Tutik Sriani

Design and Fabrication of Multi-Layered Microfilter by Electropolishing Technique

In this paper, we present electropolishing method to fabricate a thin-structural layer of microfilter which is used for filtering blood in hemodialysis system. The electropolishing method removes material based on electrolysis process, in which material removal is done through electrical current which trigger material removal by chemical reactions. The preliminary experiment shows that the SS 316L structural layer was able to be fabricated in less than 7 minutes, under machining parameter of 7 V of DC voltage, 2 cm gap between tool electrode and workpiece, and utilizing 15% of NaCl in pure water. This promising result has indicated that electropolishing could further be used as a method to make thin-structural layer of microfilter for hemodialysis system.

Study on the Effect of Nano and Micro MoS2 Powder in Micro-Electrical Discharge Machining

The application of powder mixed dielectric to improve the efficiency of electrical discharge machining (EDM) has been acknowledged extensively. However, the study of micro-size powder suspension in micro-EDM field is still limited. In this research, nano and micro size powder of MoS2 were used as catalyst agent. Powder suspension in different size was able to provide significant improvement in material removal rate and surface quality to increase the efficiency in μ- EDM processes.

Portable Desalination Chamber Utilizing Water Permeable Polyethersulfone (PES) Membrane

This paper presents design and fabrication of portable desalination chamber utilizing water permeable polyethersulfone (PES) membrane. The chamber has four stages of desalination process. Each stage has a membrane clamped by filter plate to desalinate sea water and an outlet to qualify the desalinated water from each stage. The chamber works without electrical power, hence desalination process can be carried out in remote areas where electricity source is difficult to find. The water stream is used to test the pumping system of the chamber to pump the water from the water container. The test shows that the pumping system of the chamber is working properly in delivering water to each stage of the chamber without any leakage. The membrane used in each chamber is a modified PES membrane which has high water permeability. Water permeability of the membrane will guarantee that the salt water will permeate easily through the membrane porous during desalination process, hence results in producing fresh water at the final outlet.

Effect of Time Variation on Shot Peening Process to the Surface Properties of SS-316L Osteosynthesis Plate

Shot-peening is one of the surface modification methods to increase material hardness and smoothen its surface at the same time. SS-316L, one type of biocompatible material, is commonly used in medical field particularly for joining fractured bones. However, the surface-crack-prone characteristic of SS-316L has limited its application to be used for such application. In this research, steel balls with diameter 0.4 mm is subjected to the surface of SS-316L Osteosynthesis Plate with variation of time; 9, 10, 11 and 12 minutes holding at constant pressure of 6 bar. The nozzle-to-plate distance is fixed at 100 mm. The impact of the shot balls is a deformed surface and produces a flat-like structure on osteosynthesis plate shot in 12 minutes time. The result shows that shot peening of SS 316L gives its best microstructure after 12 minutes of treatment.

Design and Analysis of Exoskeleton as a Rehabilitation Device

Exoskeleton is an external cantilever to support inner living organism organs. Some animals have the exoskeleton attached naturally on their body as those found in a million species of arthropods order. The word “Arthropods” itself are related to their body plan—their segmented body, hard exoskeleton, and jointed appendages [1]. This structure inspired us to implement the exoskeleton to help humans who are permanently or temporarily have problems with their lower limb, for example those who are recovering from stroke or road-accidents. Stroke is a condition where lower limb is partially paralyzed (Hemiplegia) and causes inability to walk normally or to do other physical activities [2].The exoskeleton consists of four main parts; frame for the leg (XOTF), frame for the thigh (XOF), the belt, and the controller stick. The frame is designed using lightweight material. Considering the material’s availability and price at the local market, we choose Aluminum Composite Panel (ACP) as frame’s material. The belt acts as the brain for the exoskeleton, where it provides electrical power and the source of motion. There are four frames on the exoskeleton which moves simultaneously while walking. In the design, we use two joy-sticks as main controller to adjust position of each exoskeleton frame. The sticks are attached to standing-canes which help the user to improve stability. The sticks have buttons and lever to control the exoskeleton and adjust thighs and legs fit for several moves; stand, sit, walk, going up and downstairs, or any other position which need balance and power.The exoskeleton design has been tested for its motion and stability. The results show that the design is suitable for those who are fully or partially paralyzed on their lower limb.

Effect of Shot Peening Pressure Variation on Surface Characteristic of SS-316L Dynamic Compression Plate (DCP)

Dynamic Compression Plate (DCP) is a plate made of biomaterials like stainless steel 316L (SS-316L) or titanium, which is used for joining fractured/broken bones for fast recovery. Due to its excellent properties on corrosion, toughness, and hardness; SS-316L is widely used for medical application. Despite its excellent properties, the surface of SS-316L commonly degraded after machining. Therefore, the surface of SS-316L needs to be treated before further use. Shot peening is one of the methods to increase the surface hardness and roughness of material. This research aims to investigate the effect of shot peening to the surface of DCP made of SS-316L from its microstructures, surface roughness, and hardness. In this research, the DCP is designed for joining arms, which are upper-arm (humerus) and forearm (radius and ulna). First we machined the DCP to have holes and bend the plate to match the user bone structure. The DCP is 105 mm × 12 mm × 4 mm in dimension and has 6 holes, 5 mm diameter each, with holes aligned to the plate. After machining, the surface is modified by shot peening using following properties: steel ball (0.4 mm in diameter and hardness 250 HV), 100 mm nozzle-to-plate distance, and shot for 10 minutes. Our parameters are variations in pressure, ranging from 4 to 6 bar. The microstructure of the treated surface was analyzed after shot peening. The result shows that the shot peening treatment of SS-316L has increases its surface hardness and roughness with significant change on its microstructure, which makes a better surface characteristics for DCP.

Fabrication of Hydroxyapatite Disc as Filtration Membrane in Waste Water Treatment System

Due to the increase of industrial activities both at local and national level, the quality of water in Indonesia is significantly degraded by time. Heavy metal wastes from industrial activities have become serious contaminants in the water. The contamination dangers human’s health since most people living near the river-bank still use the water to fulfill their daily needs. In this paper, we present the fabrication of Hydroxyapatite (HA) disc as a filtration medium in waste water treatment system. HA is one of biomaterial which can be derived from animal’s bone and is capable to absorb dangerous heavy-metal contaminants such as lead (Pb) in the water. Our produced HA was made by extracting cortical bovine bones into cortical bone HA powder. The cortical bovine bones were processed using physical method by heating the bones at 900oC to gained powder then followed by forming green bodies and sintering at 1000oC and 1400oC. Those powders were then pressed into a disc form and will be used as filtration media in HA modular purifier. SEM/EDX results show the disk surface has interconnected micropores and Ca/P ratio value on sintered HA disc at 1000oC and 1400oC are 2.20 and 1.85, respectively.

Electrode Design for Orbiting EDM: An Experimental Approach

This work presents an experimental work in orbiting EDM which design of the electrode used adopt the non-uniform offset method formulated by the authors. A brief explanation about the design principle is presented in this paper as well as comparison of experimental machining results between uniform tool offset and the said method. The design method is implemented in a commercial CAD software and the system has been proven effective to cut design lead time and reduce error. The experimental part on orbiting EDM adopting the said-method yields improved machining accuracy and machined surface quality.

Electrode Design for Oscillating EDM

In die-sinking EDM, the electrode is moved only in the Z-axis direction, while in oscillating EDM, electrodes are oscillated in both the X-axis and Y-axis directions to realize high accuracy machining. There are many ways of designing electrodes for oscillating EDM. However, because the form of electrodes and subsequently the oscillating patterns of these electrodes depend on the shapes of the die/mold used, they become complicated when the die/mold shape is complicated, and electrode design takes hours in such cases. This paper therefore proposes a new approach of designing electrodes for oscillating EDM. Some oscillating patterns based on the proposed approach are also analyzed from the viewpoint of usefulness.