Investment casting, also known as wax-loss casting, is a wax mold made of wax to be cast into parts, and then the wax mold is coated with mud, which is the mud mold. After drying the clay mould, melt the internal wax mould in hot water. The clay mold of the melted wax mold is taken out and roasted into a pottery mold. Once roasted. In general, when making mud moulds, the gate is left, and then the molten metal is poured into the gate. After cooling, the required metal parts are made.

Past generations of investment casting:

Key words: time-consuming and expensive

Investment casting is also called wax loss casting. The wax loss method in China originated in the Spring and Autumn Period and has a long history.

Loss wax casting is a wax pattern made of wax to be cast into parts, and then the wax pattern is coated with mud, which is the mud pattern. After drying the clay mould, melt the internal wax mould in hot water. The clay mold of the melted wax mold is taken out and roasted into a pottery mold.

The steps of investment casting for 3D printer are introduced below.

Eight steps of 3D printing investment casting:

1. CAD Modeling, 3D Printing Lost Foam

The digital files of molten casting model are designed by using CAD software, and then exported in. STL format and printed out by using 3D printer (SLA technology is recommended for 3D printer). The printing process usually takes only a few hours.

2. Check whether there are any holes in the molten casting model.

Surface polishing and other post-processing work are carried out on the 3D printed model to remove the surface lamination. Then carefully check whether the model has any loopholes or cracks.

3. Surface coating

When the model is sent to the foundry, the surface of the model is first covered with ceramics slurry. The slurry layer should be closely connected with the investment casting model, and the quality of the first slurry layer will directly affect the surface quality of the final casting.

4. Shelling

After the ceramics slurry is coated, the outer layer of ceramics slurry is viscous sand. After drying, repeat the steps of coating slurry and sticking sand until the shell reaches the desired thickness.

5. Roasting and cleaning

When the shell is dry, it is put into the furnace and burned until all the melt casting models inside are burned clean. At this time, the shell will become ceramics as a whole because of heating. After being removed from the furnace, the inner surface of the furnace should be thoroughly cleaned up by washing, and then dried and preheated.

6. Casting

By means of dumping, pressure, vacuum suction and centrifugal force, the molten liquid metal is filled with the empty shell and then cooled.

7. Demodelling

After the liquid metal is completely cooled and formed, the ceramic shell outside the metal is cleaned by mechanical vibration, chemical cleaning or water flushing.

8. Post-processing

The dimensional accuracy, density and other mechanical properties of metal models can also be measured by surface treatment or further machining.

The SLA 3D printer of SHDM can be used to make plastic moulds by using fusible and high temperature resistant materials. It is very suitable for casting parts by wax loss method.

After the printing of the plastic mould is completed, the residual powder particles will be removed, and then wax infiltration will be used to ensure that the plastic mould is closed and clean to improve the quality of investment casting parts.

The subsequent treatment process is the same as the traditional manufacturing method: first, the ceramic coating is coated on the surface of the plastic mould, and then it is put into the kiln.

When the temperature exceeds 700 C, the plastic mould burns completely without any residue, which is also the origin of the name of wax loss method.

3D printing can realize highly complex design, and make investment casting mould quickly, simply and economically. It is widely used in automobile, jewelry, machinery manufacturing and other industries.