Bu çalışmada, Bilgisayarlı Sayısal Denetimli (BSD) freze tezgâhında boydan boya delik delme sürecinde değişen işleme parametrelerinin, delik sonu çıkışında çapak oluşumuna etkisi incelenmiştir. Deneysel çalışmalarda; iki farklı sertlikteki soğuk iş takım çeliği (AISI D2, 20 HRC ve AISI D3, 28 HRC), iki farklı çap (Ø 8 mm ve Ø 10 mm) ve dört farklı uzunlukta HSS matkap uçlarıyla delinmiştir. Deneylerde üç farklı kesme hızı (5, 10 ve 15 m/dak) ve üç farklı ilerleme hızı değeri (0.04, 0.05 ve 0.06 mm/dev) değerleri kullanılmıştır. Deney sonuçlarına göre, ilerlemenin artmasına bağlı olarak delik sonu çapak yüksekliğinin azaldığı; delik sayısı, kesme hızı ve malzeme sertliğinin artmasına bağlı olarak da delik sonu çapak yüksekliğinin arttığı tespit edilmiştir.

This study investigated the effects of process parameters on acceleration amplitude in the drilling of AISI D2 and AISI D3 cold work tool steels using HSS twist drills of two different lengths. Workpiece hardness, drill length/tool overhang, cutting speed, feed rate, and number of holes drilled were chosen as the process parameters. In the tests made by using the full factorial (FF) design technique, the values of induced machining vibrations occurring on the workpiece during drilling were specified as the acceleration amplitude. Measurement results were evaluated by linear regression analysis, and a second-order equation was developed for the prediction of the acceleration amplitude. The correlation coefficient of the predictive equation at a 95 % confidence level was calculated as R 2 =0.703. The main and interaction effects of the process parameters on the acceleration amplitude were evaluated, and the percentage contributions of the process parameters to the acceleration amplitude were determined by variance analysis. In addition, scanning electron microscope (SEM) and optical microscope images of the drill wear were taken, and the wear characteristics and acceleration amplitude were correlated. The most effective parameters on acceleration amplitude were determined as the number of holes drilled, workpiece hardness, cutting speed, and feed rate. No significant effect of drill length/tool overhang was observed. With increasing cutting speed, number of holes drilled and the drill length/tool overhang, the acceleration amplitude values increased, although they decreased with increasing workpiece hardness.

In this study, Al matrix composites consisting of different amounts of Zn, Cu, and Mg were produced using the powder metallurgy technique. In the alloying, powders were ball milled for 120 min via mechanical alloying. After alloying process, the powders were pressed at 800 MPa at room temperature. Sintering (2 h at 600?C in argon atmosphere), solution treatment (2 h at 480?C), and aging processes (3, 6, 9, and 12 h, respectively, at 120?C) were applied to the samples. The hardness and tribo-metallurgy properties of the products were investigated. After sintering, the hardness values of the three alloys were close to each other; however, the solution treatment after sintering caused the hardness values to increase significantly. It was determined that the Al-2Zn-5Cu-4Mg alloy had the highest hardness increase with the 6-h aging heat treatment. The wear resistance of the materials in all the compositions had increased. The highest wear resistance and lowest friction coefficient were obtained for the Al-2Zn-5Cu-4Mg alloy with the 6-h aging heat treatment.

This study investigated the effects of aging and deep cryogenic treatment applied to Al7075 alloy on hardness and wear behavior. In this context, two different categories were created for the aging process. For the first group, after solutionizing the samples at 520 °C for 2 h, aging was applied at 120 °C for 12 h to reach 177 HV hardness. In the second group, after solutionizing at 520 °C for 2 h, the aging process was applied at 200 °C for 8 h to reach a hardness value of 164 HV. In addition, deep cryogenic treatment (12 h, 24 h, and 36 h at −140 °C) was applied to the samples after the solutionizing and aging processes. The pin-on-disc wear test was carried out according to the ASTM G99 standard in order to examine the effects of the aging and cryogenic processes on wear behavior. The highest wear resistance was obtained with the Al7075 sample aged at 120 °C for 12 h followed by the 12-h deep cryogenic treatment. Hardness values and wear test results showed that the applied cryogenic process had positively affected the wear behavior.

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