modelling shrinkage and porosity during vacuum

State

Porosity in a casting is attributed to both solidification shrinkage and high gas content The inability of the liquid metal to feed through the interdendritic regions to compensate for the volume shrinkage during solidification causes porosity The rejection of hydrogen gas from solution during solidification can also cause porosity It is

Prediction and improvement of shrinkage porosity in TiAl

shrinkage porosity in TiAl based alloy Male born in 1964 Ph D Professor His research interests mainly focus on metal solidification and microstructure control material automatic processing and processing equipment E-mail: zhanghubuaa edu cn Received: 2010-08-15 Accepted: 2010-12-10 *Zhang Hu Gao Yong 1 Zhang Lijing Gao Wenli2 and *Zhang Hu1 (1 School of Materials Science

Vacuum

The role of vacuum mixing on the reduction of porosity and on the clinical performance of cemented total hip replacements remains uncertain We have used paired femoral constructs prepared with either hand-mixed or vacuum-mixed cement in a cadaver model which simulated intra-operative conditions during cementing of the femoral component

Shrinkage characteristic of potato slices based on

shrinkage of samples and mechanisms involved The quality of the dehydrated product depends on the extension of these changes Regarding to the changes in volume and porosity high shrinkage and low porosity lead to products with poor rehydration capability (Mayor et al 2011) Shrinkage during dehydration of fruits and vegetables

STRUCTURAL CHANGES DURING AIR DRYING OF

Shrinkage Loss of water during a drying process originates a reduction in the size of the cellular tissue which is usually referred as shrinkage phenomenon Reeve (1943) and Crafts (1944) reported pioneer studies of shrinkage at microscopic level related to dehydration processes of carrots potatoes and

Modelling shrinkage and porosity during vacuum

Modelling shrinkage and porosity during vacuum dehydration (AGR:IND21803824) Abstract Citations specific volume and internal porosity were investigated during vacuum dehydration of banana apple carrot and potato at various moisture contents and pressures The pressure was found to effect significantly the apparent density and porosity of the materials examined while for the true

Modelling of vacuum osmotic dehydration of food

Modelling of mass transfer during osmotic dehydration of apples Influence of vacuum treatment on mass transfer during osmotic dehydration of fruits Impregnation and osmotic dehydration of some fruits: effect of the vacuum pressure and syrup concentration

Latest Advancements in Modelling and Simulation in High

Latest Advancements in Modelling and Simulation for High Pressure Die Castings Christian Kleeberg MAGMA Engineering Asia-Pacific Pte Ltd Singapore 1 0 Introduction: Innovations and modifications in the techniques of high pressure die casting or tooling are forced by trends in part design part load as well as by costs and times for development and manufacturing processes All current trends

Available from Deakin Research Online: Copyright

The porosity defect can be divided into three major types which are gas porOsity shrinkage porosity and flow porosity In HPDC the first two types of porosity are mostly encountered The gas porosity is the porosity in casting due to the presence of gas This type can arise from gas produced during process entrapped air and melt composition

Design Analysis of Heat Sink High

like air porosity cold shut shrinkage warpage apart from these there are many flaws Thus these castings defects will occur due to an improper gate runner design Improper locating of overflows While manufacturing the casting defects occurs due to wrong machine parameters also in this project we discuss the errors that arises due to improper design 2 Design of gate runner system for

TheEffect of Drying Kinetic on Shrinkage of Potato Slices

shrinkage amount of potato slices during drying process using vacuum-infrared method Methods: In this work the effect of the infrared radiation powers (100 150 and 200 Watt) and absolute pressure levels (20 80 140 760 mmHg) at different thickness (1 2 and 3 mm) on bulk volumetric shrinkage were investigated Results: Data analysis showed that shrinkage percentage decreased with decrease

CASTING SIMULATION SUITE

During solidification simulation the evolution of the solid fraction is calculated and used to predict shrinkage locations Air back pressure calculations together with appropriate user-defined pressure conditions allow the simulation of vacuum casting processes High Pressure Die Casting

Materials

The absolute pressure strongly affects the porosity and mechanical properties of castings produced by vacuum high-pressure die casting (V-HPDC) technology The pore size quantity and distribution of AlSi9Cu3 samples under three absolute pressures were evaluated by X-ray tomography and optical and electron microscopy The paper presents an elaboration the stress concentration mechanism of

Vacuum

The role of vacuum mixing on the reduction of porosity and on the clinical performance of cemented total hip replacements remains uncertain We have used paired femoral constructs prepared with either hand-mixed or vacuum-mixed cement in a cadaver model which simulated intra-operative conditions during cementing of the femoral component

Guide to Cast Top Quality Jewelry: Problems and Solutions

Shrinkage Porosity This defect occurs due to the shrinkage of liquefied metal when it solidifies (hence the name) In normal circumstances the molten metal mixes and forms a continuous surface however when the shrinkage from solidification occurs some spaces are left out

Mathematical modeling to study influence of porosity on

Krokida MK Zogzas NP Maroulis ZB Modelling shrinkage and porosity during vacuum dehydration Int J Food Sci Technol 1997 32:445–458 doi: 10 1111/j 1365-2621 1997 tb02119 x Krokida MK Karathanos VT Maroulis ZB Effect of freeze-drying conditions on shrinkage and porosity of dehydrated agricultural products

Porosity

Porosity or void fraction is a measure of the void (i e empty) spaces in a material and is a fraction of the volume of voids over the total volume between 0 and 1 or as a percentage between 0% and Strictly speaking some tests measure the accessible void the total amount of void space accessible from the surface (cf closed-cell foam) There are many ways to test porosity in a

SHRINKAGE OF POROUS MATERIALS DURING MICROWAVE

Shrinkage tlicro-computer Temperature (command) Sensors Fig 1 Experimental system based system was developed for the automatic control of the drying process and to gather measurement data on the sample (Figure I) This system enables to follow a predetermined mass profile during the heat cycle The

Three

Hydrogen-induced porosity formed during solidification of aluminum-based alloys has been a major issue adversely affecting the performance of solidification products such as castings welds or additively manufactured components A three-dimensional cellular automaton model was developed for the first time to predict the formation and evolution of hydrogen porosity coupled with grain growth

State

Porosity in a casting is attributed to both solidification shrinkage and high gas content The inability of the liquid metal to feed through the interdendritic regions to compensate for the volume shrinkage during solidification causes porosity The rejection of hydrogen gas from solution during solidification can also cause porosity It is

Modelling of vacuum osmotic dehydration of food

Modelling of mass transfer during osmotic dehydration of apples Influence of vacuum treatment on mass transfer during osmotic dehydration of fruits Impregnation and osmotic dehydration of some fruits: effect of the vacuum pressure and syrup concentration

#0081 Thermal History Prediction Modeling Tool for

Thermal History Prediction for Investment Ca L Maestro1 A Eguidazu 1 I Vicario1 A Zryd 2 J A Torroba2 E C M 1Precicast Bilbao SA Barakaldo-Bizkaia Spain 2 University of Applied Sciences Western Switzerland 4 Calcom ESI SA PSE-A EPFL CH-1015 Lausanne Switzerland 5IMDEA #0081 Due to the high cost and variability of investment casting process simulation tools are needed to

Porosity : establishing the relationship between drying

The factors influencing porosity during the various drying methods are explored in depth as well as porosity's overall effect on food properties The chemical reaction and stability of porosity are also covered including sensory and mechanical properties The work looks closely at the relationship between drying conditions pore characteristics and dried food quality Porosity: Establishing

Modeling of Hot Tearing and Other Defects in Casting Processes

Defects that form during solidification are important not only to the casting engineer but also to engineers involved in subsequent manufacturing processes and evaluation Solid-ification defects are responsible for many of the defects in final manufactured products and failures in service They originate from inclu-sion entrapment segregation shrinkage cav-ities porosity mold-wall

Latest Advancements in Modelling and Simulation in High

Latest Advancements in Modelling and Simulation for High Pressure Die Castings Christian Kleeberg MAGMA Engineering Asia-Pacific Pte Ltd Singapore 1 0 Introduction: Innovations and modifications in the techniques of high pressure die casting or tooling are forced by trends in part design part load as well as by costs and times for development and manufacturing processes All current trends

Effect of Hot

During FD the whole dehydrating process is accomplished in the state of high vacuum and low temperature which almost retains the original color shape smell and nutritional ingredients in fresh materials [1–3] An industrial-scale FD process for most fruits and vegetables generally consists of 4 main stages including pretreating freezing freeze-drying (primary drying and secondary

US Patent for Apparatus and method for cold chamber die

A vacuum die-casting machine has a sprue cavity with sufficient depth facing the shot cylinder that the shot cylinder piston can easily crush with a pressure of less than 1000 psi the thin cylindrical shell of solidified metal which develops into the biscuit and continue to advance after the die cavity becomes fried with molten metal to inject additional molten metal into the die cavity to

Guide to Cast Top Quality Jewelry: Problems and Solutions

Shrinkage Porosity This defect occurs due to the shrinkage of liquefied metal when it solidifies (hence the name) In normal circumstances the molten metal mixes and forms a continuous surface however when the shrinkage from solidification occurs some spaces are left out

THE EFFECTS OF SHRINKAGE ON DRYING CHARACTERISTICS OF

area of the slice were measured every 5 minute during drying Shrinkage showed almost linear relation with moisture content It was found that air temperature and relative humidity had no significant effect on shrinkage Drying took place entirely in the falling rate period Slices dried at 70oC showed more bend than slices dried at 50 and 60oC Effective diffusivity values by considering the

Guide to Cast Top Quality Jewelry: Problems and Solutions

Shrinkage Porosity This defect occurs due to the shrinkage of liquefied metal when it solidifies (hence the name) In normal circumstances the molten metal mixes and forms a continuous surface however when the shrinkage from solidification occurs some spaces are left out

STUDY OF SHRINKAGE PHENOMENON DURING CONVECTIVE

The sample thickness was the dimension with larger shrinkage compared to its air flow transversal area During the early drying stages samples bulk density increased sensibly until a certain moisture content of papaya samples but close to the equilibrium condition its value decreased indicating an increase on samples porosity

ADVANCED CASTING SIMULATIONS

by the presence of porosity [4] In most of simulation software today porosity prediction is limited to macro-shrinkage porosity which corresponds to the contraction of the metal during solidification This approach does not take into account for gas and interdendritic shrinkage porosity Gas porosity