oalib
Search Results: 1 - 10 of 100 matches for " "
All listed articles are free for downloading (OA Articles)
Page 1 /100
Display every page Item
Pengaruh Kecepatan Putar Pada Proses Pengecoran Aluminium Centrifugal  [cached]
Sugiharto Sugiharto,Soejono Tjitro
Jurnal Teknik Mesin , 2004,
Abstract: One of the methods in casting process is centrifugal casting. Generally, it is used to make a product in the form of cylinder or symmetric on spin mold. Thus, it is necessary to discuss further about the influence of rotation velocity variation on the quality of Aluminum casting product that enwrap mechanical characteristic and micro structure. The velocity variations that chosen are 150 rpm, 180 rpm and 200 rpm. This experiment is executed by looking at micro structure that is produced on each rotation variation especially the part of cross section of casting product. Then, it can be done a discussion about micro structure relation towards the hardness number on each rotation variation. In the observation of micro structure, grain structure that is produced by centrifugal casting is generally equiaxed and columnar with the orientation of direction in accordance with the direction of machine velocity. From the result of Vickers hardness test, it can be seen that rotation variation on 200 rpm show higher hardness number rather than another rotation variation. Abstract in Bahasa Indonesia : Salah satu metode dalam proses pengecoran adalah pengecoran centrifugal yang pada umumnya digunakan untuk menghasilkan benda berbentuk silinder atau benda kerja yang simetris pada cetakan yang berputar. Oleh karena itu perlu dikaji lebih lanjut tentang pengaruh variasi kecepatan putar cetakan terhadap kualitas pengecoran alumunium yang meliputi sifat mekanik (kekerasan) dan struktur mikro. Variasi kecepatan yang dipilih sebesar 150 rpm, 180 rpm dan 200 rpm. Percobaan dilakukan dengan melihat hasil struktur mikro yang dihasilkan pada setiap variasi putaran terutama bagian penampang melintang produk cor. Selanjutnya dapat dilakukan pembahasan mengenai hubungan struktur mikro terhadap angka kekerasan setiap variasi putaran tersebut. Pada pengamatan struktur mikro, bentuk butir yang dihasilkan pengecoran centrifugal secara umum berbentuk equiaxed dan columnar dengan orientasi kemiringan sesuai dengan arah putaran mesin. Dari hasil uji kekerasan Vickers, terlihat bahwa variasi putaran 200 rpm menunjukkan angka kekerasan yang lebih besar dibandingkan dengan variasi putaran lainnya. Kata kunci: pengecoran centrifugal, aluminium, kekerasan, struktur mikro.
Desain Eksperimen untuk Mengoptimalkan Proses Pengecoran Saluran Keluar Teko  [cached]
Mashuri Santoso,Gan Shu San,Soejono Tjitro
Jurnal Teknik Mesin , 2003,
Abstract: The most frequently found defect in the casting process of making teapots out flue is that the outlet is too narrow or even blocked at the end of the casting process. There are many factors influence that defect. This defect condition can be represented as the thickness of the casting product. In this paper, the significant factors that influence the thickness of the out flue resulted from the casting process will be analyzed and further got their optimum conditions. Design experiments methods will be implemented here, especially the factorial design method to determine the significant factors along with their optimum conditions. Also, the response surface method will be applied to obtain the approximation model for the thickness of the out flue as a function of the factors found earlier so that the most optimal result can be obtained under a design optimization method. It is concluded from the experiments results and analysis that the significant factors for the thickness of out flue are pouring temperature, sprue radius and holding time. The optimum conditions of those factors are 475°C, 29.6 mm and 8 seconds respectively with 2.54 mm thickness. Abstract in Bahasa Indonesia : Kondisi cacat yang paling banyak dijumpai pada proses pengecoran saluran keluar teko adalah lubang saluran keluar pada ujung teko yang terlalu sempit bahkan tertutup di akhir proses pengecoran. Banyak faktor yang mempengaruhi proses pengecoran ini sehingga menyebabkan cacat tersebut. Kondisi cacat ini dapat direpresentasikan dengan ketebalan dari produk cor saluran keluar teko. Pada makalah ini akan dianalisa faktor yang paling signifikan mempengaruhi ketebalan saluran teko hasil cor. Metode yang digunakan adalah metode desain eksperimen khususnya metode desain faktorial untuk menentukan faktor-faktor yang signifikan serta kondisi optimumnya dan metode response surface untuk mendapatkan model pendekatan untuk ketebalan saluran teko sebagai fungsi dari faktor-faktor tersebut sehingga dapat diperoleh kondisi keseluruhan yang paling optimal. Dari analisa hasil eksperimen ini ditemukan bahwa faktor yang signifikan terhadap ketebalan adalah temperature tuang, radius sprue dan holding time. Dapat pula disimpulkan bahwa kondisi optimum dari factor-faktor tersebut adalah temperatur tuang 475°C, radius sprue 29.6 mm dan holding time 8 detik yang menghasilkan ketebalan sebesar 2.54 mm. Kata kunci : pengecoran, desain eksperimen, desain faktorial, response surface, optimasi.
Squeezing Operator and Squeeze Tomography  [PDF]
Octavio Castanos,Ramon Lopez-Pena,Margarita A. Man'ko,Vladimir I. Man'ko
Physics , 2004,
Abstract: Some properties of Plebanski squeezing operator and squeezed states created with time-dependent quadratic in position and momentum Hamiltonians are reviewed. New type of tomography of quantum states called squeeze tomography is discussed.
Two Different Squeeze Transformations  [PDF]
D. Han,Y. S. Kim
Physics , 1996,
Abstract: Lorentz boosts are squeeze transformations. While these transformations are similar to those in squeezed states of light, they are fundamentally different from both physical and mathematical points of view. The difference is illustrated in terms of two coupled harmonic oscillators, and in terms of the covariant harmonic oscillator formalism.
Spectral properties of the squeeze operator  [PDF]
Dariusz Chruscinski
Physics , 2004, DOI: 10.1016/j.physleta.2004.05.046
Abstract: We show that a single-mode squeeze operator S(z) being an unitary operator with a purely continuous spectrum gives rise to a family of discrete real generalized eigenvalues. These eigenvalues are closely related to the spectral properties of S(z) and the corresponding generalized eigenvectors may be interpreted as resonant states well known in the scattering theory. It turns out that these states entirely characterize the action of S(z). This result is then generalized to N-mode squeezing.
The densification mechanism of squeeze casting  [PDF]
Xiao-Hui Chen,Xu Huang,Xue-Ping. Ren
Physics , 2009,
Abstract: The solidification process during squeeze casting is analyzed based on the classical solidification and plastic deformation theory. The linear relationship between punch velocity and the solidification rate is established if the density change of molten meals is neglected. To obtain defect-free castings, the punch velocity should be larger than the solidification rate. The densification mechanism is also discussed. The plastic deformation will result in the radical movement of the central molten metals, which reduces the temperature gradient from the center to the mold wall, which provides the condition to obtain defect-free castings: simultaneous nucleation.
Rheodynamic lubrication of a squeeze film bearing under sinusoidal squeeze motion
Kandasamy, A.;Vishwanath, K.P.;
Computational & Applied Mathematics , 2007, DOI: 10.1590/S0101-82052007000300004
Abstract: lubricants with variable viscosity are assuming importance for their applications in polymer industry, thermal reactors and in biomechanics. with the bearing operations in machines being subjected to high speeds, loads, increasing mechanical shearing forces and continually increasing pressures, there has been an increasing interest to use non-newtonian fluids characterized by an yield value. the most elementary constitutive equation in common use that describes a material which yields is that of bingham fluid. in the present work, the problem of a circular squeeze film bearing lubricated with bingham fluid under the sinusoidal squeeze motion has been analyzed. the shape and extent of the core for the case of sinusoidal squeeze motion has been determined numerically for various values of the bingham number. numerical solutions have been obtained for the bearing performances such as pressure distribution and load capacity for different values of bingham number, reynolds number and for various amplitudes of squeeze motion. the effects of fluid inertia, non-newtonian characteristics, and the amplitudes of squeeze motion on the bearing performances have been discussed.
Rheodynamic lubrication of a squeeze film bearing under sinusoidal squeeze motion  [cached]
A. Kandasamy,K.P. Vishwanath
Computational and Applied Mathematics , 2007,
Abstract: Lubricants with variable viscosity are assuming importance for their applications in polymer industry, thermal reactors and in biomechanics. With the bearing operations in machines being subjected to high speeds, loads, increasing mechanical shearing forces and continually increasing pressures, there has been an increasing interest to use non-Newtonian fluids characterized by an yield value. The most elementary constitutive equation in common use that describes a material which yields is that of Bingham fluid. In the present work, the problem of a circular squeeze film bearing lubricated with Bingham fluid under the sinusoidal squeeze motion has been analyzed. The shape and extent of the core for the case of sinusoidal squeeze motion has been determined numerically for various values of the Bingham number. Numerical solutions have been obtained for the bearing performances such as pressure distribution and load capacity for different values of Bingham number, Reynolds number and for various amplitudes of squeeze motion. The effects of fluid inertia, non-Newtonian characteristics, and the amplitudes of squeeze motion on the bearing performances have been discussed.
Study on heat treatment blister of squeeze casting parts  [PDF]
TONG Wen-jun,QI Lin,QI Pi-xiang
China Foundry , 2007,
Abstract: Heat treatment blister is one of the common defects found in squeeze casting parts, which is related to squeeze mode, process and mold. For direct squeeze-casting parts, solution heat treatment can be performed smoothly as long as oil-based paint is not used and air exhaust is well arranged. For indirect squeeze casting parts, solution heat treatment can also be applied when additional factors are taken into consideration, including well designed internal feeding system and strictly controlled liquid metal filling velocity to prevent from inclusions.
Pengaruh Tekanan dan Temperatur Die Proses Squeeze Casting Terhadap Kekerasan dan Struktur Mikro Pada Material Piston Komersial Lokal  [cached]
Duskiardi Duskiardi,Soejono Tjitro
Jurnal Teknik Mesin , 2002,
Abstract: Squeeze casting which often known as called liquid metal forging where molten metal is solidified under relatively high external pressure. Contact between molten metal with punch and die enable to increase the rate of heat transfer. The microstructure of the casting will be more homogenous and the mechanical properties will be improved. The material used this investigation is taken from commercial piston product with the following composition bal. : 12.62 wt% Si, 2.83 wt% Cu, 1.58 wt% Ni, 0.89 wt% Mg, 0.38 wt% Fe, 0.15 wt% Mn, 0.078 wt% Zn, 0.016 wt% Pb, 0.009 wt% Sn, 0.006 wt% Ca dan Al. The material melted up to 700oC, the specimens were made using direct squeeze casting by combining pressure and temperature. Finally the specimens were examined through hardness, porosity and microstructure. The results show the solidification rate significantly improves the properties of the specimen. The process decrease quantity of the porosity up to 85.15 % and increase the Britnell hardness 5.29% after heat treated (T6). The optimum pressure and temperature is 70 - 100 MPa and 400 - 700oC. Abstract in Bahasa Indonesia : Squeeze casting sering juga disebut dengan liquid metal forging, dimana logam cair dibekukan dibawah tekanan eksternal yang relatif tinggi. Terjadinya kontak antara logam cair dengan punch dan die pada saat penekanan memungkinkan terjadinya perpindahan panas yang cukup cepat. Ini akan menghasilkan struktur mikro yang lebih homogen serta perbaikan sifat mekanik. Material yang digunakan untuk pengujian ini dan sekaligus sebagai pembanding diambil dari produk piston komersial lokal dengan komposisi bal. 12.62 wt% Si, 2.83 wt% Cu, 1.58 wt% Ni, 0.89 wt% Mg, 0.38 wt% Fe, 0.15 wt% Mn, 0.078 wt% Zn, 0.016 wt% Pb, 0.009 wt% Sn, 0.006 wt% Ca dan selebihnya Al. Material dilebur pada 700 o C, benda uji dibuat dengan menggunakan teknik squeeze casting dengan jalan memvariasikan tekanan dan temperatur. Selanjutnya benda uji dikarakterisasi berupa kekerasan , porositas dan struktur mikro. Pada pengujian yang dilakukan, laju pendinginan material akibat pengaruh tekanan dan temperatur die sangat signifikan pengaruhnya terhadap perbaikan sifat benda uji. Dari hasil pengamatan, proses ini mampu menurunkan porositas sampai 85.15 % dan memperbaiki kekerasan sebesar 5.29 % setelah dilakukan perlakukan panas T6. Tekanan serta temperatur die optimal didapatkan pada 70 - 100 MPa dan 400 - 450 0C. Kata kunci: pengecoran squeeze, struktur mikro, kekerasan.
Page 1 /100
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.