Investment mold precision casting furnace bar

The following are several factors that lead to defects in the dimensional accuracy of precision castings:

1, the impact of casting construction. Investment mold precision casting chuck casting thickness, shrinkage rate, casting wall thin, shrinkage rate is small; random shrinkage rate is large, hindering shrinkage rate is small.

2. The impact of investment casting valve body casting material. The greater the carbon content of the material, the smaller the line shrinkage rate, the lower the carbon content, the higher the line shrinkage rate; general material forging shrinkage is casting shrinkage rate K = (LM-LJ)/LJ × 1, LM is the cavity specifications, LJ casting specifications, K is affected by wax mold K1. casting construction K2. alloy type K3. pouring temperature K influence these factors.

3. casting line shrinkage rate affects mold making. Melting mold specifications affect the injection wax temperature, injection wax pressure, holding time * injection wax pressure is obvious to ensure that the molten mold after molding the molten mold holding time * wax (mold) material line shrinkage rate of about 0, the result is very little impact on the specifications; 9-1.1%; molten mold storage will be further shrinkage, shrinkage value of about 10% of the total shrinkage, but after 12 hours of storage molten mold specifications are basically stable; wax mold axial shrinkage rate is only 30-40% of the long direction shrinkage rate, injection wax temperature on the random shrinkage rate is much greater than the impact of shrinkage resistance * injection wax temperature 57-59 Jia ℃, the more shrinkage, the greater the temperature.

4. The effect on the shell material, choose zirconium ore, zirconium quartz powder, Shangdian sand, due to its small expansion coefficient, Shangdian powder is only 4.6×10-6/℃, so it can be ignored.

5. Due to the small expansion coefficient of the shell, the temperature of the shell is 11500, so the effect of shell baking at ℃ is only 0. So it can also be ignored 053%.

6. The influence of pouring temperature, the greater the pouring temperature, the higher the shrinkage rate, the lower the pouring temperature, the smaller the shrinkage rate, so the pouring temperature should try.