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”).
Generally, there are three methods to prevent the phase transformation of Y-TZP against ageing- (1) additive, (2) grain size, (3) coating, (4) surface recrystallization.
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...
Bronzes are made by making two molds (one larger than the other), pouring melted bronze in...
-Developed and implemented strip casting overseas to eliminate a step in the steel making process
This following report on sheet metal forming consists of forming study of two components one given in the course and an another outside of our field of work, it details the materials used and their metallurgical properties and alternative materials that can be considered. Detail the forming process used and an alternative route. Also Detail the forming effects such as spring back and the methods to reduce them.
Melting Point Determination of Alum 1. 0.5 g of dry alum was crushed with the mortar and pestle, and then the crushed alum was packed to the bottom the capillary tube. The alum measured about 0.5 cm from the bottom of the tube. Then the tube was fastened to the thermometer with the rubber band, and the thermometer was fastened to the ring stand with the universal clamp. 2.
Plastics Engineering manufacturing and handbook (Volume 2) (Dominik V Rosato, Donald V Rosato, Nick R Schott) PAGE: 1300-1303
Stress Singularity -- sharp re-entrant corners will cause the mesh an increasing values of stress as the component size reduces. To reduce to problem is to model the component with a material which can model plastic
Various alternative sizes and shapes are obtainable. The dilutant sheet isn't cheaper. forged acrylic prices quite extruded and has rather poorer tolerances. it's less internal stresses and glues higher. it's superior flatness, higher surface end, and a lot of thermal stability.
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.
The stress raiser which is in the nature of geometrical or in metallurgical or combination of two. Geometrical stress raiser in the shape of the parts such as step changes in diameter, sharp corners and surface discontinuities like notches and machining marks etc. are non-uniformities. Metallurgical stress are stress raiser which may be corrosion pits, brittle second-phase particles, gross metallic inclusions, quench cracks etc. Also, the initiation of fatigue failures where microstructure of the material plays a vital role but also the fatigue crack to cause failure of the material during the progressive growth. Near free surface Fatigue initiation occurs frequently, where nominal stress will be higher. While doing manufacturing and fabrication processes where machining can form surface irregularities or discontinuities which is the point of stress concentration also initiate the fatigue
The Web. The Web. 28 Apr. 2014. The 'Standard' of the 'Standard'. Metal Melting 101 - How To.
In summary, the rate of cooling from the austenite phase is the main determinant of final structure and properties.