Causes of Blowholes in Castings and Preventive Measures

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Causes of Blowholes in Castings and Preventive Measures

Posted By wearresistant William     June 17, 2019    


Casting products often appear in the manufacturing process, so today we will talk about the characteristics and forming reasons of casting pores.


Air holes are holes on the surface or inside of the casting, which are round, oval or irregular. Sometimes many pores form air masses, usually pear-shaped under the skin. The orifice has irregular shape and rough surface. Cavitation is a concave part on the casting surface, and the surface is relatively smooth. The appearance inspection of the opening shows that the subcutaneous hole can only be found after mechanical processing.

Reasons for formation:

1. The preheating temperature of the mold is too low, and the liquid metal cools too fast when passing through the gating system.

2. The exhaust design of the mold is poor, and the gas cannot be smoothly exhausted.

3, coating is not good, exhaust is not good, even volatilize or decompose gas.

4. There are holes and pits on the surface of the mold cavity. After the liquid metal is injected, the gas in the holes and pits expands rapidly, compressing the liquid metal to form a blocked hole.

5. The surface of the mold cavity is rusted and not cleaned.

6. Raw materials are improperly stored and not preheated before use.

7. Poor deoxidizer, insufficient dosage or improper operation, etc.

Prevention methods:

1. The mold should be completely preheated. The particle size of the coating should not be too fine and the air permeability should be good.

2. Pouring by tilting pouring method.

3. Raw materials shall be stored in a ventilated and dry place and preheated during use.

4. Select deoxidizer with good deoxidizing effect.

5, pouring temperature should not be too high.

Shenyang Gongda Heavy Equipment Manufacturing Co., Ltd., a prominent and highly recognized manufacturer and supplier of high quality metal castings, founded in 2003, specializes in the production, machining and R&D of wear resistant castings, alloy steel castings and Cu & Al alloy castings for mining, milling, earth handling, building materials, power stations, and other key industries, with an annual production capacity of about 10,000 tonnes.

If you want to find high quality casting manufacturers or suppliers, you can click here to learn more: