PENGARUH SANDBLASTING DAN ELECTROPOLISHING TERHADAP KEKASARAN PERMUKAAN, KEKERASAN, STRUKTUR MIKRO DAN KETAHANAN KOROSI BAJA TAHAN KARAT AISI 316L

Electropolishing is the surface finishing/polishing technique electro chemically and sandblasting is the surface treatment method for improving the mechanical properties of the material. In this study, both methods are used in stainless steel AISI 316L. The purpose of this study is to analyze the effect of sandblasting on the changes in microstructure and the hardness of stainless steel AISI 316L and the combination effect of sandblasting and electropolishing to surface roughness, hardness, and corrosion resistance in stainless steel AISI 316L. Surface roughness of specimens were tested before and after the sandblasting and the electropolishing process. The tool used was sandblasting machine with a working pressure of 5-7 kg/cm2 with a duration of 10 minutes. The sand used was silica sand with a size of 500-800 μm. The tools used in the electropolishing process is the DC power supply with a maximum output of 2x100A. Anode and cathode material was stainless steel AISI 316L. Electrolyte solution consisted of 96% mass fraction of sulfuric acid (H2SO4) and 85% mass fraction of phosphoric acid (H3PO4) with a ratio of 1:1. The parameters used in the electropolish process was voltage of electrical, distance of electrodes and duration of electropolishing process. The results show that increasing the voltage, decreasing the distance, and increasing the duration in the process of electropolishing decrease the surface roughness up to more than 28 times, increase the hardness up to 69% and corrosion resistance up to 37%

PENGARUH TEMPERATUR TUANG TERHADAP FLUIDITAS, AKURASI, POROSITAS, KEKASARAN PERMUKAAN, KEKERASAN DAN STRUKTUR MIKRO BESI COR KELABU DENGAN PENGECORAN LOST FOAM

Lost foam casting is a casting process used polystyrene foam pattern. The pattern is coated with a thin layer of ceramic, buried in unbonded sand and compacted with vibration. The polystyrene foam vaporizes when molten metal enters the molding. This casting is appropriate for the complex shapes because it is without the a core, cup and drag. The effect of pouring temperature on the thin shape, physical and mechanical properties has to be investigated to reduce of the defects. The aim of this research is to investigate the effect of the pouring temperature on hardness, fluidity, porosity, accuration, surface roughness and microstructure of grey cast iron in lost foam casting. The grey cast iron has Carbon 3.35 %, Silicon 2.29 %, Mangan 0.449 % and Pospor 0.189 %. This research used polystyrene foam 9 kg/m3 of density, unbonded sand 51 of AFS grain fineness number, 0.5 mm of amplitudo, 23 Hz of frequency and 60 second of time in vibration. The pattern had 10 mm of width, 2 mm, 3.5 mm, 5 mm and 6.5 mm of thickness without coating. The pouring temperature was 1300, 1325, 1350, 1375 and 1400 oC. The fluidity of the grey cast iron increases with the pouring temperature.. Inconsistent in the fluidity on 1350 0C is caused by a low pouring temperature rate and fall out of the sand in down sprue. The accuration of cast product is larger than that of the pattern about at 1.02-1.51 %. In this research, the effect of pouring temperature to the accuration is not in clear .The porosity increases with the pouring temperature. The bulk density is 7.490 � 7,430 gr/cm3 for temperature of 1300 � 1400 oC. The surface roughness increases with pouring temperature of 4.017 - 6.814 μm for temperature of 1300 � 1400 oC. The hardness decreases from 529 - 420 BHN with the pouring temperature of 1300 � 1400 oC. It is caused by a higher grafit formation on temperature of 1400 oC than that on 1300 oC. Ledeburit microstructure dominates in product beacuse of 3.35% carbon composition and a fast solidification

SISTEM MOLDING PADA PENGECORAN LOGAM BERTEKANAN (PRESSURE DIE CASTING) UNTUK INDUSTRI KECIL DAN MENENGAH KOMPONEN OTOMOTIF

The purposes of this research are to investigate of mold temperature, melt temperature, and pressure on the micro structure and hardness. The alloy where this research uses is Al-Si 7,79% with the High Pressure Die Casting (HPDC) method. HPDC is a casting method with injection the metal molten to the molding with specific speed and pressure. This research used three variation, they are molding temperature (250°C, 300°C, 350°C), pressure (50 bar, 75 bar, and 100 bar), and melting temperature (700°C, 750 °C, 800°C), Observations were made on the micro structure of the alloys show that Al-Si 7.79% showed some similar changed which is the tendency of the silicon phase will become thick silicon chip and the primary is likely to change even greater. This condition is caused by an increase in time solidification with increasing melt temperature and the mold temperature. The hardness in general will increase with increasing temperature and pressure. The highest hardness is 79,94 BHN at mold temperature of 250 °C, melt temperature of 750 ° C and pressure of 75 bar

PERANCANGAN DAN SIMULASI PEMBENTUKAN HIP JOINT PROSTHETIC

Hip joint is one of the largest joint in the body that supports about 3/8 of the total body weight. These joints are susceptible to damage due to accident

PENGARUH DEFORMASI DINGIN DAN SURFACE MECHANICAL ATTRITION TREATMENT (SMAT) TERHADAP KEKERASAN, STRUKTUR MIKRO, DAN KETAHANAN KOROSI BAJA TAHAN KARAT AISI 316L

AISI 316L stainless steel has been widely used for biomedical material implants that needs high corrosion resistance and strength. Some methods have been developed in order to obtain its high performances, such as cold deformation and SMAT. This research aims to study the effects of combined methods (cold deformation and SMAT) in microstructure, hardness, and corrosion resistance of AISI 316L stainless steel. The dimension of specimen used in this investigation is 15 mm X 15 mm X 3mm. The cold deformation has been done to reduce the thickness by 47% using hydraulic press machine and followed by SMAT process. In SMAT process, 250 ball mill and motor speed of 1400 rpm are used with variation in dimension of 3.18 mm, 3.97 mm, 4.76 mm, and 6.35 mm. Besides, there is variation in duration: 5, 10, and 15 minutes. The results showed that cold deformation can increase the hardness about 127% and decrease the corrosion rate about 37%. Then combination cold deformation and SMAT can improve the hardness up to 16% and increase corrosion rate up to 40%

OPTIMASI SISTEM PROSES PRODUKSI DAN PEMASARAN PRODUK INDUSTRI KECIL DAN MENENGAH PENGECORAN KOMPONEN OTOMOTIF

The objectives of this research are to know the most marketable product and technically easy to be done mechanically high pressure die casting (HPDC), determining optimal production process and determine result of economy analysis in the small and medium industry of automotive component casting by applying method of HPDC. This research used two methods, market survey and experiment. Economic analysis was done by using Microsoft excel software to count five parameters namely net preset value (NPV), interneal rate of return (IRR), net benefit cost ratio (Net B/C), gross of benefit cost ratio (Gross B/C) and of profitability ratio (PR). The survey result of from market show that handle put on the brakes with mean sale of month is 52 items, but technical it considers technically it is difficult for making handle the rem so it makes adaptor disk of brake and lamp holder of megapro. The optimum process of die casting is with mold temperature 300oC, melt temperature 700oC, pressure 50 kg/cm2 and with mold temperature 350oC, melt temperature 750oC, pressure 75 kg/cm2 b by 24 hours production system. Results of economic analysis by five parameters are NPV, IRR, Net B/C Gross B/C and PR show that over minimum value so the moulding effort of otomotif component is visible to be achieved