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Casting 2012

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Casting has been used since 4000 BC, with uses in ancient Greece for bronze statues and 15th century England for cast iron cannons. There are two main casting processes - expendable mold where the mold is destroyed and permanent mold where the reusable metal mold makes multiple castings. Common casting methods include sand casting using bonded sand molds, investment casting using a refractory material mold, and die casting using metal dies.

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Casting 2012
Casting since about 4000 BC 2 Ancient Greece; bronze statue casting circa 450 BC Iron works in early Europe, e.g. cast iron cannons from England circa 1543
Two Categories of Casting Processes 1. Expendable mold processes - mold is sacrificed to remove part 2. Permanent mold processes - mold is made of metal and can be used to make many castings
Casting Methods Sand Casting High Temperature Alloy, Complex Geometry, Rough Surface Finish Investment Casting High Temperature Alloy, Complex Geometry, Moderately Smooth Surface Finish Die Casting High Temperature Alloy, Moderate Geometry, Smooth Surface
Sand Casting Uses sand to hold the desired shape to be cast Bonded with chemicals or clay with water or oil Many different types of sand casting
Sand Casting
Sand Casting Steps cope: top half drag: bottom half core: for internal cavities pattern: positive funnel sprue runners gate cavity {risers, vents}
Investment Casting A refractory material (investment) is poured around or built up on a pattern The investment is hardened by drying or heating The pattern is removed by melting or burning Metal is poured into the resulting cavity
Investment Casting
(a) Wax pattern (injection molding) (b) Multiple patterns assembled to wax sprue (c) Shell built immerse into ceramic slurry immerse into fine sand (few layers) (d) dry ceramic melt out the wax fire ceramic (burn wax) (e) Pour molten metal (gravity) cool, solidify [Hollow casting: pouring excess metal before solidification (f) Break ceramic shell (vibration or water blasting) (g) Cut off parts (high-speed friction saw) finishing (polish) Investment Casting Steps
Die Casting Huge numbers of small, light castings can be produced with great accuracy. Little surface finishing is required. Permanent mold (dies can be used over and over)
Die Casting
Die Casting Steps
Reference: Metal Casting book http://en.wikipedia.org

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Casting 2012

  • 2. Casting since about 4000 BC 2 Ancient Greece; bronze statue casting circa 450 BC Iron works in early Europe, e.g. cast iron cannons from England circa 1543
  • 3. Two Categories of Casting Processes 1. Expendable mold processes - mold is sacrificed to remove part 2. Permanent mold processes - mold is made of metal and can be used to make many castings
  • 4. Casting Methods Sand Casting High Temperature Alloy, Complex Geometry, Rough Surface Finish Investment Casting High Temperature Alloy, Complex Geometry, Moderately Smooth Surface Finish Die Casting High Temperature Alloy, Moderate Geometry, Smooth Surface
  • 5. Sand Casting Uses sand to hold the desired shape to be cast Bonded with chemicals or clay with water or oil Many different types of sand casting
  • 7. Sand Casting Steps cope: top half drag: bottom half core: for internal cavities pattern: positive funnel sprue runners gate cavity {risers, vents}
  • 8. Investment Casting A refractory material (investment) is poured around or built up on a pattern The investment is hardened by drying or heating The pattern is removed by melting or burning Metal is poured into the resulting cavity
  • 10. (a) Wax pattern (injection molding) (b) Multiple patterns assembled to wax sprue (c) Shell built immerse into ceramic slurry immerse into fine sand (few layers) (d) dry ceramic melt out the wax fire ceramic (burn wax) (e) Pour molten metal (gravity) cool, solidify [Hollow casting: pouring excess metal before solidification (f) Break ceramic shell (vibration or water blasting) (g) Cut off parts (high-speed friction saw) finishing (polish) Investment Casting Steps
  • 11. Die Casting Huge numbers of small, light castings can be produced with great accuracy. Little surface finishing is required. Permanent mold (dies can be used over and over)
  • 14. Reference: Metal Casting book http://en.wikipedia.org