scholarly journals Determination of Solidification of Rigidity Point Temperature Using a New Method

2020 ◽  
Vol 10 (7) ◽  
pp. 2472
Author(s):  
Ester Villanueva ◽  
Iban Vicario ◽  
Jon Mikel Sánchez ◽  
Ignacio Crespo
Keyword(s):  
Solidification Process ◽  
Casting Process ◽  
Hot Tearing ◽  
Alloying Elements ◽  
Point Temperature ◽  
Optimization Of Process Parameters ◽  
Correct Determination ◽  
The Aluminum Industry ◽  
Solidification Parameters

This work aims to calculate the rigidity point temperature of aluminum alloys by three new methods and compare them with currently employed methods. The influence of major and minor alloying elements over the rigidity point temperature is also discussed. Until now it has been difficult to determine the exact temperature of the rigidity point, since small variations in the data obtained give variable results, making it difficult to automate the process with high accuracy. In this work we suggested three new mathematic methods based on the calculation of higher order derivatives of (dT/dt) with respect to time or temperature compared to those currently employed. A design of experiments based on the Taguchi method was employed to compare the effect of the major and minor alloying elements for the AlSi10Mg alloy, and to evaluate the accuracy of each developed method. Therefore, these systems will allow better automation of rigidity point temperature (RPT) determination, which is one of the most important solidification parameters for solidification simulators. The importance of the correct determination of this parameter lies in its relation to quality problems related to solidification, such as hot tearing. If the RPT presents very low-temperature values, the aluminum casting will be more sensitive to hot tearing, promoting the presence of cracks during the solidification process. This is why it is so important to correctly determine the temperature of the RPT. An adequate design of chemical composition by applying the methodology and the novel methods proposed in this work, and also the optimization of process parameters of the whole casting process with the help of the integrated computational modeling, will certainly help to decrease any internal defective by predicting one of the most important defects present in the aluminum industry.

Solidification Process, Microstructure, Density and Hardness of the Mg-Al Alloys with Zn, Cu, Ni and AlTiB Additions

2011 ◽  
Vol 176 ◽  
pp. 91-98
Author(s):  
Franciszek Binczyk
Keyword(s):  
Thermal Analysis ◽  
Regression Analysis ◽  
Operating Temperature ◽  
Solidification Process ◽  
Al Alloys ◽  
Pouring Temperature ◽  
Significance Level ◽  
Solidification Parameters ◽  
Microstructure Density

The paper presents the results of the investigations of the solidification process of magnesium alloys containing 5 and 10 wt.% Al, the additions of Zn, Cu, Ni, and of an AlTiB master alloy. The plotted DTA (derivative thermal analysis) curves were used for the determination of solidification parameters Tliq, Teut and Tsol. Knowledge of these parameters is very important in determination of alloy pouring temperature and maximum casting operating temperature. On samples taken from the area of temperature measurements, the chemical composition and microstructure were determined. The density and hardness HB were measured as well. Applying the method of multiple regression analysis at the significance level α = 0.1, the intensity and direction of the effect of alloying elements on the solidification parameters, density and hardness HB of castings were evaluated.

The Influence of the Tablet Height and Plunger Pressing Velocity on the Final Porosity of Die Casting

2018 ◽  
Vol 916 ◽  
pp. 244-248
Author(s):  
Stefan Gaspar ◽  
Jan Pasko ◽  
Dusan Knezo
Keyword(s):  
Die Casting ◽  
Casting Process ◽  
Factors Affecting ◽  
Correct Determination ◽  
Casting Cycle ◽  
Gate System ◽  
Final Porosity ◽  
Die Casting Process ◽  
Pressure Die Casting

With a pressure die casting process, one of the important factors affecting the quality of castings represented by porosity is plunger pressing velocity determines the regime die cavity filling and correct determination of dose mass of a molten metal required for one casting cycle. The mass is given by a total of the net mass of a casting, overflows, a gate system and a metal rest inside a filling chamber (the tablet height). As a rule, the tablet height represents the largest mass ratio regarding the waste metal. A correct determination of the tablet height is important from both economical and qualitative aspect of a pressure die casting process.

Numerical Simulation of Thermal Stress Fields of Steel Casting

2011 ◽  
Vol 179-180 ◽  
pp. 1118-1123 ◽  
Author(s):  
Dun Ming Liao ◽  
Li Liang Chen ◽  
Jian Xin Zhou ◽  
Rui Xiang Liu
Keyword(s):  
Residual Stress ◽  
Thermal Stress ◽  
Hot Spot ◽  
Solidification Process ◽  
Casting Process ◽  
Simulation System ◽  
Hot Tearing ◽  
System A ◽  
Fem Method ◽  
Stress Simulation

Many defects relative to stress occur during the complicate casting process, such as hot tearing, residual stress concentration and distortion. Modeling of casting thermal stress during casting solidification process is of great significance to predict and analyze casting stress defects. Involving too many complex influencing factors, the stress simulation is very difficult and retains a hot spot of macro simulation in foundry engineering. Currently most researchers adopt integrated FDM/FEM method, i.e. using finite difference method (FDM) to calculate solidification and heat transferring, while finite element method (FEM) to simulate stress. Some universal commercial FEA packages are usually adopted. This study has tried two kinds of approaches to simulate casting thermal stress. One is based on ANSYS, a well-known powerful FEA analysis software. Another is to develop an independent own copyrighted casting stress simulation system based on FDM. The routes of these two methods were given respectively. To calibrate the simulation system, a stress frame sample and a real practical casting were simulated and pouring experiment was also carried on. The results of simulation were in agreement with the experiment results and practical cases. It indicates that these two approaches can all meet demands. When adopting FDM method, thermal analysis and stress analysis can use the same FD model, which can avoid the nodes matching between different models and reduce the errors of thermal load transferring. It makes the simulation of fluid-flow field, temperature field and stress field unify into one model. This system takes full advantages of mature FDM technology and can be used to simulate the forming of residual stress and predict the occurrence of hot tearing.

Numerical Simulation of Casting Thermal Stress and Deformation Based on Finite Difference Method

2013 ◽  
Vol 762 ◽  
pp. 224-229 ◽  
Author(s):  
Tao Chen ◽  
Dun Ming Liao ◽  
Jian Xin Zhou
Keyword(s):  
Numerical Simulation ◽  
Thermal Stress ◽  
Finite Difference ◽  
Finite Difference Method ◽  
Difference Method ◽  
Solidification Process ◽  
Casting Process ◽  
Hot Tearing ◽  
Stress And Deformation ◽  
Stress Simulation

Thermal stress simulation is an important part in the numerical simulation of casting process. It provides engineers with insights into the evolution of displacement, strain and stress of castings in the solidification process. With thermal stress simulation, some defects of casting, i.e. hot tearing, cold cracking and large deformation can be predicted and the engineers are instructed to optimize and improve the casting process. Based on the finite difference method (FDM), this paper presents an integrated numerical method to simulate the thermal stress and deformation of casting in the solidification process. Practical examples show that the method is capable to predict stress distribution and deformation as well as the defects in the experiment.

scholarly journals The Influence of Casting Velocity on Structure of Al Continuous Ingots

2017 ◽  
Vol 62 (3) ◽  
pp. 1609-1613
Author(s):  
D. Bartocha ◽  
T. Wróbel ◽  
J. Szajnar ◽  
W. Adamczyk ◽  
W. Jamrozik ◽  
...  
Keyword(s):  
Continuous Casting ◽  
Primary Structure ◽  
Crystallization Front ◽  
Cooling Water ◽  
Solidification Process ◽  
Casting Process ◽  
Ansys Fluent ◽  
Fluent Software ◽  
Continuous Casting Mould

AbstractThe aim of paper was determination of influence of the casting velocity in horizontal continuous casting process on solidification phenomenon and next primary structure of aluminum ingots. In the range of studies was conducted the experiment concerning continuous casting of Al ingots with diameter 30 mm at velocity from 30 to 80 mm/min. Moreover was developed adequate to the real the virtual model of cooled water continuous casting mould, which was used in simulation of solidification process of Al continuous ingot, made in ANSYS Fluent software. In result was determined the influence of casting velocity and temperature of cooling water on position of crystallization front inside the continuous casting mould. While the shape and size of grains in primary structure of Al continuous ingots were determined on the basis of metallographic macroscopic studies. On the basis of the results analysis was affirmed that increase of casting velocity strongly influences on position of crystallization front and causes increase of temperature of ingot leaving the continuous casting mould. In result the increase of casting velocity supposedly leads to decrease of temperature gradient on crystallization front what creates coarse grains in primary structure of aluminum continuous ingots and caused low usable properties i.e. suitability to plastic deformation.

Foundry Technique Designing of the Nodular Cast Iron Casting

2014 ◽  
Vol 1004-1005 ◽  
pp. 1162-1165
Author(s):  
Bin Feng He
Keyword(s):  
Solidification Process ◽  
Casting Process ◽  
Nodular Cast Iron ◽  
Simulation Software ◽  
Casting Simulation ◽  
Filling Process ◽  
Original Technique ◽  
Correct Determination ◽  
Filling And Solidification ◽  
Casting Simulation Software

The traditional method has been used to the foundry technique for the melt block mobile plate. The pouring position,the parting face and some of the casting parameters were determined, such as the allowance for finish, stripping taper, the rate of shrinkage and soon on. The commercial casting simulation software was introduced into the casting process, the filling and solidification process were calculated by it. The results shown that there are some shrinkage exists in the original technique and the filling process were inordinate. The gating system was optimized and according to the simulation results, the shrinkages in the original technique were eliminated and the filling process is smoothly which could help the designer to make a correct determination.

scholarly journals Manufacturing PLA/PCL Blends by Ultrasonic Molding Technology

Polymers ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2412
Author(s):  
Inés Ferrer ◽  
Ariadna Manresa ◽  
José Alberto Méndez ◽  
Marc Delgado-Aguilar ◽  
Maria Luisa Garcia-Romeu
Keyword(s):  
Molecular Weight ◽  
Crystallization Rate ◽  
Raw Material ◽  
Small Particle Size ◽  
Polymer Mixtures ◽  
Crystallinity Degree ◽  
Correct Determination ◽  
Production Stages ◽  
Process Speed

Ultrasonic molding (USM) is a good candidate for studying the plasticization of polymer mixtures or other composite materials due to either the little amount of material needed for processing, low waste or the needed low pressure and residence time of the mold. Thus, the novelty of this research is the capability of USM technology to process PLA/PCL blends and their corresponding neat materials, encompassing all the production stages, from raw material to the final specimen. The major findings of the work revealed that the thermal properties of the blends were not affected by the USM process, although the crystallinity degree experienced variations, decreasing for PLA and increasing for PCL, which was attributed to the crystallization rate of each polymer, the high process speed, the short cooling time and the small particle size. The employed ultrasonic energy increased the molecular weight with low variations through the specimen. However, the degradation results aligned with the expected trend of these material blends. Moreover, this study also showed the effect pellet shape and dimensions have over the process parameters, as well as the effect of the blend composition. It can be concluded that USM is a technology suitable to successfully process PLA/PCL blends with the correct determination of process parameter windows.

Evaluation of methods for detection of β-lactamase production in MSSA

2021 ◽  
Author(s):  
Robert Skov ◽  
David R Lonsway ◽  
Jesper Larsen ◽  
Anders Rhod Larsen ◽  
Jurgita Samulioniené ◽  
...  
Keyword(s):  
Susceptibility Testing ◽  
Confirmatory Test ◽  
Disc Diffusion ◽  
Broth Microdilution ◽  
Confirmatory Tests ◽  
Correct Determination ◽  
Primary Test ◽  
Zone Edge ◽  
Evaluation Of Methods

Abstract Objectives Correct determination of penicillin susceptibility is pivotal for using penicillin in the treatment of Staphylococcus aureus infections. This study examines the performance of MIC determination, disc diffusion and a range of confirmatory tests for detection of penicillin susceptibility in S. aureus. Methods A total of 286 consecutive penicillin-susceptible S. aureus blood culture isolates as well as a challenge set of 62 MSSA isolates were investigated for the presence of the blaZ gene by PCR and subjected to penicillin-susceptibility testing using broth microdilution MIC determination, disc diffusion including reading of the zone edge, two nitrocefin tests and the cloverleaf test. Results Using PCR-based detection of blaZ as the gold standard, both broth microdilution MIC testing and disc diffusion testing resulted in a relatively low accuracy (82%–93%) with a sensitivity ranging from 49%–93%. Among the confirmatory tests, the cloverleaf test performed with 100% accuracy, while zone edge interpretation and nitrocefin-based tests increased the sensitivity of β-lactamase detection to 96%–98% and 82%–96% when using MIC determination or disc diffusion as primary test, respectively. Conclusions This investigation showed that reliable and accurate detection of β-lactamase production in S. aureus can be obtained by MIC determination or penicillin disc diffusion followed by interpretation of the zone edge as a confirmatory test for apparently penicillin-susceptible isolates. The more cumbersome cloverleaf test can also be used. Nitrocefin-based tests should not be used as the only test for confirmation of a presumptive β-lactamase-negative isolate.

IMPROVEMENT OF THE CAMERAL CHECKS PROCESS IN RUSSIA BASED ON FOREIGN EXPERIENCE

2020 ◽  
Author(s):  
Darya Sergeevna Kareva ◽  
◽  
Sevinj Mahmud kyzy Ismailova ◽  
Elena Evgenievna Dozhdva ◽  
◽  
...  
Keyword(s):  
United States ◽  
The United States ◽  
Foreign Experience ◽  
Correct Determination

The article substantiates the need to reform cameral tax control in Russia based on the experience of the United States. The necessity of introducing into the procedure of cameral control the mechanism of requesting all documents confirming the correct determination of tax obligations is determined. The aim of improving the process of desk audits of control is that the new procedure for conducting audits will reduce the likelihood of tax violations.

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