Mahir Uzun

CK45 steel has various industrial uses due to its durability, wear resistance and strength. It is generally used in machinery, automotive industry, hydraulic cylinders, bearings, gears and similar applications. It is important to investigate the machinability properties of CK45 steel, which is frequently used in the manufacturing industry, in different cooling/lubrication environments. This study focused on the effects of a synthetic-based nanofluid cooling strategy and different cutting parameters during the milling of CK45 steel. Additionally, Taguchi analysis was performed to reduce the number of experiments and costs. Sustainable cooling/lubrication techniques were used during milling. A three-axis computer-controlled machine was used for the milling process. According to the findings, flank wear, surface roughness, and energy consumption were reduced by machining in the nanofluid environment. It was observed that Cu nanoparticles added into the nanofluid increased the machinability properties. Furthermore, statistical analysis was employed to ascertain the predominant control variables influencing the response parameters. Machinability efficiency can be increased by using nanoparticulate fluids as a coolant during milling. In addition, costs can be reduced by identifying the most effective factors in the experiment through statistical analysis.

Gears are machine elements widely used in the industry. A gear mechanism can consist of two gears, or machines with many gears of different sizes can be used. Particularly when many gears are used, this significantly increases the weight and cost of the machine. With the advancement of technology in recent years, production methods have also developed, making it possible to manufacture parts with almost any geometry. In this study, utilizing the capabilities of advanced production methods, designs with triangular, square, and hexagonal geometries were made on the body of a spur gear to minimize the weight of the gear. To find the lightest gear that can work without damage, different designs with various edge lengths and fill thicknesses were modeled separately using the Solidworks software package. The finite element analysis of the modeled gears was performed using the ANSYS software package. As a result of the analyses, among the gears with three different designed geometries and hollowed bodies, the gear with a square profile achieved the lightest weight. Compared to the solid-bodied gear, a significant weight reduction of 63,65% was achieved with this designed gear.

This study aims to modernize commonly preferred hybrid aluminum composites in the automotive and defense industries. For this purpose, Al-4Cu/B₄C-SiC hybrid composites were manufactured using the hot pressing method and their microstructure, mechanical, and tribological properties were investigated. SEM/EDS analyses of the samples were conducted to examine morphological characteristics. Hardness, relative density, and three-point bending tests were performed on the produced samples. Additionally, wear tests were conducted under dry sliding conditions and different loads (5-10-15 N) to investigate tribological properties. The addition of hybrid reinforcements resulted in high hardness (88.54 HB) and relative density (98.83%) values. The highest bending stress (556.9 MPa) was observed in sample AC-4 (Al-4Cu/2B₄C-2SiC). The lowest mass loss (1.1 × 10⁻³ g) was encountered in sample AC-6 (Al-4Cu/6B₄C-6SiC), where all reinforcements were present together. Plastic deformation, oxidation, and residual wear mechanisms were identified on the worn surfaces of the samples. Consequently, the addition of hybrid reinforcements to Al-4Cu composites shows promising potential in enhancing the mechanical and tribological performance of the composites.

Polimer malzemeler endüstride özellikle farklı makine elemanları olarak yaygın bir şekilde kullanılmaktadırlar. Kullanıldıkları ortamlarda, metal malzemelere kıyasla aşınma dayanımları özellikle kimyasal ortamlar da söz konusu olduğunda oldukça düşük olmaktadır. Dolayısı ile polimer malzemeler, bu ortamlara daha dayanıklı elementler ile kaplanabilirlerse dayanımları çok daha yüksek olacaktır. Bu çalışmada, dayanımı arttırabilmek amacıyla literatürde rastlanılmayan PEEK (polieter eter keton)’un PVD yöntemlerinden biri olan manyetik alan sıçratma yöntemi ile kaplaması gerçekleştirilmiştir. Altlık malzeme olarak 30x30 mm² boyutlarında kare kesitli, 3 mm kalınlığında 3 adet saf PEEK numuneler kullanılmıştır. Numunelerin yüzeyi, kalın taneliden ince taneliye doğru sırası ile 400, 600 ve 1200 numara kum zımparası ile yüzey pürüzlülük değeri ortalama Ra=0.248 olana kadar parlatılmıştır. Daha sonra PEEK numuneler PVD (Fiziksel Buhar Biriktirme) kaplama yöntemlerinden olan manyetik alanda sıçratma yöntemi kullanılarak biri VN diğeri ise CrY(V)N ile kaplanmıştır. Kaplama işleminden sonra numunelere sertlik ve aşınma testi uygulanmıştır. Sonuç olarak, saf haldeki PEEK numuneye göre VN kaplanmış PEEK numunenin sertlik değerinin %34 arttığı, CrY(V)N kaplanmış PEEK numunede ise sertlik değerinin yaklaşık %40 arttığı görülmüştür. Aşınma deneyi ile ilgili olarak yükteki artış sonucunda, numunelerde aşınma kayıpları da artmıştır. En yüksek kütle kaybının CrY(V)N ve VN kaplı numunede olduğu görülmüştür.

This research aims to assess the mechanical characteristics of high-performance copper composites made utilizing powder metallurgy. The composites were produced by adding reinforcement elements (Al₂O₃-Cr₃C₂) at different rates (3-6–9 wt.%) into copper-graphite (Cu-5Gr) via hot pressing technique. The microstructure, hardness, three-point bending and wear performance were analysed. The results determined that hybrid reinforced composites exhibited higher density, hardness and bending strength compared to Cu-Gr composites. The highest hardness of 73.02 HB was found in the CG-4 (copper graphit-4) sample. The maximum bending stress of 151.06 MPa occurred in sample CG-2. In addition, it was observed that the wear resistance increased significantly with the addition of the hybrid reinforcements. The lowest specific wear rate of 7.961 × 10⁻⁷ mm³/N.m occurred in sample CG-6. As a result, 15.92%, 58.16% and 83.21% improvements were achieved in hardness, bending strength and wear performance, respectively. The current work indicates that certain mechanical properties of copper can be improved via the powder metallurgy process and the addition of reinforcements which could expand the applications and use of this metal in different industries.