Casting - Basic Casting Process Pouring or forcing fluid...

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Basic Casting Process *Pouring or forcing fluid material into a mold cavity and solidifying *Nearly any material that can be liquid and solidified can be cast *Metal, plastic, chocolate, wood composites, wax, ceramics, concrete Basic Casting Process *Casting is a very old process. *The primary restriction until the 1800s was the development of high temp furnaces. *Casting is not considered to be a very rapid production method. *Casting is usually considered to be a basic processing method since so many parts use some component of the casting process. *Most cast components usually undergo some additional processing. Casting Advantages *The primary advantage of casting is the ability to make parts w/ intricate internal cavities like Plumbing fixtures, Engine components, chocolate bunnies, *Use of less material than if cut from solid - economic *Ability to design into components geometric features that would be expensive or difficult to produce in other processes Basic Requirements for Metal Casting *Method of melting the metal *Mold cavity *Molds must be designed to allow for air/gases to escape and not overly restrict the movement of the casting upon shrinkage during cooling *Provisions must be made for removal of pattern and core material (if necessary), and the final cast part Patterns *Patterns are a copy of the final part with a shrinkage allowance. *Cast iron 1/8” per foot *Steel 1/4” per foot *Aluminum 5/32” per foot *Can be made of metal, plastics or wood. *Can be a single piece or composed of multiple sections depending upon part. *Patterns must have draft to allow removal from the mold. Typically draft is 2 to 3 degrees. *Additional features could include a machining allowance or core prints. Basic Mold *Section view of mold showing sprue, runner and gating system, risers (feeders), cores and pattern draft. Sand Casting *Most common metal casting mold material. *Easily molded *Reusable *Inexpensive *Withstands very high temperatures *Almost no limit on size, shape, or weight of part *Green sand – sand, clay and moisture *Oil bond (Petro-Bond) Green Sand Casting : (cores occupy space where you don’t want metal) *Traditional GM V8 engine block with cores. * Disadvantages of Sand Casting *Machining allowance is almost always required. *Distortion of part. *Surface finish is typically poor. *A new mold is required with every pour. *Thin sections cannot be made since they would wash away with the pouring of the molten metal. Investment Casting (lost wax) *Pattern is made of wax. *A ceramic shell is built around the wax pattern. *Wax pattern is melted out of the shell.
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Casting - Basic Casting Process Pouring or forcing fluid...

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