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Casting Defects - Coggle Diagram
Casting Defects
Gas
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Improper design
Air inclusion
due to high pouring temperature, poor gating design ( such as straight sprue
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Pin hole porosity
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critical, cause fluid leakage under high operating
pressure.
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Blow holes
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spherical, flattened, elongated cavity inside/on surface inside called blow holes, on surface called open blow
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Molding material
Metal penetration
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due to sand too coarse, high pouring temperature
Fusion
due to low refractoriness character of clay, pouring temperature too high
appropriate type, amount of bentonite
fusion of sand grains with the molten metal, giving brittle, glassy appearance.
Cut and washes
caused by erosion of sand molding (low strength of sand mold, high velocity metal flow
choice correct molding sand, increase the gates size, using multiple ingates.
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Run out
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due to faulty mold making, faulty mold flask
Rat tail and buckles
excessive heat of molten metal, sand expand
poor expansion properties and hot strength, heat in pouring metal too high, facing sand not enough carbonaceous (cushioning effect)
Metallurgical
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Hot spots
caused by chilling of the casting ‐ chilled surface (certain element on the surface ‐ hard – difficult for machining)
Pouring Metal
Cold shuts
‐ two metal streams, not fuse together properly, causing discontinuity or weak spot
lower fluidity of the molten metal, section thickness too small
Slag Inclusion
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slag must be remove. Otherwise, if enter in mold cavity, weakening, spoil the surface
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