MIT Casting Lecture
China circa 3000BC
Casting
2.810
Prof. Timothy Gutowski
Casting since about 4000 BC…
Ancient Greece; bronze statue casting circa 450BC
Iron works in early Europe,
e.g. cast iron cannons from
England circa 1543
Outline
• Sand Casting, Investment Casting, Die Casting
• Basics and countermeasures
• Phase Change, Shrinkage
• Heat Transfer
• Pattern Design
• Variations & Developments
• Environmental Issues
Casting
Readings;
1.
Kalpakjian, Chapters 10, 11,
12
2.
Booothroyd, “Design for Die
Casting”
3.
Flemings “Heat Flow in
Solidification”
4.
Dalquist “LCA of Casting”
Note: a good heat transfer reference can be found by
Profs John Lienhard online http://web.mit.edu/lienhard/www/ahtt.html
Casting Methods
• Sand Casting
• Investment Casting
• Die Casting
High Temperature Alloy,
Complex Geometry,
Rough Surface Finish
High Temperature Alloy,
Complex Geometry,
Moderately Smooth Surface
Finish
High Temperature Alloy,
Moderate Geometry,
Smooth Surface
Sand Casting
Sand Casting
Description: Tempered sand is packed into wood or metal pattern halves, removed form the pattern, and assembled with or without cores, and metal is poured into resultant cavities. Various core materials can be used. Molds are broken to remove castings. Specialized binders now in use can improve tolerances and surface finish.
Metals: Most castable metals.
Size Range: Limitation depends on foundry capabilities. Ounces to many tons. Tolerances:
Non-Ferrous ± 1/32″ to 6″
Add ± .003″ to 3″, ± 3/64″ from 3″ to 6″.
Across parting line add ± .020″ to ± .090″ depending on size.
(Assumes metal patterns)
Surface Finish:
Non-Ferrous: 150-350 RMS
Ferrous: 300-700RMS
Minimum Draft Requirements:
1° to 5°
Cores: 1° to 1 1/2°
Normal Minimum Section Thickness:
Non-Ferrous: 1/8″ - 1/4″
Ferrous: 1/4″ - 3/8″
Ordering Quantities: All quantities
Normal Lead Time:
Samples: 2-10 weeks
Production 2-4 weeks A.S.A.
Sand Casting Mold Features
Vents, which are placed in molds to carry off gases
produced
Casting
2.810
Prof. Timothy Gutowski
Casting since about 4000 BC…
Ancient Greece; bronze statue casting circa 450BC
Iron works in early Europe,
e.g. cast iron cannons from
England circa 1543
Outline
• Sand Casting, Investment Casting, Die Casting
• Basics and countermeasures
• Phase Change, Shrinkage
• Heat Transfer
• Pattern Design
• Variations & Developments
• Environmental Issues
Casting
Readings;
1.
Kalpakjian, Chapters 10, 11,
12
2.
Booothroyd, “Design for Die
Casting”
3.
Flemings “Heat Flow in
Solidification”
4.
Dalquist “LCA of Casting”
Note: a good heat transfer reference can be found by
Profs John Lienhard online http://web.mit.edu/lienhard/www/ahtt.html
Casting Methods
• Sand Casting
• Investment Casting
• Die Casting
High Temperature Alloy,
Complex Geometry,
Rough Surface Finish
High Temperature Alloy,
Complex Geometry,
Moderately Smooth Surface
Finish
High Temperature Alloy,
Moderate Geometry,
Smooth Surface
Sand Casting
Sand Casting
Description: Tempered sand is packed into wood or metal pattern halves, removed form the pattern, and assembled with or without cores, and metal is poured into resultant cavities. Various core materials can be used. Molds are broken to remove castings. Specialized binders now in use can improve tolerances and surface finish.
Metals: Most castable metals.
Size Range: Limitation depends on foundry capabilities. Ounces to many tons. Tolerances:
Non-Ferrous ± 1/32″ to 6″
Add ± .003″ to 3″, ± 3/64″ from 3″ to 6″.
Across parting line add ± .020″ to ± .090″ depending on size.
(Assumes metal patterns)
Surface Finish:
Non-Ferrous: 150-350 RMS
Ferrous: 300-700RMS
Minimum Draft Requirements:
1° to 5°
Cores: 1° to 1 1/2°
Normal Minimum Section Thickness:
Non-Ferrous: 1/8″ - 1/4″
Ferrous: 1/4″ - 3/8″
Ordering Quantities: All quantities
Normal Lead Time:
Samples: 2-10 weeks
Production 2-4 weeks A.S.A.
Sand Casting Mold Features
Vents, which are placed in molds to carry off gases
produced