The manufacture of sprue cup is a complex process involving material selection, process design and quality control. The following is a detailed introduction of the manufacturing method, material selection and process design of the sprue cup:

I. Material selection of sprue cup

The material selection of the sprue cup needs to comprehensively consider the factors such as refractoriness, thermal shock resistance, slag corrosion resistance, mechanical strength and cost;

Refractory materials: Commonly used materials include high alumina silicate, refractory clay, alumina and zircon powder. These materials have high fire resistance (usually between 1670℃ and 1770℃) and can remain stable in high temperature environment.

Thermal shock resistant materials: aluminum titanate composite and high-density calcium silicate have good thermal shock resistance and are suitable for casting environments with frequent temperature changes.

Slag corrosion resistant materials: Alumina, zircon powder and other materials have good slag corrosion resistance, which can effectively prevent impurities in molten metal from eroding the sprue cup.

Cost and machinability: On the premise of meeting the performance requirements, the cost and machinability of materials are also important factors. For example, high-density calcium silicate materials are low in cost and easy to process into required shapes.

II. Manufacturing process of sprue cup

Design and modeling:

Use professional software to design the model of the sprue cup, ensure that its shape and size meet the actual needs, and consider the fluidity and cooling performance during casting.

According to the design model, the wax mold is made, and the mandrel is embedded in the mold.

Wax model making:

The wax is heated to a proper temperature and injected into a mold for molding.

After the wax pattern is made, demoulding is carried out to ensure that the surface of the wax pattern is smooth and free from defects.

Shell-making process:

Fix the wax pattern in the preparation fixture and plug the opening.

The outer surface of wax mold is coated with prefabricated inner layer slurry, prefabricated sand and prefabricated outer layer slurry in turn, and each layer needs to be dried after coating.

Precast inner layer slurry is usually made by mixing nano silica gel solution and zircon powder with particle size of 325 mesh, and the ratio is 3.8 ~ 4.4: 1.

The ratio of the prefabricated outer layer slurry is 2.9 ~ 3.5: 1, and the prefabricated sand can choose capacitor alumina with different particle sizes.

Dewaxing and sintering:

The coated shell is dewaxed, usually by high temperature steam or chemical dewaxing.

After dewaxing, the shell is sintered, and the sintering temperature is usually above 1600℃ to improve the strength and fire resistance of the shell.

Post-processing:

After sintering, the shell is polished to remove burrs and impurities on the surface.

Check the size and quality of the shell to ensure that it meets the design requirements.

III. Process design of sprue cup

Structural design of sprue cup;

The sprue cup usually consists of three parts: the first part is connected with the molten metal storage container, the second part is provided with a buffer runner, and the third part is connected with the casting shell.

The design of the buffer runner can absorb the impact of molten metal, reduce turbulence and ensure the molten metal to flow smoothly into the casting shell.

Size and shape design:

The size and shape of the sprue cup should be optimized according to the casting structure, alloy characteristics and casting process.

For castings with complex structure, the design of sprue cup should ensure that molten metal can fill the mold smoothly and quickly.

Design of filtration and slag prevention;

A filtering structure can be installed at the third part of the pouring cup for filtering impurities in the molten metal.

The outer end faces of the first part and the third part of the sprue cup are respectively provided with annular protrusions for preventing sintered impurities from flowing into the sprue cup.

Operation convenience and safety:

The position and height of the pouring cup should be convenient for workers to operate, and at the same time, safety issues such as preventing molten metal from splashing and overflowing should be considered.

IV. Quality control of sprue cup

Surface quality: the surface of the sprue cup should be smooth and free of particle bumps to prevent impurities from being generated when molten metal impacts.

Dimensional accuracy: the size of the sprue cup should be strictly controlled within the design range to ensure the docking accuracy with the casting shell.

Strength and fire resistance: improve the strength and fire resistance of the sprue cup by high temperature sintering process to ensure its stability in high temperature environment.

Through the above material selection, manufacturing process and process design, high-quality sprue cups can be produced, thus improving the quality and production efficiency of castings.