What are the three stages of shrinkage during casting?
There are three distinct stages of shrinkage as molten metal alloys solidify:
- liquid shrinkage.
- liquid-to-solid shrinkage.
- solid shrinkage.
What is solidification time in casting?
The solidification time of a casting is a function of the volume of a casting and its surface area (Chvorinov’s rule). Solidification time of a casting is given by the formula: Where C is the constant that reflects (a) the mold material, (b) the metal properties (including latent heat), and (c) the temperature.
What is the relationship known as Chvorinov’s rule in casting?
The amount of heat which has to be emitted by a casting to the mold during solidification is directly proportional to the weight of the casting and the chosen superheat.
How can you tell whether cavities in a casting are due to porosity or to shrinkage?
How can you tell whether a cavity in a casting is due to porosity or shrinkage? Cavities due to porosity are generally spherical with smooth walls. In contrast, cavities due to shrinkage are rough and angular. Do you think early formation of dendrites in a mold can impede the free flow of molten metal into the mold?
How can we alter the properties of cast product?
Heat Treatment of Castings
- Annealing. The annealing process is used primarily to reduce hardness, improve ductility and relieve the stress built up within a casting during solidification.
- Precipitation Strengthening.
- Tempering.
- Case Hardening/Carburising.
- Normalising.
- Quenching.
What are the major defects of casting?
In die casting the most common defects are misruns and cold shuts. These defects can be caused by cold dies, low metal temperature, dirty metal, lack of venting, or too much lubricant. Other possible defects are gas porosity, shrinkage porosity, hot tears, and flow marks.
How do you test for casting defects?
Non-destructive testing (NDT) is a common method for inspecting castings without having to damage the product under assessment. NDT can help identify defects that adversely affect the material strength. Cracks appear after a melt has solidified in the form of thin fissures on the casting surface.
Why do most metals shrink when they are cast?
Solidification shrinkage occurs because metals are less dense as liquids than solids. Risers and chills are used to address this problem. Risers feed a continuous supply of molten metal to the casting as it solidifies. They help to equalise the rate of solidification in thicker areas of the metal casting.
What is an example of secondary processing?
Secondary processing is when the primary product is changed to another product – for example, turning wheat flour into bread.
What are the examples of secondary sector?
Activities associated with the secondary sector include metal working and smelting, automobile production, textile production, chemical and engineering industries, aerospace manufacturing, energy utilities, engineering, breweries and bottlers, construction, and shipbuilding.
What are secondary processes?
Secondary manufacturing processes are those processes that are done after the initial manufacturing processes—like injection molding, CNC machining production, and so on. As the name suggests, these processes are used to refine the workpiece in some manner.
What are the four types of secondary manufacturing processes?
Name four types of secondary manufacturing processes. Casting, Molding, separating and forming.
What is primary and secondary process?
The primary processes, directly animated by the drives, serve the pleasure principle and work to actualize a free flow of psychic energy. Secondary processes, which presuppose the binding of this energy, intervene as a system of control and regulation in the service of the reality principle.
What do you know about secondary sector?
In macroeconomics, the secondary sector of the economy is an economic sector in the three-sector theory which describes the role of manufacturing. It encompasses the industries which produce a finished, usable product or are involved in construction.
Is Tesco a secondary sector?
Tesco is a secondary sector because they make some items themselves like when the products have the Tesco brand make on it. It means it’s made by them and tertiary because they provide variety of different services like home insurance, car insurance, phone contracts etc.
What are jobs in the secondary sector?
Primary jobs involve getting raw materials from the natural environment e.g. Mining, farming and fishing. Secondary jobs involve making things (manufacturing) e.g. making cars and steel. Tertiary jobs involve providing a service e.g. teaching and nursing. Quaternary jobs involve research and development e.g. IT.
What are the two types of secondary industry?
The types of secondary industries are:
- Electrical industry.
- Chemical Industry.
- Energy industry.
- Metallurgical industry.
- Construction Industry.
- Food Industry.
- Glass industry.
- Textile and clothing industry.