2 Casting Flashcards
(13 cards)
Describe ingot.
An ingot is usually associated with primary metals industries.
It describes a large casting of simple shapes intended for subsequent reshaping by processes such as rolling or forging.
Describe Shape Casting
Shape casting involves the production of complex shapes that is closer to the final desired shape of the part or product.
What are the advantages of Casting?
- create complex shapes
- capable of producing parts to net shape or near net shape
- can create large parts
- can be used for mass production
- applicable for any metal that can be heated to liquid state
What are the disadvantages of Casting?
- poor dimensional accuracy
- poor surface finish for some casting methods
- limitations on mechanical properties and porosity
- safety hazard to humans
- environmental problems
Describe a mold.
- mold contains a cavity. The geometry of the cavity determines the shape of the cast part
- shape and size of mold must be slightly bigger to allow for shrinkage
- mold should be designed for a specific metal depending of their heat expansion coefficient (metal’s shrinkage)
- mold materials: sand, plaster, ceramic and metal
- 2 main types: closed and open mold
Describe the two kinds of cast molding.
1) Expendable-mold casting
- mold destroyed after casting
- made of sand, plaster or similar materials
- make complex shapes
2) Permanent-mold casting
- mold can be used multiple times
- made of metal or refractory material
- consists 2+ parts
- high production rates
How do you calculate the solidification time?
Chorinov’s rule:
T = C (V/A)^n
T = solidification time (mins) C = mold constant V = volume (cm^3) A = area (cm^2) n = exponent (usually 2)
Give examples of expendable-mold casting.
- sand casting
- shell molding
- investment casting
Give examples of permanent-mold casting.
- Die casting
(- hot chamber die casting)
(- cold chamber die casting)
What is casting?
What are the two kinds of casting?
Casting = a process in which molten metal flows by gravity or other force into a mould where it solidifies in the shape of the mould cavity.
- Casting of ingot
- Casting of shapes (shape casting)
What is shell moulding?
Casting process where mold is a thin shell made of sand held together by thermosetting resin binder.
What is investment casting?
Pattern made of wax is coated with a refractory material to make the mold, after which the wax is melted away prior to poring the molten metal.
What is die casting? What are the two kinds?
Permanent-mold process where molten metal is injected into mold cavity under high pressure.
- hot-chamber machines
- cold-chamber machines
