Porosity Is One Of The Most Common Precision Casting Defects

  Porosity is one of the most common precision casting defects, stomata refers to the precise location of precision castings appear smooth hole defects. The stomata are usually found after machining. Precision casting technology staff with years of experience in the workshop, the precision casting of the reasons for the emergence of stomata and prevention methods are summarized as follows:

  First, the reasons for the formation of: 1. Most of the cases of stomata is mainly because the precision casting shell roasting is not sufficient, pouring molten steel when the shell suddenly produce a lot of gas can not be successfully discharged, and then into the metal liquid to form pores; Process or shell material reasons, shell breathable bad, the cavity of the gas is difficult to discharge into the metal liquid to form pores; 3. pouring into the molten steel in the air can not be discharged to cause the casting porosity.

  Second, the prevention method 1. In the case of precision casting conditions permit, in the complex structure of the highest set of exhaust holes. 2. In the design of pouring system, to fully take into account the shell exhaust demand. 3. Shell firing temperature, time should be reasonable, the insulation time should be sufficient. 4. Dewaxing wax material should be completely ruled out. 5. Properly reduce the pouring mouth to the gate cup distance, pouring the speed to be uniform, to ensure that the steel filled with smooth cavity, as little as possible into the molten steel in the air, so that the cavity and the molten steel can be successfully discharged.