Casting specifications for precision casting

Precision casting casting as small as a few millimeters to thousands of millimeters can be cast, the specifications are relatively broad, usually precision casting small aperture of 1 mm. The wall thickness is 0.5 mm. Precision casting can achieve high casting accuracy and relatively accurate shape. Precision casting is the first to do the demand of the blank electrode, and then the application of electrode corrosion mold to the detailed interior, constitute a cavity. The original wax mold was obtained by casting the wax. Brush the wax mold layer by layer with liquid sand resistant to high temperature., Wait until enough thickness to dry. To stop and reheating, melt the internal wax mold, and obtain the cavity divided with the blank. Then cast molten iron in the type cavity, cure and peel off the shell, we can get the precision manufacturing we need.
Common precision casting defects have bubbles, bubbles refer to the individual location of fine casting lubrication hole defects.
Bubbles are usually found only after machining. Jibang precision casting technicians have separated for many years of workshop consumption experience, and the reasons and prevention methods of bubbles in precision casting are summarized as follows:
1. Composition cause:
1. In most cases, bubbles are mainly due to the roasting of fine cast outer shell is not abundant, and the pouring of molten steel shell suddenly produces a large amount of gas can not be smoothly discharged, and then invade the bubbles in the metal liquid;
2. Due to the shell making process or shell type data, the air permeability of the shell is poor, and the gas is difficult to discharge from the type cavity, and the bubbles are formed into the metal liquid;
3. The casting bubbles formed by the air involved in the steel water during pouring.
2. Preventive measures
1. When the precision casting conditions permit, exhaust bubbles shall be set at the highest point of the complex casting.
2. When designing the pouring system, we should fully think about the exhaust demand of the type shell.
3. The shell roasting temperature and time should be reasonable, and the insulation time should be sufficient.
4. The wax material should be thoroughly cleaned when dewaxed.
5. Appropriate reduce the interval between the pouring mouth and the pouring cup, the pouring speed should be equal to ensure that the steel degree is stable of the overflow cavity, as little as possible into the steel water air, so that the gas in the cavity and the steel water can be discharged smoothly.