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Electric discharge machining (EDM) is a non-conventional machining process, which has gained popularity in the manufacturing industries. In this study, analytical models have been presented to calculate the surface roughness and material removal rate based on multiple-craters geometry. To begin, the geometry of a single crater is calculated that was converted into multiple craters. Following on, the material removal rate (MRR) and average surface roughness were calculated. The model was able to estimate crater depth, width, average roughness and MRR with a deviation of 3–5%, 5–7%, 4–7% and 5–8%, respectively. It was found that as the pulse energy is 20 times greater as compared to the lower capacitance thereof, a deeper crater is realized. The pulse energy becomes quadruple as open voltage upsurges from 60 to 120 V, but the capacitance remains unchanged. The crater depth, on the other hand, does not increase as the open voltage is increased. The crater's width expands linearly as the capacitance and open voltage increase. This is attributed to the expansion of plasma radius at higher magnitude of pulse energy, causing the crater to widen. [ABSTRACT FROM AUTHOR]

To avoid the effects of the overlap phenomenon among powder particles, the concept of an effective particle number was introduced, and multi-parameter analytical models for laser powder-fed additive manufacturing (LPF-AM) cladding geometric characteristics were established based on the laws of energy and mass conservation. Experimental research on the LPF-AM of a FeCr alloy was carried out, and the theoretical results are discussed and compared with the experimental data from the perspective of the laser energy density and powder density. The results showed that the cladding area was proportional to both the laser energy density and powder density. The mixing area and dilution rate decreased gradually with increasing powder density, while they increased first and then decreased with increasing laser energy density. The analytical model calculation values fit well with the experimental measurements. The microstructure of the cladding layer and substrate showed good metallurgical bonding, and the micro-hardness variation from the mixing to the cladding zone ranged from 423 to 627 HV. [ABSTRACT FROM AUTHOR]

In this paper, the BTA deep drilling is analysed experimentally and by modelling. Drilling tests shows the significant effect of feed rate and the slight effect of cutting speed on the recorded axial force. Characterisation of the BTA drill inserts shows that the wear is relatively uniformed along cutting edges, except on the nose radius of the central insert. A new analytical thermomechanical model for assessment of cutting forces in the BTA drill and for tool design is then proposed. The friction coefficient involved in the model is adjusted to take into account the effect of lubrication and guide pads on cutting forces. The model predicts axial and radial forces, and torque applied on inserts of the BTA drill. Firstly, the model is validated with recorded axial force, obtained from drilling of a workpiece made of mild steel 18MND5, where the effect of cutting speed and feed rate is highlighted. A parametric study is conducted to highlight the effect of tool geometry (approach and rake angles of inserts) on the axial and radial forces and torque. This shows the potential of the model for further use as a tool design of BTA drills, based on optimal geometric parameters (e.g. cutting angles, cutting edges length) leading to a minimum loading acting on the BTA drill. [ABSTRACT FROM AUTHOR]

Selective laser melting (SLM) is a transformative manufacturing process due to its ability to manufacture complex metal parts directly from various bulk powders. With the capability of reducing powder consumption and decreasing fabrication times, lattice structures, which are used as infilling materials within hollow parts, offer an effective solution for decreasing the high costs that currently impede the wider application of SLM in various industries. The assessment of mechanical properties of SLM-built lattice structures, however, remain challenging due to their complicated geometries, while pursuing experimental studies proves to be time-consuming due to the requirement of numerous part fabrication and physical testing. To address these research challenges, this study proposes an analytical modelling approach conducting quasi-static analysis on Ti6Al4V (Ti64) lattice structures. In order to investigate the structures' mechanical properties, dynamic balance equation of the structures under compression loads were first established, and the stress distribution of the structures was calculated explicitly using central difference method. The modelling approach was validated by conducting uniaxial compression tests on samples fabricated using SLM. The experiments showed that the equivalent elastic modulus ( E*) and the ultimate stress ( UTS) values of the Ti64 structures predicted by the analytical method were in good agreement with the experimental results. The paper also discusses the design principles of SLM-built lattice structures (mainly the selection of proper topologies and relative densities) and examines the necessity and flexibility of the proposed analytical approach compared with conventional theoretical methods and their experimental studies in the context of SLM process. [ABSTRACT FROM AUTHOR]

In this work, a predictive machining theory, based on an analytical thermomechanical approach of oblique cutting (Moufki et al., Int J Mech Sci 42:1205-1232, ; Moufki et al., Int J Mach Tools Manuf 44:971-989, ), is applied to the peripheral milling process. The material characteristics such as strain rate sensitivity, strain hardening and thermal softening are considered. In the primary shear zone, thermomechanical coupling and inertia effects are accounted for. Due to the fact that the reference frame associated to the primary shear zone moves with the tool rotation, an analysis of the inertial effects has been performed. As the heat conductivity of Ti-6Al-4V is low, the thermomechanical process of chip formation is supposed to be adiabatic; thus, the problem equations are reduced to a system of two non-linear equations which are solved numerically by combining the Newton-Raphson method and Gaussian quadrature. The present analytical approach leads to a three-dimensional cutting force model for end milling operations. Calculated and experimental results extracted from the literature are compared for several operations: full immersion, up-milling and down-milling and for different cutting conditions. Although the present model was established for stationary conditions and for continuous chips, it gives acceptable predictions for machining titanium alloy for which the chips are usually segmented. The proposed model appears as an interesting alternative to the mechanistic approach which requires many experimental tests to determine the milling cutting force coefficients. [ABSTRACT FROM AUTHOR]

In the shape rolling process, the reduction of the number of passes is a challenging topic for the steel industry. This can be achieved by enhancing the design approach or by developing new rolling passes that allow the production of high cross-section reductions such as with the slit roll pass. However, in order to design a robust roll pass, the lateral spread of the workpiece must be predicted correctly to prevent incomplete, or even worse, excessive roll groove fulfilling (which may cause roll damage). In the present investigation, the possibility of using a finite element model to predict the lateral spread in a slit roll pass is investigated. The results of the finite element model are then used to adapt and calibrate two analytical models that were developed originally for strip rolling and shape rolling with concave grooves. [ABSTRACT FROM AUTHOR]

To reduce the irregularities of machined surface, burnishing is used as a finishing process by plastic deformation. This process does not only improve surface finish but also generates compressive residual stresses throughout the surface. In this work, an analytical study and a finite element modelling were performed to provide a fundamental understanding of the burnishing on an AISI 1042 workpiece. The analytical results were concentrated on the surface roughness and on some burnishing parameter effects. The simulations were devoted to the study of the surface profile, the residual stresses and the influence of burnishing parameters (penetration depth, feed rates, diameter of the ball of burnishing tool and initial surface quality) on surface roughness and the residual stress distribution. It has been noted that burnishing improves surface quality and introduces compressive residual stresses. These results were successfully compared to experimental data obtained in previous works. [ABSTRACT FROM AUTHOR]