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​Common defects of investment castings

Defect 1--sand hole Defect 2--gas cavity Defect 3--shrinkage cavity
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
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
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

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.