Lost wax castingThe average annual growth of major economic indicators in the machinery industry is above 30%, which is higher than the average growth level of the machine tool industry. In particular, the profit growth is faster, the average annual profit growth is as high as 46%, and the market sales level is maintained at a high level. In addition, the complete set of resin sand casting equipment can basically meet the needs of the domestic market, changing the situation of relying mainly on imports in the past; it has been able to produce higher-level automatic casting production lines, reaching the level of partially replacing imports, and partially solving the problem of car engines. Cylinder blocks, cylinder heads and other casting blanks are also imported; high-level automatic core making machines, automatic casting cleaning machines, automatic sand processors, large-scale automatic die-casting machines, precision casting equipment and other casting machinery can basically be produced in China . It should be said that during the "Tenth Five-Year Plan" period, the product level of the precision casting machinery industry has been greatly improved, laying a good foundation for the further development of China's casting machinery industry in the future.

The following can causeGuangdong alloy steel castingSeveral factors of dimensional accuracy defects:

1. The influence of casting structure. The casting wall is thick, the shrinkage rate is large, and the casting wall is thin, and the shrinkage rate is small; the free shrinkage rate is large, and the hindering shrinkage rate is small.

2. The influence of casting material. The higher the carbon content in the material, the smaller the linear shrinkage rate, and the lower the carbon content, the greater the linear shrinkage rate; the casting shrinkage rate of common materials is casting shrinkage rate K=(LM-LJ)/LJ×100%, LM Is the cavity size, LJ is the casting size, and K is affected by the wax mold K1, the casting structure K2, the alloy type K3, and the pouring temperature K4.

3. Molding pairGuangdong carbon steel castingThe influence of piece line shrinkage. The wax injection temperature, wax injection pressure, and pressure holding time have the most obvious influence on the investment size, followed by the wax injection pressure. The pressure holding time has little effect on the final size of the investment after the investment is formed; wax The linear shrinkage rate of the (mold) material is about 0.9-1.1%; when the investment mold is stored, it will shrink further, and its shrinkage value is about 10% of the total shrinkage, but after 12 hours of storage, the investment size is basically stable; The radial shrinkage rate of the wax mold is only 30-40% of the lengthwise shrinkage rate. The wax injection temperature has a far greater influence on the free shrinkage rate than the hindered shrinkage rate (the best wax injection temperature is 57-59°C, the higher the temperature The higher the shrinkage, the greater).

4. The influence of the shell-making materials is zircon sand, zircon powder, Shangdian sand, and Shangdian powder. Because of its small expansion coefficient, only 4.6×10-6/℃, it can be ignored.

5. The influence of the molding shell baking, due to the small expansion coefficient of the molding shell, when the temperature of the molding shell is 1150℃, it is only 0.053%, so it is also negligible.

6. The influence of the casting temperature, the higher the casting temperature, the greater the shrinkage rate, and the lower the casting temperature, the smaller the shrinkage rate, so the casting temperature should be appropriate.