Abstract: The thin-walled component is mostly used in the aerospace industry. During machining the thin-walled components, deflection of wall occurs and causes the surface dimensional error. This paper focuses on the effect of end mill helix angle on the surface dimensional error and surface roughness when machining thin wall structure. End mills uncoated carbide were fabricated with a difference helix angle which are 25°, 30°, 35°, 40° and 45°. The results show, helix angle 35° produce smaller surface dimensional error and smoothest followed by 40°, 45°, 30° and 25°. The smaller helix angle provided high cutting force that causes more surface dimensional error due to chatter and reduction of contact time when then end mill engage with the workpiece material. Results from this research help to guide the machinist to machine thin-wall component with the right cutting tool.
Abstract: This research aims to determine the effect of ceramic substrates surface roughness on the deposition of silver-titania (AgTiO2) coating. The ceramic substrates were prepared from three batch mixture of waste glass namely transparent glass (99 wt. %): carbon black (1 wt. %), green glass (85 wt. %): ball clay (15 wt. %) and transparent glass (85 wt. %): ball clay (15 wt. %) deposited with AgTiO2 using sol gel dip coating method. Ti and Ag phases have been identified via glancing angle X-Ray diffraction analysis (GAXRD). The thickness and morphology of coatings were characterized using Scanning Electron Microscopy (SEM). Analyses conducted have confirmed that AgTiO2 coating layers have been successfully deposited into various types of selected ceramic substrates. Microstructure analysis shows that coatings deposited on ceramic substrate with a moderate surface roughness of 2.13 (green glass: ball clay) produced the most homogeneous surface and uniform thickness.
Abstract: Geopolymer is associated with the alkali activation of materials rich in Si and Al, and alkali activator such as sodium hydroxide is used for the dissolution of raw material with the addition of sodium silicate solution to increase the dissolution process. However, the trend of strength development of geopolymer using sodium hydroxide alone is not well established. This paper presents an evaluation on compressive strength of fly ash–based geopolymer by varying curing time with respect to different curing temperature using sodium hydroxide as the only activator. The samples were cured at room temperature and at an elevated temperature (60°C). Further analysis on the microstructure of geopolymer products cured at 60°C was carried out using Field Emission Scanning Microscopy (FESEM). It can be observed that the compressive strength increased as the curing time increased when cured at room temperature; whereas at elevated temperature, the strength increased up to a maximum 65.28 MPa at 14 days but gradually decreased at longer curing time. Better compressive strength can be obtained when the geopolymer was cured at an elevated temperature compared to curing at room temperature.
Abstract: The application of Taguchi method to reduce warpage in an injection moulding process is studied. The objective of this paper is to analyze the effect of injection moulding parameters, i.e., injection time, packing time, melt temperature and mould temperature, on the warpage defect in dumbbell plastics part. Optical comparator horizontal type was used to measure the difference of warpage value on each part. L9 orthogonal array with 3 replications was done with 27 totals of specimens. The result collected was optimized using Taguchi method and percentage of contribution was calculated using analysis of variance (ANOVA). According to the analysis, it is found that the significant factors affected warpage are injection time (32.01%), packing time (29.73%), mould temperature (24.39%) and melt temperature (13.87%). The optimum parameters for minimizing the warpage were injection time (1s), packing time (5s), melt temperature (270 °C) and the mould temperature (21 °C). By using Taguchi method and ANOVA analysis, optimum parameters and the percentage of contribution of parameters can be obtained. Thus, it shows that design of experiment method is the good quality tools to get the best quality for production.
Abstract: The machining ability of Electrical Discharge Machining (EDM) die-sinking on material characteristics of LM6 (Al-Sil2) is studied. This is due to the machining process on sharp edge, pocket, deep slot and micro hole cannot be performed by milling and turning machine. The objective of this paper is to determine the relationship between the machining parameters such as pulse on time, pulse off time, peak current and voltage on material removal rate (MRR) that are electrode wear rate (EWR) and surface roughness (Ra). Graphite tool of diameter 15mm was chosen as an electrode. Taguchi method is used as analysis technique to develop experimental matrix that is used to optimize the MRR, EWR and Ra. The analysis was done by using the Minitab software version 16. It is found that the current and pulse off time are significantly effected the MRR, EWR and Ra while pulse on time and voltage are less significant factors that affected the responses. From the Taguchi method, the best setting of optimum value was obtained. Thus, it shows that Taguchi method is the best quality tools that can be applied for production.
Abstract: This paper discusses the influence of residence time and iron concentration factors on the impregnation yield for preparation of the carbon nanofiber supported iron material by incipient wetness impregnation. The samples were characterized by nitrogen physisorption, thermogravimetric analysis and electron spectroscopy techniques. The technique of effective impregnation was studied by atomic adsorption spectrophotometry. The results show that the morphology of the iron was distributed and well supported and the size of iron was in a wide range of 1μm to less than 2nm. The impregnation yield has been achieved 78% for 3 hours of residence time of 3%wt Fe/CNF sample with surface area of 102.292 m2/g.
Abstract: The effect of substrate cleaning using ultrasonic cleaner on tungsten carbide was investigated. The surface energy of the substrate was measured using two liquids with dominant polar and dominant dispersion components which were distilled water (DI) and methylene iodide. Owens-Wendt method was carried out to calculate the surface energy of the substrate. The result showed that the cleaning process using solvent B (alkaline, DI, acid, DI, DI, alcohol) for 20 minutes without the wiping process led to the highest surface energy of 126.3399 dyne/cm with the polar component of 80.538 dyne/cm. Findings from this research suggested that type of solvent, cleaning time, and interactions among solvent type, cleaning time, and wiping process significantly influenced surface energy of the substrate.
Abstract: Twist forming is one of a critical process in a sheet metal forming process that has a complex profile. There are a few parameters that need to be taken into consideration, such as twist angle, workpiece geometries including length, width and thickness and material properties of the workpiece material. In this study, the preliminary result of the twist forming behavior of an aluminum alloy strip with uniform section will be studied. The experiment is conducted using torsion test machine. At this stage, the torque pattern was studied and compared with the published work to validate the experiment test rig. The result showed an agreement with the published work.
Abstract: Thiosulfinates (TS) found in garlic extract is the main compound which determines the effectiveness of this plant towards inhibition. TS shows its ability to inhibit other compounds has been proved by several researchers especially in medical application. However, TS is an unstable compound and transform into more stable compound with time. Therefore, TS concentration may decrease. During analysis, garlic extract was stored at two different temperatures: 25°C and 4°C to determine the suitable temperature for TS to maintain its composition in garlic extract for a long time. After 10 and 60 storage days, the extract was tested for its TS content by reaction of L-cysteine and 5,5'-dithiobis-(2-nitrobenzoic acid), DTNB with garlic extract. As result, TS concentration was high and shows slight difference for both storage temperatures at 10 storage days. Meanwhile, at 60 storage days, TS concentration at 25°C has lower reading compared to 4°C. This is due to TS rapid transformation to other compound at warmer temperature. Low concentration of TS reduces garlic extract efficiency towards inhibition. Therefore, the best storage temperature for garlic extract long term analysis is at 4°C.