Statistical analysis of surface roughness for turning AISI 1040 steel

The fact that the expense items of manufacturing expenditures are large and therefore the costs are also large. Also very low tolerances are demanded in the manufacturing sector, so planning becomes complicated during production. Correct cutting parameters must be determined to produce the desired geometries, reduce costs and obtain a good surface. Accurate selection of parameters affecting surface integrity and surface roughness plays an important role in minimizing defects. In this thesis, in order to obtain the lowest surface roughness in the machining of cylindrical parts by turning operation, it is aimed to determine the most suitable levels of cutting parameters. For this reason, according to the cutting speed, feed and chip depth as cutting parameters, a test list was created in Taguchi L9 orthogonal array. In our study as a test sample, AISI 1040 manufacturing steel was used which is frequently preferred manufaturing industry today. Cylindrical materials obtained by heat treatment with 41 HRc hardness were machined in the CNC lathe machine to determine the cutting conditions that obtained the minimum surface roughness. Work pieces were machined with using CVD coated carbide insert. The experiments were carried out under dry conditions without the use of coolant. At the end of the experiments, the average surface roughness values (Ra) of the work pieces were measured. The signal/noise (S/N) ratios were found with Taguchi design. According to the results of the experiments, the most important effect for the average surface roughness among the three parameters was determined by the feed rate parameter. Furthermore, ANOVA analysis showed that the feed rate was 95% confidence level.