What are the advantages of casting over other metal working methods?

Answer 1

A casting may be defined as a " metal object obtained by allowing molten metal to solidify in a mold ", the shape of the object being determined by the shape of the mold cavity. Certain advantages are inherent in the metal casting process. These often form the basis for choosing casting over other shaping processes such as machining, forging, welding, stamping, rolling, extruding, etc. Some of the reasons for the success of the casting process are: ; The most intricate of shapes, both external and internal, may be cast. As a result, many other operations, such as machining, forging, and welding, can be minimized or eliminated. ; Because of their physical properties, some metals can only be cast to shape since they cannot be hot-worked into bars, rods, plates, or other shapes from ingot form as a preliminary to other processing. ; Construction may be simplified. Objects may be cast in a single piece which would otherwise require assembly of several pieces if made by other methods. ; Metal casting is a process highly adaptable to the requirements of mass production. Large numbers of a given casting may be produced very rapidly. For example, in the automotive industry hundreds of thousands of cast engine blocks and transmission cases are produced each year. ; Extremely large, heavy metal objects may be cast when they would be difficult or economically impossible to produce otherwise. Large pump housing, valves, and hydroelectric plant parts weighing up to 200 tons illustrate this advantage of the casting process. ; Some engineering properties are obtained more favorably in cast metals. Examples are: : :: More uniform properties from a directional standpoint; i.e., cast metals exhibit the same properties regardless of which direction is selected for the test piece relative to the original casting. This is not generally true for wrought metals. :: Strength and lightness in certain light metal alloys, which can be produced only as castings. :: Good bearing qualities are obtained in casting metals. ; A decided economic advantage may exist as a result of any one or a combination of points mentioned above. The price and sale factor is a dominant one which continually weighs the advantages and limitations of process used in a competitive of enterprise. There are many more advantages to the metal-casting process; of course it is also true that conditions may exist where the casting process must give way to other methods of manufacture, when other processes may be more efficient. For example, machining procedures smooth surfaces and dimensional accuracy not obtainable in any other way; forging aids in developing the ultimate of fiber strength and toughness in steel; welding provides a convenient method of joining or fabricating wrought or cast products into more complex structures; and stamping produces lightweight sheet metal parts. Thus the engineer may select from a number of metal processing methods that one or combination, which is most suited to the needs of his work.

Answer 2

Metal Casting

• Casting is a complex concept, so understanding the basics is necessary before you can look at the disadvantages. Of the many types of casting processes, all depend on the materials in question. Some of these techniques include sand casting, investment casting, die casting and metal mold casting. Metal casting is used in a variety of industries, such as automotive, tools, mechanical parts, pipes and valves. The disadvantages differ greatly depending on the casting techniques.

Defectiveness

• Three major defects are associated with metal casting. Holes are a major area of a concern, which consist of either sand holes or air holes. These appear as small holes or pits on the surface or interior of the metal. Surface holes are not normally a problem, but interior ones make the final product unusable. The second problem is known as shrinkage, which also consists of holes scattered irregularly throughout the product. Unlike sand and air holes, shrinkage cannot be ignored and automatically renders the metal useless. The third defect is cracking. Specifically related to steel, cracking appears once the casting process is complete. Cracking also cannot be ignored.

Limitations

• A serious disadvantage of metal casting is its lack of universality. Although some of the casting methods could be used interchangeably, using the wrong one can be costly or provide an inadequate finished product. Some casting processes, such as mold casting, cannot be used on metals that contain iron. Consequently, this process costs more than other forms of casting. Sand casting is the cheapest process but also the least accurate, thus making it unsuitable for precise work. In short, metal casting requires a trade-off between quality and cost.

Risks

• Another disadvantage of metal casting is that it is extremely dangerous. People involved in this industrial process must be highly trained, and even then, accidents happen. Molten metal can reach temperatures of over 1,000 degrees Fahrenheit, so one small mistake or equipment malfunction can lead to serious injury or death.

Answer 3

Casting allows for complex shapes to be easily produced, reduces the amount of machining required, and can utilize a wide range of metals and alloys. It is also a cost-effective method for producing large quantities of parts.

Answer 4

Poor surface finish