Thesis Type: Postgraduate
Institution Of The Thesis: Gazi Üniversitesi, Fen Bilimleri Enstitüsü, Turkey
Approval Date: 2012
Student: MUSA BİLGİN
Supervisor: HASAN BASRİ ULAŞAbstract:
In this study, the machinability of AISI 6150 tempered steel with 311HB hardness has been investigated. The characteristic parameters of the specimens have a diameter of 38 mm and the length of 220 mm. During the experiments, effects of different parameters over main cutting force, surface roughness, tool wear and chip formation shapes were taken into consideration in the process of longitudinal CNC turning. The specimens were machined by four different cutting tools namely Ti (C, N) +A12O3+TiN covered coated carbide by means of CVD method, uncoated carbide, Ti (C, N) covered coated cermet using PVD method and uncoated cermet. The experiments were carried out in five different cutting speeds for both carbide cutting tools and cermet cutting tools. The cutting speed values are 150,200,250,300 and 350 m/min used for carbide tools and 150,175,200,225 and 250 m/min for cermet tools. Other machining parameters are same for all the cutting tools which are three different feed rate of (0,12 - 0,16 and 0, 20 mm/rev), three different cutting depth (0,5 1 and 1, 5 mm) and three different cutting tool nose radius of (0,4 -0,8 and 1,2 mm). All experiments are conducted with a new unused cutting tool without using cooling fluid at dry conditions and 3500 mm3 chip were removed from each individual specimen. The experiments were carried out in accordance with exact factorial principle and the results were discussed by means of graphs obtained from OriginPro 8.5 software. After experimental studies are finished, cutting tool wears are discussed on the basis of the observation of tool microscope. According to experimental results, the only failure of tool is observed on uncovered carbide tool. All examined machine parameters affect surface roughness, main cutting force, tool wear and chip formation shape. The most effective parameters are these; feed rate on surface roughness, chip depth on main cutting force, tool wear on cutting tool material, feed rate on chip formation shapes. It is observed that the optimum mean surface roughness (RA) is 0,298 um and the minimum main cutting force (Fc) is 200, 59 N.