Precision Casting Of The Casting Specifications Are Relatively Broad
Precision casting of the casting specifications are relatively broad
Precision cast castings as small as a few millimeters to thousands of millimeters can be cast, the specifications are relatively wide, the usual precision casting of the smallest aperture of 1 mm below. Wall thickness of the thinnest of 0.5 mm. Precision casting to obtain a higher casting accuracy and relatively accurate shape. Precision casting is usually the first to do the needs of the rough electrode, and then apply the electrode corrosion mold to the internal, constitute the cavity. Cast casting method to cast wax, to obtain the original wax mold. In the wax mold on a layer of brush on the high temperature of the liquid sand. Wait until the thickness is enough to dry. To stop the reheating, melt out the internal wax mold, and rough to obtain the cavity. And then in the cavity cast hot metal, after curing the shell will be stripped, we can get the precision manufacturing we need.
Common precision casting defects have bubbles, bubbles are fine castings individual position showing lubrication hole eye defects. Bubbles are usually found after machining. Precision casting technology staff separation years of experience in the workshop, the precision casting of the reasons for the emergence of bubbles and preventive measures are summarized as follows:
First, the composition of the reasons: 1. Most of the conditions of the bubble is mainly due to fine cast shell shell is not abundant, pouring molten steel when the shell suddenly produce a lot of gas can not be successfully discharged, and then into the metal liquid bubbles;
2. Due to the shelling process or shell type of information, shell permeability is too bad, the cavity of the gas is difficult to discharge into the metal liquid to form bubbles;
3. The air in the molten steel that is poured into the molten steel during casting is not discharged to form the casting bubbles.
Second, the precautionary approach 1. In the case of precision casting conditions permit, in the construction of complex casting at the highest set of exhaust bubbles.
2. In the design of the pouring system, to be fully aware of the shell exhaust demand.
3. Shell firing temperature, time should be reasonable, the insulation time should be sufficient.
4. Wax should be completely removed when the wax material.
5. Properly reduce the pouring mouth to the gate cup spacing, pouring the speed to be uniform, to ensure that the degree of steel steady overflow cavity, as little as possible into the molten steel in the air, so that the cavity and the molten steel can be successfully discharged.