Sand Casting ■Pattern(模样) Full-size model of part enlarged to account for shrinkage and post-casting machining allowance Made of wood,plastics,metals Pattern type: Riser pattern -Pattern -Plate Cope pattem Gating system Drag (a) (b) (c) (d) pattern Shanghai Jiao Tong University 11
Shanghai Jiao Tong University 11 Sand Casting n Pattern（模样） n Full-size model of part enlarged to account for shrinkage and post-casting machining allowance n Made of wood, plastics, metals n Pattern type:
Sand Casting Core for internal surfaces Supported by mold walls and/or chaplets a Chaplets will be an integral of part after solidification Subject to Buoyancy force (of molten metal during pouring！ Core Chaplet Riser Downsprue Parting line Mold Cavity Shanghai Jiao Tong University 12
Shanghai Jiao Tong University 12 Sand Casting n Core for internal surfaces n Supported by mold walls and/or chaplets n Chaplets will be an integral of part after solidification n Subject to Buoyancy force（浮力）of molten metal during pouring!
Buoyancy in Sand Casting Core subjects to buoyancy of the molten metal. Might dislocate！ Shanghai Jiao Tong University
Shanghai Jiao Tong University 13 Buoyancy in Sand Casting n Core subjects to buoyancy of the molten metal. n Might dislocate!
Permanent Mold Casting Sand casting has the disadvantages that for each casting,a new hold has to Water-cooled be made(since the mold is destroyed) metal molds and there is possibility of dimensional Casting surfaces may be coated with a ceramic variation from mold to mold. slurry to prevent mold damage In permanent mold casting,the mold is made of either metal or graphite(石墨) Permanent mold casting is used to cast iron and steel,and alloys of aluminum, magnesium or copper. Permanent mold castings provide better dimensional accuracy and smoother surfaces than sand casting. Shanghai Jiao Tong University 14
Shanghai Jiao Tong University 14 Permanent Mold Casting Sand casting has the disadvantages that for each casting, a new hold has to be made (since the mold is destroyed) and there is possibility of dimensional variation from mold to mold. In permanent mold casting, the mold is made of either metal or graphite（石墨）. Permanent mold casting is used to cast iron and steel, and alloys of aluminum, magnesium or copper. Permanent mold castings provide better dimensional accuracy and smoother surfaces than sand casting
Die Casting Die casting is different from permanent casting in that the molten metal is forced into the mold under pressure and held under pressure during solidification. The combination of metal molds,dies and pressure allow achievement of thin sections and fine detail with long mold life. ■High production rate Higher tolerance/good surface finish Shanghai Jiao Tong University 15
Shanghai Jiao Tong University 15 Die Casting n Die casting is different from permanent casting in that the molten metal is forced into the mold under pressure and held under pressure during solidification. n The combination of metal molds, dies and pressure allow achievement of thin sections and fine detail with long mold life. n High production rate n Higher tolerance/good surface finish