Urip Agus Salim

Effect of cold working and sandblasting on the microhardness, tensile strength and corrosion resistance of AISI 316L stainless steel

The aim of this work is to investigate the effect of cold working and sandblasting on the microhardness, tensile strength and corrosion rate of AISI 316L stainless steel. The specimens were deformed from 17% to 47% and sandblasted for 20 min using SiC particles with a diameter of 500–700 μm and an air flow with 0.6–0.7 MPa pressure. The microhardness distribution and tensile test were conducted and a measurement on the corrosion current density was done to determine the corrosion rate of the specimens. The result shows that the cold working enhances the bulk microhardness, tensile and yield strength of the specimen by the degree of deformation applied in the treatment. The sandblasting treatment increases the microhardness only at the surface of the specimen without or with a low degree of deformation. In addition, the sandblasting enhances the surface roughness. The corrosion resistance is improved by cold working, especially for the highly deformed specimen. However the follow-up sandblasting treatment reduces the corrosion resistance. In conclusion, the cold working is prominent to be used for improving the mechanical properties and corrosion resistance of AISI 316L stainless steel. Meanwhile, the sandblasting subjected to the cold worked steel is only useful for surface texturing instead of improving the mechanical properties and corrosion resistance.

Three Dimensional Morphometry of Distal Femur to Design Knee Prosthesis for Indonesian Population

El objetivo fue disenar una protesis a medida para una determinada poblacion, por tanto la morfometria debia ser medida para proporcionar datos basicos para disenar el tamano ideal de una protesis total para la artroplastia de rodilla en poblacion de Indonesia. Se realizo un estudio antropometrico sobre 100 sujetos sanos indonesios, basados en tomografias computadorizadas (TC) de la superficie resecada del femur distal. Los parametros que se midieron fueron longitud femoral mediolateral (FML), longitud femoral anteroposterior (FAP), longitud femoral medial anteroposterior (FMAP), longitud femoral lateral anteroposterior (FLAP), y razon de aspecto femoral (FR). Las medias FAP y FML fueron 54,60±5,71 y 65,98±6,51, respectivamente. La morfometria del femur distal fue significativamente diferente entre hombres y mujeres (mayor tamano en hombres), sin embargo uno de los parametros mostro resultados diferentes, la FLAP. Las personas indonesias son de menor tamano en comparacion con su contraparte occidental. Las dimensiones propuestas se pueden utilizar como los datos basicos para disenar el tamano ideal para una protesis de rodilla a medida para la poblacion de Indonesia.

Three Dimensional Morphometry of Proximal Femur to Design Best-Fit Femoral Stem for Indonesian Population

Para disenar protesis a medida en una poblacion determinada, la morfometria necesita ser conocida. El objetivo de este estudio fue obtener resultados que sean utiles en la investigacion para disenar el tamano ideal de una protesis total de artroplastia de cadera para la poblacion de Indonesia. Fue realizado un estudio antropometrico en 100 sujetos sanos de raza mongoloide de Indonesia, en los que se estudio la parte proximal del femur por tomografia computadorizada (TC). Se consideraron como parametros la cabeza del femur (CF), posicion de la cabeza del femur (PCF), diametro de la cabeza del femur (DCF), angulo cervicodiafisario (ACD), ancho anteroposterior (AAP) y ancho-lateral en 3 lugares diferentes. La poblacion Indonesia tiene una morfometria menor del femur proximal en comparacion con la poblacion occidental. El valor medio de todos los parametros en hombres fueron mayores a las mujeres. Por otra parte, CF y PCF mostraron diferencia significativa entre hombres y mujeres e indico una ubicacion superior del centro de la cabeza del femur en hombres, en comparacion con las mujeres. Se encontro que la dimension del canal femoral fue mediolateral oval, 1,43, 1,28, y 1,34, en 3 cortes diferentes, respectivamente (20 mm superior y 40 mm inferior del trocanter menor e istmo). La dimension del femur proximal en la poblacion de Indonesia es de menor tamano en comparacion con la contraparte occidental. Las dimensiones propuestas se pueden utilizar como datos basicos para el diseno de un tamano ideal de vastago femoral para la poblacion Indonesia.

Fabrication of Bicycle Frame of A356 Aluminum Alloys by Using Sand Casting

Bicycle frames on the market are generally made from a pipe connected by welding process. Bicycles are made by big companies, because it requires forming technology of raw materials for the pipe production and complex welding technologies. In order to reduce the dependence on raw materials and pipe welding processes, an alternative technology for bicycle frame manufacturing process is investigated. This study is aimed to examine the use of casting technology in the manufacturing process of bicycle frame. Production of bicycle frames in limited quantities is possible by using the casting process. To achieve these objectives, it is necessary to redesign the bicycle frame suitable for the casting process. Prototypes have been produced and the first bike is in the testing phase. Initilly , the bicycle is relatively heavy (7 kg). The optimization of the design reduces to a light and strong frame. The frame has a weight of 3.74 kg. The prototype of the frame has been succesfully casted by sand casting method.

Increasing Yield Strength of AISI 316L Plastically Deformed by Expanded Hole Techniques

AISI 316L has been used to produce implant plates such as dynamic copmresion plates (DCP). The implant plates might experienced failure due to either suffer higher stresses exceeding the allowable maximum strenght or presents small crack growing through fatigue mechanism. Most of DCP fractures occured at the gliding holes region. This study conducted improving strength of DCP locally on the gliding holes. Strengthening on the gliding holes of DCP was performed by cold working method involving plastically deformation using an expanded hole technique. This study was conducted by both experimental and numerical simulation. Increasing strength locally on the gliding hole region was evaluated by measuring some parameters incorporated with strain hardening mechanism such as hardness and residual stresses. Increasing yields strength locally on the hole region was estimated by Takakuwa’s formulas. By this method, yields strength of the gliding hole of DCP made of AISI 316L increased from 325 MPa to be 600−1050 MPa.

Development of the Gliding Hole of the Dynamics Compression Plate

The gliding hole of the dynamics compression plate is designed to facilitate relative movement of pedicle screw during surgery application. The gliding hole shape is then geometrically complex. The gliding hole manufactured using machining processes used to employ ball-nose cutting tool. Then, production cost is expensive due to long production time. This study proposed to increase productivity of DCP products by introducing forming process (cold forming). The forming process used to involve any press tool devices. In the closed die forming press tool is designed with little allowance, then work-pieces is trapped in the mould after forming. Therefore, it is very important to determine hole geometry and dimensions of raw material in order to success on forming process. This study optimized the hole sizes with both geometry analytics and experiments. The success of the forming process was performed by increasing the holes size on the raw materials. The holes size need to be prepared is diameter of 5.5 mm with a length of 11.4 mm for the plate thickness 3 mm and diameter of 6 mm with a length of 12.5 mm for the plate thickness 4 mm.

Design of mini interchanged rolling mill

Dynamic Compression Plate (DCP) Is the most popular type of implant plate that facilitate compressing the fracture bone during implantation. However, the price of DCP is still expensive according to developing contries people. The price of DCP mostly related to its manufacturing that involved many machining processes. The proposed solution offered in this study was to change DCP manufacturing process mainly on the gliding holes making used by machining process to be the forming process. DCP-manufacturing process sequences that proposed was to be: a) making a hole on the plate, b) cutting lengthwise plates to size, c) bending the plate and d) making holes gliding. To bend the plate was used to performed by the press machine. This study introduced rolling process in order to bend the plate. Unfortunately, there was no rolling machine available in market to perform this process, it need to design the rolling machine. This study therefore conducted designing rolling machine required to bend the plate by rolling process prior to make the gliding holes. The rolling design was based on thickness reduction capacity of machine performed by flat roller. The design is limited with power of 3 horsepower electric motor. By mathematical calculations, the horsepower can used to reduce the plate by 0,42mm performing on the 316L stainless steel plate with dimensions of 50 mm in wide and 5 mm in thickness.