Studi Pemotongan Optimum pada Pemesinan Kering Baja Aisi-1045 Menggunakan Pahat Karbida Berlapis dan Perbandingannya dengan Pemesinan Basah

Abstract

For the purpose of increasing the machinability of carbon steel, it is crucial to carry out research in order to obtain the optimum cutting condition. However, it is noted that today machining process should be done dry due to effort in saving environment thet while reducing production cost. In dry machining, tool is exposed directly to heat generated during machining and it is potential to deteriorate the cutting tool and surface finish. In order to realize the objective of research reported in this thesis, the cutting tool made of carbide (WC-Co) and carbide which was coated by ceramic based materials (TiC+Al2O3+TiN) under Chemical Vapor Deposition (CVD) method was selected This cutting tool was used to machine carbon steel AISI-1045 under wet and dry cutting environment. In the meaning of obtaining the optimum cutting condition for increasing the machinability of carbon steel, the Response Surface Methodology (RSM) with Central Composite Design (CCD) at a = 1 was utilized The preliminary study to determine the cutting parameter as stipulated in JSO-3685 shows that cutting speed (V) of 250 mlmin, feed (I) of 0.1 mm/rev and depth-of-cut (a) of 1.5 mm is the minimum cutting condition, while the maximum is cutting speed (V) of 320 m/min, feed (I) of 0.2 mm/rev and depth-of-cut (a) of 2.5 mm. The data obtained from machining test was analyzed using a shareware Minitab-14 software and the results were classified into 3 groups and then further analyze with the second order mathematical equation for resulting the mathematical model of surface roughness (Ra) and cutting time (tc). From the results, it was determined 4 (four) points which met the optimum condition, i.e. V 285 m/min, f 0.169 mm/rev, a 2 mm, Ra 5.22 micron, tc 11.25 minute (resulted under minimum cutting condition) and V 285 mlmin, f 0.185 mm/rev, a 1.939 mm, Ra 6.23 micron, tc JO.OJ minute (resulted under maximum cutting condition). The optimum cutting conditions resulted under dry cutting were also tested under wet cutting environment. The results between dry and wet are Ra (dry) 5. 7166 and Ra (wet) 5. 7417, and tc (dry) 11. 7992 minute and tc (wet) 12. 9479 minute. Moreover, in term of tool wear, the microanalysis using scanning electron microscope (SEM) shows the different between wear mode (flank wear was observed) and surface topography (feed mark) was insignificant under dry and wet cutting. Statistic test also proves that the different between dry and wet is insignificant. From this experimental work, it is concluded that RSM method is useful to obtain the optimum cutting condition as the objective of this study. Moreover, dry machining is possible to be implemented for increasing the machinability of AISI 1045 by using the CVD-coated carbide.