Common defects of investment castings
| Defect 1--sand hole | Defect 2--gas cavity | Defect 3--shrinkage cavity |
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| filled with sand in the surface or internal of investment castings | smooth and unequal-sized holes are exsited in the surface or internal.Normally are spherical pores,looks like round balls or smilar. | irregular holes,rough hole wall with dendrite shape.Often appear in the final solidification of investment castings. |
| Defect 4--sand burning | Defect 5--cold shut | Defect 6--sand cut |
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| It is often covered with a mixture of metal and sand in the surface or inside of castings,or a layer of sintering sand. |
colls shut is imcomplete syncretic cracks ir hollow pit of castings,which edge of handover is round.More appear on the positions of surface,thin wall,metal flow conflunce or chiling of investment castings. |
a rought and irregular metal tumor of casting surface,often near the sprue gate of castings.Other positions often appear sand holes. |
| Defect 7--burrs | Defect 8--insufficient pouring | Defect 9--damage |
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| Spiny metal lumps in the casting surface,which are especially irregular. | Some position is lacked as the liquid metal is nor completed filled with cavity. | completeness is damaged when moving or clearing investment castings. |
| Defect 10--casting fin | Defect 11--drop sand | Defect 12--deformation |
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Sheet metal bumps,which thickness is not uniform.More appear in the parting surface and core head position. |
massive metal lumps in the surface of castings,which shape is similar as the dropped sand lump. |
shape and sizes do not accord with drawingsshape and size does not accord with drawings,caused by shrinkage stress or wall deformation and cracking of the casting. |