phases formed during solidification and elimination of microsegregation, precipitation of the dispersoids, insoluble phases’ transformation as well as particles re-precipitation during cooling. The novelties in the extrusion of magnesium alloys and aluminium-based composites are shortly reported. Specifics of the extrusion dies design and their working conditions, which limit the products quality and working life of the tools, are extensively reported. The computer-aided designing (CAD) and finite-element method (FEM) and 3D optical scanning were used in analysis aimed at dimensional deviations of the dies and the extruded products. The surface engineering techniques such as welding techniques, diffusion layers and protective coatings such as produced by physical vapour deposition (PVD), plasma-enhanced physical vapour deposition (PAPVD), chemical vapour deposition (CVD) and plasma-enhanced chemical vapour deposition (PECVD) are described. Various original methods of extrusion including the severe plastic deformation processes (SPD), such as cyclic extrusion compression (CEC), equal-channel angular pressing (ECAP) and hydrostatic extrusion (HE) are discussed. The above techniques as well as the new KOBO extrusion process with oscillating die movement generate significant refining of the microstructure of metals and alloys and enable consolidation of the powdered materials. The application of the rapid solidification process connected with the hot extrusion permits production of beneficial microstructure and above-standard mechanical properties of the extruded products. Finally, the opportunities and directions of development of the extrusion process of metals and alloys are indicated.