Porosity is one of the common defects of precision casting, precision casting porosity refers to individuallocation to appear smooth hole defects. Porosity can often found after machining. Yanzi precision castingtechnicians with many years production experience, the precision casting in the causes and prevention methods of porosity are summarized as follows:
One, cause pores appear 1 in most cases is mainly because of precision casting shell roasting is not sufficient,pouring molten steel shell the moment a large amount of gas can not be successfully discharged,and then invade thepore forming metal in liquid; 2 for shell making process or shell material, shell permeabilityis poor, difficult to discharge gas in the cavity, pore forming into the liquid metal in the molten steel during pouring; 3 in the air can not be discharged to cause the blowhole.
Two, prevention of method 1 in allowing the precision casting conditions, the exhaust holes in castings topcomplex structure. 2 in the design of gating system, should give full consideration to the shell exhaust demand.3 mold shellroasting temperature, time should be reasonable, holding time should be sufficient. 4 dewaxingwax material should be eliminated. 5 appropriate to reduce the ladle nozzle to the pouring cup distance,casting speed should be uniform,in order to ensure that the steel level stable filled cavity, air into molten steelas little as possible, so that the cavitygas and molten steel can be discharged smoothly.