Sri Nugroho

Characterization chip formation of commercial steel materials at low speed cylindrical grinding processes

Cylindrical grinding is the process of metal removal using multiple cutting point. The objective of the study is to investigate the chip characteristics (shape and width) and surface roughness materials. The materials are AISI 1020, AISI 1045, AISI 1090, AISI D2, and AISI 4340 with a grinding wheels WA46K8V. The research is using cylindrical grinding processes at low-speed workpiece 100 rpm, depth of cut 0.5 mm, in dry condition. Result of research is comparing characteristic chip with variable feet rate 120 mm/min, 420 mm/min, 1300 mm/min. The result is to show the increasing feedrate lead, the growth of chip width and high surface roughness value. On materials AISI 1020, AISI 1045, AISI 1090, and AISI 4340 show that chips width is related to hardness value.

Hardness and microstructure analysis of damaged gear caused by adhesive wear

This study was a result from research on repairing project of damaged elevator gear box. The objective of this research is to analyze the failure part on elevator gearbox at flourmill factory. The equipment was damaged after one year installed and running on factory. Severe wear was occurred on high speed helical gear. These helical gear was one of main part of elevator gearbox in flour mill manufacture. Visually, plastic deformation didn’t occurred and not visible on the failure helical gear shaft. Some test would be performed to check the chemical composition, microstructure and hardness of failure helical gear. The material of failure helical gear shaft was a medium carbon steel alloy. The microstructure was showed a martensitic phase formed on the surface to the center area of gear shaft. Otherwise, the depth of hardness layer slight formed on surface and lack depth of hardness layer was a main trigger of severe wear. It was not enough to resist wear due to friction caused by rolling and sliding on su...

Surface Roughness Identification of Cutting Product on Design Aspect Variation of Modular Axis Mechanism

The use of modular component in machine tool structure is an attempt to reduce the production cost. This paper presents the development of machine tool structure for low cutting force using the modular axis mechanism. Single axis mechanism was designed and varied the mover bearing, the length of slideway and the diameter of lead-screw. Cutting test was then performed using the variation. The experimental result shows that the dimension tolerance of linear bearing is the dominant aspect which affect on the product surface roughness. While the use of ball bearing in mover system, the motion looseness can be minimized affects on improving product surface finish.

In Situ Synthesis of Alumina Matrix Composites by Spark Plasma Sintering

Al2O3 matrix composites reinforced with Ba-b-Al2O3 phase were synthesized through reactive sintering using Al2O3 and BaCO3 as starting powders. Dense Al2O3/Ba-b-Al2O3 composites can be obtained by spark plasma sintering from Al2O3/BaO•Al2O3 powder, which was prepared by calcining Al2O3/BaCO3 powder mixture. The Ba-b-Al2O3 reinforcing phase exhibited an elongated morphology due to preferred diffusion of Ba cations. The existence of Ba-b-Al2O3 phase as well as low sintering temperature and short holding time during reactive sintering inhibit grain growth and thus result in small grain sizes of the Al2O3 matrix.