The influence of the microstructural arrangement of 3D-printed polylactic acid (PLA) on its mechanical properties is studied using both numerical and experimental approaches. Thermal cycling during the laying down of PLA filament is investigated through infra-red measurements for different printing conditions. The microstructure induced by 3D printing is determined using X-ray micro-tomography. The mechanical properties are measured under tensile testing conditions. Finite element computation is considered to predict the mechanical performance of 3D-printed PLA by converting the acquired 3D images into structural meshes. The results confirm the leading role of the printing temperature on thermal cycling during the laying down process. In addition, the weak influence of the printing temperature on the stiffness of 3D-printed PLA is explained by the relatively small change in porosity content. However, the influence of the printing temperature on the ultimate properties is found to be substantial. This major influence is explained from finite element predictions as an effect of pore connectivity which is found to be the control factor for tensile strength.

In this research, we had studied the sensitivity for machining of cobalt-based superalloy Haynes 188 with ceramic cutting tool. The investigation had focused on the effects of the cutting speed, on the cutting forces, and on the surface roughness based on Taguchi’s experimental design. The effects of machining parameters were determined using Taguchi’s L27 orthogonal array. The signal-to-noise ratio was calculated for the average of surface roughness and the cutting forces, and the smaller were used to determine the optimal cutting conditions. The analysis of variance and the signal-to-noise ratio had effects on the parameters on both surface roughness and cutting. Three different types of cutting tools had been used in the experiment, namely KYON 4300, KYS 25, and KYS 30. The cutting force of Fz was considered to be the main cutting force. Depending on the material which had been used as cutting tool, the Fz had the lowest cutting speed and the lowest surface roughness with the KYS25 ceramic tool. The cutting force and the surface roughness of KYON 4300 cutting tool had shown better performance than other cutting tools. The flank wear and notch were found to be more effective in the experiments. The long chips were removed at low and medium cutting speeds, while the sawdust with one edge and narrow pitch at high cutting speeds was obtained.

Rene 41 superalloy developed to withstand severe mechanical stresses and high temperature operation, and are widely used in aircraft and space vehicles, especially nickel-based ones, due to their high corrosion resistance. In this study, three different cutting forces and surface roughness qualities were evaluated depending on the cutting speed in the machining of Rene 41 superalloy with three different ceramic tools KYON 4300, KSY25 and KSY30. In this work, The experimental results have revealed that the feed rate had a serious effect on the cutting forces, while the effect of turning speed and type of the cutting tool on the cutting forces are relatively small. On the other hand, the most important factor influencing the surface roughness was cutting speed followed by tool type and feed rate, respectively. The presented findings can help for understanding the machinability and surface characteristics of Rene’41 during high speed turning. In the experiments, it was observed that the cutting forces decreased as the cutting speed increased.

Rene'41 is a nickel-based superalloy that has high strength at high temperatures and can be hardened by aging. It is frequently used in the automotive and aircraft industries, especially in jet engines. Due to the high strength of these materials, their machinability parameters need to be analyzed. In this study, the effects of turning conditions on cutting forces and surface roughness during turning of Rene'41 superalloy using ceramic cutting tool inserts were examined. Machinability tests were conducted at three cutting speeds, feed rates and tools. Factors affecting the machinability of Rene'41 were optimized using the Taguchi method. According to the test results, the cutting force in the machining of Rene'41 superalloy is most affected by the increase in feed rate, and the effects of cutting speed and cutting tool material do not seem to be much. On the other hand, the factors affecting surface roughness are cutting speed, tool type and feed, respectively. The results may help understand the machinability and surface properties of Rene'41 during high-speed turning. Finally, the cutting parameters affecting the machinability of Rene'41 superalloy were optimized in terms of cutting forces and surface quality using the gray relational approach