On the road to real applications, although there are lots of efforts focusing on mechanical and physical features in the literature, their machining abilities were examined in a very limited manner. In this study, machining properties of pumice reinforced AA7075 syntactic foams manufactured via the newly offered sandwich infiltration technique were investigated by performing face turning. Physical and microstructural (optical and SEM works) analyses were conducted on fabricated foams to carry out sample characterization. All machining forces were measured for different cutting speeds (25, 50, and 100 m/min) and feed rates (0.05, 0.10, and 0.15 mm/rev). After the turning operation, areal surface roughness values were measured using a 3D surface profilometer and material removal rate (MRR) values were calculated. Besides, chip mixtures including pumice and metal fragments were collected to probe chip morphology in detail. The results showed that machining forces were affected by the operation parameters differently, and the lowest surface roughness was detected at the cutting speed of 100 m/min and 0.05 mm/rev feed rate. Furthermore, the shape of the metal chips changed from long/continuous characteristic to saw-tooth morphology depending on increasing cutting speed levels while pumice particles exhibited breakaway tendency as the feed rates went up.

Selective laser melting (SLM) is a three-dimensional (3D) printing process that can manufacture functional parts with complex geometries as an alternative to using traditional processes, such as machining wrought metal. If precision and a high surface finish are required, particularly for creating miniature channels or geometries smaller than 1 mm, the fabricated parts can be further machined. Therefore, micro milling plays a significant role in the production of such miniscule geometries. This experimental study compares the micro machinability of Ti-6Al-4V (Ti64) parts produced via SLM compared with wrought Ti64. The aim is to investigate the effect of micro milling parameters on the resulting cutting forces (Fx, Fy, and Fz), surface roughness (Ra and Rz), and burr width. In the study, a wide range of feed rates was considered to determine the minimum chip thickness. Additionally, the effects of the depth of cut and spindle speed were observed by taking into account four different parameters. The manufacturing method for the Ti64 alloy does not affect the minimum chip thickness (MCT) and the MCT for both the SLM and wrought is 1 μm/tooth. SLM parts exhibit acicular α martensitic grains, which result in higher hardness and tensile strength. This phenomenon prolongs the transition zone of micro-milling for the formation of minimum chip thickness. Additionally, the average cutting force values for SLM and wrought Ti64 fluctuated between 0.072 N and 1.96 N, depending on the micro milling parameters used. Finally, it is worth noting that micro-milled SLM workpieces exhibit lower areal surface roughness than wrought ones.

Carbon fiber-reinforced plastics (CFRPs) have been specially developed to enhance the performance of commercial and military aircraft because of their strength, high stiffness-to-density ratios, and superior physical properties. On the other hand, fasteners and joints of CFRP materials may be weak due to occurring surface roughness and delamination problems during drilling operations. This study’s aim is to investigate the drilling characterization of CFRPs with different drilling parameters and cutting tools. Drilling tests were performed with the Taguchi orthogonal array design (L18: 2^1 3^3). Tests were conducted with three levels of cutting speed (15, 30, 45 m/min), three levels of feed rate (0.05, 0.1, 0.2 mm/rev), two levels of drill diameter (3 and 5 mm), and three different types of drills (two twist drills with a point angle of 138° and 120° and one brad drill). Thrust forces were recorded during drilling tests, and afterwards surface roughness and hole delamination were measured. Obtained results were analyzed with Taguchi and two-way ANOVA. The general tendency was that low cutting speed, high feed rate, and small diameter drill caused an increase in thrust force. Surface roughness decreases with increasing tool diameter, decreasing feed, and cutting speed. Delamination factors of the samples dropped depending on decreasing thrust force levels. Remarkably, it is possible to control the delamination factor values via better surface quality. The brad drill and larger point angle have a negative effect on the drilling quality of CFRPs. According to all results, the cutting speed of 45 m/min and feed rate of 0.05 mm/rev using a type II drill having a 120° point angle and 5 mm diameter (12th trial) and the cutting speed of 30 m/min and feed rate of 0.05 mm/rev using a type II drill having a 120° point angle and 3 mm diameter (2nd trial) were determined as optimum drilling conditions.

Cellular structures such as regular/irregular honeycombs and re-entrants are known as lighter, high level flexibility and more efficient materials; these cellular structures have been mainly designed with topology optimization and obtained with new additive manufacturing methods for aircraft industry, automotive, medical, sports and leisure sectors. For this aim, the effect of cellular structures such as the honeycomb and re-entrant on vibration and stress-strain behaviors were determined under compression and vibration condition by finite elements analyses (FEA). In FEA, the re-entrant and honeycomb structures were modeled firstly and then the stress and displacement values for each structure were obtained. Secondly, vibration behaviors of these foam structures were estimated under determined boundary conditions. In conclusion, the effect of topology in foam structures on vibration and mechanical behaviour were exhibited in FEA results. The obtained stress results of FEA show that all stresses (?x, ?y, ?vm, ?xy) are lower on honeycomb structure than reentrant structure. Besides, natural frequency values (?1, ?2, ?3) and appearance of each structure were observed by using FEA.

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