The aim of this study was to investigate the effects of process parameters on tensile strength for PLA specimens produced by fused deposition modeling (FDM). For this purpose, two different density rates (20% and 100%), printing speeds (100 and 130 mm/s), and nozzle temperatures (180 and 220oC) with three different hatching patterns including elliptical and diagonal (Gyroid, Cross 3D ve Grid) were selected. In the study, higher tensile stress was obtained at a rate of 100%, compared to a 20% density rate. When the samples with a 20% density rate are compared among themselves, the highest tensile stress value obtained was measured as 38.76 MPa for the Grid-patterned specimen produced at a nozzle temperature of 2200C and printing speed of 100 mm/s. Statistical analysis was also done for specimens with a 20% density rate. As a result of the variance analysis (ANOVA) method, the confidence level was achieved as 96%. When comparing in terms of specific strength, it was determined that the closest pattern to the full-filled sample with a specific strength of 5,893 MPa/gr was Cross 3D-patterned sample with a value of 5.458 MPa/gr.

Çalışmada eriyik yığma modelleme (FDM) yöntemi ile 3B yazıcı kullanarak üretilen PLA numunelerin mekanik özelliklerden olan çekme dayanımına işlem parametrelerinin etkisi belirlenmesi amaçlanmıştır. Bu amaçla çalışmada işlem parametreleri olarak 2 farklı doluluk oranı (%20 ve %100), 3 farklı baskı hızı (100,150 ve 200 mm/s), 3 farklı nozul sıcaklığı (180, 205 ve 220°C) ve 3 farklı desen çeşidi (Cubic, Grid, Triangle) seçilmiştir. Çalışmada, %20 doluluk oranına göre %100 doluluk oranında daha yüksek çekme gerilmesi elde edilmiştir. %20 doluluk oranındaki numuneler kendi aralarında kıyaslandığında elde edilen en yüksek çekme gerilmesi değeri 2200C nozul sıcaklığında, 100 mm/s baskı hızında yapılan Grid desen çeşidinde 43.12 MPa olarak ölçülmüştür. %100 doluluk oranında ise en iyi sonuç 2200C de, 100 mm/s baskı hızında üretilen numunede 59.21 MPa çıkmıştır. Çalışmada %20 doluluk oranındaki numuneler için istatistik analiz yapılmıştır. Varyans analiz (ANOVA) yöntemi sonucu güven düzeyi %94,4 elde edilmiştir.

For using ultrafine-grained metals and alloys in industry, further machining sequences and studying their possible effects are necessary to attain these products in their ultimate dimensions. In this work, the machinability of ultrafine-grained pure copper and the corresponding coarse-grained counterpart investigated systematically. The results showed that the processed copper could be machined as efficiently as its initial one. Also, the machining of the Cu sample with the polycrystalline diamond tools requires much less force than tungsten carbide tools. The produced cutting forces were smaller for the processed copper as compared to the initial copper. Also, similar tool wear mechanisms were detectable for the copper specimen before and after the process. Chip morphology altered less through the machining, and the surface quality enhanced during machining the ultrafine-grained copper. Eventually, the polycrystalline diamond tool increased the surface roughness of initial and processed specimens since it caused less than 50% roughness compared to the tungsten carbide tool.