Analisa Kegagalan dan Mekanisme AUS Pahat Karbida pada Pembubutan Hijau Bahan Automotif Al 6061 -T6

Abstract

This thesis reports results of experimental and research on dry machining of Aluminium 6061-T6 using carbide insert cutting tool. The alternative to wet machining is dry machining (green machining), since there is no used cutting fluid going to pollute the environment no fog from the cutting fluid that shall endanger the operator and the chip shall not be contaminated by the cutting fluid The problems on dry machining including a friction between the surface of working material and the cutting tool, chip formation mechanism and chip flow and cutting temperature which all related to the machining parameter and the geometry of cutting tool. The uncoated carbide cutting tool (ISO KIO) and the coated carbide tool (ISO KIO TiN) are used in this research and the experiment conducting an incremental design and performed using CNC TU 2A lathe machine tool. The objective is focused to obtain the characteristic of the wear mechanism and the failure mode of cutting tool such as the progression of land wear and crater wear, brittle fracture and tool life. Base on experimental and reseach results obtained that the failure mode of carbide ISO Kl 0 is britlle fracture, plastic deformation, flank wear, flaking and excesssive chipping. These failure modes dominantly on carbide ISO Kl 0 and they are due to the fact that speed of chip flow is slower than the cutting speed and the radius of chip (Ro) smaller than the radius chip breaker (R). The chip produce is snarled helix-ribbon with irregularly entangled and this chip flows curlly up and side with length > 5. 0 cm. The flow mechanism of this chip begins with laminating the nose cutting tool so that abrasive wear mechanism is occured and sometimes the chip covers the wear area and it propagates to flaking and chipping. The maximum flank wear on carbide ISO Kl 0 is at zone C (0.035 mm). On carbide ISO KIO TiN, there is noflakingfound, and this cutting tool has lower flank wear (0. 023mm) than ISO Kl 0. This value indicated that ISO Kl 0 TiN 34.29 % better than the performance of ISO KIO. At cutting condition of 300 ml min depth of cut of 0. 8 mm and feed rate of 0. 14 mm/rev shows the worst result for both cutting tools. From the primer shear angle point of view and the radius of chip point review, the critical condition that caused the the failure mode of both cutting tools are at <jJ = 24.68- 33.53 ° and Ro= 0.129- 0.447 mm respectively. From the aspect of surface roughness using ISO Kl 0 or ISO Kl 0 TiN, it is obtain that the value of Ra achieved by carbide ISO Kl 0 TiN is better than ISO Kl 0 for all cutting condition tested The range of surface roughness for ISO KIO is 0.75 -9.27 μm while for ISO KIO TiN is 0. 63 - 8. 60 μm. These =result are believed due to the capability of TiN layer as a coolant and a solid lubricant.