All the advantages of the clad sand casting process

With the rising prices of raw and auxiliary materials and labour, the profitability of castings has been on a downward trend. It is necessary to find a low-cost, convenient and practical casting process to replace the traditional process. Adopting coated sand casting process, the scale accuracy of coated sand casting process is CT7~CT8. the surface roughness Ra value is 6.3~12.5m, and the moulding quality can reach the level of water-glass fusion mould casting process, which is an ideal process method. Here we will look at the advantages of cladding sand casting process.

1. Low cost

(1) a one-time investment of less than the use of coated sand casting process modelling (core) artificial hot core box core shooter and mould one-time investment.

(2) low production costs. As long as the use of coated sand and release agent, only one core shooting machine consumes electricity.

(2)Fewer shell-making links, high efficiency.

Fewer shell-making links, short production cycle, the use of air pressure will be covered sand blown into the metal cavity, the use of electric heating rods to heat the metal type, so that the covered sand hardening, and then the formation of the shell, which can be used for casting in a closed box. The result is that the quality of castings is greatly improved and scrap is significantly reduced. Because of the good rigidity of the film sand castings, the casting of the dimensional accuracy and denseness are significantly improved. So what are the main problems that need to be solved in the process design and actual production of cladding sand casting, iron wall thickness and sand film thickness, as well as their co-ordination in order to meet the solidification and cooling of the various conditions of the casting with different wall thickness and material.

Coated sand also has the strength characteristics suitable for physical objects. Not only can be made of high-strength shell core cladding sand, but also can be made of strength hot core box cladding sand and low-strength non-ferrous alloy cladding sand. It is also better fluidity, the production of moulds and cores of clearer contours, the structure is also very dense, can produce complex sand core, such as cylinder water jacket core and cylinder head. Coated sand castings are more resistant to moisture, longer storage time, more conducive to transport, storage and use.

The preparation process of coated sand mainly has three kinds of cold, mild and hot, which is commonly used is the hot method of coated, the method has the characteristics of low numerical dosage and high production efficiency.

1, cold. The original sand and thermosetting powder phenolic resin into the sand mixer and mix well, and then add the appropriate amount of solvent to continue mixing until the powder resin melted attached to the surface of the sand particles, the solvent volatilisation, the sand particles can be crushed off the sieve. This method of sand mixing time is long, solvent consumption, volatile solvent gas is prone to explosion, it is rarely used.

2, warm. Mix the thermosetting liquid phenolic resin with the original sand at 60-80 ℃, mixing 2-3 minutes, that is, into the sand, after cooling, crushing, sieving.

3、Heat. Firstly, the raw sand is heated to a certain temperature, and then mixed and stirred with resin, aqueous solution and calcium stearate respectively, after cooling, crushing and sieving. Due to the difference of equipment and proportion, the mixing process is different.