Metal Casting

How The Process Works

The process of metal casting involves pouring metal which has been melted down to liquid into a mold. The mold is in the shape of the part you want. Once the metal cools down it solidifies and remains in the shape of the mold. It is then broken out of the mold. The two main types of metal casting are expendable and non-expendable casting. 

Expendable casting consists of using molds that cannot be reused. The mold must be reformed after each use. Examples of this are sand casting and plaster mold casting. Molds are made for sand casting by mixing sand with another substance like clay, and either packing it around the desired shape to create a mold, or carving out the shape you want. This is a relativity cheap for of casting, but the sand must be reformed after each use. Plaster mold casting is a similar process, but can only be used with low melting point materials like aluminium or copper.

Sand Casting Video - https://www.youtube.com/watch?v=K8SYhISGxN4

Non-expendable mold casting involves the use of reusable molds. Main types of casting include permanent, die, and centrifugal  casting. Permanent molds are usually made from metal, most commonly gray cast iron. While these molds are reusable, they also wear out  after a certain amount of use. These types of molds are also limited to metals with low melting points. 

Permanent molds are usually made from metal, most commonly gray cast iron. While these molds are reusable, they also wear out after a certain amount of use. These types of molds are also limited to metals with low melting points. 

Die casting mostly utilizes nonferrous metals like zinc, copper, and aluminum-based alloys, but ferrous metals are also used at times. The die casting process forces motel metal under high pressure into mold cavities. This process is good for creating small to medium-sized parts with good details, fine surface quality and dimensional consistency.

The centrifugal casting process is when molten metal is poured into the mold and solidifies the as the mold is rotating. Centrifugal casting is good for creating small art pieces like jewelry.

Continuous casting (strand casting) is the prices where molten metal is solidified into a semi-finished slab or bloom. That slab or bloom is then rolled in the finishing mills. Steel, aluminum, and copper are used to continuously cast objects. Continuous casting is good for creating the materials that manufactured items are created from like metal sheets.

What It Is Useful For

Metal casting is useful for making complex shapes that would be difficult to make with other methods. It allows for a degree of freedom to form manufactured goods from metal for any aspect of society. There are many different processes and metals that can be cast and many different products that can be created. Cast metal products offer extreme strength and durability, which make them especially useful for heavy machine applications in the manufacturing industry (i.e. farming, automobile, water processing industry). Metal casting is also used to make various types of art and jewelry due to the malleable nature of metal.

What Are Its Limitations

Some types of casting are limited to certain metals, some have to reform molds after each use so are not suitable for large scale production, and some molds are difficult to make and maintain. Parts that can be made are limited to the shape of mold you are able to create. Metal casting is highly dangerous and people involved in the industrial process of metal casting must be highly trained.

How Much Does It Cost To Use

The price of casting a part varies creating depending not eh type of metal and the casting process used. For example casting an aluminum part using sand casting could could approximately $32, while the same part would be roughly $16 if made by die casting. The tools necessary to perform each different process also varies. 

Where On Campus Metal Casting Is Supported & How To Gain Access To Each Facility

- Center for Iron and Steelmaking Research (Doherty A303) | MSE Major

- Small Metals in Sculpture & Physical Computing (Doherty B303/308) | CFA student (safety training & participant in a metals class)