Ergün Ekici

Investigation of the WEDM of Al/B4C/Gr reinforced hybrid composites using the Taguchi method and response surface methodology

Abstract In this study, the effects of machining parameters on the material removal rate (MRR) and surface roughness (Ra) were investigated during the cutting of Al/B4C/Gr hybrid composites by wire electrical discharge machining (WEDM). Wire speed (WS), pulse-on time (Ton) and pulse-off time (Toff) were chosen as the control factors. The L27 (33) orthogonal array in the Taguchi method was used in the experimental design and for the determination of optimum control factors. Response surface methodology was also used to determine interactions among the control factors. Variance analysis (ANOVA) was applied in the determination of the effects of control factors on the MRR and Ra. According to the ANOVA results, the most effective parameters on MRR and Ra were wire speed with a 85.94% contribution ratio, and pulse-on-time with a 47.7% contribution ratio. The optimum levels of the control factors for MRR and Ra were determined as A3B3C3 and A1B1C2. In addition, second-order predictive models were developed for MRR and Ra; correlation coefficients (R2) were calculated as 0.992 and 0.63.

Evaluation of surface roughness and material removal rate in the wire electrical discharge machining of Al/B4C composites via the Taguchi method

This study researched the effects of machining parameters on surface roughness and material removal rate in the wire electrical discharge cutting of high-density Al/B4C metal matrix composites produced via the hot pressing method. Wire tension, reinforcement percentage, wire speed, pulse-on time and pulse-off time were set as the control factors. The Taguchi L18 (21 × 34) orthogonal array was used in the experiment design and determination of the optimum control factors. Variance analysis was applied to determine the effects of the control factors on the surface roughness and material removal rate. The results showed the most effective parameters to be pulse-on time (30.22%) for surface roughness and wire speed (83.20%) for material removal rate, and the optimum levels of the control factors to be A2B1C2D1E1 and A2B2C3D2E2, respectively. Predictive equations were then developed by applying linear regression analysis, and the adjusted correlation coefficients were calculated as 0.61 for surface roughness and 0.785 for material removal rate.

The machinability of Al/B4C composites produced by hot pressing based on reinforcing the element ratio

Abstract In this study, the effects of the particle reinforcement ratio on cutting forces and surface roughness were investigated when milling particle-reinforced metal matrix composite (MMCp) produced by hot pressing with different cutting tools. Alumix 123 alloy as the matrix material and B4C particles with an average size of 27 μm and 5%, 10% and 15% ratio as reinforcing elements were used for the manufacture of composite materials. The experiments were carried out in dry cutting conditions with four different cutting speeds, constant feed rate and depth of cut. Changes depending on the increased reinforcement ratio in cutting forces and surface roughness values were investigated; the effects of 10% B4C reinforced composite on tool wear were also examined. It was observed that cutting forces increased with the increase in cutting speed and particle ratio with carbide cutting tools, and it was seen that the cutting forces on the cutting tools decreased when cutting speed decreased and the cutting forces increased as the reinforcement ratios increased. In addition, with increasing the cutting speed, the surface roughness of the machined surfaces of composite samples increased with the carbide tools, while the cubic boron nitride (CBN) tools have the opposite effect. While it was seen that flank and crater wear occurred on the cemented carbide cutting tools, abrasive, adhesive and other wear mechanism tools in addition to the main wear mechanism, no remarkable flank and crater wear occurred on CBN cutting tools.

Mechanical and fracture behavior of B4C reinforced Al composites produced by hot pressing

Abstract In this study, the effects of particle addition on the microstructure, mechanical properties and fracture behaviors of Al/B4C particle reinforced composite produced by hot pressing method were investigated. After the production of 5, 10 and 15 wt.-% of B4C reinforced composites, T6 heat treatment was applied. It was specified that a strong interface bond occurred between the matrix and particles, and during the fracturing of composites, this effect increased the particle fracture. It was observed that particles were fractured parallel to the fracture surface and to each other fracture surface of MMCp. In general, cavity of particle separated from the matrix was not seen. In the production of MMCp, it was also observed that hot pressing provided a density higher than 99 %. After the heat treatment the maximum hardness value of 173 HB was reached with 15 wt.-% B4C reinforced sample. The transverse rupture strength (TRS) decreased with the increase of reinforcement ratio. The highest TRS was 510 MPa with the 5 wt.-% reinforced material, whereas the lowest value was obtained to be 387 MPa with the 15 wt.-% B4C reinforced material.

Milling behavior of Hadfield steel with cryogenically treated tungsten carbide inserts

Abstract In this study, the performance of cryogenically treated tungsten carbide inserts in the milling of Hadfield steel (X120Mn12) was evaluated in terms of surface roughness (Ra) and tool wear (VB). Cutting tools were assessed under three conditions: untreated (U), cryogenic treated (CT) and cryo-tempered (CTT). For the cutting parameters, three different cutting speeds (70, 100 and 130 m·min−1) and feed rates (0.08, 0.14 and 0.2 mm·rev−1) were used. The experiments were carried out under a fixed depth of cut and dry cutting conditions. To determine the factorial effects, the procedure Taguchi L27 (33) was used. For the estimation of Ra and VB, the response surface method (RSM) was employed and mathematical models were developed. In terms of Ra, the effective parameter was feed rate (89.45 %) and in terms of VB, it was the cutting speed (60.42 %). For Ra and VB, the optimum levels of factors were determined as A3B3C1 and A3B1C1, respectively. The effects of the factors were also assessed by RSM.