What causes the shrinkage of silica sol investment casting?

Cause: The most basic reason for shrinkage cavity is that the silica sol precision casting factory found that a certain position (usually the hot spot of final solidification) of the casting could not be fed with liquid metal in time when the aluminum alloy was in the process of liquid retraction and solidification, which caused shrinkage cavity.

For carbide aluminum alloy or aluminum alloy with narrow solidification temperature range, its castings are easy to produce centralized shrinkage cavity. When the alloy composition is on time, the shrinkage cavity is usually caused by uneven casting thickness, too many hot spots, too large, unreasonable design of the gating and riser control system, which is not conducive to sequential solidification, so that the hot spots of the silica sol precision casting accessories cannot be filled with liquid metal. Or the pouring temperature is too high.

Countermeasures to avoid:

1: Improve the casting structure, ensure the thickness is uniform, reduce the hot spot, or make the thickness change beneficial to lead to sequential solidification.

2: The software of the gating and riser system is effectively set, resulting in sequential solidification. The software of gating and riser system for complex parts with several hot spots should be considered more comprehensively.

3: The module can be effectively assembled, so that there is a certain distance under the silicon sol precision casting workpiece to avoid the difficulty of partial heat removal.

4: The pouring temperature of shell and liquid metal shall be suitable, and the pouring temperature shall not be too high

5: During pouring, it shall be ensured that the sprue and riser are full of liquid metal, and heating agent and heat insulation agent will be added to the sprue cup and riser

6: Improve smelting process, reduce waste gas and metal oxides in molten metal, and improve liquidity and feeding level