Effects of flux application and melting parameters in investment casting of pure aluminium by in-situ melting technique

Investment cast aluminium suffers porosity defect attributed to the complex combination of various factors including melt quality, casting process parameter and pouring technique. Even though, melt treatment and controlled of the process parameter have promising result, however turbulence developed during pouring of molten aluminium increasing the formation of porosity as a result of the entrainment of the surface oxide (Al2O3) film known as bifilm. Currently, turbulence free filling system was applied in casting process using tilt casting, bottom filling integrated with low pressure and also in-situ casting or in-situ melting techniques to address the porosity problem. However, in-situ melting technique has not been studied to reduce the porosity of the investment cast aluminium due to the oxidation of the granular aluminium occurs during heating hinders the complete melting of the granules. This research develops a procedure for investment casting of aluminium granules of 99.4% purity by in-situ melting technique. The aluminium granules were filled in ceramic moulds and heated at four different temperatures of 700, 750, 800 and 850oC for 30 and 60 min in a high temperature muffle furnace in ambient. As the heating temperature and duration were increased, the aluminium granules incompletely melt and produced a casting, however the granules agglomerate and replicate the shape of the ceramic mould. The aluminium granules oxidised during heating, encapsulated by a layer of complex oxides composed of stable [α-Al2O3], metastable [γ-Al2O3] and hydroxides. The thickness of the oxide layer formed on the surface of the air-heated granules increased as the heating temperature and duration were increased. The aluminium granules then were heated at the temperature of 850oC for 30 min in argon environment at the flow rate of argon gas 0.5, 2.5 and 5 l/min to reduce the oxidation of the aluminium granules. The thickness of the oxide layer formed on the argon-heated granule (5 l/min) was reduced by 60%, but failed to produce a casting. NaCl-KCl flux was applied, which was mixed and sprinkled on the aluminium granules at the Al:Flux ratio of 1:0.2, 1:0.25 and 1:0.33 and heated at the temperature of 850oC for 30 min to break the oxide layer that encapsulate the granules during heating. At the Al:Flux ratio of 1:0.33, 99% of the aluminium granules were successfully melted and produced a casting. The granules began melting at the temperature range 657.2 to 658.4oC and completely melted in 16 min with final melting temperature between 660.1 and 660.6oC. The average porosity level of the casting was 1.22%, which is lower than the investment cast aluminium produced by current pouring technique (2.48%). The low porosity level was attributed to micro-intergranular porosity present in the casting due to volume shrinkage. Investment casting of aluminium granules by in-situ melting technique with application of NaCl-KCl flux at the Al:Flux ratio of 1:0.33 mixed and sprinkled on the granules heated at the temperature of 850oC for 30 min producing low porosity aluminium casting

Characteristics of Oxide Layer Formed on the Aluminium (LM6) Alloy and Aluminium (ADC12) Alloy During In-Situ Melting

In-situ melting also known as in-situ casting is a new alternative in casting process offering a pouring free casting technique which reducing the formation of porosities in aluminium (Al) castings. However, oxidation of the Al during in-situ melting influence its melting phenomenon. This study aims to determine characteristics of oxide layer formed on surface of Al alloy (LM6) and (ADC12) cubes during in-situ melting. Al alloy cubes with approximate dimension (L:1.0cm, W:1.0cm, and H:1.0cm) were placed in a ceramic plate and heated for 30 minutes in a laboratory furnace at the temperatures of 700°C and 750°C for 30 min. The heated samples were prepared for microstructure and elemental analysis using Optical Microscope (OM), Scanning Electron Microscope (SEM) equipped with Energy Dispersive Spectroscopy (EDS), and X-ray Diffraction (XRD). Both Al alloys deformed from a solid uniform cube to a distorted shape after heated at the temperatures of 700°C and 750°C while the colour changed from a shiny and silvery grey to dark grey. Al LM6 alloy cube changed from its shiny and silvery grey (raw sample) to dusty and dark grey mixed with yellow brown at 700°C, while at 750°C it turned to charcoal grey. For Al ADC 12 alloy sample, the colour changed from its shiny and silvery grey to slightly darker grey at 700°C and mixed with yellowish grey at 750°C. The colour changes indicating oxidation of the Al alloys cubes during in-situ melting had occurred, forming superficial layer of aluminium oxide Al2O3. XRD analysis revealed the oxide compounds on the surface of Al LM6 alloy cubes were a complex oxide including Al2O3 hydroxide and spinel. While XRD analysis for Al ADC 12 alloy oxide after heating at the temperature of 750°C contains aluminium oxide hydroxide, suggesting that the aluminium alloy was transformed to the final or stable phase of aluminium oxide (Al2O3)

Implementation of Education Affirmation Policies in World Universities

Abstract Affirmative action policies for college admissions are common practice throughout the world to reduce discrimination by providing access to educational opportunities that would otherwise be unavailable to individuals from disadvantaged groups. This study aims to determine the implementation of educational affirmation policies around the world, by collecting articles from various sources. The data were analyzed using the Nvivo 12 application. The results showed that the implementation of affirmation policies in the world is very diverse. Various countries are implementing educational affirmations because of protests, riots, and for justice. The implementation preferences also vary, consisting of the quality of graduates, job readiness, and the choice of majors available. The impact of the affirmative policy received a positive, negative response, and a combination of both. The targets of the educational affirmation policy are minorities, African students, African-American students, and Asian students. The advantage of this research is that it focuses on a netnographic approach because netnography usually focuses on social problems, but this research focuses on policy. The drawback of this study is that the number of data selected is only 30, but it is hoped that further research can collect more data

Minimization of tool path length of drilling process using particle swarm optimization (PSO)

In the era of challenging economic, the industry in our country has been forced to produce a good quality product and increase the productivity of machining process simultaneously in order to compete with other countries. Drrilling process is one of a very important cutting process in industry. In a drilling for machining by Computer Numerical Control (CNC) such as drilling machines, the parameter of the tool routing path for the machining operation plays a very important role to minimize the machining time (Tiwari 2013, Rao and Kalyankar 2012) . This machine can be used with procedures for drilling, spreading, weaning and threading with a lot of the holes precisely. In order to increase the efficiency and productivity of drilling process, optimization on parameters of process can lead to better performance. Optimization of holes drilling operations will lead to reduction in time order and better productivity of manufacturing systems. Optimizing the tool path has played an important role, especially in mass production because reducing the time to produce one piece eventually lead to a significant reduction in the cost of the entire series (Pezer, 2016). In various publications and articles, scientists and researchers adapted several methods of artificial intelligence (AI) or hybrid optimization method for tool path artificial immune system (AIS), genetic algorithms (GA), Artificial Neural networks (ANN) Ant Colony Optimization (ACO) and Particle Swarm Optimization (PSO) (Narooei and Ramli, 2014). These methods were been proven that can produce better performance and increase the productivity of drilling process. Therefore, in this study, the Particle Swarm Optimization (PSO) algorithm was develop in order to minimizing the tool path length in the drilling process which can produce the better results for the required machining time process. For this study, the main purpose is to apply the Particle Swarm Optimization (PSO) algorithm for use in searching for the optimal tool routing path for in simulation of drilling proces

Application of wavelet analysis in tool wear evaluation using image processing method

Tool wear plays a significant role for proper planning and control of machining parameters to maintain the product quality. However, existing tool wear monitoring methods using sensor signals still have limitations. Since the cutting tool operates directly on the work-piece during machining process, the machined surface provides valuable information about the cutting tool condition. Therefore, the objective of present study is to evaluate the tool wear based on the workpiece profile signature by using wavelet analysis. The effect of wavelet families, scale of wavelet and statistical features of the continuous wavelet coefficient on the tool wear is studied. The surface profile of workpiece was captured using a DSLR camera. Invariant moment method was applied to extract the surface profile up to sub-pixel accuracy. The extracted surface profile was analyzed by using continuous wavelet transform (CWT) written in MATLAB. The re-sults showed that average, RMS and peak to valley of CWT coefficients at all scale increased with tool wear. Peak to valley at higher scale is more sensitive to tool wear. Haar was found to be more effective and significant to correlate with tool wear with highest R2 which is 0.9301

The Influence of Organizational Culture on Employee Performance

Abstract This study aims to determine 1) organizational culture at PT. Pelindo IV (Persero) Makassar Container Terminal Branch; 2) Employee performance at PT. Pelindo IV (Persero) Makassar Container Terminal Branch; and 3) The influence of organizational culture on employee performance at PT. Pelindo IV (Persero) Makassar Container Terminal Branch. This research uses a quantitative approach with associative research type. The study population was 125 people and a sample of 56 people. The Slovin formula is used to determine the number of samples. Data collection techniques used were observation, questionnaires (questionnaire), interviews and documentation. The data analysis technique used is descriptive statistical analysis and inferential statistical analysis. The results showed that the organizational culture at PT. Pelindo IV (Persero) Makassar Container Terminal Branch obtained a value of 67.59 percent or it is in the quite good category. Employee performance at PT. Pelindo IV (Persero) Makassar Container Terminal Branch obtained a value of 70.71 percent and is in the quite good category. From the inferential results obtained a correlation coefficient of = 0.579, so it can be concluded that organizational culture has a positive and significant correlation with the performance of employees of PT. Pelindo IV (Persero) Makassar Container Terminal Branch with a moderate / sufficient correlation level. From the inferential results obtained a correlation coefficient of = 0.579, so it can be concluded that organizational culture has a positive and significant correlation with the performance of employees of PT. Pelindo IV (Persero) Makassar Container Terminal Branch with a moderate / sufficient correlation level. From the inferential results obtained a correlation coefficient of = 0.579, so it can be concluded that organizational culture has a positive and significant correlation with the performance of employees of PT. Pelindo IV (Persero) Makassar Container Terminal Branch with a moderate / sufficient correlation level

Microstructure analysis of aluminium metal matrix alloy with silicon carbide and hexogonal boron nitride

Aluminum metal matrix composite (AMMCs) are considered a group of new advance material for its light, weight, high strength, modulus, low co-efficient of thermal expansion and good wear properties. In recent years, Metal Matrix Composite (MMCs) have attracted much attention due to excellent mechanical properties such as high specific strength and wear resistance (Poletti et al., 2008). AMMCs are widely used in aircraft, aerospace, automobile and various others field. The MMCs encompasses a wide range scale and microstructure. MMCs could be a material with a least two constituent elements. One necessary to be metal whereas another could also be special metal or alternative material like reinforcement ceramic. Metal matrix composite attract great deal of attentions nowadays due to their great mechanical properties and also their application in advance industry. The network is bulk and nonstop material though support is short and end material improved into matrix. The reinforcement should be stable in given working temperature and non-reactive too. The most commonly used reinforcement are silicon carbide (SiC) and aluminum oxide (Al2O3). The primary function of the reinforcement in MMCs is to carry most of the applied load, where the matrix binds the reinforcement together, and transmit and distributes the external load to the individual reinforcement. Good wetting is an essential condition for the generation for satisfactory bond between particles between particles reinforcement. The composite microstructure may be subdivided, as depicted in, according to whether the reinforcement is in the form of continuous fibers, short fibers or particles

Work design improvement of food steamer at Pau Mira Frozen Food Industry

Pau Mira is a frozen food company located at kilometer 13, Kampung Tanah Merah, Pagoh Muar, Johor. It was devloped by a family in Kampung Tanah Merah. Pau Mira was initially made and sold daily, nearby the road side. Currently, the brand has continued to flourish in the food industry when its entrepreneur Mr. Misnan Ramijo, succeeded in establishing a company to supply increasingly popular frozen food especially its main product which is the frozen ‘pau mira’. The pau is a traditional and local steamed bun made of flour and yeast with various filling inside. It is also called as bao or baozi which is well known in the chinese cuisine. However, the term pau will be further used in this chapter

PEMANFAATAN SARANA DAN PRASARANA DALAM PROSES PEMBELAJARAN PENDIDIKAN ANAK USIA DINI

Penelitian ini bertujuan untuk mengetahui pemanfaatan sarana dan prasarana dalam proses pembelajaran pendidikan anak usia dini di TK Adilika sebagai salah satu Taman Kanak-kanak di provinsi Sulawesi selatan. Penelitian ini berdasarkan penelitian deskriptif kualitatif dengan sampel kelas B. pengumpulan data dilakukan dengan metode observasi dan wawancara terstruktur dengan narasumber, yakni kepala sekolah TK Adilika dan guru kelas B, hasilnya diolah menggunakan teknik analisis data model interaktif, dimana analisis data dilakukan dengan empat tahapan, yaitu dimulai dari pengumpulan data, reduksi data, penyajian data dan penarikan kesimpulan atau verifikasi. Adapun sarana dan prasarana pembelajaran alat permainan edukatif indoor meliputi: lego, puzzle, balok, ular tangga, mobil-mobilan, media gerakan shalat, mozaik, kartu bentuk dan warna, miniature rambu lalu lintas, buku bacaan, dan lain sebagainya. Sarana dan prasarana pembelajaran alat permainan edukatif outdoor meliputi: seluncuran, terowongan, jungkat-jungkit kayu, jungkat-jungkit berbentuk hewan, ayunan kursi, ayunan gantung, dan kolam pasir. Di TK Adilika memiliki 3 ruang kelas belajar, ruang kepala sekolah, ruang guru, aula, dapur, WC, kantin, dan halaman yang luas

Mechanical characterization of ABS recyling based electric and electronic equipment (WEEE) by using injection molding

Nowadays, recycling process become more and more importantly mostly due to the impressive increase in the production of waste and to growing attention to the environment friendly. Increasing of demand of new products and waste electric and electronic of waste polymer from many sectors is being recycled to reduce an economic, environment and energy issues. According to Rosa et al., (2010) and Tarantili et al., (2010), the term of polymer usually refers to thermoplastic material rather than thermosets and some typical representative’s acrylonitrile-butadiene-styrene copolymer (ABS), polycarbonates (PC), polyamides (PA) and poly (ethylene terephthalate) (PET)