Performance evaluation of different types of graphite electrodes on titanium (Ti - 6A1 - 4V)

This thesis presents the EDMing of Titanium (Ti-6A1-4V) using POCO EDM 3 and POCO EDM C3 graphites electrodes with diameter of 10 mm. The main purpose of this study was to investigate the influenced of various parameters involved in EDM on the machining characteristics, namely, material removal rate (MRR), electrode wear ratio (EWR), surface roughness (Ra), recast layer (RL) and heat affected zone (HAZ) after undergone EDMing process and to compare the performance of both electrodes. The Full Factorial Design of Experiment (DOE) approach with two-level was used to formulate the experimental layout, to analyze the effect of each parameter such as pulse on (ON), pulse off (OFF), peak current (IP) and servo voltage (SV) on the machining characteristics EDM . In this investigation, the machining operation for titanium was performed using a Sodick linear motor EDM sinker series AQ55L. Meanwhile, for the measurement equipments; Mitutoyo Surftest SJ-400 was used to measure the surface roughness, and the thickness of recast layer and heat affected zone were examined using the Scanning Electron Microscope XL40. In general, results revealed that pulse on (ON) and peak current (IP) have appeared to be the most significant effect to all responses investigated. In term of performance, POCO C3 gives better material removal rate (MRR) value compare to POCO 3 but in term of electrode wear ratio (EWR) and also surface roughness (SR) POCO 3 gives better result compare to POCO C3. On the Recast layer and HAZ both the good and the worst came from POCO 3. The lowest recast layer achieved was 13.5 fxm and the lowest HAZ achieved was 12.7 Hm. Confirmation tests were also conducted for the optimum conditions for each machining characteristics in order to verify and compare the results from the theoretical prediction using Design Expert software and experimental confirmation tests. Overall, the results from the confirmation tests showed that the percentage of performance was acceptable due to all the results obtained were within the allowable values which was less than 15% of margin error

Assessment of residual strength of corrosion damaged concrete structures

The corrosion of steel reinforcement in concrete is one of the major problems with respect to the durability of reinforced concrete structures. In addition, the residual strength of concrete with corroded reinforcement is much debated. This is because many parameters are implicated when assessing reinforcement corrosion, such as by using the percentage of loss of bar area, percentage of mass loss, reduction of bar radius, percentage of corroded area in the overall beam, and the width of the surface crack. The aim of the current study is to integrate correlations between deterioration and strength degradation into a systematic methodology for estimation of the residual strength of concrete structures based on their serviceability limit state. In the numerical analysis, the objective is to understand the effects of corrosion expansion on the behaviour of surface crack width. Results from the numerical study are used to determine parameters for the experimental investigation. The experimental approach is used to assess the influence of corrosion parameters, which are quantified as a percentage of the section loss, radius loss or corrosion penetration, and crack width on the residual bond strength based on different bar locations, casting positions, and impressed currents. Results from the experimental analyses show that the corrosion level on the main reinforcing bar in this study cannot be used as an indicator in assessing the residual bond strength due to many factors consideration during the assessment. However, corrosion-induced crack width on the bottom cast correlated well with residual bond strength. When crack width increased, most of the bar had a lower residual bond strength value

The Machinability Performance of RBD Palm Oil Dielectric Fluid on Electrical Discharge Machining (EDM) of AISI D2 Steel

Electrical discharge machining (EDM) is a high-precision manufacturing process that may be implemented to any electrically conductive material, notwithstanding its of mechanical residences. It’s far a non-contact process using thermal energy that is used in a wide range of applications, especially for difficult-to-cut materials with complicated shapes and geometries. The dielectric is critical in this process as it focuses the plasma channel above the processing and also serves as a debris carrier. The long-term use of dielectric used in EDM process pollutes to the atmosphere and is harmful to the operator's health. This study compares the efficiency of refined, bleached, and deodorized (RBD) palm oil (cooking oil) with traditional hydrocarbon dielectric, kerosene using copper electrode in the finishing process of AISI D2 steel. Low peak current, Ip 1A to 5A and pulse duration, ton up to 150μs were chosen as the main parameters. The effects of material removal rate (MRR), electrode wear rate (EWR), and surface roughness (Ra) were evaluated. The result shows that RBD palm oil has higher MRR which is 33.4821mm3/min while kerosene is 22.4888mm3/min, both at Ip=5A and ton=150µs. The improvement when RBD palm oil is used as dielectric is 48.88% compared to kerosene. With the increase in peak current, the EWR increases but it is inversely proportional to the pulse duration. The lowest EWR is obtained at the same IP=1A and ton=150µs for both RBD palm oil and kerosene which is 0.0010mm3/min and 0.0002mm3/min respectively. The minimum value of Ra for RBD palm oil is 2.15µm at IP=1A and ton=150µs, while for kerosene it is 2.11µm at IP=1A and ton=150µs. In terms of finishing process efficiency, RBD palm oil, a biodegradable oil-based dielectric fluid, has shown significant potential in EDM processing of AISI D2 steel

Surface Roughness and Surface Topography of Inconel 718 in Powder Mixed Dielectric Electrical Discharge Machining (PMEDM)

In high speed EDM, maximum material removal rate (MRR) is a desirable to increase productivity rate and reducing production cost to the need of industry. However, the surface finish of the machined surface also cannot be neglected since it related to product quality and safety factor especially when to cut difficult to machine material such Inconel 718, which is widely used in aerospace industry. Surface roughness as one of the surface integrity criteria was choose as a response in this research. High discharge current from 20A to 40A, longer pulse on-time (pulse duration) from 200µs to 400µs and the different concentration of the nano Alumina powder were selected as the main parameters, respectively. The effect of powder mixed dielectric in EDM performance in terms of surface roughness was evaluated. The dielectric circulating system known as High Performance Electrical Discharge Machine (HPEDM) was attached to the conventional EDM machine to run the experiments involving powder mixed dielectric. The experiment results shows that, the highest peak current deteriorated the surface roughness. The surface roughness, Ra was increased with the increasing of the peak current. The result also shows that an increasing of the pulse duration the surface roughness was slightly improved. It is observed that, the value of Ra was closely related to the surface topography characteristic of the machined surfaces and directly depends on the applied discharge energy. There is no improvement in surface roughness when powder additive was mixed in a dielectric fluid

Impact test and bioactivity properties of polycaprolactone (PCL) by addition of nano-montmorillonite (MMT) and hydroxyapatite (HA)

This report described the Impact Test result and Bioactivity Properties of biodegradable Polycaprolactone (PCL) blend with nano- Montmorillonite (MMT) and Hydroxyapatite (HA). The amount of nano-MMT is varies from 2 to 4 by weight % meanwhile the amount of HA is fixed to 10 by weight percentage (wt%). The addition of nano-MMT and HA filler is to tune and indirectly improve the mechanical and bioactive properties of PCL. The samples for these test are injected from injection molding machine. The Impact test are conducted using Charpy Method. From the analysis it is found that the toughness of PCL are decreased by the addition of these fillers. PCL/MMT composites gives a better result compare to PCL/MMT/HA composites. This is due to the HA characteristic which is brilttle and tends to reduce the ductile properties of the polymer. From the Simulated Body Fluis (SBF) result, formation of apatite layer at the surface of the composites is evidence of excellent bioactivity properties of HA. The enhance of bioactivity has been proved while incorporation of HA into PCL/MMT composite. SEM-EDX image showed the bulk formation of apatite layers on the composite surface with 10 wt% HA after 3 days immersed in SBF solution

Mechanical Properties of PCL/PLA Composite Sample Produce from 3D Printer and Injection Molding

Currently there are a lot of studies have been carried out regarding on composite material that can be used for 3D printing. The main reasons is to minimize the cost related to the molds that need to be prepared for injection molding. The question is how far will be the differences in term of mechanical properties for part produce from this 2 techniques. This study are done to investigate the mechanical properties of PCL/PLA composite sample prepared from Fused Deposition Modelling (FDM) 3D printer. The mechanical properties that were evaluated are tensile, flexural and impact. The result were later compared with samples produced from injection molding. The dimensional accuracy result shows a very minimal percentage error on samples produced using 3D printer for mechanical testing. The parameter of 3D printer used to produce sample was 136°C print temperature, 0.12mm deposition of height, 20mm/s print speed and 22mm/s travel speed. The mechanical properties of PCL/PLA prepared by injection molding generally came superior in all the conducted test if compared to those of 3D printer. Tensile strength result showed that injection molding value was higher than 3D printer which is 10MPa and 6.513MPa respectively. The results of tensile strength and modulus of elasticity showed injection molding ware better than 3D printing with value of 118.26MPa and 61.223MPa respectively. For flexural strength, the highest values were injection molding which is 7.59MPa while 3D printing is 4.96Mpa. While the highest for flexural modulus are 35.33GPa for injection molding and 30.911GPa for 3D printing. Impact strength for PCL/PLA sample was 1.33 Joule for injection molding and 0.543 Joule for 3D printer method

Mechanical Properties of PCL/PLA/PEG composite blended with different molecular weight (MW) of PEG for Fused Deposition Modelling (FDM) filament wire.

In tnis study, Polycaprolactone/Polylactide (PCL/PLA) was plasticized by Polyethylene Glycols (PEGs) with three different molecular weights (Mw=400, 6000 and 10,000g/mol) with the objective to determine the effect of different molecular weight and percentage of PEG on the mechanical properties of PCL/PLA/PEG composites. The effects of content and molecular weight of PEG on the mechanical properties of PCL/PLA/PEG were studied by tensile and impact tests. The tensile test were carried out using Instron 5567 Universal Testing Machine meanwhile the impact test were carried out using Charpy Impact Testing Machine. The results revealed that, increasing in molecular weight of PEG could signiï¬cantly improve the tensile and impact strenght of PCL/PLA. The results also shows that with increasing molecular weight of PEG, the tensile strength and modulus of elasticity of PCL/PLA/PEG composite were also increased. However, with the increasing of PEG content from 5phr to 15phr on PCL/PLA/PEG composites, it decreases the tensile strength and Young's modulus. Meanwhile from the Charpy impact test, it shows that the impact strength of PCL/PLA/PEG composites increased as the molecular weight of PEG increased from 400 to 10,000. The overall results demonstrated better mechanical properties of PCL/PLA/PEG composites can be achieved by optimizing the content and molecular weight of PEG. The introduction of PEG molecular weight increased the intermolecular force and enhanced the mobility of PCL/PLA chains, thus improving mechanical properties of PCL/PLA

EFFECT OF ZINC DOPED CALCIUM PHOSPHATE THROUGH MECHANOCHEMICAL SYNTHESIS

ABSTRACT In this research, zinc was doped into calcium phosphate through mechanochemical synthesis. Zinc mol concentration was varied from 0.1%, 0.3% and 0.5%. The main precursors employed in this work are calcium hydroxide, phosphoric acid and zinc hydroxide. The synthesized powders were examined through FTIR and XRD analyses to validate the presence of all the chemical elements. The synthesized powders were then compacted into green bodies and sintered at 1000 o C. Density test showed a linear change towards the different concentration on the zinc where zinc dopants improved the densification and microstructure of the calcium phosphate