4.1 Shrinkage Defect:
4.1.1 Definition
• Shrinkage defects occur when standard feed metal is not available to compensate for shrinkage as the thick metal solidifies.
• The shrinkage defect usually forms at the top of the hot spots. They require a nucleation point, so impurities and dissolved gas can induce closed shrinkage defects.
• Solidification leads to volumetric contraction which must be compensated by feeding. If this compensation is inadequate either surface shrinkage or internal shrinkage defects are produced making the casting weaker.
• While the material is changing from liquid to solid Contraction takes place at varying rates, which causes irregularly shaped shrinkage cavities depressions.
• This defect occurs in all castings but more frequently in heavy sections in all alloys with along solidification range. This is different from hot tears and creaks.
Figure – 4.1.1 Identification of Shrinkage defect.
4.1.2 Causes of Shrinkage Defect
The various causes for shrinkage defect are given below.
Failure to obtain direction solidification of the casting, because of low pouring temperature or incorrect gating system.
Inadequate risers for heavy section.
Unsatisfactory casting design.
Excessive or inadequate pouring temperature.
Due to improper design of gate and riser.
4.1.3 Remedies of shrinkage defect
1. Ensure directional progressive solidification.
For solidification in a casting component for proper way is shown in fig.
Figure 4.1.2 Solidification rate diagram
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...l casting component.
That’s why this pouring temperature range (1390◦c to 1420ºc) is selected during the pour of molten metal in the mould.
CONCLUSION:
• From this project we have solved the casting defects such as Blow hole and Shrinkage.
• The Blow Hole solution is done by some remedies in pump part (Upper housing and Lower housing)
• The Shrinkage defect is solved by simulation process in Automobile part (Steering joint).
• The simulation process is done in softCAST software.
• In final, the shrinkage defect is solved by some of changes in pouring temperature (1370◦c to 1470◦c).
• From this pouring temperature shrinkage defect is generated in spure and riser.
• After all spure and riser is cut in fettling shop and casting component is defect free.
Combined with corrosion fatigue” (“Silver”).
The bottom of the capillary tube and the thermometer were submerged in a beaker of heating water. The water was stirred occasionally and heated very quickly. However, when the water reached 80 ˚C it was heated very slowly in order to not pass the melting point. 3. The temperature when alum melted was recorded in the data table.
...the more stable there is. However, the fracture toughness decreases if the phase is too stable. While tetragonal phase transform to monoclinic, the mechanical properties decrease at the same time but fracture toughness will increase.
This new form was called hydraulic die-forming. Hydraulic stems from the Greek word hydro meaning water and aulos meaning tube (McCreight, 2004). In today’s society, hydraulic pressing and stamping of dies are used for everything from making small pots and pans to the more extravagant automobile body models. Another use that has recently developed is the more artistic use of, producing form in silver and gold. In order to achieve this smaller, cheaper scale of die-forming experiment were conducted by Richard Thomas and Ruth Girard, which eventually led to the development of the pourable epoxy steel...
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The reflux ratio is kept constant so the liquid flowing down has uniform flow and only the power input to the reboiler can be adjusted. The boil-up rate is obtained by varying the heat energy to the reboiler and this affects the velocity of the vapour passing up the column. As the velocity of the vapour passing up the column increases, the vapour flow will generate more pressure drop due to the resistance force that is acting against the holes in the sieve tray and the liquid that is flowing down the column. In addition, increasing the vapour flow means that increasing the contacting time between liquid and vapour phase inside the column resulting in higher pressure drop. This is proven clearly from the graph that the pressure drop is linearly related with boil-up rate.
Technology Is What You Make It The articles “How Computers Change the Way We Think” by Sherry Turkle and “Electronic Intimacy” by Christine Rosen argue that technology is quite damaging to society as a whole and that even though it can at times be helpful it is more damaging. I have to agree and disagree with this because it really just depends on how it is used and it can damage or help the user. The progressing changes in technology, like social media, can both push us, as a society, further and closer to and from each other and personal connections because it has become a tool that can be manipulated to help or hurt our relationships and us as human beings who are capable of more with and without technology. Technology makes things more efficient and instantaneous.
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Plastics Engineering manufacturing and handbook (Volume 2) (Dominik V Rosato, Donald V Rosato, Nick R Schott) PAGE: 1300-1303
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