How to prevent sand sticking to alloy steel precision castings

Sometimes, the surface of castings produced by alloy steel precision casting factories is covered with a layer of impurities, usually a mixture of metal or sand, which makes the surface rough and difficult to remove. If impurities are present on the surface of the casting, it indicates that the casting has sand sticking.

So how to prevent alloy steel precision castings from sand sticking? First, appropriately lowering the pouring temperature and increasing the pouring speed can reduce the chemical reactions caused by light sand thermodynamics and physical operations; secondly, the molding sand should be evenly distributed, which can reduce the friction between sand particles. Clear the gap, repair the molding sand and core, and avoid local shrinkage. The coating should be a coating that does not crack at high temperatures, which can greatly ensure the quality of alloy steel precision castings.

To prevent slag inclusion in mechanical equipment, the following countermeasures can be adopted:

1. Avoid high metal liquid hydrostatic head; when considering casting metal casting standards, the height of the riser should not be too high; prevent the watering bag from being directly poured on the sprue, and use a basin-shaped watering cup to buffer the metal flow if necessary. Produces a constant high static pressure head.

2. Use casting sand with finer particle size distribution as much as possible.

3. The sand mold should be tight and fine. The equipment design should not be overweight. The air compression provided by the alloy steel precision casting molding machine should maintain the required pressure to prevent the molding sand from being too wet or having a long storage period. Since it cannot be tightened, the core box must be ventilated The holes (clogging) cannot be clogged; the design of the resin sand and the choice of core making must not only rely on the excellent fluidity of the molding sand, but also ensure the tightness and increase vibration if necessary.

4. Avoid casting "explosion" or "suffocation". Do not add too much pulverized coal and water to the molding sand. Make pores and ventilation holes for the core as much as possible to improve the casting breathability.

5. To alleviate the dynamic pressure generated in the mold. The casting should be provided with more pores and more air holes; the exhaust pipe groove (ventilation groove or ventilation groove) can be set on the high-density casting analysis surface.

6. Alloy steel precision casting castings or cores should be properly painted. That is, fill the gaps between the sand grains on the surface of the mold and the core. If the paint is too thick, it is likely to crack, allowing molten metal to penetrate into the sand. At this time, you can use thin coating on the first or second floor, and then use regular or thick coating.